Internship presentation


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Internship presentation at Century paper and board mills

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Internship presentation

  1. 1. Introduction of Company
  2. 2. Century paper and board mills Ltd belongs to LAKSON GROUP . Others belonging to LAKSON GROUP are
  3. 3. Products Coated Brand 1) Century (Bleached Board) 2) Elegant (Bleached Board) 3) Captain 4) 7-Star 5) Polo Uncoated Brand 1) Ascot 2) Simplicity 3) Guard (Liner) MF Paper 1) Hi-Brite 2) Impressions 3) Pearl 4) Royal 5) Scholar 6) Graduate MG Paper 1) IBIS 2) Dove 3) Atlas Corrugated Boxes
  4. 4. Our Clientele •Philip Morris International •Nestle Pakistan •Unilever •English Biscuits •Pakistan Tobacco •Qarshi •Shan •Kolson •Continental Biscuits •Colgate •Tetley Clover •GreenStar •National Foods •Candy Land
  5. 5. Technical Experience
  6. 6. ELECTRONIC MOTOR PROTECTION RELAY ( EMPR ) It is controlled electronically by picmicrocontroller . Following are its main parts : PIC microcontroller Analogue multiplexer Current transformer Ac to dc converter Relays comparator Following is its circuit , this circuit can be modified according to requirements and outputs .
  7. 7. Function of PIC microcontroller Its functions are some of following Analogue to digital conversion of DC signal Control the multiplexer inputs and thus the channel selection Compare with the reference voltage level Perform the function of comparator Control the output contacts/relays Speed Speed depends on parallel prcessing of signals. Usually speed of pic is too fast , so we don’t need parallel processing . In some cases speed might be important .
  8. 8. Three Phase Induction Motor Most widely used in industry today It has a squirrel cage rotor with copper conductors shorted at both ends.
  9. 9. Winding Structure
  10. 10. Single Phase Induction Motor Winding Structure It also has a squirrel cage rotor .
  11. 11. Power Optimisation in Motors Percent change in voltage
  12. 12. DC Motor
  13. 13. Stator
  14. 14. Rotor
  15. 15. HIGH VOLTAGE MOTORS Rated Voltage: 3300 V Rated Power: 1000 KW High Torque Motors
  16. 16. GIPAM This is microprocessor based device which monitors all the activities in motor supply and in case of any faults it trips the motor . Its functions are also to start and stop the motor .
  17. 17. Over Temperature Protection . RTD are present in motors . Output of RTDs is fed to SHIMAX MAC5B , which gives digital output to controlling circuitary for tripping and reset of motors at high temperature . Temperature limits for output can be adjusted in it .
  18. 18. CURRENT TRANSFORMERS 10 times of rated primary current injected means 5 percent of composite error is created . 5 - composite error . P- protection. 10- accuracy limiting factor 5P10,Means 5%(5P) Of Ration Error Even if 10 Times fo Rated current pass through the primary of CT these r the standard ALF list - 5 , 10 , 15 ,20 ,30 composite error is related to harmonics Class PS is an abbreviatioin for Protection-Special Class of CT's. These are used generally for Differential Protection applications
  19. 19. For grounding system, ZCT is used with Ground Relay for ground fault detection. Cable and earth cable also should be placed through window .
  20. 20. Genral Motors Protection
  21. 21. Various Industry Motor Applications •Fans, Blowers •Pumps, Compressors •Grinders, Chippers •Conveyors, Shredders •Crushers, Mixers •Cranes, Extruders •Refiners, Chillers
  22. 22. Thermal Stress Causes Motor Failure •Most of the motor failure contributors and failed motor components are related to motor overheating. •Thermal stress potentially can cause the failure of all the major motor parts: Stator, Rotor, Bearings, Shaft and Frame.
  23. 23. Overvoltage Protection •The overall result of an overvoltage condition is a decrease in load current and poor power factor. •Although old motors had robust design, new motors are designed close to saturation point for better utilization of core materials and increasing the V/Hz ratio cause saturation of air gap flux leading to motor heating. •The overvoltage element should be set to 110% of the motors nameplate unless otherwise started in the data sheets.
