This document discusses balancing of critical rotating machinery. It begins with fundamentals of vibration measurement and analysis tools. It then differentiates unbalance from other vibration causes through case studies. The document covers theories of static, dynamic, and couple unbalance. It provides examples of unbalance caused by blade loss and rotor rubbing. Additional cases discuss issues like misalignment from swash errors. The document outlines the balancing process and considerations like influence vectors and weight splitting.
This document discusses dynamics of rotating machinery with an emphasis on balancing. It covers balancing fundamentals, critical speeds and vibratory modes, damping, bearings and support structures. Case studies on balancing of a 115 MW generator rotor are presented, showing vibration measurements before and after balancing. Details of the generator rotor, balancing planes and trial weights used are provided. Common vibratory modes like rocking, conical and bending modes are explained. The document also discusses turbo machinery damping mechanisms and hydrodynamic bearings.
This document provides information about balancing high speed rotors. It defines balancing as correcting the mass distribution of a rotor so that vibration forces and displacements are within specified limits when the rotor is rotating. It discusses the different types of unbalance that can occur, including static, couple, quasi-static and dynamic unbalance. The causes of unbalance are described as design errors, material faults, and machining/assembly errors. The balancing procedure and standards followed at BHEL Hyderabad are outlined, including low and high speed balancing of flexible rotors using modal and influence coefficient methods.
This document discusses machine balancing and provides definitions and explanations of key terms. It describes the different types of unbalance including static, couple, and dynamic unbalance. It explains the causes of unbalance such as uneven mass distribution, wear, corrosion, and assembly issues. The document also outlines the methods used for static and dynamic balancing of rigid and flexible rotors. It provides standards and formulas for determining acceptable balance tolerances.
This document provides an overview of orbit plot analysis, which is used to assess the condition of machine bearings and diagnose vibration issues. It explains that orbit plots visualize the motion of a machine shaft using signals from two probes, and may include a phase reference from a keyphasor. Common orbit shapes are described that indicate issues like misalignment, unbalance, oil whirl, rotor rub, and oil whip. The steps to create a spectrum plot from the vibration signal are outlined, and how spectra differ for circular and elliptical orbits. In summary, orbit plot analysis is a vibration analysis technique that visually depicts shaft motion to identify potential machine faults.
Balancing of rigid rotor and balancing of flexible rotor-A ReviewRahul Kshirsagar
The presentation details about types of rigid rotors and flexible rotors used in mechanical systems and experimental method of balancing these rotors to avoid mechanical vibrations.
1. Unbalance vibration occurs when the center of mass of a rotating object is not aligned with its center of rotation, causing a wobbling motion.
2. There are three main types of unbalance: static, couple, and dynamic. Static unbalance can be corrected by adding or removing weight in one plane, while couple and dynamic require weights added in two or more planes.
3. Unbalance vibration produces a single frequency vibration at the object's rotational speed and can cause damage, noise, and reduced machine life if not addressed.
This document discusses machine vibration diagnosis through FFT analysis. It provides examples of using FFT analysis to diagnose issues like rotor unbalance, shaft misalignment, field asymmetry, and a loose belt drive wheel. FFT analysis allows identifying fault frequencies in the machine's vibration spectrum to pinpoint the root cause of issues. The document also discusses ISO standards for vibration severity, components vulnerable to damage, and practical diagnosis techniques.
This document discusses mechanical looseness in machines. It defines mechanical looseness as improper contact between component parts, characterized by high amplitude vibrations at harmonics of the running frequency. There are two types of mechanical looseness: non-rotating caused by loose stationary parts, and rotating caused by clearance between rotating and stationary elements. Specific causes mentioned include loose foundation bolts, bearing liner loose in cap, and loose impeller on a shaft. The effects are increased vibration levels and potential for detached parts to cause damage. Vibration spectrum analysis can help identify the type of looseness based on the harmonic frequencies present.
This document discusses dynamics of rotating machinery with an emphasis on balancing. It covers balancing fundamentals, critical speeds and vibratory modes, damping, bearings and support structures. Case studies on balancing of a 115 MW generator rotor are presented, showing vibration measurements before and after balancing. Details of the generator rotor, balancing planes and trial weights used are provided. Common vibratory modes like rocking, conical and bending modes are explained. The document also discusses turbo machinery damping mechanisms and hydrodynamic bearings.
This document provides information about balancing high speed rotors. It defines balancing as correcting the mass distribution of a rotor so that vibration forces and displacements are within specified limits when the rotor is rotating. It discusses the different types of unbalance that can occur, including static, couple, quasi-static and dynamic unbalance. The causes of unbalance are described as design errors, material faults, and machining/assembly errors. The balancing procedure and standards followed at BHEL Hyderabad are outlined, including low and high speed balancing of flexible rotors using modal and influence coefficient methods.
This document discusses machine balancing and provides definitions and explanations of key terms. It describes the different types of unbalance including static, couple, and dynamic unbalance. It explains the causes of unbalance such as uneven mass distribution, wear, corrosion, and assembly issues. The document also outlines the methods used for static and dynamic balancing of rigid and flexible rotors. It provides standards and formulas for determining acceptable balance tolerances.
This document provides an overview of orbit plot analysis, which is used to assess the condition of machine bearings and diagnose vibration issues. It explains that orbit plots visualize the motion of a machine shaft using signals from two probes, and may include a phase reference from a keyphasor. Common orbit shapes are described that indicate issues like misalignment, unbalance, oil whirl, rotor rub, and oil whip. The steps to create a spectrum plot from the vibration signal are outlined, and how spectra differ for circular and elliptical orbits. In summary, orbit plot analysis is a vibration analysis technique that visually depicts shaft motion to identify potential machine faults.
Balancing of rigid rotor and balancing of flexible rotor-A ReviewRahul Kshirsagar
The presentation details about types of rigid rotors and flexible rotors used in mechanical systems and experimental method of balancing these rotors to avoid mechanical vibrations.
1. Unbalance vibration occurs when the center of mass of a rotating object is not aligned with its center of rotation, causing a wobbling motion.
2. There are three main types of unbalance: static, couple, and dynamic. Static unbalance can be corrected by adding or removing weight in one plane, while couple and dynamic require weights added in two or more planes.
3. Unbalance vibration produces a single frequency vibration at the object's rotational speed and can cause damage, noise, and reduced machine life if not addressed.
This document discusses machine vibration diagnosis through FFT analysis. It provides examples of using FFT analysis to diagnose issues like rotor unbalance, shaft misalignment, field asymmetry, and a loose belt drive wheel. FFT analysis allows identifying fault frequencies in the machine's vibration spectrum to pinpoint the root cause of issues. The document also discusses ISO standards for vibration severity, components vulnerable to damage, and practical diagnosis techniques.
This document discusses mechanical looseness in machines. It defines mechanical looseness as improper contact between component parts, characterized by high amplitude vibrations at harmonics of the running frequency. There are two types of mechanical looseness: non-rotating caused by loose stationary parts, and rotating caused by clearance between rotating and stationary elements. Specific causes mentioned include loose foundation bolts, bearing liner loose in cap, and loose impeller on a shaft. The effects are increased vibration levels and potential for detached parts to cause damage. Vibration spectrum analysis can help identify the type of looseness based on the harmonic frequencies present.
The document discusses critical speed in rotating shafts. When a rotor is mounted on a shaft, its center of gravity is often displaced from the axis of rotation. This causes an eccentric centrifugal force when the shaft rotates. The force bends the shaft in the direction of the rotor's eccentricity, causing violent vibrations perpendicular to the axis at a particular speed known as the critical speed. Calculating critical speed involves equating the maximum kinetic and potential energies using methods like Rayleigh's method or Dunkerley's method.
This document discusses orbit plot analysis for analyzing vibrations. It was written by four authors and discusses various topics related to orbit plot analysis including:
- How orbit analysis measures vibration in an X-Y plot using proximity probes
- How polar and orbit plots can determine unbalance and faults in machines
- The different types of orbits including floating, absolute, filtered, and overall
- Common causes of vibration that can be identified using orbit plots like unbalance, misalignment, rotor rub, oil whirl/whip
- How full spectrum plots provide additional information on orbit direction and can differentiate between issues like rubs and fluid instability
- Other analysis methods like cascade plots to show vibrations at different speeds and waterfall plots
Vibration analysis uses FFT to transform time domain vibration data into the frequency domain spectrum. Key parameters like acceleration, velocity, crest factor, kurtosis, and noise levels are used to monitor rotational forces, impacts/shocks, and friction within machines. Fault frequencies corresponding to machine components like bearings and gears are identified and compared to spectral peaks to diagnose issues. Phase analysis can also identify unbalance or misalignment. Proper data collection and machine parameters like RPM are critical for effective vibration analysis.
Misalignment in rotating equipment can occur in two types - angular or offset. Angular misalignment produces axial vibration at 1X RPM while offset produces radial vibration at 2X or 3X RPM. Misalignment is characterized by high axial vibration levels at 1, 2, and 3X shaft RPM as well as high radial vibration at these frequencies. The waveform will be repeatable with one or two clear peaks per revolution and a 180 degree phase shift across couplings. If the 2X amplitude is over 50% of 1X, coupling damage can occur, and over 150% requires stopping for correction.
The document discusses various aspects of condition monitoring through vibration analysis. It defines condition monitoring and different types of maintenance. It explains why condition monitoring is important and some key physical parameters that are measured. It then focuses on condition monitoring through vibration analysis, discussing concepts like amplitude, frequency, causes of vibration, and analyzing case studies of different machines. Key points covered include vibration measurement and analysis, identifying issues like unbalance, misalignment, looseness and bearing defects.
This document discusses vibration analysis at thermal power plants. It outlines the objectives of vibration monitoring, which include improving equipment protection, safety, maintenance procedures, and extending equipment life. Vibration monitoring measures characteristics like amplitude and frequency to identify abnormal conditions. Common defects that can be detected through vibration analysis are unbalance, misalignment, loose components, rotor rub, bearing issues, and blade/vane pass frequencies. Online monitoring systems are used at thermal plants to continuously monitor critical equipment like turbines, generators, and pumps to detect faults early and avoid failures. Standards provide guidelines for effective vibration analysis and maintenance.
According to ISO 1940/1:
- ISO 1940/1 defines balance quality grades (G values) that represent the maximum permissible vibration caused by unbalance at operating speeds. Lower G values indicate better balance quality requirements.
- Specific unbalance is the product of the rotor's center of gravity displacement and angular velocity. It is measured in units like mm/s.
- Maximum permissible residual unbalance (Uper) is calculated based on factors like specific unbalance, rotor weight, balancing radius, and rotor geometry. Formulas are provided to calculate Uper for general, symmetrical, overhung, and narrow rotors.
The document discusses vibration theory, including definitions of acceleration, velocity, displacement and simple harmonic motion. It describes quantifying vibration amplitude using peak-to-peak, peak, average and RMS levels. It also covers the differences between time and frequency domain analysis and concepts of phase angle measurement in condition monitoring. Condition monitoring strategies aim to focus on critical machinery by defining detectable faults and relevant measurement parameters.
The document describes a three rotor system with rotors A, B, and C connected by a shaft. Rotor A has an inertia of 0.15 kg-m2, rotor B has an inertia of 0.30 kg-m2, and rotor C has an inertia of 0.09 kg-m2. The system can vibrate with nodes forming between rotors C and A or between rotors C and B depending on the direction of rotation. The task is to find the natural frequency of the torsional vibrations using the given inertias, shaft dimensions, and modulus of rigidity.
This document provides an overview of machine alignment, including definitions of different types of misalignment, causes of misalignment, effects of misalignment, and methods for detecting and correcting misalignment. It discusses alignment techniques such as using straight edges, dial indicators, and lasers. Precise alignment requires preparing machines by checking for issues like soft foot, pipe strain, coupling gaps, and runout before implementing alignment methods.
This document discusses shaft alignment, including definitions, symptoms of misalignment, pre-alignment checks, types of alignment, alignment methods, and effects of misalignment. It defines shaft alignment as positioning rotational centers of two or more shafts to be co-linear under normal operation. Symptoms of misalignment include premature failures, vibration, high temperatures, leakage, and structural issues. Methods discussed include indicator-based rim and face alignment and reverse shaft alignment using graphical techniques. Laser alignment is highlighted as an efficient modern method. Misalignment can cause excessive vibration, noise, lost production, poor quality, and reduced profits.
Rotordynamics is the branch of engineering that studies the vibrations of rotating shafts. There are three main modes of vibration during rotation - torsional, longitudinal, and lateral vibrations, with lateral vibrations being the greatest concern. Factors like unbalance, misalignment, and bearing failures can cause rotor failure. Critical speeds occur when the rotational speed matches the natural frequency of the system, potentially leading to resonance. Stability and unbalance response are also major areas of concern in rotordynamics analysis.
The document discusses static and dynamic balancing of rotating masses. Static balancing ensures the center of gravity remains stationary during rotation by balancing out centrifugal forces in any radial direction. Dynamic balancing prevents vibration during rotation by statically balancing and also balancing out moments and couples involved in accelerating moving parts. The types of balancing are defined as static, where forces due to gravity are balanced, and dynamic, where inertia forces are balanced in addition to static balance. Benefits include reduced vibration, noise, stresses, and increased quality, bearing life, and efficiency. Balancing is necessary to prevent problems from vibration like noise, abrasion, and shortened machine life.
Unit 5- balancing of reciprocating masses, Dynamics of machines of VTU Syllabus prepared by Hareesha N Gowda, Asst. Prof, Dayananda Sagar College of Engg, Blore. Please write to hareeshang@gmail.com for suggestions and criticisms.
Vibration analysis is used to identify issues in rotating machinery by analyzing vibration signatures. Common issues that can be identified include unbalance, misalignment, looseness, bearing faults, and resonance. Vibration signals are analyzed in the time, frequency, and phase domains to identify characteristic frequencies, amplitudes, and phase relationships that correspond to different problem sources. Overall vibration levels and narrowband spectrum peaks are monitored over time for trends that may indicate developing issues.
This document provides an overview of vibration analysis and predictive maintenance. It discusses maintenance philosophies like breakdown, preventive, predictive, and proactive maintenance. Predictive maintenance uses condition monitoring techniques like vibration analysis to determine the condition of machines and identify faults. Vibration analysis measures characteristics like displacement, velocity, acceleration, frequency, and phase to determine how much vibration is present, what defects are causing it, and which machine parts are affected. Understanding vibration signatures can reveal problems like unbalance, misalignment, looseness, and bearing defects.
Maintenance of pocket type journal bearing D500 steam TurbineFaisal Nadeem
Maintenance of Pocket type Journal bearing ,
measuring clearances
eccentricity crush clearance ,Hydrodynamic lubrication,
rotor position in bearing
General overview of Hydrodynamic lubrication and bearing
This document discusses vibration analysis and diagnostics. It outlines an 8 step analysis procedure including defining the problem, determining machine history and details, visual inspection, data collection, frequency confirmation, vibration direction/phase analysis, and probing studies. Specific vibration issues covered include unbalance, resonance, misalignment, bent shafts, and component failures. Diagnosing the root cause involves analyzing vibration frequency spectra and amplitudes across machine components.
This document provides information about balancing high speed rotors. It defines balancing as correcting the mass distribution of a rotor so that vibration forces are within limits. There are four main types of unbalance: static, couple, quasi-static, and dynamic. Unbalance is caused by design errors, material faults, and machining errors. Flexible rotors require balancing at multiple speeds approaching critical speeds to account for deflection. Standards specify limits for vibration amplitudes and bearing forces for acceptance of balancing quality.
The document discusses critical speed in rotating shafts. When a rotor is mounted on a shaft, its center of gravity is often displaced from the axis of rotation. This causes an eccentric centrifugal force when the shaft rotates. The force bends the shaft in the direction of the rotor's eccentricity, causing violent vibrations perpendicular to the axis at a particular speed known as the critical speed. Calculating critical speed involves equating the maximum kinetic and potential energies using methods like Rayleigh's method or Dunkerley's method.
This document discusses orbit plot analysis for analyzing vibrations. It was written by four authors and discusses various topics related to orbit plot analysis including:
- How orbit analysis measures vibration in an X-Y plot using proximity probes
- How polar and orbit plots can determine unbalance and faults in machines
- The different types of orbits including floating, absolute, filtered, and overall
- Common causes of vibration that can be identified using orbit plots like unbalance, misalignment, rotor rub, oil whirl/whip
- How full spectrum plots provide additional information on orbit direction and can differentiate between issues like rubs and fluid instability
- Other analysis methods like cascade plots to show vibrations at different speeds and waterfall plots
Vibration analysis uses FFT to transform time domain vibration data into the frequency domain spectrum. Key parameters like acceleration, velocity, crest factor, kurtosis, and noise levels are used to monitor rotational forces, impacts/shocks, and friction within machines. Fault frequencies corresponding to machine components like bearings and gears are identified and compared to spectral peaks to diagnose issues. Phase analysis can also identify unbalance or misalignment. Proper data collection and machine parameters like RPM are critical for effective vibration analysis.
Misalignment in rotating equipment can occur in two types - angular or offset. Angular misalignment produces axial vibration at 1X RPM while offset produces radial vibration at 2X or 3X RPM. Misalignment is characterized by high axial vibration levels at 1, 2, and 3X shaft RPM as well as high radial vibration at these frequencies. The waveform will be repeatable with one or two clear peaks per revolution and a 180 degree phase shift across couplings. If the 2X amplitude is over 50% of 1X, coupling damage can occur, and over 150% requires stopping for correction.
The document discusses various aspects of condition monitoring through vibration analysis. It defines condition monitoring and different types of maintenance. It explains why condition monitoring is important and some key physical parameters that are measured. It then focuses on condition monitoring through vibration analysis, discussing concepts like amplitude, frequency, causes of vibration, and analyzing case studies of different machines. Key points covered include vibration measurement and analysis, identifying issues like unbalance, misalignment, looseness and bearing defects.
