TRACK GP 3842988 - Caterpillar

The high voltage that is produced by an operating generator set can cause severe injury or death. Before performing any maintenance or repairs, ensure that the generator will not start.Place the engine control switch in the "OFF" position. Attach "DO NOT OPERATE" tags to all starting controls. Disconnect the batteries or disable the starting system. Lock out all switchgear and automatic transfer switches that are associated with the generator.
Static Adjust of the Current Limit
Follow the procedure below in order to perform a static adjustment of the current limit:
Illustration 1 g01742013
Static setup for the "R438" Automatic Voltage Regulator (AVR) (1) "P5" current limit adjustment (2) Step-down transformer with 120 primary and a of 48 to 96 VAC secondary (3) Double-Pole Single-Throw (DPST) switch for the R438 supply voltage (4) DPST switch for the R438 voltage sensing circuit (5) "P2" voltage adjustment
Shut down the generator set. Lock the generator with a safe lockout procedure.
Disconnect the power supply wires for the R438 from terminals "X1","X2" and "Z1","Z2".
Disconnect the wires for voltage sensing from the "0", "110V", "220V" and "380V" terminals.
Connect the secondary of the transformer (2) to terminals "X1" and "X2". Refer to Illustration 1.
Connect a DPST switch (3) to the primary of the transformer (2) .
Connect a DPST switch (3) to the voltage sensing terminals "0" and "110". Refer to Illustration 1.
Wire both of the DPST switches to a 120 VAC power source. The 120 VAC source must be switched off and back on as required. Ensure that the 120 VAC source is switched off before it is wired to the circuit.
Install a 10 AMP DC ammeter in series with the exciter field.
Ensure that "P5" is fully counterclockwise.
Ensure that both DPST switches are closed.
Apply power to the circuit by switching on the 120 VAC source.
If the ammeter does not display a current, adjust "P2" clockwise in order to obtain a steady current reading.
Adjust "P5" clockwise until the required maximum current is obtained.Note: Ensure that the current is no more than 8 Amperes.
Switch the 120 VAC power source off for at least 10 seconds. Reapply the 120 VAC power to the circuit.
Verify that the current limit setting returns to the correct value.
Switch off the 120 VAC power source. Testing the R438 Internal Protection
Note: Ensure that the generator is safely locked out.Perform this test with the circuit in Illustration 1. Follow this procedure in order to test the over current protection of the R438 in a simulation of a short circuit on a generator:
Switch on the 120 VAC power source.
Open switch (4). The excitation current that is viewed on the ammeter should rise to the value of the current limit that was set in Step 13 of "Current Limit Static Adjust". The current should remain stable for 10 seconds. The current should then drop to approximately 1 amp.
Reset the R438 by opening DPST switch (3) for 10 seconds and then close switch (3) again.
The R438 exciter current should return to the current limit level.
Remove power from the R438.
Remove the test wiring from