R250 Automatic Voltage Regulator Caterpillar

The R250 Automatic Voltage Regulator (AVR) is a microprocessor based AVR. The AVR is used in order to regulate the output voltage of the generator. The AVR measures the output voltage from the generator. The AVR will use this measurement in order to adjust the excitation current to the generator. The excitation current will adjust the output voltage at the desired voltage level. The R250 AVR receives operating power from the input that is used for sensing the voltage output from the generator.

The R250 AVR has two different modes of operation in order to regulate a block load. Load performance can be selected with the V/Hz feature or the Load Assistance Module (LAM) feature. The block load performance and the operating frequency are selected with the "FREQ. & L.A.M CONFIG" switch (3) .

The R250 is used only with shunt excited generators (self-excited generators). The R250 cannot be used with a Permanent Magnet Generator (PMG) excited generator or with an Auxiliary Winding Regulation Excitation Principle (AREP) excited generator. A generator with shunt excitation does not have the capability for sustaining a short circuit.

Connections to the R250 are made through a terminal strip. The voltage level and the voltage stability are adjusted with potentiometers that are located on the R250 AVR. The R250 also has a terminal strip that is used for connecting a remote potentiometer for adjusting the voltage.

Illustration 1	g01676989
(1) "F1" fuse (2) "P1" voltage adjustment (3) Frequency/V/Hz/LAM selector (4) "P2" stability adjustment