This document discusses vibration analysis at thermal power plants. It outlines the objectives of vibration monitoring, which include improving equipment protection, safety, maintenance procedures, and extending equipment life. Vibration monitoring measures characteristics like amplitude and frequency to identify abnormal conditions. Common defects that can be detected through vibration analysis are unbalance, misalignment, loose components, rotor rub, bearing issues, and blade/vane pass frequencies. Online monitoring systems are used at thermal plants to continuously monitor critical equipment like turbines, generators, and pumps to detect faults early and avoid failures. Standards provide guidelines for effective vibration analysis and maintenance.
According to ISO 1940/1:
- ISO 1940/1 defines balance quality grades (G values) that represent the maximum permissible vibration caused by unbalance at operating speeds. Lower G values indicate better balance quality requirements.
- Specific unbalance is the product of the rotor's center of gravity displacement and angular velocity. It is measured in units like mm/s.
- Maximum permissible residual unbalance (Uper) is calculated based on factors like specific unbalance, rotor weight, balancing radius, and rotor geometry. Formulas are provided to calculate Uper for general, symmetrical, overhung, and narrow rotors.
The document discusses vibration theory, including definitions of acceleration, velocity, displacement and simple harmonic motion. It describes quantifying vibration amplitude using peak-to-peak, peak, average and RMS levels. It also covers the differences between time and frequency domain analysis and concepts of phase angle measurement in condition monitoring. Condition monitoring strategies aim to focus on critical machinery by defining detectable faults and relevant measurement parameters.
The document describes a three rotor system with rotors A, B, and C connected by a shaft. Rotor A has an inertia of 0.15 kg-m2, rotor B has an inertia of 0.30 kg-m2, and rotor C has an inertia of 0.09 kg-m2. The system can vibrate with nodes forming between rotors C and A or between rotors C and B depending on the direction of rotation. The task is to find the natural frequency of the torsional vibrations using the given inertias, shaft dimensions, and modulus of rigidity.
This document provides an overview of machine alignment, including definitions of different types of misalignment, causes of misalignment, effects of misalignment, and methods for detecting and correcting misalignment. It discusses alignment techniques such as using straight edges, dial indicators, and lasers. Precise alignment requires preparing machines by checking for issues like soft foot, pipe strain, coupling gaps, and runout before implementing alignment methods.
This document discusses shaft alignment, including definitions, symptoms of misalignment, pre-alignment checks, types of alignment, alignment methods, and effects of misalignment. It defines shaft alignment as positioning rotational centers of two or more shafts to be co-linear under normal operation. Symptoms of misalignment include premature failures, vibration, high temperatures, leakage, and structural issues. Methods discussed include indicator-based rim and face alignment and reverse shaft alignment using graphical techniques. Laser alignment is highlighted as an efficient modern method. Misalignment can cause excessive vibration, noise, lost production, poor quality, and reduced profits.
Rotordynamics is the branch of engineering that studies the vibrations of rotating shafts. There are three main modes of vibration during rotation - torsional, longitudinal, and lateral vibrations, with lateral vibrations being the greatest concern. Factors like unbalance, misalignment, and bearing failures can cause rotor failure. Critical speeds occur when the rotational speed matches the natural frequency of the system, potentially leading to resonance. Stability and unbalance response are also major areas of concern in rotordynamics analysis.
The document discusses static and dynamic balancing of rotating masses. Static balancing ensures the center of gravity remains stationary during rotation by balancing out centrifugal forces in any radial direction. Dynamic balancing prevents vibration during rotation by statically balancing and also balancing out moments and couples involved in accelerating moving parts. The types of balancing are defined as static, where forces due to gravity are balanced, and dynamic, where inertia forces are balanced in addition to static balance. Benefits include reduced vibration, noise, stresses, and increased quality, bearing life, and efficiency. Balancing is necessary to prevent problems from vibration like noise, abrasion, and shortened machine life.
Unit 5- balancing of reciprocating masses, Dynamics of machines of VTU Syllabus prepared by Hareesha N Gowda, Asst. Prof, Dayananda Sagar College of Engg, Blore. Please write to hareeshang@gmail.com for suggestions and criticisms.
Vibration analysis is used to identify issues in rotating machinery by analyzing vibration signatures. Common issues that can be identified include unbalance, misalignment, looseness, bearing faults, and resonance. Vibration signals are analyzed in the time, frequency, and phase domains to identify characteristic frequencies, amplitudes, and phase relationships that correspond to different problem sources. Overall vibration levels and narrowband spectrum peaks are monitored over time for trends that may indicate developing issues.
This document provides an overview of vibration analysis and predictive maintenance. It discusses maintenance philosophies like breakdown, preventive, predictive, and proactive maintenance. Predictive maintenance uses condition monitoring techniques like vibration analysis to determine the condition of machines and identify faults. Vibration analysis measures characteristics like displacement, velocity, acceleration, frequency, and phase to determine how much vibration is present, what defects are causing it, and which machine parts are affected. Understanding vibration signatures can reveal problems like unbalance, misalignment, looseness, and bearing defects.
Maintenance of pocket type journal bearing D500 steam TurbineFaisal Nadeem
Maintenance of Pocket type Journal bearing ,
measuring clearances
eccentricity crush clearance ,Hydrodynamic lubrication,
rotor position in bearing
General overview of Hydrodynamic lubrication and bearing
This document discusses vibration analysis and diagnostics. It outlines an 8 step analysis procedure including defining the problem, determining machine history and details, visual inspection, data collection, frequency confirmation, vibration direction/phase analysis, and probing studies. Specific vibration issues covered include unbalance, resonance, misalignment, bent shafts, and component failures. Diagnosing the root cause involves analyzing vibration frequency spectra and amplitudes across machine components.
This document provides information about balancing high speed rotors. It defines balancing as correcting the mass distribution of a rotor so that vibration forces are within limits. There are four main types of unbalance: static, couple, quasi-static, and dynamic. Unbalance is caused by design errors, material faults, and machining errors. Flexible rotors require balancing at multiple speeds approaching critical speeds to account for deflection. Standards specify limits for vibration amplitudes and bearing forces for acceptance of balancing quality.
Condition monitoring & vibration analysisJai Kishan
Condition monitoring and vibration analysis are used to monitor the health and integrity of machines in a chemical plant. Non-destructive testing techniques like vibration analysis are used to detect issues like unbalance, misalignment, looseness and resonance before they cause breakdowns. The document outlines the various non-destructive testing and condition monitoring activities performed at NFL Bathinda, including scheduled vibration monitoring and analysis of rotating equipment, alignment checks, ultrasonic testing, and more. Specific fault detection methods and vibration signatures that could indicate issues like unbalance, misalignment, looseness, and resonance are also described.
This document describes a generator synchronizing simulator. It explains that synchronizing involves matching the voltage, frequency, and phase angle of an incoming generator to a running electrical system before connecting the two. The simulator displays controls for matching the generator's voltage and speed to the system and indicates when the two are in phase using a synchroscope. The user brings the generator up to speed, matches its voltage and frequency to the system, and closes the circuit breaker when the synchroscope indicates a matched phase to successfully synchronize the generator.
Reducing The Vibration Level Of The Blast Fanharlandmachacon
The document summarizes a study on reducing vibration from the blast fan of an air-cooled Volkswagen Beetle engine. Vibration readings were taken and found to be severe, exceeding IEEE standards. The root cause was identified as defective bearings in the alternator through a risk analysis. The defective bearings were causing mechanical looseness. The housings were re-machined and sleeves added to properly fit new bearings. Vibration readings after the correction showed reduction in vibration levels.
Agnes muszynska rotor and bearing stability problemsjumadilsyam
1) The document proposes a mathematical model of a symmetric rotor supported by one rigid bearing and one fluid-lubricated bearing. The model accounts for the rotational character of fluid forces and yields solutions for synchronous vibrations, self-excited vibrations like oil whirl and oil whip, and stability thresholds.
2) Various dynamic phenomena are observed in real rotors like oil whirl and oil whip vibrations. The model shows good agreement with these observed phenomena and how parameters affect the rotor-bearing system behavior.
3) A simple linear model is proposed to analyze the rotor-bearing system dynamics and stability thresholds, though the phenomena involve nonlinear factors.
Condition monitoring of induction motor with a case studyIAEME Publication
This document summarizes a study on condition monitoring of an induction motor. The study utilized multiple monitoring techniques including temperature monitoring, vibration analysis, motor current signature analysis, and shaft voltage measurement. Temperature, vibration, and shaft voltage readings were found to be within normal limits, indicating the motor was in good health. Motor current signature analysis detected no issues, further confirming the healthy state of the motor. The study demonstrated how a combination of condition monitoring techniques can evaluate the overall condition and help plan preventive maintenance for motors.
Condition monitoring of induction motor with a case studyIAEME Publication
This document summarizes a study on condition monitoring of an induction motor. It discusses various monitoring methods like temperature monitoring, vibration analysis, motor current signature analysis, and shaft voltage measurement. Temperature monitoring identified hotspots indicating potential insulation or cooling issues. Vibration analysis found peaks corresponding to unbalance, misalignment, and bearing or looseness issues. Motor current signature analysis identified rotor bar and joint issues by analyzing current waveforms. Together these methods provided a comprehensive assessment of the motor's health to guide maintenance.
