Repair manual

HOW THE ELECTRIC (WARRICK
RELAY) WATER LEVEL CONTROLS
OPERATE — ON ELECTRIC STEAM
GENERATORS (WITH 3 PROBES)
Inside Cleveland Range Co. boilers which have electric water
level controls, there are three probe extensions vertically
oriented above the water with their lower ends positioned at
various levels. Water is admitted to the boiler and is shut off
in response to the water level sensed by the tips of the short
and the medium length probe extensions. The electrical
conductance of the water is used in this system for controlling
its level.
The third probe extension is a low water safety cutout sensor
and operates on the same principle.
Operation Sequence — Water Level Control
Assume an empty boiler. To fill dose Switch S for the following
operations:
1) Solenoid SV² is energized allowing the boiler to fill with
water at the same time the primary circuit of Transformer T² is
also energized.
2) The boiler will continue to fill until the water level reaches the
Water Off probe extension completing the T, secondary circuit,
and energizing Relay Coil RC².
3) When Relay Coil RC² is energized the normally closed
contact opens, de-energizing Solenoid SV², stopping the water
fill. The normally open contact is closed, completing the
circuit to the Water On probe.
When the water boils away below the end of the Water On
probe extension the following occurs:
1) The secondary Circuit of Transformer T² is broken and the
Relay Coil RC, is de energized.
2) When Relay Coil RC² is de-energized the normally open
contact opens, breaking the circuit to the Water Off probe
extension. And. the normally closed contact closes, energizing
Solenoid SV² allowing the boiler to fill as in Step 2 above.
Operation — Low Water Safely Cutout
When Switch S is closed the following operations occur
1) The primary circuit of Transformer T² is energized.
2) When the water level reaches the low water safety cutout
probe extension and the momentary reset switch is manually
closed. Relay Coil RC² is energized.
3) When Relay Coil RC, is energized the normally open
contacts close, completing the low water safety circuit through
Contacts 7 and 8. and completing the circuit through Contacts
3 and 4, energizing Contactor Coil C which closes the heater
circuit.
If the water level drops below the Low Water Safety Cutout
probe extension, the following occurs:
1) The secondary circuit of Transformer T² is broken and
the Relay Coil RC² is de-energized. Contacts 7 and 8 and
3 and 4 open. breaking the circuits to Contactor C.
thereby turning off the heaters.