G533 - (GE) Static SCT-PPT Excitation

4 days - 2.6 Continuing Education Units Awarded

GE Static Excitation System reliability and availability can be a matter of skilled routine maintenance activity and proficient troubleshooting capability. Proficient troubleshooting is greatly aided by a solid operational understanding of the excitation system.

This course gives technicians and engineers the necessary knowledge to maintain, repair and calibrate the GE Static Excitation System by:

1. Using effective routine maintenance practices.
2. Knowing what checks may be performed on-line and how to perform these checks without causing an equipment shutdown.
3. Increasing the likelihood of accurate problem diagnosis by thoroughly understanding how the equipment operates.
4. Increasing the likelihood of accurate problem diagnosis by understanding any given board?s impact upon operations; ie., quickly linking the symptom(s) to the faulty board.
5. Verifying a suspected faulty board by analyzing voltage levels and/or signal traces.
6. Understanding the necessary calibrations, after the faulty part has been replaced, including how the calibrations are performed.

HPC's Excitation System course makes heavy use of prints, on which the participants are encouraged to take notes. This provides a valuable reference for future use. In addition, the student manuals contain a complete description of the excitation system operation.

OBJECTIVES
Upon successful completion of this course the participant will be able to:

1. Discuss how an excitation system accomplishes voltage and VAR control.
2. Discuss the primary and secondary roles of an excitation system.
3. Discuss the major excitation system components, including limit and protective features.
4. Discuss the purpose and operation of the Power Potential Transformer (PPT).
5. Discuss the purpose and operation of the Saturable Current Transformers (SCTs).
6. Discuss the role of the linear reactors.
7. Discuss the purpose and operation of the DC Regulator, including voltage/signal levels.
8. Discuss the purpose and operation of the AC Voltage Regulator, including voltage/signal levels.
9. Discuss the purpose and operation of the Power Rectifier Bridge, Discuss the purpose and operation of the Firing Controls, Underexcited Reactive Ampere Limit (URAL), Reactive Current Compensator (RCC), Overexcitation Protection Circuit, Transfer & Tracking Circuit, Volts Per Hertz (V/Hz) Protection Circuit, Field Flash Circuit.
10. With the use of prints, trace a given signal change through the excitation system.
11. Discuss routine maintenance including what can and cannot be done on-line.
12. Discuss troubleshooting of the Excitation System, including expected voltage/signal levels.
13. For a given symptom, list the most probable fault location(s).
14. Discuss the options available to quickly narrow down the fault location.
15. Discuss the necessary calibration, for each board, following board replacement.

COURSE OUTLINE

1. Introduction
2. Major Components
   1. Power Potential Transformer (PPT)
   2. Saturable Current Transformers (SCTs)
   3. Linear Reactors
   4. DC Regulator
   5. AC Regulator
   6. Rectifier Section
3. DC Regulator
   1. Purpose
   2. Operation
   3. Voltage Levels
   4. Motor Operated Volts Adjuster (MOVA)
4. Firing Circuits
   1. Purpose
   2. Role and Function of Magnetic Amplifiers
   3. Operation
5. AC Regulator
   1. Purpose
   2. Operation
   3. Voltage Levels
   4. Interface with other Circuits (Reactive Current Compensator - RCC, Underexcited Reactive Ampere Limit - URAL, Transfer and Tracking)
6. Relaying And Control Circuits
   1. Field Flash
   2. Overexcitation Protection Relay
   3. Volts per Hertz Protection Relays
   4. Field Ground Relay
7. SCR Rectifier Bridge
   1. Purpose
   2. Operation
   3. Expected Voltage Levels/Waveforms
8. Routine Maintenance
9. Troubleshooting & Repair
   1. Six-step Troubleshooting Method
   2. Symptom Analysis
   3. Expected Voltage/Signal Levels
   4. Most Common Failures
   5. Post Replacement Calibration