This document provides an introduction and classification of power system stability, including rotor angle stability, voltage stability, and frequency stability. It defines each type of stability and describes some of the basic phenomena associated with each. Rotor angle stability deals with the ability of synchronous machines to remain in synchronism after a disturbance and includes small-disturbance and transient stability. Voltage stability is defined as the ability to maintain steady state voltages and is affected by the balance between load demand and supply. Frequency stability concerns the ability to maintain steady state frequency following a severe upset.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
QuickSilver Controls develops servo control technology for microstep motors. Their system uses a standard 2-phase stepper motor but controls the current in the motor windings using a closed-loop servo controller with position feedback from an encoder. This allows the motor to be driven like a servo motor, with variable speed and torque control for applications requiring precision, speed, and efficiency compared to traditional stepper systems. The document provides background on stepper motors and servo motors, and explains how QuickSilver's technology combines aspects of both to achieve servo performance from lower-cost stepper motors.
A stepper motor is a brushless DC motor that rotates in discrete step increments when electrical pulses are applied in a sequence. There are three main types - variable reluctance, permanent magnet, and hybrid. Stepper motors provide controlled movement and are well-suited for applications requiring rotation angle, speed, position, and synchronization control. They generate torque depending on factors like step rate and current. Stepper motors find applications in computer-controlled precision positioning equipment, industrial machines, and commercial devices like printers.
This document discusses variable switch reluctance motors (VSRM). It describes the basic components and operation of a VSRM, including how torque is produced through energizing winding pairs in a precise sequence. The document also compares VSRMs to other motor types and discusses their advantages like low material cost and ability to be precisely programmed to match different loads. Control of VSRMs requires switching winding excitation on and off using techniques like advanced DSP control schemes. Both advantages and shortcomings of VSRMs are examined.
Beebe - Balancing by timed oscillation (AUS)Ray Beebe
This document discusses methods for balancing rotating machinery using a mobile phone stopwatch to time oscillations. The Timed Oscillation Method involves attaching a swing mass to the rotor and using a phone stopwatch to time oscillations. Times are plotted against position and the maximum/minimum times are used to calculate an imbalance correction mass. This method was successfully used to balance pump impellers and fans. The document also discusses trial and error balancing without instrumentation by drilling holes in positions that cause rotor oscillations to vary.
The Dewesoft Balancing solution is a powerful tool to eliminate unbalance on-site and reduce downtime. It ensures fast and simple setup and configuration.
A stepper motor converts electrical pulses into discrete mechanical movements of its shaft. The shaft rotates in discrete step increments that correspond directly to the sequence and frequency of input pulses. There are three main types of stepper motors: variable-reluctance, permanent magnet, and hybrid. Stepper motors provide controlled movement and are well-suited for applications that require control of rotation angle, speed, position, and synchronization. They have advantages like full torque at standstill and excellent response to starting, stopping, and reversing.
- Stepper motors are brushless DC motors that rotate in discrete steps in response to control signals. They are excellent for positioning applications as their rotation can be accurately controlled.
- There are three main types of stepper motors: permanent magnet, variable reluctance, and hybrid. Permanent magnet motors are the most common.
- Key components include the rotor, stator, and windings. Pulses sent to the windings energize the stator poles and rotate the motor.
- Stepper motors have advantages like low cost control, simplicity, and ability to operate without feedback but disadvantages like higher current draw and need for a driver circuit.
- Common applications include printers, CNC machines, robotics, and
This document discusses force and strain measurement techniques. It begins by defining force and describing Newton's second law of motion. Common force measurement methods include balancing against gravitational force, measuring deflection of an elastic member, translating to a fluid pressure, and measuring acceleration. Devices for force measurement include load cells, proving rings, and dynamometers. The document also discusses strain, strain gauges, and methods of measuring strain including resistance strain gauges, rosette gauges, mechanical strain gauges, and electrical strain gauges.
Similar to Field Balancing of Critical Rotating Machines (20)
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Software Engineering and Project Management - Introduction, Modeling Concepts...Prakhyath Rai
Introduction, Modeling Concepts and Class Modeling: What is Object orientation? What is OO development? OO Themes; Evidence for usefulness of OO development; OO modeling history. Modeling
as Design technique: Modeling, abstraction, The Three models. Class Modeling: Object and Class Concept, Link and associations concepts, Generalization and Inheritance, A sample class model, Navigation of class models, and UML diagrams
Building the Analysis Models: Requirement Analysis, Analysis Model Approaches, Data modeling Concepts, Object Oriented Analysis, Scenario-Based Modeling, Flow-Oriented Modeling, class Based Modeling, Creating a Behavioral Model.
Design and optimization of ion propulsion dronebjmsejournal
Electric propulsion technology is widely used in many kinds of vehicles in recent years, and aircrafts are no exception. Technically, UAVs are electrically propelled but tend to produce a significant amount of noise and vibrations. Ion propulsion technology for drones is a potential solution to this problem. Ion propulsion technology is proven to be feasible in the earth’s atmosphere. The study presented in this article shows the design of EHD thrusters and power supply for ion propulsion drones along with performance optimization of high-voltage power supply for endurance in earth’s atmosphere.
artificial intelligence and data science contents.pptxGauravCar
What is artificial intelligence? Artificial intelligence is the ability of a computer or computer-controlled robot to perform tasks that are commonly associated with the intellectual processes characteristic of humans, such as the ability to reason.
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Artificial intelligence (AI) | Definitio
Applications of artificial Intelligence in Mechanical Engineering.pdfAtif Razi
Historically, mechanical engineering has relied heavily on human expertise and empirical methods to solve complex problems. With the introduction of computer-aided design (CAD) and finite element analysis (FEA), the field took its first steps towards digitization. These tools allowed engineers to simulate and analyze mechanical systems with greater accuracy and efficiency. However, the sheer volume of data generated by modern engineering systems and the increasing complexity of these systems have necessitated more advanced analytical tools, paving the way for AI.
AI offers the capability to process vast amounts of data, identify patterns, and make predictions with a level of speed and accuracy unattainable by traditional methods. This has profound implications for mechanical engineering, enabling more efficient design processes, predictive maintenance strategies, and optimized manufacturing operations. AI-driven tools can learn from historical data, adapt to new information, and continuously improve their performance, making them invaluable in tackling the multifaceted challenges of modern mechanical engineering.
Null Bangalore | Pentesters Approach to AWS IAMDivyanshu
#Abstract:
- Learn more about the real-world methods for auditing AWS IAM (Identity and Access Management) as a pentester. So let us proceed with a brief discussion of IAM as well as some typical misconfigurations and their potential exploits in order to reinforce the understanding of IAM security best practices.
- Gain actionable insights into AWS IAM policies and roles, using hands on approach.
#Prerequisites:
- Basic understanding of AWS services and architecture
- Familiarity with cloud security concepts
- Experience using the AWS Management Console or AWS CLI.
- For hands on lab create account on [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
# Scenario Covered:
- Basics of IAM in AWS
- Implementing IAM Policies with Least Privilege to Manage S3 Bucket
- Objective: Create an S3 bucket with least privilege IAM policy and validate access.
- Steps:
- Create S3 bucket.
- Attach least privilege policy to IAM user.
- Validate access.
- Exploiting IAM PassRole Misconfiguration
-Allows a user to pass a specific IAM role to an AWS service (ec2), typically used for service access delegation. Then exploit PassRole Misconfiguration granting unauthorized access to sensitive resources.
- Objective: Demonstrate how a PassRole misconfiguration can grant unauthorized access.
- Steps:
- Allow user to pass IAM role to EC2.
- Exploit misconfiguration for unauthorized access.
- Access sensitive resources.
- Exploiting IAM AssumeRole Misconfiguration with Overly Permissive Role
- An overly permissive IAM role configuration can lead to privilege escalation by creating a role with administrative privileges and allow a user to assume this role.
- Objective: Show how overly permissive IAM roles can lead to privilege escalation.
- Steps:
- Create role with administrative privileges.
- Allow user to assume the role.
- Perform administrative actions.
- Differentiation between PassRole vs AssumeRole
Try at [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
2. 2
Introduction
I have started the presentation with
fundamentals of vibration and tools (plots)
used in machinery diagnostics.
Differentiate unbalance from other causes of
high vibrations with case studies.
Theory behind balancing with my experiences
in balancing of rotating machinery with case
studies.
3. 3
FUNDAMENTALS OF
VIBRATION
Mechanical vibration is the dynamic motion of
machine components.
Vibration measurement is the measurement
of this mechanical vibration relative to a
known reference, viz. machine pedestal or
ground.
The four transducer systems to measure
dynamic motion machine components are:
Proximity Transducers, Velocity Transducers
Accelerometer & Velomitor Transducers
4. 4
FUNDAMENTALS OF
VIBRATION
What we measure
Vibration & Position
Rotor Speed
Bearing Temperature
Process Condition and its effect on
machines
5. 5
FUNDAMENTALS OF
VIBRATION
Rotor Vibration Frequency ranges – 1/4 X to
3X shaft rotative speed (Machine rotative
speed varies – 1200 to 3600 RPM)
These Machines Generate Rotor related
Vibration Signal ranging from 10 - 200Hz
(600-12000RPM).
