Vulcan-Hart ML-126852, ML-126857 Water Level Controls, Low Level Cut-Off & Differential Control

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VHX SERIES STEAMER - ELECTRICAL OPERATION

WATER LEVEL CONTROLS

Low Level Cut-Off & Differential Control

The steamer is equipped with three water level sensing probes (high, low and low level cut-off) and a 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 water level control (WLC) board has input voltage (120VAC) across terminals 11 and 12 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 WLC board relay coils (LLCO and HL) and to the inverse latching relay (ILR) electronic circuit on the WLC board. As water enters the boiler, it becomes part of the WLC board circuit. When the water level in the boiler reaches a probe, that circuit is completed.

The inverse latching relay of the WLC board is de- energized, 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 high level (HL) relay, closes HL-1 normally open contacts, and illuminates the HL relay LED. With the HL-1 contacts closed, the boiler fill solenoid is energized and water begins filling the boiler.

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-1 contacts closed, the heat source can be energized provided the auxiliary control(s) in the heating circuit are satisfied. 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 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 of the WLC board is energized and locked through the low level probe

(LL)and ILR-1 contacts. With ILR-2 contacts open, HL relay is de-energized and the HL LED goes out. With the HL-1 contacts open, the boiler fill solenoid is de-energized, stopping the flow of water into the boiler.

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 boiler fill solenoid is energized through HL-1 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.

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F25154 (February 2004)

 

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Contents VHX24E Shown VHX Boiler Base Series High Efficiency Electric SteamerTable of Contents VHX Series Steamers Model Number of Pans PAN Depth PER Compartment Inches INSTALLATION, Operation Cleaning IntroductionGeneral Water Conditioning SpecificationsBoiler Code Descriptions Boiler PressureElectrical ToolsStandard SpecialPressure Switch Control BOX Components Removal and Replacement of PartsMain Control BOX Components Left Side View Shown Water Level Gauge AssemblyHeating Elements Heating Elements Heating Element Mounting PlateRight Side View Shown Boiler AssemblyDescaler Cathodic Protector Removal Cooking Compartment DoorsGasket HandleLatch Assembly Boiler Service Procedures and AdjustmentsMain Water Level Control Water Level Probe Housing BlowdownWater Level Controls Test Auxiliary Low level Cut-Off Control Cycling Pressure Switch Adjustment Boiler Fill and Cold Water Condenser Solenoid Valves High Limit Pressure Switch AdjustmentCold Water Condenser Thermostat Adjustment Cooking Compartment Intake Shut-Off Valve Adjustment Steam FlowHeating Element Test Door Latch Adjustment Door Sealing AdjustmentElectrical Operation Reset Switch ManualComponent Function Cold Water CondenserSteam Solenoid Valve Compartment Pressure SwitchBlowdown/Drain Boiler Base Controls Component LocationsBoiler Base Controls Cooking Compartment Controls Low Level Cut-Off & Differential Control Water Level ControlsAuxiliary Low Level Cut-Off Relay Board Layout, Legend & Diagnostic Test PointsSchematic Initial Fill and Preheat Sequence of OperationBoiler Blowdown/drain Water Refill After Initial FillVHX Series Steamer Electrical Operation Schematics Cooking Compartment Controls Wiring Diagrams VHX Series Steamer Electrical Operation Heating Element Circuits Cooking Compartment Controls Boiler Base Controls TroubleshootingSymptom Possible Causes Symptom Possible Causes Symptom Possible Causes Cooking Compartment Controls VHX Series Steamer VHX Series Steamer Part Number Description Condensed Spare Parts ListVHX24E, VHX24E5, MHB24E
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