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voltage sensing circuit allows the battery failure relay to drop out when the battery potential drops
below a level of about 60 percent of nominal for a period of several seconds. If a low battery voltage
is sensed, the appropriate battery failure relay will drop out and lock the other one in.
If Battery No.1 goes low or fails, 10CR will drop out. Its Normally Closed (N.C.) contacts
(terminals 1 and 7) close and keep 11CR energized independent of the VS circuit. These contacts
also lock the battery switching relay 5CR in the energized position by way of the Alternating (AR)
on the main logic board. With 5CR held energized, its Normally Open (N.O.) contacts (terminals
4,7,6, and 9) will be held closed so that cranking power can be provided only by Battery No.2
through 7CR contacts to 1T Terminal 10. 10CR N.C. contacts (terminals 1 and 7) energize the
Alarm Relay 13CR through diode D24 to sound the alarm. If Battery No.2 fails, 11CR drops out and
locks in 10CR through 11CR N.C. contacts (terminals 1 and 7). 10CR N.C. contacts (terminals 1 and
7) open and 11CR contacts (terminals 5 and 8) stay open and keep 5CR from energizing. The N.C.
contacts (terminals 1,3,7, and 9) of 5CR remain closed so that cranking power can be provided only
by Battery No.1 through 7CR contacts to 1T Terminal 9. 11CR N.C. contacts (terminals 1 and 7)
energize the alarm relay 13CR through diode D29 and sounds the alarm.
When the two batteries are turned on, the first one on will energize its battery failure relay and lock
out the other one. Pressing the "Battery Reset" pushbutton, 3PB, will pull in the second battery
failure relay if the battery voltage is high enough. Any time a battery failure is sensed and one of the
corresponding relays drops out, the "Battery Reset" pushbutton must be pressed to reset the circuit.
Diodes D68 and D23 on the main logic board are used to isolate the VS circuit from the alarm
circuit.
C. Automatic Operation: For automatic operation, the selector switch is in the "Auto" position. The
Controller is then in a standby mode, and all automatic functions are ready for operation. The
"Auto" light and both battery lights should be on. The Controller will start from any of the following
demand signals:
1. Closing of pressure switch contacts due to a drop in water pressure.
2. Remote start switches.
3. Deluge switch.
5. Power Failure Start (Option P).
All automatic starting is accomplished through the auto start relay 8CR. In sequential start
controllers, auto starts from the pressure switch and deluge switch are delayed by the Sequential Start
Timer (3TR).
D. Drop in Water Pressure: On a drop in water pressure, the pressure switch contacts close, applying
power to the coil of auto start relay 8CR. In sequential start controllers, the pressure switch contacts
apply power to the coil of the Sequential Start Time delay relay (3TR), and the contacts of 3TR
operate the coil of 8CR after the time delay set on 3TR. 8CR locks in through its own N.O. contacts
(terminals 6 and 9). 8CR is locked in and remains energized even after the pressure switch contacts
open until either the "Stop" pushbutton (4PB) contacts are opened, the ERT contacts open, or the
selector switch is turned to "Off". If the pressure switch contacts remain closed, turning the selector
switch to "Off" is the only means to de-energize 8CR and stop the engine.
With 8CR energized, its N.O. contacts (terminals 7 and 4) close to apply power to the Fuel Solenoid
relay 6CR, to the Crank Control (CC) circuit through 9CR N.C. contacts (terminals 1 and 7), and to
the Crank relay 7CR. At this time the CC unit starts timing the first crank period. 7CR energizes
closing its N.O. contacts (terminals 7 and 4) to apply battery power through 5CR N.C. or N.O.
contacts (terminals 3 and 9 or terminals 6 and 9) to 1T Terminals 9 or 10 depending on whether or
not 5CR is energized. Battery power on Terminals 9 or 10 energizes the engine starting contactor,
and, thus, cranking of the engine starts as soon as the pressure switch closes.
After a period of approximately 15 seconds, if the engine has not started, the Crank Control circuit
energizes 1CR. When 1CR energizes, its N.C. contacts (terminals 3 and 9) open and 7CR
de-energizes, thus stopping the crank cycle. N.C. contacts of 7CR (terminals 2 and 8) energizes the
Alternating Relay (AR) circuit which in turn energizes and de-energizes 5CR alternately each crank
cycle. 5CR contacts transfer to switch to Battery 2 (Battery 1) power and to 1T Terminal 10 (1T
Terminal 9). After approximately 15 seconds rest, 1CR de-energizes and 7CR energizes, thus
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