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Electro Mechanical - Low level Cut-Off &
Differential Control
The steamer is equipped with three water level
sensing probes (high, low and low level cut-off), a
differential level control (1G1GO) and a low level
cut-off control (1D1DO). The low-level cut-off is an
additional control that is identical to the differential
level control but serves as the safety backup to shut
off the heat source in case the water level drops
below the low level cut-off (LLCO) probe. The
differential level control maintains the water level
between the low and high water level probes.
Each control is powered by input voltage (120VAC)
on terminals 1 and 2 which also connect to the
primary side of the internal transformer. The
transformer secondary (300VAC) will provide power
to the internal contactor coil through a series path
going from one side of the secondary winding,
through the contactor coil, through the water level
control probe, through the water in the boiler and to
the boiler for ground. The other side of the
transformer secondary is attached to ground.
When the main power switch is turned ON, both
water level controls are energized. The boiler fill
solenoid is then energized through the normally
closed contacts (terminals 3 & 4) on the differential
level control and water begins filling the boiler.
VL SERIES STEAMER - ELECTRICAL OPERATION
Page 40 of 88
When the water level reaches the low level cut-off
(LLCO) probe, the internal contactor coil on the low
water level control is energized. With the contacts
on terminals 7 & 8 now closed, the heat source is
then energized. The internal contactor coil will
remain energized until the water level in the boiler
drops below the LLCO probe.
When the water level reaches the low level (LL)
probe, power to terminal 7 on the differential level
control will be present but no switching occurs.
After the water level reaches the high level (HL)
probe, the differential control contactor coil is
energized and the normally closed contacts on
terminals 3 & 4 open, which de-energizes the boiler
fill solenoid and stops the flow of water into the
boiler. The internal contactor coil will have a locking
path through contacts 7 & 8 to the low level probe to
keep the coil energized after the water level drops
below the high level probe.
When the water level drops below the low level (LL)
probe, the internal contactor coil is de-energized,
returning contacts 3 & 4 back to their normally
closed state and energizing the boiler fill solenoid to
refill the boiler. The water level must then fill to the
high level probe again, to energize the internal
contactor coil. The differential control will toggle ON
and OFF during a cooking cycle as needed.
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