Gear-Box and Rolling Element Bearings
generate higher frequency components that
requires high frequency measuring
transducers (Accelerometers).
6. 6
FUNDAMENTALS OF
VIBRATION-INVESTIGATION
Know the machine that is investigated –
Impulse/Reaction Turbine, Steam admission
(partial/full arc), bolted /welded Gas Turbine design,
Bearing type, Coupling type, etc.
Every machinery malfunction has an exciting force or
forcing component – Find the excitation force (root-
cause analysis – RCA).
Know the history of the machine to be analyzed –
previous failures.
Request for machine build-up information – alignment
figures, bearing clearances etc.
7. 7
FUNDAMENTALS OF
VIBRATION-INVESTIGATION
Every machine has its own signature, use both
vibration and process data to determine it.
Believe in what the vibration data tells you.
4 Ws – essential tool for root-cause analysis
Validate your findings/diagnostics.
Visual inspection of the machine – essential tool to
look for abnormalities. Look-out for a changes that
might influence performance – oil leaks, structural
change, heat etc.
Continuously analyze the performance of the machine.
8. 8
DATA PLOTS
Timebase Plot
Orbit
Average Shaft Centerline
Polar
Bode
APHT
Half and Full Spectrum
Trend
9. 9
DATA PLOTS
Machinery Diagnostics plots can be divided
into two categories:
1. Steady-state data analysis – when
the machine is on load and there is no
change in speed. Vibration data is
collected with-respect-to time.
2. Transient data analysis – Vibration
data captured on the machine during Run-
Up, Run-Down and Over-Speed test.
Vibration data is collected with-respect-to
speed and Time.
10. 10
DATA PLOTS
Collection/display of vibration data is also
categorized into Synchronous and
Asynchronous format. Most vibration
diagnostic equipment collects/display data
plots in both formats.
1. Synchronous plots are collected/
displayed with reference to the machine
speed (keyphasor).
2. Asynchronous plots are collected/
displayed without speed reference.
11. 11
DATA PLOTS- INFORMATION AVAILABLE
FROM STEADY-STATE PLOTS
Machine behavior on steady state with Amplitude &
Phase information in Trend format.
Orbit plots - direction of shaft precession, bearing
loading (pre-load), Rub condition, oil instability etc.
Spectrum plots – major vibration vector & frequency
is used to determine machine malfunction.
Waterfall plots – vibration spectra is displayed over a
period to determine periodic machine malfunction.
Acceptance region (Polar) Plots – change in machine
condition caused by machine malfunction
12. 12
DATA PLOTS- INFORMATION
AVAILABLE FROM TRANSIENT PLOTS
Slow Roll Speed / Slow Roll Run-out Vector
Amplitude, Phase, and Frequency of Res.
Synchronous Amplification Factor
High / Heavy Spot Relationship
Structural and Split Resonance
Rotor Mode Shape / Deflection Shape
Preload Identification
Frequency Relationships
14. 14
UNBALANCE
Unbalance is “offset” between geometrical
centerline and mass centerline of a Rotor
System.
Unbalance can also be described as vector
resultant of unequal distribution of cast
material and off-center machining of bore.
Primary symptom of Unbalance is an
increased 1X vibration levels on a rotor
system.
Vibration = Force / Dynamic Stiffness
15. 15
UNBALANCE
Reasons for mechanical unbalance on a
running machine
Loss of mass from rotor system (gradual or
sudden)
Thermal bow – caused by a “rubbing”
between stationary and rotating components
of rotor system.
In both cases change in “slow roll” vectors
(run-out) and 1X vibration levels through
rotor’s balance resonance is recorded.
16. 16
STATIC UNBALANCE
Static unbalance the balance condition
where the principal inertial axis is offset from
the rotor rotational axis by a parallel
distance ‘r ’.
This locates the Center of Gravity (CG) away
from the axis of the rotation resulting in an
unbalance force.
17. 17
STATIC UNBALANCE
Static unbalance can be corrected in either
of two methods.
1. In the first method, a correction weight can
be located directly 180° opposite the
unbalance, (CG) and at the appropriate
radius from the rotor centerline to equal the
unbalance.
2. In the second method, the weight is divided
and distributed to each end of the rotor. The
location of the weights must remain in line
with the weight location of the first method,
i.e. 180 ° opposite the CG of the rotor.
18. 18
COUPLE UNBALANCE
Couple unbalance is a condition where the mass
centerline intersects the rotor rotational axis and this
intersection is also the CG.
A rotor with couple unbalance will have no static
unbalance (the CG lies on the rotor rotational axis),
but, if rotated, the opposing forces produce vibration
in the bearings.
Couple unbalance must be addressed by making
weight corrections in the same axial plane of the
unbalance at each end of the rotor, i.e. 180°apart.
19. 19
DYNAMIC UNBALANCE
Dynamic Unbalance is the balance condition where
the mass centerline (principal inertial axis) does not
intersect either the rotor rotational axis or the CG of
the rotor.
This condition is a combination of static and couple
unbalance wherein the static component lies in an
axial plane different from one of the couple
unbalance forces. This type of unbalance is common.
Like couple unbalance, dynamic unbalance must also
be addressed by making weight corrections in a
minimum of two planes.
20. 20
UNBALANCE
Other malfunctions that appear like
unbalance:
Run-out – mechanical or electrical
Rotor bow (thermal)
Coupling problems
Shaft-crack
Loose components
Rubs
Misalignment
21. 21
CASE 1-Unbalance caused by blade loss on a LP-rotorCASE 1-Unbalance caused by blade loss on a LP-rotor
• While operating at constant load, two (2) step changes in shaft displacement level were
displayed across the LP Turbine in the trend plot with a very directional vector movement
displayed on the Polar plot.
• Subsequent to this step change in levels, shaft displacement levels across the LP-turbine
displayed significant change with load.
• Unit was operated on constant load prior run-down for inspection.
Two Step changes in vibrationTwo Step changes in vibration
22. 22
•Significant increase
in shaft displacement
levels recorded
through LP rotor’s 1st
balance resonance
during unit’s Run-
Down after blade loss.
•Change in “slow roll”
vectors also observed
during the Run-Down.
•Steady-state and
transient vibration
behavior of the LP-
Turbine suggested a
blade loss close to the
center of the LP
Turbine.
•Inspection of theInspection of the
LP-Turbine revealedLP-Turbine revealed
loss of two bladesloss of two blades
on LP rotor Stage 1on LP rotor Stage 1
(Generator side).(Generator side).
RUN-DOWN PRIOR BLADE LOSSRUN-DOWN PRIOR BLADE LOSS RUN-DOWN AFTER BLADE LOSSRUN-DOWN AFTER BLADE LOSS
CASE 1-Unbalance caused by blade loss on a LP-rotorCASE 1-Unbalance caused by blade loss on a LP-rotor
23. 23
•The steam Turbine generator is a single
bearing per shaft design where the HP/IP
and LP-Turbine Rotors are each supported
on a single bearing.
•The Steam turbine operates with the HP-
turbine bypass during the run-up, i.e. the IP-
turbine drives the unit train to its operating
speed.
•Significant increase in shaft displacement
levels was recorded across the HP-Turbine
at operating speed resulting in vibration
protection trip.
•.Significant increase in 1X Vibration levels
was also seen during the unit’s Run-Down
with increased “slow roll vectors” suggesting
thermally bowed HP rotor caused by a
severe “rub condition”.
CASE 2-Unbalance caused by severe rotor rubbingCASE 2-Unbalance caused by severe rotor rubbing
24. 24
•Investigation of process parameters during
run-up revealed fluctuating ICVs of the IP-
turbine during the run-up as the unit
reached its operating speed.
•This vibration behavior had been observed
in the past and was corrected by re-tuning
the IP-turbine’s ICV controls.
•Unit was Run-Up after approximately 6
hours of barring with slightly higher 1X
vibration levels across the HP-turbine at
speed suggesting that the thermal bow
caused by the “rub condition” had not
completely cleared.
•The shaft displacement levels reduced on
load as the unit soaked and the thermal
bend cleared.
EXCITATION FORCE – Fluctuating ICVs and
thermal distortion on Pedestal 2 caused severe
rub on the HP rotor resulting in a thermal
induced bow.
CASE 2-Unbalance caused by severe rotor rubbingCASE 2-Unbalance caused by severe rotor rubbing
25. 25
•On the Steam-turbine train, pedestal
no 2 (between HP/IP turbine) is a
sliding pedestal with self aligning
spherical bearing that is free to move
and align with unit’s load change.
•This pedestal requires regular
greasing for movement.
• During unit’s load change, if the
pedestal gets “stuck” resulting in
distortion of the spherical bearing.
•The HP-Turbine rotor moves to a
position within bearing clearance that
is more susceptible to Fluid induced
instabilities and light rubs on the
steam labyrinth resulting in a thermal
bow and increase in over-all vibration
levels.
