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The supply connections.
The input connections.
The output connections.
There are no parameters related to this trip message.
A failed SCR can also cause phase loss, particularly an SCR that has failed open circuit. A failed SCR can only be diagnosed accurately
by replacing the SCR and checking the soft starter performance.
11.2.25 L1-T1/L2-T2/L3-T3 Shorted
Cause
During pre-start checks, the soft starter has detected a short-circuited SCR or a short circuit within the bypass contactor as indicated.
Troubleshooting
Consider using PowerThrough to allow operation until the soft starter can be repaired.
See also
parameter 6-19 Shorted SCR Action
.
11.2.26 Low Control Volts
Cause
The soft starter has detected a drop in the internal control voltage. This protection is not active in ready state.
Troubleshooting
Check the external control supply (terminals A7, A8, A9) and reset the soft starter.
If the external control supply is stable:
Check if the 24 V supply on the main control PCB is faulty; or
Check if the bypass driver PCB is faulty. Contact the local supplier for advice.
There are no parameters related to this trip message.
11.2.27 Low Flow
Cause
The flow sensor connected to the smart card has activated low-flow protection.
Troubleshooting
Check the following parameters:
Parameter 30-5 Flow Sensor Type
.
Parameter 30-7 Flow at 4 mA
.
Parameter 30-8 Flow at 20 mA
.
Parameter 31-2 Low Flow Trip Level
.
Parameter 31-3 Flow Start Delay
.
Parameter 31-4 Flow Response Delay
.
Parameter 36-7 Low Flow
.
11.2.28 Low Pressure
Cause
The pressure sensor connected to the smart card has activated low-pressure protection.
Troubleshooting
Check the following parameters:
Parameter 30-1 Pressure Sensor Type
.
Parameter 30-3 Pressure at 4 mA
.
Parameter 30-4 Pressure at 20 mA
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Parameter 32-4 Low Pressure Trip Level
.
Parameter 32-5 Low Pressure Start Delay
.
Parameter 32-6 Low Pressure Response Delay
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Parameter 36-5 Low Pressure
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AQ262141844215en-000401 / 175R1174 | 123
Danfoss A/S © 2020.12
Troubleshooting
VLT® Soft Starter MCD 600
Operating Guide