C15 Generator Sets Caterpillar

Voltage Regulators

Usage:

C15 GG5

VR6

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Personal injury or death can result from high voltage.
When power generation equipment must be in operation to make tests and/or adjustments, high voltage and current are present.
Improper test equipment can fail and present a high voltage shock hazard to its user.
Make sure the testing equipment is designed for and correctly operated for high voltage and current tests being made.
When servicing or repairing electric power generation equipment:

Make sure the unit is off-line (disconnected from utility and/or other generators power service) , and either locked out or tagged DO NOT OPERATE.
Remove all fuses.
Make sure the generator engine is stopped.
Make sure all batteries are disconnected.
Make sure all capacitors are discharged.

Failure to do so could result in personal injury or death. Make sure residual voltage in the rotor, stator and the generator is discharged.

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Accidental engine starting can cause injury or death to personnel working on the equipment.
To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system.

Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.

For generators with Auxiliary Winding Regulation Excitation Principle (AREP), the voltage regulator is powered by two auxiliary windings. These windings are independent from the circuit for detection of voltage. The first winding is labeled as "X1" and "X2". This winding has a voltage that is proportional with the output voltage of the generator. The second winding is labeled as "Z1" and "Z2". This winding has a voltage that is proportional to the current of the stator. The voltage from the power supply is rectified and filtered before being used by the regulator monitoring transistor. This principle ensures that regulation is not affected by interference that is generated by the load.

For generators with PMG excitation, a permanent magnet generator is added to the generator at the rear of the generator. The PMG supplies the voltage regulator with a voltage that is independent of the main generator winding. The generator has a short circuit capability of 3 X In for 10 seconds. The generator also has good immunity to distortion from the generator load.

The voltage regulator monitors the output voltage and the voltage regulator corrects the output voltage of the generator by adjusting the excitation current.

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Illustration 1	g02197113
Typical Block Diagram of SR4B Permanent Magnet Permanently Excited (PMPE) Generator with VR6 Voltage Regulator (1) Generator lines (output voltage) (2) Generator lines (sensing voltage and AC power) (3) VR6 voltage regulator (4) Jumper (removed when external voltage adjust potentiometer is installed) (5) Main stator (6) Main rotor (7) Exciter rotor (8) Exciter stator (9) Three-phase rectifiers (10) Permanent magnet stator (11) Permanent magnet (12) Generator lines (DC excitation voltage)

The VR6 voltage regulator is used on 4/6 and 10/12 lead self-excited generators and permanent magnet generators, and also used on AREP generators. The VR6 regulator is typically located in the generator terminal box. The regulator may also be located in the marshaling box. In some applications, the regulator may be remotely mounted.

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Illustration 2	g00779058
The VR6 Voltage Regulator (13) Terminal strip for attachments (14) Droop adjustment (15) Factory calibration of the voltage adjustment range (16) Voltage adjustment (17) Knee frequency adjustment (18) Stability adjustment (19) Terminal strip for sensing and power

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Illustration 3	g00928349

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The Cat VR6 presents an electrical shock/electrocution hazard. This hazard will cause serious injury or death.
Service by trained personnel only.

The terminals and heat sinks are live at hazardous voltages when power is applied and for up to 8 minutes after power is removed.

There are five adjustments on the VR6 voltage regulator:

Droop adjustment (14)
Factory calibration of the voltage adjustment range (15)
Voltage adjustment (16)
Knee frequency adjustment (17)
Stability adjustment (18)

The factory calibration of the voltage adjustment range (15) should not be adjusted by the user. For the other adjustments, refer to Specifications, Systems Operation, Testing and Adjusting, RENR2480, "VR6 Voltage Regulator".

The VR6 voltage regulator can operate in one of the following modes:

three-phase sensing
single-phase sensing

The terminal strip for attachments (13) accommodates the following optional connections:

KVAR/PF controller
External voltage adjust potentiometer
Droop current transformer (CT)
Selection of the under frequency slope
Selection of the sensing phase

Adjusting the VR6

Refer to Specifications, Systems Operation, Testing and Adjusting, RENR2480, "VR6 Voltage Regulator"

Caterpillar Digital Voltage Regulator (CDVR) (if equipped)

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Illustration 4	g01115009

The Caterpillar 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: