Guardian Technologies 4270 manual 6. - Excitation Circuit Breaker, 7. - Voltage Regulator

Section 2

MAJOR GENERATOR COMPONENTS

2

162

Figure 2-6. – Excitation Circuit Breaker

VOLTAGE REGULATOR:

Six (6) leads are connected to the voltage regulator as follows:

•Two (2) SENSING leads deliver ACTUAL AC out- put voltage signals to the regulator. These are Wires No. 11 and 22.

•Two (2) leads (4 and 1) deliver the regulated direct current to the Rotor, via brushes and slip rings.

•Two (2) leads (No. 6 and 162) deliver Stator excita- tion winding AC output to the regulator.

The regulator mounts a “VOLTAGE ADJUST” poten- tiometer, used for adjustment of the pre-set REFER- ENCE voltage. An LED will turn on to indicate that SENSING voltage is available to the regulator and the regulator is turned on.

11
22	1
4
VOLTAGE	6
	162
ADJUST POT
LED
Figure 2-7. – Voltage Regulator

ADJUSTMENT PROCEDURE:

With the frequency set at 62.5-Hertz and no load on the generator, slowly turn the voltage adjust pot on the voltage regulator until 124 VAC is measured. If voltage is not adjustable, proceed to Section 6 - Troubleshooting.

NOTE: If, for any reason, sensing voltage to the regulator is lost, the regulator will shut down and excitation output to the Rotor will be lost. The AC output voltage will then drop to a value that is equal to Rotor residual magnetism (about 7-12 VAC). Without this automatic shutdown feature, loss of sensing (actual) voltage to the regulator would result in a “full field” or “full excitation” condition and an extremely high AC output volt- age.

NOTE: Adjustment of the regulator's “VOLTAGE ADJUST” potentiometer must be done only when the unit is running at its correct governed no-load speed. Speed is correct when the unit's no-load AC output frequency is about 62.5-Hertz. At the stated frequency, AC output voltage should be about 125 volts.

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