ELECTRICAL OPERATION
Water Level Controls
SOLID STATE - LOW LEVEL CUT OFF AND
DIFFERENTIAL CONTROL
The steamer is equipped with three water level
sensing probes (High Level [HL], Low Level [LL], and
Low Level Cut Off [LLCO]) and a single Water Level
Control (WLC) board. The WLC board (Fig. 23)
performs two functions:
•
Provide low level cut-off protection to shut off the
heat source in case the water level drops below
the LLCO probe.
•
Perform as a differential level control to maintain
the water level between the HL and LL probes.
Fig. 23
The WLC board has input voltage (120VAC) across
terminals 11 and 12 (Fig. 24) 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 the internal relays
(LLCO, HL and Inverse Latching [IL]). As water enters
the boiler, it becomes part of the water level control’s
circuit. When the water level in the boiler reaches a
probe, that circuit is completed.
The IL relay is deenergized, 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 HL
relay and turms on the HL relay LED. With the HL-3
contacts close, the boiler fill solenoid is energized and
water begins filling the boiler.
Fig. 24
When the water level reaches the LLCO probe, the
LLCO relay energizes and turns on the LLCO LED.
With the LLCO-2 contacts closed the heat source is
then energized. The LLCO relay will remain energized
and its LED will stay lit until the water level in the boiler
drops below the LLCO probe.
When the water level reaches the LL probe, power to
terminal 2 on the WLC board is present but no
switching occurs.
After the water level reaches the HL probe, the IL relay
energizes and is locked ON through the LL probeand
ILR-1 contacts. With ILR-2 contacts open, this de-
energizes the HL relay and the HL LED goes out. With
the HL-3 contacts open, the boiler fill solenoid is de-
energized, stopping the flow of water into the boiler.
When the water level drops below the LL probe, power
is removed from the IL relay, the HL relay energizes
through ILR-2 and HL contacts change state. The fill
solenoid is energized through HL-3 to refill the boiler
and the HL LED is lit. The HL relay and LED will toggle
ON and OFF during a cooking cycle as needed.
SOLID STATE AUXILIARY LOW LEVEL CUT OFF
This control (Fig. 25) serves as a safety backup to the
main water level control (WLC) board to meet Cal-
Code and CSD-1 code requirements. The operation
of the auxiliary control is identical to the Low Level Cut
Off (LLCO) function of the main WLC board.
VSX BOILER BASE SERIES CONVECTION STEAMERS - ELECTRICAL OPERATION
F24627 (0916)
Page 32 of 82
