This document provides a summary of a professional development seminar on generator sizing pitfalls and how to avoid problems. The seminar addressed 10 key points, including the limitations of traditional sizing programs, load uncertainty, leading power factors, managing motor starting transients, harmonics, and other challenges. It emphasizes recognizing sizing program limitations, using historical load data when available, and addressing leading power factors and motor starting transients to properly size generators.
This document summarizes a seminar on generator sizing pitfalls and how to avoid problems. It discusses limitations of traditional sizing programs, uncertainties in sizing new loads, and issues caused by leading power factors, motor starting transients, reduced voltage starting, and harmonics from non-linear loads. The seminar provides guidance on properly accounting for these factors and selecting generator components that can manage voltage and frequency dips during large load transients.
Wind farm owners and operators are beginning to realize the need for managing the critical infrastructure of their wind projects. They are confronted with several challenges including expired OEM warranties, software vendors dropping support for their products that have reached end of life, and higher protection requirements from the security sector.
In order to meet these new demands and address the challenges, owners are opting to virtualize their SCADA/critical infrastructure. The Virtualization option results in less hardware for the technical staff to support, higher availability, and improved disaster recovery options.
View this webinar to learn:
– To learn the benefits of SCADA/critical infrastructure virtualization
-Why virtualization is becoming an option for wind farm owners/operators
-What the current challenges are for managing SCADA and server infrastructure
controltrix - we make control solutions easieranusheel nahar
We provide Research and development services in power electronics, motor drives and control system domain. We have decades of experience in solving challenging technical problems. Leverage our expertise and get solution to your problems.
For more details visit controltrix.com
This document from Operation Technology, Inc. provides an overview of arc flash hazards and guidelines for performing arc flash studies and calculations. The key points covered include: the causes and effects of arc flash incidents; relevant industry standards like IEEE 1584 and NFPA 70E; OSHA regulations regarding electrical safety; and the steps involved in performing an accurate arc flash study, including system modeling, short circuit analysis, and protective device coordination. Proper execution of an arc flash study requires thorough field verification of equipment and settings.
The document discusses challenges with current rule-based approaches to elasticity management in cloud applications and proposes a decentralized autonomous solution. It notes that rule-based systems require defining optimal thresholds upfront and do not scale well to large applications. The proposed approach uses reinforcement learning to allow instances to autonomously share load during critical events without a centralized controller. This could enable better placements of applications across instances and more efficient scaling decisions in dynamic cloud environments.
Using Six Sigma to Optimize Performance and ReliabilityTimothy Williams
This document discusses how John Deere used Six Sigma and Design for Six Sigma (DFSS) principles to optimize the performance and reliability of ground speed sensors on its tractors. It describes modeling the sensor system to better understand sources of error and improve design. It also details how vibration testing and the physics of failure approach helped identify an intermittent failure mechanism in some radar sensors caused by loose connections, and how implementing a spring clip solved the problem. The document shows how these quality improvement methods enhanced system design and understanding.
This document summarizes a seminar on generator sizing pitfalls and how to avoid problems. It discusses limitations of traditional sizing programs, uncertainties in sizing new loads, and issues caused by leading power factors, motor starting transients, reduced voltage starting, and harmonics from non-linear loads. The seminar provides guidance on properly accounting for these factors and selecting generator components that can manage voltage and frequency dips during large load transients.
Wind farm owners and operators are beginning to realize the need for managing the critical infrastructure of their wind projects. They are confronted with several challenges including expired OEM warranties, software vendors dropping support for their products that have reached end of life, and higher protection requirements from the security sector.
In order to meet these new demands and address the challenges, owners are opting to virtualize their SCADA/critical infrastructure. The Virtualization option results in less hardware for the technical staff to support, higher availability, and improved disaster recovery options.
View this webinar to learn:
– To learn the benefits of SCADA/critical infrastructure virtualization
-Why virtualization is becoming an option for wind farm owners/operators
-What the current challenges are for managing SCADA and server infrastructure
controltrix - we make control solutions easieranusheel nahar
We provide Research and development services in power electronics, motor drives and control system domain. We have decades of experience in solving challenging technical problems. Leverage our expertise and get solution to your problems.
For more details visit controltrix.com
This document from Operation Technology, Inc. provides an overview of arc flash hazards and guidelines for performing arc flash studies and calculations. The key points covered include: the causes and effects of arc flash incidents; relevant industry standards like IEEE 1584 and NFPA 70E; OSHA regulations regarding electrical safety; and the steps involved in performing an accurate arc flash study, including system modeling, short circuit analysis, and protective device coordination. Proper execution of an arc flash study requires thorough field verification of equipment and settings.
The document discusses challenges with current rule-based approaches to elasticity management in cloud applications and proposes a decentralized autonomous solution. It notes that rule-based systems require defining optimal thresholds upfront and do not scale well to large applications. The proposed approach uses reinforcement learning to allow instances to autonomously share load during critical events without a centralized controller. This could enable better placements of applications across instances and more efficient scaling decisions in dynamic cloud environments.
Using Six Sigma to Optimize Performance and ReliabilityTimothy Williams
This document discusses how John Deere used Six Sigma and Design for Six Sigma (DFSS) principles to optimize the performance and reliability of ground speed sensors on its tractors. It describes modeling the sensor system to better understand sources of error and improve design. It also details how vibration testing and the physics of failure approach helped identify an intermittent failure mechanism in some radar sensors caused by loose connections, and how implementing a spring clip solved the problem. The document shows how these quality improvement methods enhanced system design and understanding.
The document outlines 11 steps for sizing a pipe line to carry water at 100 m3/hr, including: calculating the internal pipe diameter, selecting the nearest available pipe size, determining the fluid velocity, calculating the Reynolds number and friction factor, determining equivalent length, calculating pressure drop, and comparing the available and calculated pressure drops. The goal is to select a pipe size that ensures the available pressure drop is greater than the calculated pressure drop.
This document discusses power factor, which is a measure of how effectively electrical equipment converts power into useful output. A lower power factor is caused by inductive loads that require reactive power. It is important to improve power factor to reduce utility bills, increase system capacity, and make equipment more efficient. Power factor can be corrected by adding capacitors, which generate reactive power opposing inductive loads, thereby increasing the power factor. Properly sizing and installing capacitors is an effective way for individual locations and groups to improve their power factor.
