Power Modulation Unit (Pmu)/High Limit Pcb; Pmu Purpose - Henny Penny OFE 51X Service Manual

Henny Penny

Power Modulation Unit (PMU)/High Limit PCB

PMU Purpose

Control of the electric heat system for each vat is handled by a PMU that is powered by 24 volts
DC from the Power Distribution PCB. Incoming to the PMU are main and level resistance tem-
perature detector (RTD) probe resistances for the respective vat. The RTD probes provide oil tem-
perature and level detection feedback to the control system. Each main and level RTD probe has
a baseline of 1000 ohms at 32°F (0°C) with increased resistance as oil temperature rises. Safety
circuits for the High Limit PCB and element tilt switch are connected to the PMU and must be
closed before heat is applied. Outputs of the PMU are 24 volts DC to the safety and heat con-
tactor coils along with the High Limit PCB. Two PMU e-fuses are built-in to prevent excess current
draw situations.
One PMU per vat, full or split
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PMU locations 1 through 8 with specific 3 digit address
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Odd numbered locations: Left split vat only
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Even numbered locations: Full vat or right split vat
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Analysis of main and level probes resistance input from the respective vat
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1000 ohm RTD probes for oil temperature and level detection feedback
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Safety circuits for High Limit PCB and element tilt switch
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24 volts DC output to safety and heat contactor coils
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LEDs to indicate statuses
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Two e-fuses for excess current draw
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Connected to CAN bus operations network
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Power Modulation Unit
F5/ LOV 300Open Fryer
21 FM06-077 A 2023