LINK AS-TRACK 1156302 - Caterpillar

Troubleshooting
General
Before attempting major adjustments or repairs on the SRCV Generator, the serviceman should have a thorough understanding of the operating principles of the generator, the applicable wiring diagrams, and he should verify the reported operating trouble.
Generator Rated Above 600 Volts. Do not attempt to measure line voltage or line current on generator rated 600 volts with direct reading test metering equipment. Potential and current transformers rated for applicable voltages must be used, even though test instruments have high voltage scales. DO NOT rely on test instrument insulation alone when working on power circuits above 600 volts.
Successful troubleshooting can be accomplished in a minimum of time if you: 1. Recognize the apparent operational trouble.2. Diagnose the trouble from the wiring diagram and troubleshooting guide.3. Verify the diagnosed trouble by checking with appropriate test instruments.4. Correct the trouble by adjustment or by replacing or repairing the defective components.Keep these fundamentals in mind:1. A generator is an energy converter. It can not delivery more power than the engine driving it.2. A generator is essentially a constant speed device. Driving speeds 5 to 10 percent above or below rated speed can cause large variations in terminal voltage.3. Electric motors are energy converters. Their power consumption depends on the load they drive. Automatically, they absorb more power if the connected load demands it. Power is a product of voltage and current. If the motor voltage is lower than normal, current input will increase proportionately.4. Generator heating is the result of line current. The higher the line current the greater the heat.5. Line currents do not necessarily indicate the power load on a generator because of the power factor of the load. Likewise, the line amperes will not necessarily be equal to the sum of the nameplate amperes of the connected loads since load components, such as motors, may not be fully loaded.6. When load testing a generator with a resistance load bank or a water barrel, load amperes for rated kilowatts at rated volts are determined by multiplying nameplate amperes by nameplate power factor; for example, a generator rated 240 volts, 100 amperes, 0.8 power factor will be fully loaded by a resistance bank or water barrel when delivering 240 volts and 80 amperes.7. Current will flow only through clean, solid connections. Vibration can and does loosen switchboard fasteners. Use depreciates switches and circuit breakers.8. Electrical test (and panel) instruments are not precisely accurate. A 5 percent difference in readings between two instruments is common. Multi-scale instruments can exhibit a 5 percent difference between scales. Where uniform adjustments are necessary (as in parallel operation), use the same instrument for all voltage adjustments.9. Temperature has a notable effect on electrical equipment. Resistance measurements made on a cold unit will be lower than the same measurement made at elevated temperatures. Ohmmeters in general are quite inaccurate. Variations of up to 10 percent of published resistances can be expected if the total error of instrument method, temperature, and piece part tolerance happen to add in one