Boiler feed and pump sizing c-b and grundfos july 2016(1)lorenzo Monasca
Presentacion realizada por la empresa Cleaver Brooks y Grundfos
Pasos a seguir de como seleccionar una bomba de agua de alimentacion a una caldera de media presion.
The document discusses generator protection and distance protection. It provides setting criteria for distance protection zones when used for generator backup protection, including setting Zone 1 to 80% of the generator step-up transformer and Zone 2 to 120% of the generator step-up transformer or to overreach the remote bus. It also discusses using Zone 3 for out-of-step blocking or overreaching the remote bus for system fault backup protection.
This document provides an overview of early sizing considerations for pressure safety valves (PSVs). It discusses important terminologies, types of PSVs, sizing basis, applicable standards, and the early sizing procedure. The procedure involves selecting possible orifice areas to meet capacity requirements. The objectives of early sizing are to remove holds in piping and instrumentation diagrams and allow early release of piping designs. The document also discusses inter-discipline interfaces, lessons learned, and quality management system documents related to PSV sizing.
This document provides an overview of power factor, including:
1. It defines power factor as the ratio of working power (KW) to apparent power (KVA), and explains that low power factor is caused by high reactive power (KVAR) from inductive loads like motors and transformers.
2. Improving power factor provides benefits like lower utility bills, increased system capacity, and more efficient operation of motors.
3. Power factor can be improved by adding capacitors, which generate reactive power (KVAR) to offset the reactive power drawn by inductive loads, raising the power factor.
4. An example calculation shows that installing capacitors to improve power factor from 0.65 to 1
The document discusses the implications of load angle and excitation on generator stability. It explains that the load angle is the angle between the generator induced EMF and terminal voltage. It increases as the generator transfers power from no load to load conditions. The generator operates stably when the derivative of power with respect to load angle is positive, up to a load angle of 90 degrees. Boosting excitation can reduce the load angle and increase power output at a given load angle, as long as excitation limits are respected. The generator capability curve depicts the stability limits imposed by the load angle, rotor current, and stator current limiters.
Safety is the most important factor in designing a process system. Some undesired conditions might happen leading to damage in a system. Control systems might be installed to prevent such conditions, but a second safety device is also needed. One kind of safety device which is commonly used in the processing industry is the relief valve. A relief valve is a type of valve to control or limit the pressure in a system by allowing the pressurised fluid to flow out from the system.
Pipe corrosion is caused by several factors related to water chemistry and physical properties. Low pH, high oxygen content, carbon dioxide, and bacteria can all promote corrosion by speeding up the electrochemical oxidation process. Water temperature also affects corrosion rates, with higher temperatures generally causing faster corrosion. Physical factors like flow turbulence at locations with sudden changes in direction can lead to erosion corrosion. Galvanic corrosion can occur when dissimilar metals are in contact within the piping system. Proper material selection and water treatment can help reduce corrosion in pipe lines.
This document discusses synchronous machines and synchronous generators. It contains the following key points:
1. Synchronous machines operate at a constant synchronous speed that is determined by the electrical frequency and number of poles. They can operate as generators or motors.
2. Synchronous generators are widely used in large power applications due to their high efficiency, reliability, and ability to control power factor. They have a rotor winding supplied by DC current and a stator connected to the AC supply.
3. The internal generated voltage of a synchronous generator depends on factors like flux, speed of rotation, and field current. It can supply either lagging or leading reactive current to the system.
4. An open circuit test is
the ratio of the actual electrical power dissipated by an AC circuit to the product of the r.m.s. values of current and voltage. The difference between the two is caused by reactance in the circuit and represents power that does no useful work.
Project report on 33kv Substation and Automatic Power Factor Controller in ONGCGirish Gupta
Girish Gupta completed a summer training project at the Electrical Section of Keshav Dev Institute of Petroleum Exploration (KDMIPE), which is operated by Oil and Natural Gas Corporation (ONGC) Ltd. in Dehradun, India. The project report discusses 33kV substations and automatic power factor controllers. It provides an overview of ONGC, including its history, achievements, and role in India's oil and gas production. It also describes the key components and functions of electrical distribution systems and automatic power factor correction equipment.
The document summarizes different types of excitation systems used for synchronous generators. It describes the components and operation of static excitation systems, which are now widely used. Static excitation systems provide fast acting voltage control using thyristor bridges and power electronics. They allow high response ratios of 3-5 compared to older systems like DC excitation. The key components of a static excitation system are the rectifier transformer, SCR bridges, excitation start up equipment, field discharge equipment, and regulator/control circuits.
This document discusses power factor in electrical circuits. It defines power factor as the cosine of the angle between the voltage and current. A lagging power factor occurs when the current lags the voltage in an inductive circuit, while a leading power factor occurs when the current leads the voltage in a capacitive circuit. Low power factors can be caused by inductive loads like motors and have negative effects like increased line losses. Common methods to improve power factor include adding static capacitors, using phase advancers for motors, or installing synchronous condensers. The power triangle diagram is also used to illustrate the relationships between active power, reactive power, and apparent power as it relates to power factor.
In this day and age of automated computer control valve sizing, the logic and theories behind it are invisible. In his presentation, Al Holton of Allagash Valve & Controls will look at the basic principles that apply and how they affect the application and installation of a wide range of control valve types. He will also review the reasoning behind valve type selection.
The document contains information about pipe sizes and their corresponding water flow capacities. It provides the inner diameter (ID) and outer diameter (OD) for schedule 40 steel pipes of various sizes. It then lists the gallons per minute (GPM) and gallons per hour (GPH) that can pass through each pipe size under different pressure assumptions: low pressure/suction side of pump, average pressure of 20-100 PSI, and high/peak pressure. It also notes the potential for pressure loss and noise at higher flow rates. A second table provides GPM values corresponding to different pipe sizes and pressures in PSI.
This document provides guidance on battery sizing and discharge calculations for DC power systems. It discusses (1) when batteries are needed based on load and charger capacity, (2) definitions for battery duty cycle and sizing parameters, (3) types of loads that affect sizing, (4) guidelines for classifying and combining duty cycles, (5) modeling batteries using characteristic curves, and (6) performing battery sizing and discharge studies. The goal is to properly size batteries and understand their voltage performance over time based on the system load profile.
