PISTON 4866201 - Caterpillar

Table 1
No Excitation    
Possible Problem    Repair Solution    
Interruption in the auxiliary winding circuit     Check cable connections for the auxiliary winding at the terminal block and all connections to the terminal block in the voltage regulator and supply fuse.    
Burned fuse     Replace the fuse.    
Residual voltage too low.     Disconnect the wires to the voltage regulator. Perform an external excitation with a 12 to 20 V battery. Place the negative pole on F- connection and the positive pole on the F +connection until the beginning of the excitation process. The battery used to start the generator set must not be grounded.    
Drive speed is not correct.     Measure the speed. Attempt to regulate the speed.    
Interruption in the main excitation circuit.     Check the continuity of the F- and F + cables. Confirm that all of the diodes are in working order. If there are any defective diodes, replace the defective diodes or replace the entire set of diodes.    
Relay or other components of the voltage regulator are faulty.     Replace voltage regulator.    
External potentiometer for voltage adjustment ruptured or interrupted connection.     Check the connections between terminals 11 and 12 and the potentiometer.    
Varistor protection for the diodes is not working.     If defective, the varistor must be replaced, or there is no a spare part, then remove varistor temporarily.    
Table 2
Alternator does not excite, up to rated voltage    
Possible Problem    Repair Solution    
Faulty rotating diodes     Replace the set of diodes.    
Incorrect speed     Measure the speed of the primary machine and regulate the speed.    
Adjustment below the rated voltage     Adjust the potentiometer in the regulator or the external one.    
Voltage regulator output is not correct.     Ensure that voltage regulator connections are correct.    
Table 3
In no load, the alternator excites up to rated voltage, but collapses with a load    
Possible Problem    Repair Solution    
Sharp speed decrease.     Control diesel selector.    
Faulty rotating diodes.     Replace the set of diodes.    
Table 4
The alternator, in no load, is excited through over voltage.    
Possible Problem    Repair Solution    
Faulty voltage thyristor of regulator.     Replace regulator.    
Power transformer in the regulator is defective or incorrect.     Check voltage and/or operation ratio.    
Supply of voltage regulator is not according to the desired output voltage.     Check the connections. Check the manual of the voltage regulator to make sure all of the connections are correct.    
Table 5
Oscillation on generator voltage    
Possible Problem    Repair Solution    
Stability improperly set     Adjust the stability of the regulator with the trim pot.    
Oscillations in the speed of the drive machine.     Frequent oscillations are originating from the drive machine and must be eliminated.    
Table 6
Mechanical problems    
Possible Problem    Repair Solution    
Overheating of bearings.     Faulty bearing, lack of lubrication or excessive axial clearance.    
Overheating in