BRAKE LINING GROUP (Molded) 6S8896 - Caterpillar

R438 Adjustment for Maximum Excitation
Illustration 6 g03361293
Illustration 7 g00952800The factory setting corresponds to an excitation current that is required to obtain a three-phase short circuit current of 3 X IN at 50 Hz for industrial power, unless this is specified otherwise. The maximum level of excitation may be reduced by a static method. The static method is safer for the generator and the network. Use the following steps to reduce the maximum excitation level.
Disconnect the power supply wires X1, X2, Z1 and Z2.
Disconnect sensing leads 0V, 110V, 220V and 380V on the generator.
Connect the main power supply 200V-240V, as shown. X1,X2:120V
Install a 10 Amp DC ammeter in series with the exciter field.
Turn potentiometer P5 to a full counterclockwise position and activate the power supply. If there is no output current from the voltage regulator, turn potentiometer P2 clockwise until the ammeter indicates a stable current.
Switch off the power supply. Switch on the power supply. Turn potentiometer P5 until the required maximum current is obtained. The maximum current must not be greater than 10 Amperes. Use the following steps in order to check the internal protection.
Open switch D. The excitation current should increase up to the preset maximum value and the excitation current should remain at the preset maximum value for approximately 10 seconds. The current will decrease to less than 1 Amp.
Open switch A in order to reset the internal protection. Note: The voltage must be adjusted after the maximum excitation current has been set.Special Use
The exciter is switched off by disconnecting the power supply to the voltage regulator. The connection is identical for resetting the internal protection for the voltage regulator.
Illustration 8 g00952830Use a 12 VDC power source in order to energize the field, if necessary. Refer to the following table.
Table 2
Applications B Volts Time
Voltage build-up 12 (1A) 1 - 2 seconds
De-energized parallel operation 12 (1A) 1 - 2 seconds
Standby parallel operation 24 (2A) 5 - 10 seconds
Battery starting 48 (4A) 5 - 10 seconds
Voltage that is sustained at overload 48 (4A) 5 - 10 seconds
Illustration 9 g00952821Special Use
De-energizing the Field
Damage will occur to the voltage regulator if the excitation current E+ and E- are left open when the generator set is operating.
Illustration 10 g00952821The exciter is switched off by disconnecting the power supply to the voltage regulator. The rating of the switch contacts should be at least 16A - 250 VAC. The connection is identical for resetting the internal protection for the voltage regulator.Forcing the Field
Illustration 11 g01212159Use a 12 VDC power source in order to energize the field, if necessary. Refer to the following table.
Table 3
Applications B Volts Time
Voltage build up 6 (1A) 1 - 2 seconds
De-energized parallel operation 6 (1A) 1 - 2 seconds
Standby parallel operation 12 (2A) 5 - 10 seconds
Frequency starting 24 (4A) 5 - 10 seconds
Voltage that is sustained at overload 24 (4A) 5 - 10 seconds