CASE 3 – Change in balance response due toCASE 3 – Change in balance response due to
distortion of Sliding Pedestaldistortion of Sliding Pedestal
26. 26
• Note the increase in 1X vibration
amplitude and change in phase.
•Change in 1X amplitude and phase
can be caused by
•Rub
•Rotor moving to a different
position within bearing
clearance that is normally seen
on this bearing as change in
wedge pressure and bearing
temperature.
•The Unit had to run-down and
subsequently run to resolve this issue
with regular greasing of the sliding
pedestal.
EXCITATION FORCE – Thermal distortion of Pedestal 2 causes the HP/IP
rotors to move to a different position within bearing clearance.
CASE 3 – Change in balance response due toCASE 3 – Change in balance response due to
distortion of Sliding Pedestaldistortion of Sliding Pedestal
27. 27
CASE 4 - MISALIGNMENT CAUSED BY SWASH(GAP)CASE 4 - MISALIGNMENT CAUSED BY SWASH(GAP)
AND CONCENTRICITY ERROR on a 520MW AlstomAND CONCENTRICITY ERROR on a 520MW Alstom
STGSTG
•The Exciter rotor is coupled with the
Generator rotor through a stub-shaft.
•The Generator/ Exciter coupling was
assembled with a significant gap
(swash) error and concentricity error
between the Exciter rotor and
intermediate stub-shaft.
•Although the Exciter rotor was high
speed balanced, excessive vibration
levels were witnessed during run-up
through the 1st
balance resonance and
the unit was manually tripped.
EXCITATION FORCE – significant swash (gap) error on coupling and concentricity
error
28. 28
CASE 14 - MISALIGNMENT CAUSED BYCASE 14 - MISALIGNMENT CAUSED BY
SWASH(GAP) AND CONCENTRICITY ERRORSWASH(GAP) AND CONCENTRICITY ERROR
on a 520MW Alstom STGon a 520MW Alstom STG
•The Exciter rotor was rebuild with a
reduced swash (gap) error and lower
concentricity error between exciter
rotor and stub-shaft at RWE workshop
since the equipment supplier could not
achieve the desired concentricity
figures.
•The Exciter rotor was re-balanced
prior to assembly on site.
• Excessive vibration levels were
witnessed during return-to service were
further reduced with in-situ balancing.
EXCITATION FORCE – significant swash (gap) error on coupling and concentricity
error
31. 31
BASIC BALANCING
Balancing is the process of adding forces to
the rotor to “offset” the current unbalance
distribution forces and other 1X vibration
forces in the rotor system.
Balancing is Categorized into
Single plane balancing
Multiple plane balancing
33. 33
BASIC BALANCING
-PROCESS
Decision making
1. Compensating for Run-Out (slow roll)
2. Applying 10% rule for Trial weight
3. Verify the response of trial weight and if
possible do a repeat run.
4. Apply Cal 1 and verify the response of Cal 1
before attempting further balancing and if
response is non-linear abort balancing.
34. 34
BALANCING
Unbalance results in increase in 1X vibration
levels. Other machinery malfunctions that
can increase 1X vibration levels
1. Thermal Bow
2. Rubs
3. Run-out
4. Shaft crack
5. Broken blades/ vanes
6. Internal / external misalignment.
35. 35
BASIC BALANCING –
INFLUENCE VECTORS
If the rotor system responds linear to the installed
Cal 1/ Cal 2 weights (balancing), Influence vector
can be derived for the rotor system and can be used
for future balancing.
Influence vectors determines how a balance weight
can influence the vibration response of a machine.
However, influence vectors should be used with
following caution:
1. Same operating speed.
2. Same load
3. Same process conditions.
36. 36
BALANCING – WEIGHT
SPLITTING
When a balance solution requires the
balance weight to be positioned
1. Between balance holes
2. Holes that are full
3. Require more weight that will fit in one hole
Weight splitting can be carried out that
combines the effect of two weights, mounted
on available holes, that will have the same
effect of the balancing solution.
37. 37
• Arnot Power station has single bearingArnot Power station has single bearing
per shaft design where the HP/IP andper shaft design where the HP/IP and
LP-Turbine Rotors are each supportedLP-Turbine Rotors are each supported
on a single bearing.on a single bearing.
• Bearing 2 is self-aligning sphericalBearing 2 is self-aligning spherical
bearing, 2 supports the HP/IP rotorsbearing, 2 supports the HP/IP rotors
• Massive two-dual stage LP Turbine rotorMassive two-dual stage LP Turbine rotor
(68 ton) is supported on the LP front(68 ton) is supported on the LP front
bearing (3) and self aligning Generatorbearing (3) and self aligning Generator
front bearing (5b).front bearing (5b).
• Substantial difference in vibration levelsSubstantial difference in vibration levels
is recorded through LP-Turbine 1is recorded through LP-Turbine 1stst
balance resonance during Run-Up andbalance resonance during Run-Up and
Run-Down especially after run-downRun-Down especially after run-down
down from full load.down from full load.
• The station requested to balance theThe station requested to balance the
LP-Turbine in order to reduce vibrationLP-Turbine in order to reduce vibration
levels through its 1levels through its 1stst
balance resonance.balance resonance.
Preliminary Root Cause:Preliminary Root Cause:
1.1. Alignment /Concentricity errorsAlignment /Concentricity errors
between LP-turbine/Generator.between LP-turbine/Generator.
2.2. Thermal condition of theThermal condition of the
Generator.Generator.
3.3. Thermal distortion of pedestal 2Thermal distortion of pedestal 2
restricting “freedom ofrestricting “freedom of
movement /sliding” causingmovement /sliding” causing
misalignment of rotors.misalignment of rotors.
CASE 3- Balancing of LP-Turbine’s 1st
balance resonance
38. 38
1X Vibration Vectors through
LP-Turbine 1st
Balance
Resonance during 1st
Run-Up on
29th
Dec 2010
TRIAL WEIGHT - 1X Vibration
Vectors through LP-Turbine 1st
Balance Resonance during 1st
Run-
Up on 29th
Dec 2010
CAL1 - 1X Vibration Vectors
through LP-Turbine 1st
Balance
Resonance during 1st
Run-Up on
29th
Dec 2010
Balancing weight Trial Run
Plane 2 - 280grams@Slot7 (285’)
Plane 3 - 280grams@Slot7 (285’)
Plane 2 - 280grams@Slot7 (285’)
Plane 3 - 280grams@Slot7 (285’)
Plane 4 - 280grams@Slot7 (285’)
LOCATION 1X Phase 1X Phase 1X Phase
BRG 3 – Y-Probe 206 194 140 217 102 204
BRG 5a – Y-Probe 999 854 733 275 541 277
BRG 5b – Y-Probe 254 197 168 261 116 268
CASE 3- Balancing of LP-Turbine’s 1st
balance resonance
• Adding trial weight in the centre of LP Turbine reduced vibration levels through the 1Adding trial weight in the centre of LP Turbine reduced vibration levels through the 1stst
balance resonance of LP Turbine.balance resonance of LP Turbine.
• With past experience, TSS has observed that adding additional weight on Plane 2 andWith past experience, TSS has observed that adding additional weight on Plane 2 and
3 does not give the desired results3 does not give the desired results
• Additional balance weight was added on plane 4 that reduced vibration levels throughAdditional balance weight was added on plane 4 that reduced vibration levels through
the 1st balance resonance of LP Turbine to acceptable levels.the 1st balance resonance of LP Turbine to acceptable levels.
Note: There is no physical bearing on 5a, vibration probes are installed to measureNote: There is no physical bearing on 5a, vibration probes are installed to measure
the rotor deflection shape during transients and used as guidelines tothe rotor deflection shape during transients and used as guidelines to
determine internal rubs.determine internal rubs.
39. 39
Balance weight added on plane 2, 3 & 4Balance weight added on plane 2, 3 & 4
reduced vibration levels on across the LP-reduced vibration levels on across the LP-
turbine during transient events through theturbine during transient events through the
11stst
balance resonance to acceptable levels.balance resonance to acceptable levels.
A significant improvement in vibrationA significant improvement in vibration
levels was also observed on Exciter rearlevels was also observed on Exciter rear
bearing (7) at steady state, levels reducedbearing (7) at steady state, levels reduced
from 180 um to 40 um pk-pk. Severalfrom 180 um to 40 um pk-pk. Several
unsuccessful balancing attempts wereunsuccessful balancing attempts were
carried out in the past when the balancecarried out in the past when the balance
weight was added to slip-rings, refer toweight was added to slip-rings, refer to
Case 4.Case 4.
CASE 3- Balancing of LP-Turbine’s 1st
balance resonance
40. 40
•Arnot Power station, Unit 2 had a capacityArnot Power station, Unit 2 had a capacity
increase with a new Toshiba Generator,increase with a new Toshiba Generator,
commissioned in March 2005 and Turbinecommissioned in March 2005 and Turbine
upgrade in May 2008.upgrade in May 2008.
•Since the Turbine upgrade, a substantialSince the Turbine upgrade, a substantial
increase in vibration levels had beenincrease in vibration levels had been
recorded through LP-Turbine’s 1recorded through LP-Turbine’s 1stst
balancebalance
resonance during transient event.resonance during transient event.
