PLATE 9D4476 - Caterpillar

Table 1
Worksheet For Testing The Cover Plate
Negative Probe (7) Positive Probe (8) Generator Actual Result Expected Result
Metal cover plate that the 3- phase conductors pass through. Conductor A Greater than 2.0 Megohm
Conductor B Greater than 2.0 Megohm
Conductor C Greater than 2.0 Megohm Note: 2.0 Megohm is equal to 2,000,000 Ω.
Illustration 4 g03868206
Testing the conductor lugs to the shields
(9) Negative Probe
(8) Positive Probe
Table 2
Worksheet for Testing the Conductor Lugs to Shields
Negative Probe (9) Positive Probe (8) Generator Actual Result Expected Result
Connect to shield terminal for the conductor being tested. The other end of the shield is connected to the Generator housing. Conductor A Greater than 2.0 Megohm
Conductor B Greater than 2.0 Megohm
Conductor C Greater than 2.0 Megohm Note: 2.0 Megohm is equal to 2,000,000 Ω.
Illustration 5 g03868226
Testing the Conductors to Frame Ground
(10) Negative Probe
(8) Positive Probe
Table 3
Worksheet For Testing The Conductors To Frame Ground
Negative Probe (10) Positive Probe (8) Generator Actual Result Expected Result
Frame Conductor A Greater than 2.0 Megohm
Conductor B Greater than 2.0 Megohm
Conductor C Greater than 2.0 Megohm Note: 2.0 Megohm is equal to 2,000,000 Ω.Expected Result: The insulation tester displayed a resistance measurement greater than 2.0 megohms.OK -The insulation tester displayed a resistance measurement greater than 2.0 megohms. The conductor assembly and generator stator windings are not shorted to ground.NOT OK -One or more resistances were less than 2.0 megohm. If the resistance between the HV cable and the pass through plate was less than 2.0 megohm, it indicates an issue with the HV cable conductor assembly. Go to the Repair (Conductor Assembly).If the resistance for the conductor lugs to shields or to frame ground is less than 2.0 megohm, the Generator stator has a short to ground. Go to Repair (Generator Windings).Repair: (Conductor Assembly) If the resistance between a conductor and the metal plate that the 3- phase conductors pass through was close to or below 2.0 megohm, test the conductor assembly individually. Disconnect the conductor assembly from the generator and remove it from the enclosure.Connect the negative probe to the shield terminal for the conductor being tested. Connect the positive probe to the conductor lug. Verify that all personnel are not in contact with the conductor being tested. Verify that the exposed ends of the conductor are not in contact with any other conducting surfaces. Test the resistance of each conductor at the maximum allowable 1000 V. Do not perform any insulation testing at a setting greater than 1000 V.If the resistance of a conductor is found to be close to or below 2.0 megohms, replace the complete 3- phase conductor assembly.Proceed to test the resistance directly at the Generator, even if a conductor was found to be faulty.Repair:(Generator Windings) If the resistance was close to 2.0 megohm or below 2.0 megohm one of the generator windings has a short to frame groundClean the terminals and the connector enclosure. Ensure that the area around the contacts is free of moisture, dirt, dust, or contamination of any kind.