This document discusses the debate around whether paralleling generators is a good idea for hospital standby power systems. It provides an overview of how generator paralleling works, including the requirements and components needed. The advantages of paralleling include increased reliability if one generator fails, more flexibility, and better overall system performance compared to a single generator. While paralleling equipment adds some costs, proponents argue the reliability benefits are worth it. However, some argue hospitals could save money by not using paralleling and instead implementing load shedding of lower priority equipment in an outage. The document examines both perspectives on this issue.
Alps msi condition monitoring and reporting for onsite supportalpsmsi
This document discusses condition monitoring and reporting services provided by ALPS MSI for onsite support. It outlines the impacts of machinery vibrations, how vibrations can be prevented through vibration analysis, and ALPS MSI's approach to condition monitoring using vibration analysis similar to how ECG is used to diagnose heart problems. It then provides details on ALPS MSI's certifications, services, case studies demonstrating benefits of vibration analysis, and how reducing motor load through efficiency improvements can reduce electricity costs.
Alps msi condition monitoring and reporting for onsite supportalpsmsi
This document discusses condition monitoring and reporting services provided by ALPS MSI for onsite support. It outlines the impacts of machinery vibrations, how vibrations can be prevented through vibration analysis, and ALPS MSI's approach to condition monitoring using vibration analysis similar to how ECG is used to diagnose heart problems. It then provides details on ALPS MSI's certifications, services, case studies demonstrating benefits of vibration analysis and reducing motor load, and the potential cost savings from improved condition monitoring.
The document outlines 11 steps for sizing a pipe line to carry water at 100 m3/hr, including: calculating the internal pipe diameter, selecting the nearest available pipe size, determining the fluid velocity, calculating the Reynolds number and friction factor, determining equivalent length, calculating pressure drop, and comparing the available and calculated pressure drops. The goal is to select a pipe size that ensures the available pressure drop is greater than the calculated pressure drop.
This document discusses power factor, which is a measure of how effectively electrical equipment converts power into useful output. A lower power factor is caused by inductive loads that require reactive power. It is important to improve power factor to reduce utility bills, increase system capacity, and make equipment more efficient. Power factor can be corrected by adding capacitors, which generate reactive power opposing inductive loads, thereby increasing the power factor. Properly sizing and installing capacitors is an effective way for individual locations and groups to improve their power factor.
Boiler feed and pump sizing c-b and grundfos july 2016(1)lorenzo Monasca
Presentacion realizada por la empresa Cleaver Brooks y Grundfos
Pasos a seguir de como seleccionar una bomba de agua de alimentacion a una caldera de media presion.
The document discusses generator protection and distance protection. It provides setting criteria for distance protection zones when used for generator backup protection, including setting Zone 1 to 80% of the generator step-up transformer and Zone 2 to 120% of the generator step-up transformer or to overreach the remote bus. It also discusses using Zone 3 for out-of-step blocking or overreaching the remote bus for system fault backup protection.
This document provides an overview of early sizing considerations for pressure safety valves (PSVs). It discusses important terminologies, types of PSVs, sizing basis, applicable standards, and the early sizing procedure. The procedure involves selecting possible orifice areas to meet capacity requirements. The objectives of early sizing are to remove holds in piping and instrumentation diagrams and allow early release of piping designs. The document also discusses inter-discipline interfaces, lessons learned, and quality management system documents related to PSV sizing.
This document provides an overview of power factor, including:
1. It defines power factor as the ratio of working power (KW) to apparent power (KVA), and explains that low power factor is caused by high reactive power (KVAR) from inductive loads like motors and transformers.
2. Improving power factor provides benefits like lower utility bills, increased system capacity, and more efficient operation of motors.
3. Power factor can be improved by adding capacitors, which generate reactive power (KVAR) to offset the reactive power drawn by inductive loads, raising the power factor.
4. An example calculation shows that installing capacitors to improve power factor from 0.65 to 1
The document discusses the implications of load angle and excitation on generator stability. It explains that the load angle is the angle between the generator induced EMF and terminal voltage. It increases as the generator transfers power from no load to load conditions. The generator operates stably when the derivative of power with respect to load angle is positive, up to a load angle of 90 degrees. Boosting excitation can reduce the load angle and increase power output at a given load angle, as long as excitation limits are respected. The generator capability curve depicts the stability limits imposed by the load angle, rotor current, and stator current limiters.
Safety is the most important factor in designing a process system. Some undesired conditions might happen leading to damage in a system. Control systems might be installed to prevent such conditions, but a second safety device is also needed. One kind of safety device which is commonly used in the processing industry is the relief valve. A relief valve is a type of valve to control or limit the pressure in a system by allowing the pressurised fluid to flow out from the system.
Pipe corrosion is caused by several factors related to water chemistry and physical properties. Low pH, high oxygen content, carbon dioxide, and bacteria can all promote corrosion by speeding up the electrochemical oxidation process. Water temperature also affects corrosion rates, with higher temperatures generally causing faster corrosion. Physical factors like flow turbulence at locations with sudden changes in direction can lead to erosion corrosion. Galvanic corrosion can occur when dissimilar metals are in contact within the piping system. Proper material selection and water treatment can help reduce corrosion in pipe lines.
This document discusses synchronous machines and synchronous generators. It contains the following key points:
1. Synchronous machines operate at a constant synchronous speed that is determined by the electrical frequency and number of poles. They can operate as generators or motors.
2. Synchronous generators are widely used in large power applications due to their high efficiency, reliability, and ability to control power factor. They have a rotor winding supplied by DC current and a stator connected to the AC supply.
3. The internal generated voltage of a synchronous generator depends on factors like flux, speed of rotation, and field current. It can supply either lagging or leading reactive current to the system.
4. An open circuit test is
the ratio of the actual electrical power dissipated by an AC circuit to the product of the r.m.s. values of current and voltage. The difference between the two is caused by reactance in the circuit and represents power that does no useful work.
