Guardian Technologies 4451 & 4986, 4582 & 4987, 4583 162, Voltage Regulator, Underfrequency Adjust

Section 3

DESCRIPTION & COMPONENTS

162

2

Figure 3-5. – Excitation Circuit Breaker

VOLTAGE REGULATOR:

Atypical Voltage Regulator is shown in Figure 3-6 (12.5 & 15 kW Units) or Figure 3-7 (17.5 kW Units). Unregulated AC output from the stator excitation winding is delivered to the regulator’s DPE termi- nals, via Wire 2, the Excitation Circuit Breaker and Wire 162, and Wire 6. The Voltage Regulator recti- fies that current and, based on stator AC power winding sensing, regulates it. The rectified and regulated excitation current is then delivered to the rotor windings from the positive (+) and negative (-) regulator terminals, via Wire 4 and Wire 0. Stator AC power winding “sensing” is delivered to the reg- ulator “SEN” terminals via Wires 11S and 44S.

The regulator provides “over-voltage” protection, but does not protect against “under-voltage”. On occur- rence of an “over-voltage” condition, the regulator will “shut down” and complete loss of excitation current to the rotor will occur. Without excitation current, the generator AC output voltage will drop to approximately one-half (or lower) of the unit’s rated voltage.

Figure 3-6. – Typical Voltage Regulator Found on 12.5

kW and 15 kW Units

Figure 3-7. – Typical Voltage Regulator Found on 17.5

Units

ADJUSTMENT PROCEDURE (12.5 and 15 kW Units):

The Voltage Regulator is equipped with three light emitting diodes (LED’s). These LED’s are normally on during operation with no faults in the system The RED regulator LED is on when the regulator is on and functioning. The Yellow sensing LED is powered by sensing input to the regulator from the stator AC power windings. The GREEN excitation LED is pow- ered by stator excitation winding output.

Four adjustment potentiometers are provided. They are VOLTAGE ADJUST, GAIN, STABILITY, and

UNDERFREQUENCY ADJUST.

1.Connect an AC Voltage/Frequency meter across wires 11 & 44 at the 50A Main circuit breaker. Verify frequency is between 59-61Hz.

2.On the regulator, set the adjustment pots as follows.

a.Voltage Adjust – Pot-turn fully counterclockwise

b.Gain – turn to midpoint (12 O’clock)

c.Stability – turn to midpoint (12 O’clock)

d.Under Frequency – turn to midpoint (12 O’clock)

3.Start the generator. This adjustment will be done under a no- load condition.

4.Turn the regulator’s Voltage Adjust pot clockwise to obtain a line to line voltage of 238-242 VAC.

5.If the red regulator LED is flashing, slowly turn the stability pot either direction until flashing stops.

ADJUSTMENT PROCEDURE (17.5 kW Units):

A single red lamp (LED) glows during normal opera- tion. The lamp will become dim if excitation winding AC output diminishes. It will go out on occurrence of an open condition in the sensing AC output circuit.

An adjustment potentiometer permits the stator AC power winding voltage to be adjusted. Perform this adjustment with the generator running at no-load, and

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