To replace printed circuit board (5) or annunciator panel A9 (6), proceed as follows:
Tag and disconnect wires from terminals on back of printed circuit board (5).
Disconnect hinge from printed circuit board (5) (if printed circuit board is to be replaced) or from
annunciator panel A9 (6).
Remove screws (3) to remove printed circuit board (5).
If printed circuit board (5) is to be replaced, remove any good lamp sockets (1) and lamp bulbs (2)
and store in generator set tool box for future use as spares.
If annunciator panel A9 (6) is to be replaced, remove any nameplates (4) that may be useable as
future replacements and store them in the generator set tool box.
Install replacement) printed circuit board (5) on (replacement) annunciator panel A9 (6) and secure
with screws (3).
Secure hinge to printed circuit board (5) or annunciator panel A9 (6), as required.
Make wiring connections to terminals on the back of the printed circuit board (5), as required.
SECTION II. TRANSFORMERS
10-3. GENERAL. The generator set contains 17 transformers which perform as follows:
Current Boost Transformers CT2 and CT3. The current boost transformers are mounted inside the conduit box
assembly. CT3 monitors generator G1 line T1. CT2 monitors T2. In each case, the generator line is wrapped
three times through the current boost transformer, serving as the 'primary". The "secondaries", the transformers
themselves, are cross-connected to the input terminals of current boost system Al 01. Current boost system Al
01 utilizes the input from the current boost transformers CT2 and CT3 to assist voltage regulator VR101 during
generator overload conditions and to independently supply the generator exciter field during generator short
Current Transformers CT1 0, CT1 1, and CT1 2. The current transformers are mounted in the lower rear section
of Cabinet B, accessible from the generator compartment. They sense the current through generator G1 lines
T3, T2, and T1, respectively. The generator lines pass directly through the current transformers with no turns.
The induced currents from these transformers is used as input (1, 2, or 3 phases) by current transducer AMT,
watt transducer WMT, power factor transducer PFT, AC KILONARS meter Ml 08, reverse power relay K1 09,
load sharing panel Al 04, and overcurrent relay K1 14. Current through each transformer varies from 0
(generator set at no load) to 3.71 amperes (750 kW, 0.8 power factor load).
Current Transformer CT114. Current transformer CT114 is mounted in the lower rear section of Cabinet B,
accessible from the generator compartment. It senses the current through generator G1 line T2. The current
output of CT114 varies from 0 (generator set at no load) to 5 amperes (generator set at 750 kW, 0.8 power factor
load). Transformer CT1 14 is used during isochronous parallel operation of the generator set to balance the load
between all parallel-connected generator sets on the bus. The transformers in each generator set are parallel
connected to each other, via the reactive load cable assemblies, and the output of the parallel connected
transformer network is applied to the input of the voltage regulator VR101 in each generator set. To trim and
match the current output of each CT114 on the network, each generator set has a CROSS CURRENT ADJUST
rheostat Ri 05. Zero to 1 ohm Ri 05, in parallel with 5 ohm resistor R107, limits the current applied by any
particular transformer CT114 to the transformer network. Whenever the generator set is not in paralleling mode,
transformer CT11 4 is shorted out of circuit by normally dosed contacts of paralleling relay K4C.
Ground Fault Transformer T100. Ground fault transformer T100 is mounted in the lower rear section of Cabinet
A, accessible from the generator compartment. The transformer primary is tied between generator G1 line TO
and generator set ground. Hence, the potential across the primary winding will, in normal cases, be zero. A
voltage sensing relay (GROUND FAULT relay K1 15) is connected across the secondary to sense the potential
across the primary. The GROUND FAULT relay will trap a generator set alarm and shutdown circuit if the
voltage across the secondary of T100 exceeds a preset level.
Stepdown Transformer T101. Stepdown transformer T101 is located in the lower front section of cabinet C,
accessible from the control room. Ti01 is a 10:1 stepdown transformer used to convert 2400 V ac generator G1
power to 240 V ac and 120 V ac for use by generator set circuits. 120 V ac is obtained from a grounded center
tap off the secondary of the transformer.