Voltage regulator terminals 6 and 7 allow manual adjustment of generator Gi voltage output by VOLT ADJUST
rheostat RI 01 on cabinet B door, or by reactive load voltage adjust rheostat Ri 06 inside cabinet A. Ri01 is used
when OPERATION SELECTOR SWITCH S3 is set to MANUAL. R106 is used when the switch is set to AUTO.
Voltage regulator terminals 1 and 2 are used when the generator set is in parallel operation. Paralleling current
transformer CT114 senses the reactive current of generator Gi, line T2, in each set being paralleled. When an
unbalance occurs in field excitation between paralleled set, circulating currents begin to flow between the
generators. This current will appear as a LAG on the POWER FACTOR meter of the highly excited generator,
and as a LEAD on the meter of the generator with the lower field current. This is known as the reactive
circulating current; it is controlled by reactive droop compensation when sets are in FREQUENCY DROOP or
ISOCHRONOUS mode in parallel operation.
512. VOLTAGE REGULATOR VR101 INSPECTION (3, Figure 5-9).
Inspect unit for cleanliness and apparent damage to exterior. Loosen two hexagon head screws and swing open
Inspect interior for burned and scorched components. Check security of all wiring connections. Check for
Inspect three fuses VRl1 O Fll, VRl01 F12, and VR101 F13, located inside voltage regulator VR101, and spare
fuses located on the inside of voltage regulator VR1 01 front cover, for signs of damage or deterioration.
Remove and test each fuse using a multimeter set to the RX1 scale. Multimeter should indicate zero resistance.
Replace a fuse which does not pass this test
5-13. VOLTAGE REGULATOR VR101 TEST (3, Figure 5-9).
Operate the generator set in accordance with the Operator/Crew and Organizational Maintenance Manual
(single unit operation) with a 750 kW load bank connected to the generator set output.
Voltage values may be measured across terminals F+ and F- of voltage regulator
VR1 01. Current (amperes) values may be measured by disconnecting terminal F+
of voltage regulator VR1 01 and installing a multimeter in series between the F+
terminal and lead.
The values obtained in the following tests may vary due to environmental
conditions such as temperature, humidity, etc.
Using two multimeters, check for the following outputs at VR101 F+ and VR101 F- terminals at the loads
and frequencies specified below.
(a) No load (60 Hz) - 25.1 V dc at 0.73 amperes.
(b) 1/4 load (60 Hz) - 27.3 V dc at 0.89 amperes.
(c) 1/2 load (60 Hz) - 36.5 V dc at 1.16 amperes.
(d) 314 load (60 Hz) - 44.2 V dc at 1.4 amperes.
(e) Full load (60 Hz) - 56.7 V dc at 1.79 amperes.
(f) No load (50 Hz) - 35 V dc at 1.08 amperes.
(g) 1/4 load (50 Hz) - 37 V dc at 1.2 amperes.
(h) 112 load (50 Hz) - 50 V dc at 1.55 amperes.
(i) 3/4 load (50 Hz) - 56 V dc at 1.84 amperes.
(j) Full load (50 Hz) - 70 V dc at 2.3 amperes.