Project report on 33kv Substation and Automatic Power Factor Controller in ONGCGirish Gupta
Girish Gupta completed a summer training project at the Electrical Section of Keshav Dev Institute of Petroleum Exploration (KDMIPE), which is operated by Oil and Natural Gas Corporation (ONGC) Ltd. in Dehradun, India. The project report discusses 33kV substations and automatic power factor controllers. It provides an overview of ONGC, including its history, achievements, and role in India's oil and gas production. It also describes the key components and functions of electrical distribution systems and automatic power factor correction equipment.
The document summarizes different types of excitation systems used for synchronous generators. It describes the components and operation of static excitation systems, which are now widely used. Static excitation systems provide fast acting voltage control using thyristor bridges and power electronics. They allow high response ratios of 3-5 compared to older systems like DC excitation. The key components of a static excitation system are the rectifier transformer, SCR bridges, excitation start up equipment, field discharge equipment, and regulator/control circuits.
This document discusses power factor in electrical circuits. It defines power factor as the cosine of the angle between the voltage and current. A lagging power factor occurs when the current lags the voltage in an inductive circuit, while a leading power factor occurs when the current leads the voltage in a capacitive circuit. Low power factors can be caused by inductive loads like motors and have negative effects like increased line losses. Common methods to improve power factor include adding static capacitors, using phase advancers for motors, or installing synchronous condensers. The power triangle diagram is also used to illustrate the relationships between active power, reactive power, and apparent power as it relates to power factor.
In this day and age of automated computer control valve sizing, the logic and theories behind it are invisible. In his presentation, Al Holton of Allagash Valve & Controls will look at the basic principles that apply and how they affect the application and installation of a wide range of control valve types. He will also review the reasoning behind valve type selection.
The document contains information about pipe sizes and their corresponding water flow capacities. It provides the inner diameter (ID) and outer diameter (OD) for schedule 40 steel pipes of various sizes. It then lists the gallons per minute (GPM) and gallons per hour (GPH) that can pass through each pipe size under different pressure assumptions: low pressure/suction side of pump, average pressure of 20-100 PSI, and high/peak pressure. It also notes the potential for pressure loss and noise at higher flow rates. A second table provides GPM values corresponding to different pipe sizes and pressures in PSI.
This document provides guidance on battery sizing and discharge calculations for DC power systems. It discusses (1) when batteries are needed based on load and charger capacity, (2) definitions for battery duty cycle and sizing parameters, (3) types of loads that affect sizing, (4) guidelines for classifying and combining duty cycles, (5) modeling batteries using characteristic curves, and (6) performing battery sizing and discharge studies. The goal is to properly size batteries and understand their voltage performance over time based on the system load profile.
This document discusses the debate around whether paralleling generators is a good idea for hospital standby power systems. It provides an overview of how generator paralleling works, including the requirements and components needed. The advantages of paralleling include increased reliability if one generator fails, more flexibility, and better overall system performance compared to a single generator. While paralleling equipment adds some costs, proponents argue the reliability benefits are worth it. However, some argue hospitals could save money by not using paralleling and instead implementing load shedding of lower priority equipment in an outage. The document examines both perspectives on this issue.
Alps msi condition monitoring and reporting for onsite supportalpsmsi
This document discusses condition monitoring and reporting services provided by ALPS MSI for onsite support. It outlines the impacts of machinery vibrations, how vibrations can be prevented through vibration analysis, and ALPS MSI's approach to condition monitoring using vibration analysis similar to how ECG is used to diagnose heart problems. It then provides details on ALPS MSI's certifications, services, case studies demonstrating benefits of vibration analysis, and how reducing motor load through efficiency improvements can reduce electricity costs.
Alps msi condition monitoring and reporting for onsite supportalpsmsi
This document discusses condition monitoring and reporting services provided by ALPS MSI for onsite support. It outlines the impacts of machinery vibrations, how vibrations can be prevented through vibration analysis, and ALPS MSI's approach to condition monitoring using vibration analysis similar to how ECG is used to diagnose heart problems. It then provides details on ALPS MSI's certifications, services, case studies demonstrating benefits of vibration analysis and reducing motor load, and the potential cost savings from improved condition monitoring.
Marc provides a North American perspective on hybrid energy systems, using the Nome Joint Utilities Systems of Nome, Alaska, as a case study. Marc introduces the ACEP facilities and discusses a collaborative approach, as demonstrated by the successful R&D and testing campaign integrating an energy storage flywheel with a power conversion and control system (Hatch Engineering, Williams Hybrid Power and ABB)
Alps msi condition monitoring and reporting for onsite supportalpsmsi
Condition monitoring of motors at a water utility identified a motor operating at 93.44% load instead of the rated 75% load. This resulted in excess electricity consumption of PHP 3.5 million per year. Reducing the motor load through rewinding and balancing lowered consumption and saved on electricity costs. Regular condition monitoring helps identify equipment issues and optimize operations to improve reliability and reduce energy wastage.
Narendra Charola has over 9 years of experience as an Electrical Manager at Reliance Industries Limited in Jamnagar, India. He leads a group of electrical engineers responsible for the smooth running of the crude complex, which includes two identical 325,000 barrels per day crude oil processing trains. His responsibilities include maintenance of the electrical systems and protection relays, planning and execution of maintenance activities, and ensuring plant reliability. He has experience in commissioning new projects, shutdown planning, and safety management. Narendra holds a Bachelor's degree in Electrical Engineering and has received training in areas such as process safety management, power systems, and electrical equipment.
This document discusses sales opportunities in protective relaying by upgrading from electromechanical relays to microprocessor relays. Some key opportunities include:
1) Upgrading provides customers benefits like less testing requirements, improved compliance, usability, and troubleshooting capabilities.
2) Service companies benefit from markup on the relays, engineering, commissioning, and testing labor required for upgrades.
3) Upgrading to arc flash relays provides additional customer safety benefits and opportunities for service companies to take on switching contracts and studies.
4) Regular firmware upgrades provide benefits to customers and opportunities for service work.
This document discusses options for data center owners and operators to consider when their aging infrastructure may no longer meet current or future needs. As digital traffic and the internet of things continue to grow rapidly, data center infrastructure is facing unprecedented challenges. The document outlines various strategies to evaluate such as tuning up existing facilities, targeted modernization of critical components, adopting pod-based architectures, and building new infrastructure to right-size capacity. Each option involves analyzing business needs, costs, efficiency gains, and potential downtime to determine the best path forward.
