Carrier 30XA Alarm Code 105, 106 & 107 Unverified Slide Valve Control Complete Troubleshooting Guide

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How to Troubleshoot Alarm 105, 106 , 107 Unverified slide valve control in carrier 30XA chiller, Lets understand first how actually slide valve is operated.
The 30XA units utilize screw compressors with a modulating slide valve which varies capacity from 30% to 100% of compressor capacity. The slide valve position is varied by opening and closing the 2 solenoid valves located on the compressor. To unload the compressor, both solenoids are deenergized. And To increase in capacity both solenoid valves are energized together which will cause the slide valve to slide towards the fully loaded position. To stop the loading process solenoid 2 is energized and solenoid 1 is deenergized. This will cause the slide valve to maintain its current position. There is no feedback for the position of the slide valve in carrier 30xa. So the question come how does chiller verify the slide valve control.
Answer to this question is that The control utilizes compressor current as an indicator of the slide valve position. Which means as the control energizing the solenoid coil to load the compressor its monitoring the compressor current as far energizing the solenoid coils keep increasing the compressor current chiller control takes it as valve is operating normally. Once the calculated position of the slide valve reaches 100% circuit capacity, the control will try to increase capacity again if the compressor current continues to increase. The control will continue to load the compressor until the compressor current no longer increases. At that time the control will energize both solenoids and the circuit will be considered fully loaded.
Now that we understand the how control monitors the valve position, we are ready to move to the actual problem of Unverified slide valve control alarm.
If the 100 percent load current is less than 1.1 times of 30 percent load current for 1 minute on active cooling setpoint is greater than 0 centigrade Unverified slide valve control alarm is generated.
Let us explain it in easy words
Lets assume a compressor is designed to consume 300 amperes on 100 percent capacity
And at 30 percent of capacity, it should be operating at 90 amperes.
As per above 1.1 times of 30 percent load current will be 99 amperes.
As compressor is in operation and chiller control have commanded it to work on 100 percent but the actual current of compressor is lesser than 99 amps. Chiller control will generate Unverified slide valve control alarm.
Unverified slide valve control alarm can be Due to following Reasons,
Loading and unloading solenoid valves or coils are faulty.
Slide valve is stuck at offload position
Slide valve piston gasket is leaking

[@sureshkumar-fp8bl]

30xa chiller what is setting MTAsetting it is FLA OR RLA.

[@UATechnicalSolutions]

MTA setting is for must trip amperes . In case compressor draw current morethan the mta setting it will trip the compressor
Fla and rla are not controlled by MTA