ARMY TM 9-6115-604-12
NAVY NAVFAC P-8-633-12
Single Unit Generator Set Operation.
(1 ) The engine is started and brought up to speed.
(2) As the engine approaches operating speed, magnetic pickup PU1 on the flywheel housing transmits pulses to
load sharing panel A104. The governing circuits begin steadying engine speed.
(3) If FREQUENCY SEL SW S118 has been set to 50 hertz, load sharing panel A104 will stabilize engine speed
at 1500 rpm. If set to 60 hertz, engine speed stabilizes at 1800 rpm.
It the FREQUENCY SEL SW S118 has been set to 50 Hertz, CLOCK 50 HZ M110 will function and 50 hertz
frequency relay K108 will energize. If FREQUENCY SEL SW S118 has been set to 60 hertz, CLOCK 60 HZ
M111 will function and 60 hertz frequency relay K107 will energize.
(5) If synchro check relay K116 senses a dead bus at the load terminals, load circuit breaker CB101 will be
armed. Setting BREAKER CONTROL switch S4 on cabinet B door to CLOSE will close load circuit breaker
CE)101. The output of generator G1 will then pass through main disconnect switch S120 and appear at
output terminals L1, L2, L3, and L0.
Parallel Generator Set Operation.
(1) The operating sequence of events for manual, parallel operation begins as described In steps b(1) through b
(2) When OPERATION SELECTOR SWITCH S3 is set to MANUAL, synchro check relay K116 will arm load
circuit breaker CB101 only if generator G1 output voltage, frequency, and phase are identical to bus voltage,
frequency, and phase. The operator must adjust generator G1 voltage and frequency to bring this about. By
using PHASE SEQ SEL. SW. S119 and phase sequence lights (1-2-3, 3-2-1) DS112 and DS113, the
operator can check the generator G1 and bus phase relationship GEN/BUS VOLTMETER switch S112 and
AC KILOVOLTS meter M101 allow the operator to compare generator G1 and bus voltages for each phase.
Using VOLT ADJ rheostat R101, generator G1 voltage can be matched to the bus FREQ ADJ rheostat R102,
SYNCHROSCOPE M106, and SYNCHRONIZING LIGHTS DS110 and DS111 are used to match the
frequency of generator G1 to the bus frequency. The frequency of the generator will be set only slightly
higher than the bus; that is, so that the needle of SYNCHROSCOPE M106 rotates slowly clockwise (the
direction labeled FAST on the face of M106). As the needle rotates to the 12 o'clock position,
SYNCHRONIZING LIGHTS DS110 and DS111 will go out and synchro check relay K116 arms load circuit
breaker CB101. At that moment, the BREAKER CONTROL switch S4 is activated to close load circuit
breaker CB101 and connect the load to generator G1.
Protective Relays. Protective relays monitor the output lines of generator G1 for underfrequency, reverse powers,
overvoltage, undervoltage, overcurrent, ground faults, and synchronism with the bus (when paralleling). The
relays and their functions are as follows:
(1) Underfrequency Relays K107 and K108. Underfrequency relays K107 and K108 are located inside the upper
part of cabinet B. K107 monitors the frequency through generator instrument transformer T107. K108
monitors the frequency through generator instrument transformer T106. Transformer T107 is tied to generator
G1 output line T2. T106 is tied to generator G1 output line T2. Only one underfrequency relay is in circuit at
any given time, as determined by the setting of FREQUENCY SEL SW S118. K107 is in circuit for 60 hertz
operation, K108 for 50 hertz operation. During generator set startup, fault by-pass relay K17A prevents the
normally closed contacts of relay K107 or K108 from causing a generator set underfrequency. Indication until
approximately 10 seconds after engine speed has climbed above 600 rpm. 10 seconds after the engine
reaches 600 rpm, generator G1 line frequency will exceed 46.5
1 hertz (50 Hz), and 56.5
1 hertz (60
Hz), causing underfrequency relay K107 or K108 to energize and open their contacts. 10 seconds after the
engine reaches 600 rpm, crank cycle timer M7 energizes fault by-pass relay K17A, and the underfrequency
fault shutdown circuits are armed. If the line frequency of generator G1 subsequently falls below 46.5
1 hertz depending on selected frequency the appropriate underfrenquency relay will energize
annunciator alarm system self-latching relay A11K5. Annunciator horn LS1 will sound and
UNDERFREQUENCY fault light A9DS14 on the annunciator panel will flash. Relay A11K5 also energizes
circuit breaker trip relay K30. Relay K30 energizes the trip coil of load circuit breaker CB101 opening the
breaker to disconnect generator G1 from the bus. The engine will continue to run, but load circuit breaker
CB101 cannot be closed until the annunciator alarm system has been reset via the ANNUNCIATOR RESET
pushbutton S12 on the upper door of cabinet A.