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MODEL C24EA - WATER LEVEL CONTROL COMPONENTS
F25213 (May 2006) Page 22 of 52
WATER LEVEL CONTROL COMPONENTS
WATER LEVEL CONTROLS
Low Level Cut-Off & Differential Control
The steamer is equipped with three water level
sensing probes (high, low and low level cut-off) and
a water level control board. The water level control
board performs two functions: 1) Provide low level
cut-off protection to shut off the heat source in case
the water level drops below the low level cut-off
(LLCO) probe. 2) Perform as a differential level
control to maintain the water level between the low
and high water level probes.
The water level control (WLC) board has input
voltage (120VAC) across terminals 11 and 12 which
powers the primary side of the transformer. On one
side of the transformer secondary, power is provided
to the control by a series path through chassis
ground (terminal 10). The other side of the
transformer secondary (12VAC) is attached to the
probe that directs power to the other side of WLC
board relay coils (LLCO and HL) and to the inverse
latching relay (ILR) electronic circuit on the WLC
board. As water enters the generator, it becomes
part of the WLC board circuit. When the water level
in the generator reaches a probe, that circuit is
completed.
The inverse latching relay of the WLC board is de-
energized, leaving the ILR-1 (N.O.) and ILR-2 (N.C.)
contacts in their shelf state.
When the main power switch is turned on, power is
supplied to the WLC board which energizes the high
level (HL) relay, closes HL-1 normally open contacts,
and illuminates the HL relay LED. With the HL-1
contacts closed, the slow fill solenoid is energized
and water begins filling the generator.
When the water level reaches the low level cut-off
(LLCO) probe, the LLCO relay is energized and
illuminates the LLCO LED. With the LLCO-1 contacts
closed, the heat source can be energized provided
the auxiliary control(s) in the heating circuit are
satisfied. The LLCO relay will remain energized and
its LED will stay lit until the water level in the
generator drops below the LLCO probe.
When the water level reaches the low level (LL)
probe, power to terminal 2 on the WLC board is
present but no switching occurs.
After the water level reaches the high level (HL)
probe, the inverse latching relay of the WLC board is
energized and locked through the low level probe
(LL) and ILR-1 contacts. With ILR-2 contacts open,
HL relay is de-energized and the HL LED goes out.
With the HL-1 contacts open, the slow fill solenoid is
de-energized, stopping the flow of water into the
generator.
When the water level drops below the low level (LL)
probe, power is removed from the inverse latching
relay, the HL relay energizes through ILR-2 and HL
contacts change state. The slow fill solenoid is
energized through HL-1 to refill the generator and
the HL LED is lit. The HL relay and LED will toggle
on and off during a cooking cycle as needed.