RING-WEAR 1438916 - Caterpillar

Introduction
When servicing or repairing electric power generation equipment, do the following:a. Make sure the unit is off-line (disconnected from utility and/or other generators power service), and either locked out or tagged "DO NOT OPERATE".b. Make sure the generator engine is stopped.c. Make sure all batteries are disconnected.d. Make sure all capacitors are discharged.When power generation equipment must be in operation to make tests and/or adjustments, high voltage and current are present. Make sure the testing equipment is designed for and correctly operated for the high voltage and current tests being made. Improper test equipment may fail and present a high voltage shock hazard to its user.
Do not connect the generator to a utility electrical distribution system, unless it is isolated from the system. Electrical feedback into the distribution system can occur and could cause personal injury or death.Open and secure the main distribution system switch or, if the connection is permanent, install a double throw transfer switch to prevent electrical feedback. Some generators are specifically approved by a utility to run in parallel with the distribution system and isolation may not be required. Always check with your utility as to the applicable circumstances.
Test Equipment
6V7070 Heavy Duty Digital MultimeterCaterpillar Digital Multimeters measure voltage, resistance, or current up to 10 amps. The diode function checks rectifiers. See Special Instruction SEHS7734 for the operation of 6V7070.
4C4693 Regulator TesterThe 4C4693 Regulator Tester is a bench top instrument used to test VR3 regulators. This provides a way to check a regulator without using a generator set.10/12Schematics - Pole Self-Excited Generators
VR3 - Current Two Fuse Version VR3 - Earlier One Fuse Version Troubleshooting
Introduction
Check for loose or corroded terminals. Make sure wire connections are correct. Check accuracy of voltmeter and frequency meter/tachometer.To reduce troubleshooting time, simplify the system or circuit by eliminating non-essential components such as remote voltage control, manual control, etc. If, at this point, it is determined that the basic system is functioning, the circuits or components can be added back in, one at a time until the problem is located.If elimination of non-essential components does not correct the problem, the troubleshooting procedure will check components in the basic system. If all other basic components (i.e. rotating field assembly, exciter stator, etc.) are operating correctly, then replace the VR3 regulator. As a last step after confirming correct operation under no load conditions, operate the generator under a load.The VR3 regulator is serviced as a complete unit. Its fuses are the only replaceable part. VR3 regulators must be checked through the bench test before making a claim on warranty (see Bench Test).Problem List
Problem 1 No AC Voltage.Problem 2 Low AC Voltage.Problem 3 High AC Voltage.Problem 4 Unstable AC Voltage.Problem 1 - No AC Voltage
Procedure A - Check AC Voltage Between Regulator Terminals 20 And 22* If above 200 volts: Check meters.* If 0 volts: Flash the field; see SR4 Generator Service Manual, Form No. SENR3985.* If 0 to 15 volts: Go to Procedure B. Procedure B - Isolate RegulatorDisconnect leads from regulator terminals