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# HCA Flush valve issue
The flush valve is opening at random times.
The valve is commanded to 30% when this happens. The part of the program that does this is the "Open Flush Valve on pump shutdown" LAD 14 Rung 6
The "Open Flush Valve on pump shutdown" (aka shutdown bit) is latched by this rung in LAD 6
![[HCA_Flush_valve_issue_image_1.png]]
The "PMP-100 VFD Start Command" (aka start command) bit is controlled by this rung:
![[HCA_Flush_valve_issue_image.png]]
In investigating why this open flush valve bit is being triggered, I noticed "glitching" of these bits (just B3:1/3
![[HCA_Flush_valve_issue_image_2.png]]
These bits are controlled by the HMI.
If the "PMP-100 Call to Start" (aka Start) bit drops, the start command bit drops, causing the shutdown bit to latch. The flush valve then is commanded to 30%.
The Well does not shutdown because the Start bit only momentarily drops out.
Theres a chance this is being caused by a power issue. I have noticed the AC power filter is "clicking". I put my meter on it but didn't notice any drops in voltage. also, the power filter is before the UPS, so the chances are slimmer that this is an issue.
It's also possible one of the "pump interlocks" is dropping out. most of these latch until the alarm reset is triggered. Our issue is momentary, so maybe not the problem. If the digital inputs are dropping momentarily, that could cause it.
![[HCA_Flush_valve_issue_image_3.png]]
Changes implemented:
LAD 6 Rung 1 Put a bypass on the local/remote control hmi selector logic
LAD 6 Rung 5 put temp bypass on VFD Selected and MCC Auto digital input bits
LAD 6 Rung 13 put temp bypass
LAD 14 Rung 0 put temp bypass
LAD 14 Rung 4 put temp bypass
Bypassed the power filter
Left HMI ethernet cable disconnected