G3406 and G3412 Generator Sets Voltage Regulators Caterpillar

Except for the oilfield generators, all AVSpare SR4B generators are provided with voltage regulators. The voltage regulator controls the generator output voltage.

VR3F

Illustration 1	g00626331
Adjustment Controls of the VR3F Regulator (1) Voltage droop potentiometer (2) Voltage level potentiometer (4) Fuse(s)

The VR3F regulator has voltage droop capability (1). The VR3F regulator has the voltage level control (2). However, the VR3F regulator does not have voltage gain capability.

Voltage droop and voltage level are controlled by multiturn potentiometers. The adjustment screws on the potentiometers do not have a fixed stop. When the potentiometer reaches the end of adjustment, a ratchet action begins. The beginning of a ratchet action can be felt with the adjusting tool. The adjustment screw can be turned past the potentiometer stop (ratchet action) without further changing the potentiometer setting.

Digital Voltage Regulator

Illustration 2	g00883469
Digital Voltage Regulator (DVR) (1) Display (2) Function key (3) Scroll down key (4) Scroll up key (5) Keypad (6) J1 connector (7) Screw terminals

The digital voltage regulator (DVR) is a microprocessor based voltage regulator. The parameters are preset at the factory or the parameters can be modified in order to meet the specific requirements on the site. Certain system parameters can also be monitored on the display (1) of the DVR. Keypad (5) is used to change the information that is shown on the display. J1 connector (6) is used to join the DVR to a personal computer. Screw terminals (7) are used to join the DVR to the generator and various customer options.

AVSpare Digital Voltage Regulator (CDVR)

Illustration 3	g01115009

The AVSpare Digital Voltage Regulator (CDVR) is a microprocessor based voltage regulator. Control power for the CDVR is supplied from an external 24 DCV source. The power stage of the CDVR can be supplied from a multi-pole, high frequency, permanent magnet generator (PMG), from the generator output (shunt excitation), or from auxiliary windings (AREP) that are included on some generators. Connections to the CDVR are made through three plug type connectors. The communication between the CDVR and a service tool is accomplished using a CANBUS protocol.

The CDVR has the following features:

• Three control modes:

1. Automatic voltage regulation (AVR)

2. Power factor (PF) regulation

3. Reactive power (VAR) regulation

• Programmable stability settings

• Soft start control with an adjustable time setting in AVR mode

• Dual slope voltage versus frequency (V/Hz) characteristic

• Three-phase or single-phase voltage sensing

• Single-phase current sensing

• Field current and field voltage sensing

• Ten protection functions

Adjustment Procedure for the Voltage Regulators

VR3F

Note: The VR3F regulator is protected by a fuse(s). The VR3F regulator also has a solid-state overcurrent protection. If a fuse becomes open, contact a AVSpare dealer.

1. Remove the access panel of the generator.

2. Loosen the locknut on the voltage droop potentiometer (1). Remove the protective screw from the voltage level potentiometer (2).

3. Turn voltage droop potentiometer (1) counterclockwise to zero droop. Tighten the locknut. Voltage droop potentiometer (1) is located next to the regulator.

4. Perform required maintenance on the engine before you start the engine.

5. Start the engine. Allow the engine to warm up. Refer to the Safety Section, "Engine Starting".

6. Increase engine speed to full governed rated speed (high idle).

7. Observe the voltmeter reading. If the desired voltage is not indicated, set the no-load voltage with the voltage level potentiometer (2) or the voltage adjust rheostat. The voltage adjust rheostat is located on the control panel.

8. Close the load circuit breaker. Apply full load gradually. Adjust the governor control until the nameplate frequency is on the frequency meter or until the rated speed is displayed on the tachometer. The unit of measurement for frequency is Hertz. The unit of measurement for the rated speed is RPM.

9. Remove the load. If necessary, adjust the voltage level potentiometer (2) in order to obtain the desired voltage.

10. Apply the load. Observe the voltmeter reading. Repeat Steps 8 and 9 until the voltage at no load equals the voltage at full load.

11. Tighten the locknuts. Install the protective screws on the respective potentiometers. Install the access panel of the generator. STOP.

Digital Voltage Regulator (DVR)

Refer to the Specifications, Systems Operation, Testing and Adjusting, SENR5833, "Digital Voltage Regulator".

The digital voltage regulator (DVR) can be set up for a specific application by using the configured parameters. Parameters are preset at the factory. Parameters may need to be adjusted in order to meet the specific requirements of a site. The DVR also detects faults. When a fault is detected, the DVR sets the appropriate alarm or caution. Certain system parameters can also be monitored on the display of the DVR.

Display (1) and keypad (5) are used to select parameter values. The display and the keypad are also used to manipulate the parameter values that control the operation of the digital voltage regulator. The display of the digital voltage regulator has four digits. When one of these digits is a colon, the number that is showing is a parameter code. When a colon is not present, the number that is showing is a parameter value. A decimal point in the display is used to indicate the precision of the parameter value.

Keypad (5) has three keys. The keys are listed below.

• Function key (2)

• Scroll down key (3)

• Scroll up key (4)

Display (1) has two modes. These modes are the parameter code mode and the parameter value mode. Function key (2) is used to toggle back and forth between the two modes. Scroll down key (3) and scroll up key (4) are used to change the display's value. The scroll down key will decrease the parameter number or the scroll down key will decrease the value. The scroll up key will increase the parameter number or the scroll up key will increase the value.

The operation of display (1) and keypad (5) is shown in Table 1. Pressing function key (2) toggles the display between the two columns of the table (parameter code and parameter value). The display is in the parameter code mode when a colon is present. If a colon is not present, the display is in parameter value mode.

When you press scroll up key (3), the number that is displayed will increase to the next higher number within the column. When you press scroll down key (4), the number that is displayed will decrease to the next lower number within the column. The scroll keys will not cause the display to change columns.

To configure a parameter code, follow the procedure below:

1. To select the desired parameter code, press scroll key (3) or scroll key (4).

2. Access the parameter value by pressing function key (2).

3. Select the desired parameter value by pressing scroll key (3) or (4).

4. In order to enter the selected value into the digital voltage regulator's memory, press function key (2).

AVSpare Digital Voltage Regulator (CDVR)

In order to view and configure the parameters of the CDVR, a PC with the AVSpare PC software is required.

Refer to Specifications, Systems Operation, Testing and Adjusting, RENR7941, "AVSpare Digital Voltage Regulator (CDVR)" for complete information.