A Delta C2000 STO fault indicates the Safe Torque Off (STO) function has been activated. This is a safety feature that cuts power to the motor in case of an emergency stop.

Here's a breakdown of what the STO fault means and how to address it:

Cause:

The STO fault triggers when the VFD (Variable Frequency Drive) detects that the STO input terminals (STO1 and STO2) are open circuit (not receiving voltage). This can happen due to several reasons:

• Wiring Issue: There could be a loose connection, damaged wire, or incorrect wiring to the STO terminals.
• Internal Fault: Less likely, but an internal malfunction within the VFD itself might cause the STO fault.

Troubleshooting Steps:

1. Check Emergency Stop:

• Verify if the emergency stop button was pressed intentionally. If so, reset the emergency stop and power cycle the drive (turn it off and on again).

2. Inspect Wiring:

• Ensure all connections to the STO terminals (STO1 and STO2) are secure and undamaged. Refer to the Delta C2000 user manual for the specific wiring diagram of your drive model.

3. Reset the Drive:

• Some Delta C2000 models have a parameter (Pr. 06-44) that controls automatic reset after an STO fault clears. Check the user manual for your specific model to see if this applies.