Presentation from the EPRI-Sandia Symposium on Secure and Resilient Microgrids: Micro grid design: Considerations & interconnection studies, presented by Mobolaji Bello, EPRI, Baltimore, MD, August 29-31, 2016.
When designing generator systems, consulting engineers must ensure that the generators and the building electrical systems that they support are appropriate for the specific application. Whether providing standby power for health care facilities or prime power for rural processing plants, engineers must make decisions regarding generator sizing, load types, whether generators should be paralleled, fuel storage, switching scenarios, and many other criteria. In addition to being up to speed on the applicable codes, consulting engineers must work with the authorities having jurisdiction (AHJ) to ensure approval for the generator system is attained.
Results of DigitArc Electrode Regulator and SmartArc power input optimization...AMI GE International
The document summarizes a project between North Star Steel and AMI-GE to optimize the DC electric arc furnace at North Star Steel's plant in St. Paul, Minnesota. The project involved installing AMI-GE's Digitarc regulator and SmartArc software. This led to a 13% reduction in energy consumption, a 14% reduction in electrode consumption, and other operational improvements. The optimizations exceeded initial goals and have provided ongoing benefits to North Star Steel's steelmaking processes.
1. Different tools use different descriptions for power management, making it difficult to verify configurations and keep definitions consistent across the design flow.
2. There is no automation for verifying power management definitions, requiring designers to manually verify thousands of statements.
3. The design hierarchy and syntax varies between tools and between RTL and gate representations, complicating cross-checking.
4. It is challenging to verify power functionality without changing RTL code since power and ground nets are not explicitly captured or simulated.
1. Power functionality cannot be easily verified without changing RTL code since power domains and constraints are not represented consistently across the design flow.
2. Tools from different vendors use different specifications for power management, making end-to-end verification and signoff difficult.
3. Constraints and intent for low power techniques like multi-VT, power gating, and DVFS cannot be validated without a common representation.
How to Start your Large Motors- typical Solutions or new motor design?Delcho Penkov
In the context of low oil prices and an increasing demand for cost reduction of the electrical installations, optimizing the starting solution of high power electrical motors could be highly contributive. Direct on-line start is the most common solution today, being also the simplest and most cost-effective but it may generate voltage dip during start and stresses mechanically the machine and load. Progressive starting solutions, as auto-transformer, soft-starter or variable speed drive, solve the electrical and mechanical constraints in variable levels, related to their complexity. Today, in addition to the progressive starting solutions, motor manufacturers propose to design the motors as to reduce their inrush current, in some cases down to 300% of the rated current.
In this tutorial different solutions for large motor starting will be explored and compared, with respect to their application field, flexibility of adaptation, complexity during installation and set-up, overall performances and technical and economical aspects. Some guidelines for selection will be also discussed. In the scope of analyses are traditional methods, such as direct on-line, auto-transformer, soft-starter and variable speed drive and also recent solutions as motors designed with reduced inrush current.
This document discusses power factor and methods for improving it. It defines power factor as the ratio of active power to apparent power. Low power factor is caused by inductive devices and indicates inefficient electricity use. Correcting power factor through capacitors can provide benefits like increased plant capacity and reduced utility charges. Capacitors work by opposing inductive lagging current. They can be installed at individual equipment, equipment groups, or at the main service, with various tradeoffs to consider. Harmonic distortion from devices like variable speed drives can also impact power quality if not properly addressed.
Leveraging Open Source Power Measurement Standard SolutionBayLibre
A major issue the community faces is the lack of power measurement (PM) instrumentation, coupled with poor integration: development boards not designed for it, expensive high-precision lab equipment not accessible to hobbyists (plus limited Linux support), limited low-cost solutions (precision, sampling rate) to monitor high-performance SoC (System On Chips) platforms (e.g. smartphones, tablets, IoT, …). After a brief introduction to the problematic (PM techniques, sense resistor / ADC selection, ...) and a comparative study of existing solutions, this presentation will focus on a new initiative to close these gaps and bring a full-blown multi-channel but low-cost power (and temperature) measurement equipment to the community, including the definition of an open standard PM connector. It will cover motivations, challenges and key decisions.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/how-axelera-ai-uses-digital-compute-in-memory-to-deliver-fast-and-energy-efficient-computer-vision-a-presentation-from-axelera-ai/
Bram Verhoef, Head of Machine Learning at Axelera AI, presents the “How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-efficient Computer Vision” tutorial at the May 2024 Embedded Vision Summit.
As artificial intelligence inference transitions from cloud environments to edge locations, computer vision applications achieve heightened responsiveness, reliability and privacy. This migration, however, introduces the challenge of operating within the stringent confines of resource constraints typical at the edge, including small form factors, low energy budgets and diminished memory and computational capacities. Axelera AI addresses these challenges through an innovative approach of performing digital computations within memory itself. This technique facilitates the realization of high-performance, energy-efficient and cost-effective computer vision capabilities at the thin and thick edge, extending the frontier of what is achievable with current technologies.
In this presentation, Verhoef unveils his company’s pioneering chip technology and demonstrates its capacity to deliver exceptional frames-per-second performance across a range of standard computer vision networks typical of applications in security, surveillance and the industrial sector. This shows that advanced computer vision can be accessible and efficient, even at the very edge of our technological ecosystem.
Have you ever been confused by the myriad of choices offered by AWS for hosting a website or an API?
Lambda, Elastic Beanstalk, Lightsail, Amplify, S3 (and more!) can each host websites + APIs. But which one should we choose?
Which one is cheapest? Which one is fastest? Which one will scale to meet our needs?
Join me in this session as we dive into each AWS hosting service to determine which one is best for your scenario and explain why!