•A significant difference was observedA significant difference was observed
during “COLD” and “HOT” transient events.during “COLD” and “HOT” transient events.
•Also, an increase in Vibration on bearing 6Also, an increase in Vibration on bearing 6
& 7 was observed after the Turbine& 7 was observed after the Turbine
upgrade when load was increased aboveupgrade when load was increased above
350 MW.350 MW.
•Station requested to trim balance theStation requested to trim balance the
Exciter to reduce vibration levels at speed.Exciter to reduce vibration levels at speed.
Preliminary Root Cause:Preliminary Root Cause:
1.1. Thermal condition of theThermal condition of the
Generator.Generator.
2.2. Bearing no. 7 (pedestal) notBearing no. 7 (pedestal) not
sufficiently loaded.sufficiently loaded.
CASE 4- Balancing of an Exciter on a 400MW STG
41. 41
LOCATION 1X AMP & PHASE AT 3000
RPM
Unexcited on 10 Sep 08.
1X AMP & PHASE AT 3000
RPM
Unexcited on 14 Nov 08.
1X AMP & PHASE AT 3000
RPM
at approx. 40 MW Load
Balance
weight
225 grams @135 degree 225 grams @135 degree
Probe - 6X 60 @ 296 48 @ 277 72 @ 306
Probe -6Y 36 @ 182 26 @ 45 23 @ 266
Probe - 7X 155 @ 299 46 @ 312 108 @ 350
Probe - 7Y 108 @ 189 28 @ 57 27 @ 306
Bearing 7 Orbit plot before the unit’s run-
down on 9th
Nov before adding the balance
weight – suggested bearing is not loaded
On 16 Nov after adding the balance weight
orbit suggested a slightly loaded bearing at
lower loads.
These levels however, deteriorated with time.
The spread of the balance weight was ~ 90
degrees and the OEM (Toshiba) did not allow
the use of heavy metal weights or increase
pre-load on bearing 7
CASE 4- Balancing of an Exciter on a 400MW STG
42. 42
The in vibration level
started to increase
once the unit’s speed
reached 3000 RPM
from 45 to 89 μm Pk-
Pk [1X]
Balance weight added on the Stub-shaft reducedBalance weight added on the Stub-shaft reduced
vibration levels on bearing 7 as the unit reached itsvibration levels on bearing 7 as the unit reached its
rated speed. However, an increase in vibrationrated speed. However, an increase in vibration
levels was observed at the unit’s rated speed.levels was observed at the unit’s rated speed.
The improvement in balancing could not beThe improvement in balancing could not be
achieved as increasing the weights on theachieved as increasing the weights on the
balancing plane of Stub-shaft increased the spreadbalancing plane of Stub-shaft increased the spread
and the OEM did not allow to use heavy metaland the OEM did not allow to use heavy metal
weights on the Stub shaft.weights on the Stub shaft.
CASE 4- Balancing of an Exciter on a 400MW STG
43. 43
CASE 5 – Balancing of Power
Turbine Load Shaft and Generator at
RWE Npower, Ellesmere Port
Pedestal Velocity levels of ~11 mm/s
rms on Wheel gear outboard bearing
at operating speed
Unit’ return-to-service
in November 2011
after an inspection
outage where the
alignment across the
Gas-turbine Alternator
was checked and
corrected revealed
Shaft displacement levels of
~200 um pk-pk on high speed
load shaft at operating speed
44. 44
CASE 5 – Balancing of Gas Turbine
Output Load Shaft
Transient Polar plotTransient Polar plot
indicating 1X vectorindicating 1X vector
movement of loadmovement of load
shaft was veryshaft was very
repeatable during run-repeatable during run-
up and run-down. Noup and run-down. No
significant change insignificant change in
the vibration behaviorthe vibration behavior
was observed after thewas observed after the
Flender gearbox wasFlender gearbox was
refurbishedrefurbished
Run-up - Blue; Run-down -Run-up - Blue; Run-down - RedRed
45. 45
CASE 5 – Balancing of Gas Turbine
Output Load Shaft
Balance weightsBalance weights
added on the loadadded on the load
shaft coupling (closeshaft coupling (close
to Pinion Gear DE)to Pinion Gear DE)
reduced vibrationreduced vibration
levels at operatinglevels at operating
speed to acceptablespeed to acceptable
levels.levels.
Run-up - Blue; Run-down -Run-up - Blue; Run-down - RedRed
46. 46
CASE 5 – Balancing of Gas Turbine
Output Load Shaft
A significant improvement
in shaft vibration levels was
observed on the load shaft
at Pinion Gear DE bearing
after installing a balance
weight.
No significant deterioration
in vibration levels was
observed on load (thermal)
after in-situ balancing
47. CASE 5 – Balancing of the Alternator
47
High velocity levels
recorded on the
Wheel gear O/B
bearing with levels
increasing while
the Unit operated
on load. This
bearing also
supports the
Alternator shaft and
probably caused by
the Alternator
rotor’s thermal
behavior on load
48. 48
CASE 5 – Balancing of the Alternator
• Significant improvement in
pedestal vibrations was observed
across the Alternator bearings
after installing a balance weight.
• Three (3) planes were used to
balance the Alternator with
balance weights installed on the
inboard and outboard balance
planes of the Alternator and
overhung Exciter
• No significant deterioration in
vibration levels was observed on
load (thermal) after in-situ
balancing
49. 49
CASE 6 – Balancing of Solar’s Mars 100
Gas Turbine on a Conoco Vikings Platform
Shaft vibration levels on theShaft vibration levels on the
power turbine exhaustpower turbine exhaust
/coupling end increased/coupling end increased
with speed and tripped thewith speed and tripped the
machine.machine.
In-situ balancing reducedIn-situ balancing reduced
these levels from ~2,4 milsthese levels from ~2,4 mils
pk-pk to ~0,34 mils pk-pk.pk-pk to ~0,34 mils pk-pk.
50. CASE 7 – Balancing of SPEY Gas
Turbine on a Type 23 Frigate – HMS
Argyll
50
Pedestal vibration on the
Power Turbine Aft bearing
increased to 9mm/s rms at
operating speed.
In-situ balancing reduced the
levels from 9mm/s rms to
~0,5mm/s rms to comply with
maximum allowable vibration
per marine standard DEF
STAN 02-305, Issue 3.
51. 51
•LP Gland box housing the labyrinth seals is installed on the LP Turbine casing.LP Gland box housing the labyrinth seals is installed on the LP Turbine casing.
•Restriction was observed on the LP Turbine’ s shaft-centerline “rise” during run-up.Restriction was observed on the LP Turbine’ s shaft-centerline “rise” during run-up.
•During investigations, it was found that the severe rubbing was caused byDuring investigations, it was found that the severe rubbing was caused by
restriction in expansion of the LP gland box, which is connected to the LP outerrestriction in expansion of the LP gland box, which is connected to the LP outer
casing.casing.
EXCITATION FORCE – Severe rubbing on the labyrinth seals during run-up
caused by restriction in expansion of the LP gland box fixed to the LP turbine
outer casing.
CASE 10 – Rubbing on LP Turbine Labyrinth
Seals on a 200 MW Parsons Turbine during
return to service
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CASE 14 - MISALIGNMENT CAUSED BYCASE 14 - MISALIGNMENT CAUSED BY
SWASH(GAP) AND CONCENTRICITY ERRORSWASH(GAP) AND CONCENTRICITY ERROR
on a 520MW Alstom STGon a 520MW Alstom STG
•The Exciter rotor is coupled with the
Generator rotor through a stub-shaft.
•The Generator/ Exciter coupling was
assembled with a significant gap
(swash) error and concentricity error
between the Exciter rotor and
intermediate stub-shaft.
•Although the Exciter rotor was high
speed balanced, excessive vibration
levels were witnessed during run-up
through the 1st
balance resonance and
the unit was manually tripped.
EXCITATION FORCE – significant swash (gap) error on coupling and concentricity
error
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CASE 14 - MISALIGNMENT CAUSED BYCASE 14 - MISALIGNMENT CAUSED BY
SWASH(GAP) AND CONCENTRICITY ERRORSWASH(GAP) AND CONCENTRICITY ERROR
on a 520MW Alstom STGon a 520MW Alstom STG
•The Exciter rotor was rebuild with a
reduced swash (gap) error and lower
concentricity error between exciter
rotor and stub-shaft at RWE workshop
since the equipment supplier could not
achieve the desired concentricity
figures.
•The Exciter rotor was re-balanced
prior to assembly on site.
• Excessive vibration levels were
witnessed during return-to service were
further reduced with in-situ balancing.
EXCITATION FORCE – significant swash (gap) error on coupling and concentricity
error
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ROTOR BOW
What is rotor bow
Causes of rotor bow
Diagnosing rotor bow
Removing rotor bow
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ROTOR BOW
Rotor bow is a condition that results in bent shaft
centerline.
Rotor bow can be categorized in two
Mechanical Rotor bow can be caused by improper
handling, transportation and storage of rotor system.
Thermal Rotor bow can be caused by uneven heating
/ cooling of rotor system and “rubbing” between
stationary and rotating components of rotor system.