  24. 24. Undervoltage Protection •The overall result of an undervoltage condition is an increase in current and motor heating and a reduction in overall motor performance. •The undervoltage protection element can be thought of as backup protection for the thermal overload element. In some cases, if an undervoltage condition exists it may be desirable to trip the motor faster than thermal overload element. •The undervoltage trip should be set to 80-90% of nameplate unless otherwise stated on the motor data sheets. •Motors that are connected to the same source/bus may experience a temporary undervoltage, when one of motors starts. To override this temporary voltage sags, a time delay setpoint should be set greater than the motor starting time.
  25. 25. Unbalance Protection •Indication of unbalance Î negative sequence current / voltage •Unbalance causes motor stress and temperature rise •Current unbalance in a motor is result of unequal line voltages •Unbalanced supply, blown fuse, single-phasing •Current unbalance can also be present due to: •Loose or bad connections •Incorrect phase rotation connection •Stator turn-to-turn faults Motor Relay •For a typical three-phase induction motor: •1% voltage unbalance (V2) relates to 6% current unbalance (I2) •For small and medium sized motors, only current transformers (CTs) are available and no voltage transformers (VTs). Measure current unbalance and protect motor. •The heating effect caused by current unbalance will be protected by enabling the unbalance input to the thermal model •For example, a setting of 10-15% x FLA for the current unbalance alarm with a delay of 5-10 seconds and a trip level setting of 20-25% x FLA for the current unbalance trip with a delay of 2-5 seconds would be appropriate.
  26. 26. Ground Fault Protection •A ground fault is a fault that creates a path for current to flow from one of the phases directly to the neutral through the earth bypassing the load •Ground faults in a motor occur: •When its phase conductor’s insulation is damaged for example due to voltage stress, moisture or internal fault occurs between the conductor and ground •To limit the level of the ground fault current connect an impedance between the supplies neutral and ground. This impedance can be in the form of a resistor or grounding transformer sized to ensure maximum ground fault current is limited.
  27. 27. Ground Fault Protection Zero Sequence CT Connection •Best method •Most sensitive & inherent noise immunity •All phase conductors are passed through the window of the same CT referred to as the zero sequence CT •Under normal circumstances, the three phase currents will sum to zero resulting in an output of zero from the Zero Sequence CT’s secondary. •If one of the motors phases were to shorted to ground, the sum of the phase currents would no longer equal zero causing a current to flow in the secondary of the zero sequence. This current would be detected by the motor relay as a ground fault.
  28. 28. Differential Protection •Differential protection may be considered the first line of protection for internal phase-to-phase or phase-to-ground faults. In the event of such faults, the quick response of the differential element may limit the damage that may have otherwise occurred to the motor. Core balance method: •Two sets of CT’s, one at the beginning of the motor feeder, and the other at the neutral point •Alternatively, one set of three core-balance CTs can also be used •The differential element subtracts the current coming out of each phase from the current going into each phase and compares the result or difference with the differential pickup level.
  29. 29. Differential Protection Summation method with six CTs: •If six CTs are used in a summing configuration, during motor starting, the values from the two CTs on each phase may not be equal as the CTs are not perfectly identical and asymmetrical currents may cause the CTs on each phase to have different outputs. •To prevent nuisance tripping in this configuration, the differential level may have to be set less sensitive, or the differential time delay may have to be extended to ride through the problem period during motor starting. •The running differential delay can then be fine tuned to an application such that it responds very fast and is sensitive to low differential current levels.
  30. 30. Short Circuit Protection The short circuit element provides protection for excessively high overcurrent faults Phase-to-phase and phase-to-ground faults are common types of short circuits When a motor starts, the starting current (which is typically 6 times the Full Load Current) has asymmetrical components . These asymmetrical currents may cause one phase to see as much as 1.7 times the RMS starting current. To avoid nuisance tripping during starting, set the the short circuit protection pick up to a value at least 1.7 times the maximum expected symmetrical starting current of motor. The breaker or contactor must have an interrupting capacity equal to or greater then the maximum available fault current or let an upstream protective device interrupt fault current.