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
"Frontline Battles with DDoS: Best practices and Lessons Learned", Igor IvaniukFwdays
At this talk we will discuss DDoS protection tools and best practices, discuss network architectures and what AWS has to offer. Also, we will look into one of the largest DDoS attacks on Ukrainian infrastructure that happened in February 2022. We'll see, what techniques helped to keep the web resources available for Ukrainians and how AWS improved DDoS protection for all customers based on Ukraine experience
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
Dandelion Hashtable: beyond billion requests per second on a commodity serverAntonios Katsarakis
This slide deck presents DLHT, a concurrent in-memory hashtable. Despite efforts to optimize hashtables, that go as far as sacrificing core functionality, state-of-the-art designs still incur multiple memory accesses per request and block request processing in three cases. First, most hashtables block while waiting for data to be retrieved from memory. Second, open-addressing designs, which represent the current state-of-the-art, either cannot free index slots on deletes or must block all requests to do so. Third, index resizes block every request until all objects are copied to the new index. Defying folklore wisdom, DLHT forgoes open-addressing and adopts a fully-featured and memory-aware closed-addressing design based on bounded cache-line-chaining. This design offers lock-free index operations and deletes that free slots instantly, (2) completes most requests with a single memory access, (3) utilizes software prefetching to hide memory latencies, and (4) employs a novel non-blocking and parallel resizing. In a commodity server and a memory-resident workload, DLHT surpasses 1.6B requests per second and provides 3.5x (12x) the throughput of the state-of-the-art closed-addressing (open-addressing) resizable hashtable on Gets (Deletes).
Fueling AI with Great Data with Airbyte WebinarZilliz
This talk will focus on how to collect data from a variety of sources, leveraging this data for RAG and other GenAI use cases, and finally charting your course to productionalization.
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
1. PROFESSIONAL
DEVELOPMENT
Welcome to GPS 100
SEMINAR
SERIES Generator Sizing Pitfalls
“Avoid the Pain”
Bob Colum
Pete Happ
Huntington Power
Generator Sizing Pitfalls
“Avoid the Pain”
2. Ten Points of Sizing Pain
1. Limitations of Traditional Sizing Programs
2. Load Uncertainty in New Construction
3. Leading Power Factor Problems
4. Managing Motor Starting Transients
5. Avoiding Reduced Voltage Surprises
6. Planning for Harmonics
7. IGBT Rectification Surprises
8. Soft Starters
9. VFDs and Regeneration – Elevators & Cranes
10. UPS Sizing
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 2
3. 1) Traditional Sizing Program Limitations
• What traditional generator sizing programs do well
– Analyze a few discrete loads
– Analyze a transient load with given pre-load (like a motor start)
• Can traditional generator sizing programs accurately size generators?
– No, why:
Entering a complete load list assumes all loads are energized
– Most programs don’t support multiple load diversity factors
Entering too many loads in a single load step creates a “false” condition
– Most loads sequence naturally with limited concurrent starting
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 3
4. 1) Traditional Sizing Program Limitations
• Common limitations of traditional generator sizing programs
– Most programs don’t accurately model and analyze non-linear loads
Non-linear loads require harmonic analysis
Simple rule of thumb multipliers are not adequate
– Soft starter sizing varies significantly based on starter configuration
Transient conditions and harmonic content change
Most sizing programs treat all soft starters the same
– UPS sizing needs to be based on the technology of the UPS
UPS technology significantly varies generator sizing
• Sizing programs need to be smarter to match today’s technical
loads and devices
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 4
5. 2) Load Uncertainty – New Construction
• What types of loads will be connected?
– Resistive
– Motor Loads
– Non-Linear
• What is the anticipated load level (new construction)?
– Often services are sized conservatively (actual loads of 50% are not uncommon)
– Typically, the generator is sized less robust than the service
• What circuits are going to be connected?
– End users often want a large load list initially
– THEN DECIDE: What loads are essential & what are optional?
• New construction should be sized using engineering judgment
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 5
6. 2) Load Uncertainty – Load Growth
• What is the expected load growth?
– Does the end user have an aggressive growth plan?
– How certain is the business model?
– What is the value of different capital expenditures?
• Would the end user benefit from an expandable solution?
– Is paralleled generation an option?
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 6
7. 2) Load Uncertainty – Transient Loads
• What are the largest load steps on the generator?
– Starting large motor loads can challenge system sizing
• What are the acceptable transient limits?
– Generators are not infinite sources
– Expect voltage & frequency dips
– Size for total power and transient performance
Size based upon largest load step while powering the building
For general (non-dedicated) loads, limit the voltage dip to 20%
For general (non-dedicated) loads, limit the frequency dip to 5 to 10%
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 7
8. 2) Load Uncertainty – Existing Facilities
• Billing History
– Demand charges (capture peak kW)
Captures seasonality & business cycles
Peak power over 15 minute average
Compare summer to winter peaks = Air conditioning
• Power Analyzer
– Snapshot / short history (measures transient spikes)
– Capture power quality
Harmonic content
Power factor
• Existing facilities should utilize historical & measurement data
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 8
9. 3) Leading Power Factor (PF)
• Generators are rated for .8 pf (lagging) to 1.0 pf
• Leading power factor can cause self excitation resulting in
– Voltage instability
– Over-voltage shutdowns
• Sources of leading power factor
– Power factor correction capacitors at the service
– Lightly loaded (less than 30%) UPS’s with filtering -CHANGES
• If power factor is leading
– Remove the leading power factor elements
– Add offsetting lagging power factor loads
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 9
10. Key Point Summary
• Recognize the limitations of the sizing program you utilize
– Be cautious of entering too many loads into a single load step
• When sizing a building
– Matching the service size will often oversize the generator
– Use billing history & actual data (when available)
– Consider expandable, paralleled solutions if load growth is uncertain
• Leading power factor can cause generator voltage issues
– Utility power factor correction must be disabled while on generator
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 10
11. PROFESSIONAL
DEVELOPMENT
SEMINAR
SERIES
Motor Starting
Generator Sizing Pitfalls
“Avoid the Pain”
12. 4) Motor Starting Transients
Alternator Engine
- Starting kVA - Starting kW
- Voltage dip - Frequency dip
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 12
13. 4) Motor Starting Transients (starting kVA)
• Starting KVA is a function of motor speed
This graphic shows the
skVA requirements for a
typical “across-the-line”
motor start.
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 13
14. 4) Motor Starting Transients (starting kVA)
• What happens when a contactor closes to start an electric motor?
