HOSE & TUBE AS 4196161 - Caterpillar

Troubleshooting Active Ground Faults
Note: The APC contains two filter capacitors that are used in the ground fault detection system. One filter capacitor is internally connected between the positive ("+") DC Power Bus (contact A) and the housing for the APC (frame ground). The other filter capacitor is internally connected between the negative ("-") DC Power Bus (contact B) and the housing for the APC (frame ground). Some specific conditions that can cause a level 3 ground fault to be activated can also damage the filter capacitors in the APC. A ground fault in the motor windings or a Generator windings could damage the filter capacitors. When the APC is operated with a damaged filter capacitor, the APC will detect a constant ground fault condition when no ground fault condition exists. After a ground fault that is caused by the winding of a motor or the winding of a generator is repaired, the filter capacitors must be tested to detect any damage. If a ground fault has occurred in the windings for the drive motor or in the windings for the Generator, call the Dealer Solution Network (DSN). The DSN will provide further instructions on the procedure to follow to verify the status of the filter capacitors in the APC.Insulation Testing
Illustration 1 g01515993
Handheld Insulation Tester
When a ground fault is present in the AC section of the power train electrical system, the integrity of the isolation material can be tested. An insulation tester will be used to check the degree of insulation resistance between the conductors or the motor windings and frame ground.The Insulation Tester can also be used to check the integrity of the isolation material that is used in the DC section of the system. Using an Insulation Tester on some components in the DC section of the system could damage system control modules if not used correctly. Only use an insulation tester on control modules in the DC section of the system when instructed to in a procedure.When an insulation tester, the positive side probe of the insulation tester is connected to a copper conductor or to a winding connection. The negative side probe of the insulation tester is connected to frame ground, a grounded component housing or, a ground wire. The insulation tester will be used to induce a voltage that is higher than normal into the conductor or winding that is being tested. The insulation tester will measure the voltage potential that is present on the frame of the machine or on a ground wire. The insulation tester will calculate the amount of resistance that is present in the isolation material that is between the two probes.The resistance value that is measured will indicate whether the condition of the insulation that is being tested is in good condition or is not in good condition. When a conductor or a component such as a motor or a generator is tested, a reading of two megohms (two million ohms) or less of resistance between the component conductor or