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 TM 55-1905-220-14-8
4-21. SEWAGE SYSTEM MOTOR CONTROLLER AND GAGE PANEL-MAINTENANCE
INSTRUCTIONS (Continued).
(f) When PS1 contacts reclose on decreasing vacuum, self-maintaining Relay 2CR is energized
through closed 3CR contacts.2CR contacts close to energize 2VP, and open to drop
3CR.2VP contacts close to connect the No.2 motor across the line. If PS2contacts close,
1VP is energized, connecting the No.2 motor across the line. When PS1 and PS2 contacts
open, 2CR, 1VP and 2VP are de-energized removing both motors from the line.
(g) Reclosing of PS1 contacts will energize 1CR placing control of 1VP on PS1 and 2VP on PS2
as described initially (alternator).
(h) To stop the pumps, press the Vacuum Pump No.1 and Vacuum Pump No.2 OFF release
bars. This drops 1VP and 2VP, If one and not the other pump is de-activated in this manner,
the other will alternately cycle by action of the PS1 and PS2 switches if vacuum is
maintained by one pump.
(4) Over board discharge pump.
(a) Closing of LR1 contacts above the tank empty level allows manual starting of the overboard
discharge pump. To start the pump, momentarily press the OVERBOARD DISCHARGE
PUMP START/JOG pushbutton which energizes self maintaining Contactor EP and the
"OVERBOARD DISCHARGE PUMP MOTOR RUN "indicating light. EP main contacts close
to connect the pump motor across the lines.
(b) Opening of LR1 contacts on tank empty level drops EP removing the motor from the line.
The tank can be pumped further by pressing the START/JOG pushbutton and holding it
depressed.
(c) EP can be dropped by pressing the SYSTEM STOP pushbutton to stop the pump motor. This
will also initiate stopping of the vacuum pumps and canceling of local SUM ALARM
indication. At this point the system must be restarted, alternation of the vacuum pumps will
revert to PS1 control of 1VP, and vacuum pump overrun timing will recycle.
(d) After normal pump "DOWN" operation, press the SUM ALARM RESET button to cancel
summary alarm.
(5) Power failure.
(a) During a power failure, all coils are dropped and all indicating lights are de-energized. All
motors are removed from the line.
(b) Upon restoration of power, press the system START push button and RESET the summary
alarm. Control of 1VP will revert to PS1 and vacuum pump over run timing will restart at 0.
Restart the tank over board discharge pump when full tank level is reached by pressing the
START/JOG pushbutton (low voltage protection).
4-727
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