– Immediate inrush of current
– Inrush is referenced as:
Locked rotor current
Inrush current
Motor starting current
Start kVA
– 100 hp, 480 VAC example
Exact skVA required to start the motor =623
Note: “s” indicates the motors starting period
“r” indicates the motors running period
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 14
15. 4) Motor Starting Transients (starting kVA)
• Starting codes
– Determines skVA
– NEMA standard
Always check motor plate for NEMA Code
• Example:
– 100hp x 6.0 skVA/hp = 600 skVA
(Code G Motor)
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 15
16. 4) Motor Starting Transients (Starting Codes)
• Starting codes
– Three phase
Typically have a NEMA starting code
– Single phase
May not have a NEMA starting code
Starting kVAs vary broadly
– IEC vs. NEMA
European motors (IEC) typically have higher starting currents
– High efficiency
High efficiency motors have higher starting currents
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 16
17. 4) Motor Starting Transients (alternator response)
• Each line is the response for successively larger motors
– Point B represents the suggested alternator maximum capability limit
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 17
18. 4) Motor Starting Transients (alternator response)
• Operating beyond 35% voltage dips
– Typically results in collapsing the alternator output voltage
– Often resulting in application issues (motor contactors dropping out)
– Only one manufacturer uses this measurement (–CAT actually rejects this in their spec)
35% Instantaneous
90% Sustained
100% Recovery
Recovery
Voltage Safe Zone
35% 50%
skVA
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 18
19. 4) Motor Starting Transients (alternator response)
• Why does the alternator voltage dip?
– Ohm’s law : V = IR
• How do we minimize the voltage dip?
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 19
20. 4) Motor Starting Transients (alternator response)
• Improve motor starting
– Minimize X “d (generator reactance)
Upsize the Alternator
Rule of Thumb Formula
100hp x 6.0 skVA /hp = 600 skVA
Vdip 35% 25% 20% 10%
Alternator
Model
175 230 275 750
Minimize voltage dip by upsizing alternator
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 20
21. 4) Motor Starting Transients (engine response)
• How does the engine respond to motor starting?
– Frequency dips
Level of dip is engine size, type, and technology dependant
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 21
22. 4) Motor Starting Transients (engine response)
• Why does the engine speed dip during a motor start?
– PF = kW/kVA
skW = skVA x sPF
– Example of skW (Start kW)
100 hp x 6.0 (skVA/hp) = 600 skVA
600 skVA x .3 sPF = 180 skW
– Starting PF
Function of motor size & design
Typical three phase 1000hp~5hp (.25 to .45)
Increases when kVA decreases
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 22
23. 4) Motor Starting Transients (engine response)
• Engine speed (frequency)
– Frequency will dip
– kWstarting = 2 x motor hp (conservative estimate for across line starting)
• Engine performance
– 10 hertz dip @ 100% load step (average diesel performance)
• Load acceptance
– Most loads are tolerant of frequency dips
– Some loads are not
Be careful with some UPS technologies (more on UPS systems later in presentation)
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 23
24. 4) Motor Starting Transients (rules of thumb)
• Alternator
– skVA =̃̃ hp x 6.0
– rkVA =̃̃ hp
• Engine
– skW =̃̃ hp x 2
– rkW =̃̃ hp x .85
EXCEPTIONS: SPECIALTY MOTORS
Submersible Pumps
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 24
25. 4) Motor Starting Transients (exercise)
• If these three motors are at a pump station, which would
you start first?
– 50hp, 100hp, 200hp
• Exercise 1 (start sequence 200hp, 100hp, 50hp)
• Exercise 2 (start sequence 50hp, 100hp, 200hp)
• Exercise 3 (start all the motors simultaneously)
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 25
26. 4) Motor Starting Transients (exercise)
Example 1 Start sequence – 200hp 1st, 100hp 2nd, 50hp 3rd
Start 200hp x 2 = 400 skW (need 400 kW genset minimum)
Run 200hp x .85 = 170 rkW (preload for next load step)
Start 100hp x 2 = 200 skW + 170 rkW = 370 skW (400 kW genset is still enough)
Run 300hp total x .85 = 255 rkW (preload for next step)
Start 50hp x 2 = 100 skW + 255 rkW = 355 skW (400 kW engine)
To determine alternator size for voltage dip
assume skVA = 6 x hp = 6 x 200hp = 1200 skVA
To determine voltage dip, use alternator motor starting table / specs
Recommended Size 400 kW
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 26
27. 4) Motor Starting Transients (exercise)
Example 2 Start sequence – 50hp 1st, 100hp 2nd, 200hp 3rd
Preload of 150hp x .85 = 130 rkW (approximately)
Start 200hp x 2 = 400 skW + 130 rkW = 530 skW (500 or 600 kW genset)
Recommended Size 500-600 kW
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 27
28. 4) Motor Starting Transients (exercise)
Example 3 Start sequence - all three instantaneously
Start 350hp x 2 = 700 skW
Recommended Size 700 kW
Load sequence impacts generator sizing!!
An accurate sizing program will support load steps
that assume natural load sequencing as well as the
traditional concurrent starting load step process.
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 28
29. 5) Reduced Voltage Starting
• Electro-Mechanical reduced voltage starters
– Reduce voltage & current
– Significantly reduce skVA & skW
– Also reduce starting torque
Starting % volts
Method at motor % skVA % LR Torque
Full Voltage 100 100 100
Autotrans.
80% tap
80 64 64
65% tap 65 42 42
50% tap 50 25 25
Star-Delta 57 33 33
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 29
30. 5) Reduced Voltage Starting
• What happened at 75% speed? (motor switches to full voltage -- early)
– What will happen to the alternator?
– What is the assumption inside most sizing programs?
– This effect is typically problematic only in single motor load applications.
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 30
31. Key Point Summary
• Starting motors cause significant transients
– Voltage and frequency dips
– The generator is not an infinite source, like the utility
• Reduced voltage starters may significantly reduce transients
– Motor must reach full speed before transitioning to full voltage
– If transition occurs early, size for across the line motor start
• NEMA starters can handle up to about 30% VD
• Solid state starters may reset if VD is >15%
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 31
33. 6) Harmonics
• A non-linear load is often one of the following:
– Computers, UPS, VFD, battery chargers
– AC converting to DC
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 33
34. 6) Harmonics
• How does a non-linear load affect a generator?
– It causes harmonic voltage distortion (THVD)
– This is 10% voltage distortion – max. recommended limit of IEEE 519
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 34
35. 6) Harmonics
• Why are generators affected?
