Case Study: Persistent Hydraulic Float Alarm – DC Power Supply Issue / Shorting Out

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Hydraulic Float Alarm

Description of Problem: Hydraulic low-level float sensor setting off alarm. Wash unable to start, even in manual mode.

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Things to check:

1- Any incidents that occurred shortly before the problem first began?

 

2- Check for 24 volts dc on hydraulic level float inputs 38 and 39. Can also be checked by searching for green light on the monitor page.

> Customer confirmed that those inputs did not have 24 volts. Additionally, none of the inputs listed on the monitor page had a green light.

 

3- Check 24 volt power supply for status lights, which should read “DC OK” and display a green light (Above).

>Customer confirmed 24 volt power supply was down

 

4- Check power to power supply, should be 120 volts AC

 

Analysis: Based on the power supply status (no lights on “DC OK”) and the active 120 volt AC connection to it, the problem is suspected to be a failure within the power supply or a short in the wiring. Diagnose a short in the wiring by removing one wire at a time from the input terminals and checking to see if the “DC OK” light illuminates.

 

Conclusion: Customer identified a shorted wire for the hydraulic float, causing the 24 volt power supply to go into overload protection mode. The wiring was corrected and the wash started properly.

 

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