TM 9-6115-730-24
0003
DC POWER DISTRIBUTION (FIGURE FO-1, SHEETS 2 AND 3) - Continued
SYNC MODE Switch (SMS)
The SYNC MODE switch has three sections and four positions for the four sync modes: OFF, SEMI-AUTO,
AUTO, and PERMISSIVE. OFF is used when not paralleling generator sets, the other modes are for paralleling.
The first section controls the AUTO SYNC input to the GSC. The AUTO SYNC input to the GSC is grounded in
AUTO and PERMISSIVE modes. When grounded, this input enables the automatic synchronization of Generator
G1 with the load bus. The second section controls the SYNC CHECK input to the GSC. The SYNC CHECK input
to the GSC is grounded in SEMI-AUTO and PERMISSIVE. When grounded, this input enables the synchroscope
function on the GSC. The third section is integrated with the opening and closing of the load contactor K1 and is
discussed more fully with K1 operation. Note that SEMI-AUTO and PERMISSIVE are wired together.
Load Contactor K1, K1 Relay (KR), and Contactor Control Switch (CCS) aka AC CIRCUIT INTERRUPTER
Switch
Load contactor K1 is controlled by K1 Relay (KR), GSC Run Relay (RR) A1 K5, and GSC Programmable Spare
Relay (PSR) A1 K8. GSC PSR (A1 K8) is programmed to close whenever there are no alarm conditions sensed by
the GSC. When the ENGINE CONTROL switch (ECS) is placed in START (or in AUTO and a remote start
command is received), the GSC closes RR (A1 K5). The fuse labeled F7GSC is actually A1 F6. Note that the GSC
checks to be sure there are no faults present prior to closing RR and verifies that all previous faults have been
reset, otherwise RR will not be closed. As long as no faults are detected, PSR will also be closed. The cool down
relay (CDR) is normally closed and opens at the start of Cool-down Mode. Under these conditions, +24 Vdc is
connected to relay KR. The SC contacts will be closed unless the OL/SC module detects a short circuit condition.
These contacts are reset to closed by turning the engine control switch to OFF/RESET or pushing the LAMP
TEST button on Alarm Module A2. The battle short switch shorts across the next two contacts to disable them in
Battle Short Mode. The Generator Fault Relay contacts are normally closed and open when the GSC detects a
generator fault condition. The OL contacts will be closed unless the OL/SC module detects an overload condition.
These contacts are reset to closed by turning the ENGINE CONTROL switch to OFF/RESET or pushing the
LAMP TEST button on Alarm Module A2.
If the PARALLEL/UNIT switch is set to UNIT, setting the AC CIRCUIT INTERRUPTER switch to CLOSED will
apply ground to KR, which will close Load Contactor K1, as long as DBHI and DBLO are closed. Auxiliary
contacts on K1 latches KR on after KR is energized. DBHI and DBLO are relays on the final generator output
(after the load contactor K1) which monitor the output for presence of voltage. If there is no voltage on the load bus,
these relay contacts will be closed. If either 208 or 416 Vac are detected by these relays, one or the other
contacts will be open and closing of the AC CIRCUIT INTERRUPTER switch will not apply ground to KR. This will
inhibit closing the Load Contactor K1. Note that DBHI and DBLO have no affect after KR is latched on.
NOTE
Electrically, if the SYNC MODE switch is in AUTO, it does not matter which position the
PARALLEL/UNIT switch is in.
If the PARALLEL/UNIT switch is set to PARALLEL and SYNC MODE switch set to AUTO, GSC can apply ground
to relay KR by grounding the CLOSE BREAKER output. Auxiliary contacts on K1 latch KR on after KR is
energized.
0003-18