– Load generates harmonic currents
Harmonic currents flow through the alternator’s source impedance
Ohm’s Law: V = I x R or THVD ∝ XIId x IH
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 35
36. 6) Harmonics
• How to minimize harmonics to acceptable levels?
– Active or passive filtering
– Upsizing the alternator (minimize the source impedance – x”d)
– Rules of thumb for typical 6 pulse, unfiltered loads (35% THID)
Upsize the alternator (2 to 2.5 x non-linear load @ 480V)
Upsize the alternator (3 to 3.5 x non-linear load @ 208V)
Upsize the alternator (5 x for small single phase units)
– Rules of thumb for typical 6 pulse, filtered loads (10% THID)
No upsized alternator required
– Rules of thumb vary significantly based on:
The device’s harmonic current level
Size & voltage of the alternator
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 36
37. 6) Harmonics
• Don’t rely heavily on “Rules of Thumb” for harmonic loads
Rely on harmonic analysis
– Inputs are harmonic current spectrum and alternator reactance
– Output is an estimated voltage distortion
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 37
38. 7) IGBT Rectifiers
• A new type of rectifier is appearing in drives & UPSs
– IGBT (Insulated Gate Bipolar Transistor) technology
– Active power factor correction (.99 pf)
– Spec’d as very low distortion
6 Pulse
12 Pulse
IGBT
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 38
39. 7) IGBT Rectifiers
• BE AWARE
• Noise problem when IGBT is the only load on generator
– Connecting other loads solves the problem (15 – 20% of device rating)
– We have seen this with multiple suppliers (UPS & Drives)
IGBT UPS with Same UPS with
no other load on generator additional load on generator
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 39
40. Key Point Summary
• Generators must be sized based on harmonic content
– Sizing impacted by alternator size & voltage
– Sizing impacted by the characteristics of non-linear load
– Harmonic analysis approach is better than rules of thumb
• IGBT technology adds a new concern to harmonic sizing
– Other loads may be necessary
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 40
41. PROFESSIONAL
DEVELOPMENT
SEMINAR
SERIES
Soft Starters
&
Variable Frequency Drives
(VFD)
Generator Sizing Pitfalls
“Avoid the Pain”
42. 8) Soft Starters
• Soft starters are an electronic, reduced voltage motor starter
– They produce harmonics during the starting phase only
– Distortion levels are impacted by current limit setting
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 42
43. 8) Soft Starters
• Harmonics (alternator sizing)
– At 300% current limit, estimated distortion is 30 % THID
The minimum alternator size is 2 to 3 times the largest motor being started
Higher current limit settings will require a larger alternator
Harmonic analysis is preferred to using “rules of thumb”
– Sequence start when possible
Harmonics are only present during the starting phase
– Soft starters are typically factory defaulted to 425% current limit results in
harmonic current distortion of +40% during starting. Turning the current
limit setting down to 300% can help minimize harmonic issues.
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 43
44. 8) Soft Starters
• Soft starters can ramp-up voltage or step voltage
– To avoid voltage & frequency dips always enable voltage ramping
– Voltage ramping creates a soft loading of the generator
– If no voltage ramping is utilized, expect transients as listed below
– CAREFUL: Siemens elevator starters do not support voltage ramping
Current Limit skVA skW
200% 2 x Hp .12 x Hp
300% 3 x Hp .45 x Hp
400% 4 x Hp .8 x Hp
500% 5 x Hp 1.25 x Hp
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 44
45. 9) VFDs & Regeneration
• Variable Frequency Drives (VFDs)
– VFD is seen as a rectifier by the generator
• Generator sizing for VFDs
– Voltage & frequency transients are not an issue
– Harmonics are an issue
Harmonics are always present
Size as if a non-linear load
Limit system voltage dips to 15%
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 45
46. 9) VFDs & Regeneration
• Cable elevators and cranes regenerate
– When the load is going down, the drive is a brake
– Regeneration kW = hp x .8
– How is the power dissipated?
Braking Resistor
Put other loads on the generator
Unit mounted load bank
Don’t rely on the generator as a brake
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 46
47. Key Point Summary
• Soft Starters
– Sequence start to minimize harmonic content
– Limit harmonics by limiting current limit setting
– Limit transients by using voltage ramp feature
• VFDs
– Size as non-linear load
– Plan for regeneration with cable elevators and cranes
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 47
49. 10) UPS Sizing
• Three main UPS classifications
– Passive Standby (formerly off-line) (PC)
– Line – Interactive (PC)
– Double Conversion (SERVER)
• Issues & sizing varies by type
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 49
50. 10) UPS Sizing
• Passive UPS
– Simple design, low cost and small size
– Typically single phase, desktop UPS
• Sizing concerns
– Harmonics (multiple units, high THID)
– Size to control voltage distortion
– Load is stepped onto generator (not issue, small size)
• Generator kW rating is UPS x 5 (typically)
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 50
51. 10) UPS Sizing
• Line-Interactive
– Provides some output voltage regulation & no frequency regulation
– Small power applications not utilizing a generator
• Sizing concerns
– UPS sensitive to frequency variations (.5 Hz factory default)
– Load steps from UPS itself are often the main issue
– Open UPS frequency window to allowable limits
– Size based on frequency transient
– Harmonics may also be extensive (if not filtered)
• Generator kW rating of UPS x 5 (minimal)
– Assumes 2 hertz frequency window
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 51
52. 10) UPS sizing
• Double conversion
– Output voltage & frequency regulation
– Market norm for critical applications & higher power ratings
• Sizing Concerns
– No UPS load step (rectifier ramps load onto generator)
– Size alternator based on harmonic content (typically filtered – non issue)
– Consider battery recharge
– Consider HVAC requirements
• Generator kW rating is UPS x (2 to 2.5)
– Assumes HVAC on generator
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 52
53. Key Point Summary
• Passive – Harmonics
• Line-Interactive – Harmonics & Frequency Tolerance
• Double Conversion – Filtering, Recharge, & HVAC requirements
Professional Development Seminar Series – Generator Sizing Pitfalls “Avoid the Pain” 53
54. PROFESSIONAL
DEVELOPMENT
SEMINAR
SERIES
Generator Sizing Pitfalls
“Avoid the Pain”
Continuing Education Units (CEU) Available
Generator Sizing Pitfalls
“Avoid the Pain”