What is a CLF fault on the ATS48 starter?

CLF (Control Line Failure)

The CLF fault indicates a Control Line Failure. The ATS48 monitors the control voltage supplied to terminals CL1 and CL2 on the control unit.

This fault is relatively uncommon and is typically caused by a transient loss or drop in the control voltage. For a CLF fault to occur, the voltage on CL1-CL2 must fall below the specified threshold for a sufficient duration.

CLF Fault Thresholds

• ATS48...Q models: Voltage drops below approximately 88 V (40% of 220 V).
• ATS48...Y models: Voltage drops below approximately 44 V (40% of 110 V).

Possible Causes

• Loss of control voltage at terminals CL1-CL2 for at least 200 ms.
• Control voltage falling below the specified threshold.
• Poor power quality or intermittent supply issues.

Recommended Troubleshooting

1. Measure the voltage at terminals CL1 and CL2 and verify that it remains within the acceptable operating range.
2. Check the quality and stability of the incoming control power supply.
3. If the control voltage is stable and within tolerance, the issue may be related to the power board, in which case replacement of the power board should be considered.

Because this fault is often caused by a temporary voltage dip, it is important to verify the stability of the control power source before replacing any components.

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