Vulcan-Hart C24GA6, C24GA10, ML-136021, ML-136022 Electrical Operation, Water Level Controls

C24GA SERIES CONVECTION STEAMERS - ELECTRICAL OPERATION

ELECTRICAL OPERATION

WATER LEVEL CONTROLS

Low Level Cut-Off and Differential Control

The steamer is equipped with three water level sensing probes (high, low and low level cut-off) and a single 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 input voltage (120VAC) is applied across termi- nals 11 and 12 of the Water Level Control (WLC). This is applied to the primary 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 ILR). As water enters the generator, it becomes part of the water level control’s circuit. When the water level in the generator reaches a probe, that circuit is completed.

The inverse latching relay (ILR) of the board is de- energized, leaving the ILR-1 (N.O.) and ILR-2 (N.C.).

When the main power switch is turned on, power is supplied to the water level control (WLC) board which energizes the high level (HL) relay and illuminates the HL relay LED. With the HL-3 contacts closed, the generator 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-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 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 on the board is energized and locked through the low level probe (LL) and 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 generator 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 fill solenoid is energized through HL-3 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.

SEQUENCE OF OPERATION

Refer to schematic diagrams 00855693 , 00855424 and 00856656.

Initial Fill and Preheat

Conditions:

A.Power switch off.

B.Cold water thermostat open.

C.Drain cold water condenser solenoid de-energized.

D.Timer delay output open.

E.Normally closed solenoid de-energized.

F.Generator connected to correct voltage (120VAC).

G.Generator properly grounded.

H.Gas and water supply valve(s) on.

I.Main gas valve manual valve in on position.

J.Cycling pressure switch closed.

K.Air pressure switch open.

F35425 (February 2006) Page 22 of 40