Fig. 25
However, it 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 low level cutoff (LLCO) probe.
A single LLCO probe, identical to the LLCO probe on
the main WLC board, is connected to the auxiliary
control.
The auxiliary water level control has input voltage
(120VAC) across terminals 11 and 12 (Fig. 26) 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 control that
directs power to the other side of the internal relay
(LLCO). As water enters the boiler, it becomes part of
the auxiliary water level control’s circuit. When the
water level in the boiler reaches the LLCO probe, the
circuit is completed.
When the main power switch is turned ON, power is
supplied to the auxiliary WLC board but no switching
occurs. On CSD-1 models, the low water level
indicator light (amber) on the boiler control box comes
on.
When the water level reaches the LLCO probe, the
LLCO relay is energized (LLCO-2 close) and the
LLCO LED turns on. The LLCO relay will remain
energized and its LED will stay lit until the water level
in the boiler drops below the LLCO probe.
Fig. 26
When the boiler stops filling, press the manual reset
button on the boiler control box. On CSD-1 models,
this energizes the low water relay, turns off the low
water light and energizes the heat source auxiliary
control. On Cal-Code models, this closes and locks
the manual reset switch contacts to energize the heat
source auxiliary control.
ELECTRO MECHANICAL - 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]) , a differential level control
(1G1DO) 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 LLCO probe. The differential
level control maintains the water level between the LL
and HL probes.
Each control is powered by input voltage (120VAC) on
terminals 1 and 2 (Fig. 27) 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 the probe that directs power
to the other side of the internal contactor coil.
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 1G1DO control and water
begins filling the boiler.
When the water level reaches the 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.
VSX BOILER BASE SERIES CONVECTION STEAMERS - ELECTRICAL OPERATION
Page 33 of 82
F24627 (0916)
