Electro Mechanical - Auxiliary Low Level Cut Off - Vulcan-Hart VSX24G Service Manual

VSX BOILER BASE SERIES CONVECTION STEAMERS - ELECTRICAL OPERATION
When the water level reaches the LL probe, power to
terminal 7 on the 1D1DO control will be present but no
switching occurs.
After the water level reaches the HL probe, the 1D1DO
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 HL probe.
When the water level drops below the 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 LL probe again, to
energize the internal contactor coil. The 1D1DO
control will toggle ON and OFF during a cooking cycle
as needed.
ELECTRO MECHANICAL - AUXILIARY LOW
LEVEL CUT OFF
This control serves as a safety backup to the main low
level cut-off (LLCO) control to meet Cal-Code
requirements. The operation of the auxiliary control is
identical to the main low level cut-off control but
performs a single function:
• It provides auxiliary low level cut-off protection to
shut off the heat source in case the water level
drops below the LLCO probe.
F24627 (0916)
Fig. 27
A single LLCO probe identical to the LLCO probe on
the main low level cut-off control is connected to the
auxiliary control.
The auxiliary control is powered by input voltage
(120VAC) on terminals 1 and 2 (Fig. 28) which also
connect to the primary side of the internal transformer.
The transformer secondary winding (300 VAC) 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 the LLCO probe
which directs power to the other side of the internal
contactor coil.
When the main power switch is turned ON, the
auxiliary low level control is energized but no switching
occurs.
When the water level reaches the LLCO probe, the
internal contactor coil on the low level control is
energized, closing the contacts on terminals 7 & 8.
The internal contactor coil will remain energized until
the water level in the boiler drops below the LLCO
probe.
When the boiler stops filling, press the manual reset
button on the boiler control box. This closes and locks
the manual reset switch contacts to energize the heat
source auxiliary control.
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