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ROTOR BOW - Diagnosis
Mechanical bow – Permanent bow
All characteristics of mechanical unbalance are present in
vibration data.
Vibration data will be repeatable for consecutive runs.
“Slow roll” vectors will be high and orbit at “Slow roll” &
speed will be circular.
Thermal bow
All characteristics of mechanical unbalance are present in
vibration data.
Vibration data will not be repeatable for consecutive runs.
“Slow roll” vectors will be different for start-up and shut-
down.
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ROTOR BOW
Rotor can have temporary or permanent bow depending
on the stress on the rotor system
Temporary bow can occur due to uneven heating
of rotor surface or anisotropic thermal material
properties. If a “hot spot” develops on one side of the
rotor, it will expand and become longer than the other
side. If the rotor system is unconstrained, resulting
deflection will not be permanent. Temporary bow can
be cured by barring the machine for longer duration
and also “heat soak” the machine at low speed for
longer duration.
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ROTOR BOW
Permanent bow results when the rotor system has
been deformed to a condition that is not self
reversing without special intervention. It usually
happens when stresses on the rotor system has
exceeded the yield strength of material.
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CASE 18 – HP Rotor thermal bow caused
by rubbing on 400MW Alstom HP-Turbine
•This Unit the HP/IP Turbine had a severe “rub
condition” on the glands caused by fluctuating
ICVs.
•Significant increase in Vibration levels through
HP resonance was observed during the unit’s
Run-Down after severe “rub condition”.
•Change in “slow roll” vectors were also
observed during the Run-Down after the unit
had a severe “rub condition”.
•Unit was Run-Up after approximately 6 hours
of barring and had higher vibration levels
(direct & 1X) at speed suggesting that the
thermal bow caused by the “rub condition” had
not cleared.
EXCITATION FORCE – Fluctuating ICVs and
thermal distortion on Pedestal 2 moved the
HP/IP rotors into a severe “rub condition” at
speed.
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•This Unit the HP Turbine on
Pedestal 1 had a “rub condition”
resulting in an increase in 1X
vibration amplitude and change in
phase.
•Once the HP-Turbine rotor had a
“rub condition” and developed a
thermal bow it moved to a position
within bearing clearance that is more
susceptible to Fluid induced
instabilities. Increase in over-all
vibration levels.
EXCITATION FORCE – Thermal distortion of Pedestal 2 causes the HP/IP
rotors to move closer to baffle / gland clearance resulting in a “rub condition”
at speed.
CASE 19 – Thermal bow on HP rotor
caused by rub due to pedestal distortion
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GENERATOR THERMAL
Generator rotor thermal sensitivity is a phenomenon
which may occur on the generator rotor causing the
rotor vibration to change as the field current is
increased.
The thermal sensitivity can be caused by an uneven
temperature distribution circumferentially around the
rotor, or by axial forces which are not distributed
uniformly in the circumferential direction.
The primary driver of this second cause is the large
difference in coefficient of thermal expansion
between the copper coils and the steel alloy rotor
forging and components.
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GENERATOR THERMAL
If the rotor winding is not balanced both electrically
and mechanically in the circumferential direction, the
generator rotor will be unevenly loaded which can
cause the rotor to bow and cause the vibration to
change.
In most cases, a thermally sensitive rotor will not
prevent a generator from running, but may limit the
operation at high field currents or VAR loads due to
excessive rotor vibration.
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CAUSES GENERATOR
THERMAL
Shorted turns.
Blocked ventilation or Unsymmetrical cooling
Insulation variation
Wedge fit
Retaining Ring/Centering Ring Assembly Movement
Tight slots
Heat Sensitive Rotor Forging
Distance Block Fitting
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GENERATOR THERMAL
A thermally sensitive rotor is characterized by a once-
per-revolution frequency response signature due to a
change in the rotor balance arising from the rotor
bow. If the total vibration of the field stays within
acceptable limits, the field is not considered
“thermally sensitive.”
Since vibration is characterized by amplitude and
phase angle. If the vibration vector stays within the
acceptable vibration levels, the vibration is not
considered to be a problem.
Similarly if the phase angle changes also more than
the allowable limit the generator rotor is considered
“thermally sensitive.”
The change in vibration and phase angle within the
polar plot from the starting operating point to the end
operating point is called the thermal vector.
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GENERATOR THERMAL
There are two types of thermal sensitivity -
Repeatable (or reversible) & irreversible. Both types
vary with field current
Reversible type follows the field current as it is
increased and decreased. For example, if the
vibration on a field increases from 1 mil to 3 mils as
field current is increased and then decreases in the
same manner as the field current decreases, then
the thermal sensitivity is considered to be reversible.
In these case, the field can be compromised
balanced so that the thermal vector passes through
zero and the maximum vibration remains within
acceptable limits.
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GENERATOR THERMAL
Irreversible - if the vibration increases as the field
current is increased but does not respond to a
decrease in field current, then this type of thermal
sensitivity is referred to as irreversible or “slip-stick”.
If this situation occurs, the generator frequently must
be taken off-line and brought down to turning gear
speed to unlock the forces that induced the rotor
bow.
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•This Generator rotor had a thermal condition that was confirmed by the “heat run” test
performed in the 300 Ton balancing facility at Rotek works.
•When the excitation current was passed through the Generator rotor coils, the rotor
showed a thermal behavior that is associated with the bending mode of the rotor.
•Significant increase in Vibration levels were observed when the rotor was Run-Down.
CASE 22 – 400MW GENERATOR ROTOR “HEAT RUN” TEST
BEFORE REPAIRS
POLAR PLOT FOR VECTOR MOVEMENT ACROSS GENERATOR RUN-DOWN PLOTS AFTER HEAT RUN TESTPOLAR PLOT FOR VECTOR MOVEMENT ACROSS GENERATOR RUN-DOWN PLOTS AFTER HEAT RUN TEST
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•This Generator rotor’s thermal condition was acceptable after repairs done on the
Generator. “Heat run” test performed in the 300 Ton balancing facility at Rotek works
indicated small vector movements.
•When the excitation current was passed through the Generator rotor coils, the rotor
showed a slight vector movement.
•Significant decrease in Vibration levels were observed after Generator repairs.
CASE 22 – 400 MW GENERATOR ROTOR “HEAT RUN” TEST AFTER
REPAIRS
POLAR PLOT FOR VECTOR MOVEMENT ACROSS GENERATOR RUN-DOWN PLOTS AFTER HEAT RUN TESTPOLAR PLOT FOR VECTOR MOVEMENT ACROSS GENERATOR RUN-DOWN PLOTS AFTER HEAT RUN TEST
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CASE 23 – 400MW GENERATOR
ROTOR THERMAL DURING LOADING
•This Generator rotor showed a thermal
behavior on load when a significant
vector movement was seen on
Generator outboard as the unit was
loaded from unexcited to 350 MW.
•Significant increase in Vibration levels
was observed and the phase across the
generator moved from out-of-phase to in-
phase. (Change of mode shape)
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CASE 24 – 400MW GENERATOR ROTOR THERMAL CONDITION AT 1200
RPM DURING RUN-DOWN
•This Generator rotor’s thermal behaviour was confirmed by the 1X vectorThis Generator rotor’s thermal behaviour was confirmed by the 1X vector
movement when the unit was kept at 1200 Rpm (just above its balance resonance)movement when the unit was kept at 1200 Rpm (just above its balance resonance)
during run-down.during run-down.
•This allowed the generator rotor to relax (straighten) at 1200 Rpm resulting inThis allowed the generator rotor to relax (straighten) at 1200 Rpm resulting in
lower vibration levels through LP 1lower vibration levels through LP 1stst
balance resonance.balance resonance.
Both the LP Turbine’s and
Generator’s 1st
balance resonance
were close to each other at ~1100
rpm.
During run-down the generator
rotor’s 1st
balance resonance
excited the LP rotor’s 1st
balance
resonance resulting in substantially
high vibration levels through LP
rotor’s its 1st
balance resonance
resulting in severe rubbing.
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CASE 25 – Offset balance of a generator
thermal on a 40 MW Gas-Turbine
Generator
A significant generator
rotor thermal was
seen as the unit was
loaded, especially on
BB11 (Generator I/B
bearing)
Thermal offset
balancing using 3
balance planes on the
Generator, decreased
the levels to
acceptable
73. 73
CASE 26 – 12MW Alternator Rotor Instability
While the unit operated
at lower load and the LC
heaters were brought
into service, significant
variations in shaft
displacement levels was
recorded across the
Alternator bearings.
LC heater
operations
Orbit plot of Alternator DE and NDE bearings indicated significant instability
that is normally seen on rotors with fluid induced instability with the presence
of near ½ X vibration component.
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CASE 26 – 12MW Alternator Rotor Instability
Waterfall plot of Alternator DE and NDE bearings indicated presence of near
½ X vibration component.
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CASE 26 – 12MW Alternator Rotor Instability
The instability in orbit was not observed prior the LC heaters were
brought in service and after the LC heaters tripped. However, change
in orbit shape of the Alternator DE bearing was noted between LC
heaters operations (prior they were brought in service and after they
tripped)