  31. 31. Stator RTD Protection •A simple method to determine the heating within the motor is to monitor the stator with RTDs. •Stator RTD trip level should be set at or below the maximum temperature rating of the insulation. •For example, a motor with class F insulation that has a temperature rating of 155°C could have the Stator RTD Trip level be set between 140°C to 145°C, with 145° C being the maximum (155°C - 10°C hot spot) The stator RTD alarm level could be set to a level to provide a warning that the motor temperature is rising
  35. 35. Pneumatic System Compressor Air Tank Pressure Regulator Signal from Remote Area or local operation Pressure Regulator Proportional Control Valve Actuating Mechanism like Cylinder On – Off Control Loops Directional Control Valve Signal from a controller at remote location Valve Actuator Proportional Control Loops 37
  36. 36. 38
  37. 37. Types of Pneumatic Fittings • Push-In Fittings, very quick joint with the tube • Cap tight Fittings, neat, quick joint using a finger tight nut • Compression Fittings
  38. 38. Thread Characteristics Flank Angle and Taper Angle Root Crest and Root Crest Pitch is sometimes written as the number of threads within threads in one inch distance
  39. 39. Pressure Regulator If the pressure in the volume with the output port exceeds the set value, the diaphragm shuts off the input port and then opens the exhaust ports to relieve the excess pressure.
  40. 40. Pressure Regulators working 6 Bar The set screw permits adjustment of the initial tension in the diaphragm spring. The diaphragm lifts off the push rod off its seat. The push rod shuts off the exhaust port in the diaphragm.
  41. 41. Pneumatic Control Valve Actuator Actuators are of many different types.  The positioner is working on the basis of force balance principle  The input signal to positioner and stroke of the actuator are following a relation which is determined by the contour of the cam disc  This positioner can control single as well as double acting actuators
  42. 42. Internal Spool Structure of Valve 4 2 14 12 5 14 5 4 1 2 3 1 3 12 4 2 5 1 3 14 14 5 4 1 2 3 12 12
  43. 43. Electro Pneumatic Converter or I / P Converter • An I / P Converter is used for converting standard current signals to standard pressure signals Like converting 4 – 20 mA current signal to 3 – 15 psi pressure • • Essential building block of pneumatic valve positioners and many other pneumatic devices This converter is necessary for completing the control loops because controllers receive and transmit their signals in the form of current .
  44. 44. E / P Conveter Assembly
  45. 45. Pressure Booster (Doubler) This is pressure doubler .
  46. 46. Motor Starting Circuits Starting Circuits are used for protection of motors  protection of system For easy repair of motors(limiting damage to motors) Fault detection
  47. 47. DOL Starter
  48. 48. Star Delta Starter
  49. 49. Reacter Sarter Reactor is basically an inductor . It adds impedance to the motor circuit , thus limiting the current flow . After short period of starting rector is bypassed by another contactor in parallel . Two timers are used if one fails other dectects it failure and indicates its failure by tripping the motor as it can be quite dangerous if keeps running wrong.
  50. 50. Soft Starter It also protects the motor and indicates if fault occurs. It monitors Phase loss Current imbalance Over temperature Over load Shorted SCRs Shunt Trip
  51. 51. Phase shift control for soft start or dimming effect
  52. 52. Variable Frequency Drives Types of AC ASD's There are three different types of ASD's on the market that primarily differ in the type of rectification they use to convert AC to DC and back to AC. VVI - Variable Voltage Input CSI - Current Source Input PWM - Pulse Width Modulated
  53. 53. Variable Frequency Drives Basic Principle of Operation The electronic VFD can be used to vary the speed of an AC motor and at the same time retain its torque producing capability. The main power source provides a fixed voltage, fixed frequency supply that is converted into a variable voltage, variable frequency output in such a way that in most of the operating speed range, the V/f ratio is maintained constant. This of course is achieved though sophisticated microprocessor based control electronics. A VFD consists of an input rectifier (which converts AC to DC) followed by an inverter (that inverts DC to AC) connected through a DC intermediate voltage link.
