WEG AVR-A-OPT-03 Installation, Operation And Maintenance Manual page 30

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29 TROUBLESHOOT
Problem

Circulation of reactive power
between generators when
operating in parallel.

Generated voltage decreases
when load is applied, and it
doesn't return.

Alternatoroutput voltage doesn't
increase.

Generated voltage oscillates at a
no load.

Voltage overshoots.
30
l Analog Voltage Regulator AVR-A-OPT-03
Causes

Incorrect phases sequence.

CT connection inverted.

Droop adjustment very low.

The speed is falling at the starting
machine.

U/F limiter acting.

Residual Voltage is too low.

Terminals F+ and F- inverted.

Dynamic incorrectly adjusted.

Alternatorexcitation voltage
excessively low.

No sensing voltage.

Power circuit damaged.

Sensing voltage incompatible with
the voltage regulator.
Corrective Actions

Connect the phases sequence correctly.

Polarize CT in phase correctly as it shows below:
S1
Alternator
P1

Increase droop adjustment, rotating trimpot
clockwise (CW).

Correct speed regulation.

Adjust U/F limiter, by turning U/F trimpot
clockwise.

With the regulator ON, use external battery
(12Vcc) to force excitation. (*)

Invert F+ and F-.

Adjust voltage trimpot.

Insert 10/200W resistor in series with field.

Check if the generator's phases are present in the
sensing voltage.

Change the regulator.

Use one connection that supplies the right voltage
to the regulator.
S2
Load
P2