  54. 54. Energy Savings through Speed Control The power consumption of a blower or pump follows the "Cube Law", which means that by reducing the speed to 80% of the maximum value the power consumption will be reduced to about 50%. Improved Power Factor A Variable Frequency Drive offers a fundamental power factor of near unity at all loads and speeds and hence no Power Factor Correction (PFC) capacitors are required. Added to that is the advantage of substantial restriction on the Reactive Power drawing thus avoiding penalties from the electric supply company.
  55. 55. Affinity Laws governing fluid flow The characteristics of centrifugal equipment such as blowers and pumps vis-à-vis flow can be explained by the following basic equations: Flow is proportional to speed (F α N) Pressure is proportional to square of speed (P α N2) Therefore Power = F × P α N3 From the above equations it can be very easily concluded that while at the maximum flow with 100% speed the power consumption is 100%, at 50% flow with corresponding speed of 50% the power consumed is just 12.5%. A small reduction in speed therefore produces a very significant reduction in power consumption.
  56. 56. Reduction in mechanical wear and tear When a HVAC installation no longer runs at full speed additional benefits apart from those related to energy savings are available: • Increased lifetime of belt drive on fans. • With soft start/stop there is less wear and tear on bearings. • Some VFDs have automatic belt monitoring, which increases intervals between maintenance • No more jammed guide vanes/dampers. • Lower noise levels. • On pumps, fitting a VFD will result in eliminating water hammer during start/stop situations. Increased Comfort Level As a byproduct of the energy savings from reducing fan speeds, acoustic air movement noise from the fan is also reduced. Noise from fans in a quiet environment can be very annoying. If a fan sized for full occupancy is supplying a partly occupied room, the acoustic noise level can be as high as 70 dbA. The noise level will vary depending on the throttling with dampers or guide vanes. More the throttling, greater is the noise.
  57. 57. Line and Load Reactors Essentially a reactor is an inductor. Use a reactor:  To add Line Impedance.  To provide some voltage buffering against low magnitude line spikes.  To reducing Harmonics (When no link choke is present).  To compensating for a low inductance motor.  Only as part of a filter for reflected wave reduction.
  58. 58. PLC (programable logic controller) PLC Systems are designed to replace relay based logic controls . Interface Module (used for communication between different racks)
  59. 59. PLC (programable logic controller) Communication Processor module (used for conversion between different protocols). e.g to convert ethernet communication protocol to RS485 protocol diagram shows a very oversimplified diagram of the structure
  60. 60. HMI (human machine interfaces) SIMENS WinCC Flexible was used to program the HMIs . It has a Touch Screen to get the inputs and states for running the machine . It also shows outputs of different digital and analogue sensors for giving feedback status to the controller.
  61. 61. DCS (distributed control system) Due to large system and huge no of analogue inputs and outputs , it uses DCS System , which is very user friendly and Aids a lot to process engineers . DCS System have CPUs , Aspect Servers , Domain Servers ,Connectivity Servers .
  62. 62. Vaccum Circuit Breaker This is 11kV circuit breaker which has motorised (for charging) spring for making contacts and breaker has mechanical latching system for keeping the contacts closed after once contacted till the reset .
  63. 63. My Opinion Over All • Different than I thought • Lots of hands on experience • Learnt a lot • Figuring out I can be more good at some things than I thought • Getting better at many skills I considered myself to already have
  64. 64. Aditional Skills I’ve Improved: • Multi-tasking skills • Time management skills • Computer skills (Word, Power point) • Social media skills • Note taking • Research
  65. 65. Conclusion
  66. 66. First venture in Electronics , surely not the last This was a landmark experience within a young, dynamic and ambitious firm I learnt a lot on team-working and gained confidence throughout these 2 months. I pride myself on having worked on high profile engineering projects + Living at guest house helped me during my stint Thank you to the whole team @Century
  67. 67. A Special Thank you General Manager (Mr. Nadeem ullah ) Assistant Manager (Mr. Tahir ) Mr . Habib ur Rehman , Mr. Azhar , Mr.Imran , Mr. Talha , Mr . Faizan and to the whole team @ pm7 For so much kind help in all aspects .