Field circuit interrupted

What does FCI mean?

This fault indicates an open circuit or very high resistance in the field circuit of a DC motor, preventing or severely limiting current flow to the motor field winding. Without a proper field, a DC motor can become unstable or overspeed. By default, this critical condition triggers a full TRIP, inhibiting all ignition pulses and resetting the Ready signal, to prevent uncontrolled operation and potential damage. Manual reset is required.

• Loose connection at DC motor field terminals (F1, F2) or drive field output terminals.
• Broken conductor within the DC motor field cable due to fatigue or mechanical damage.
• Internal open circuit in the DC motor field winding (e.g., broken coil, poor connection).
• Blown field fuse or tripped field circuit breaker (if present) in the field excitation circuit.
• Incorrectly set field voltage (e.g., P5-01) or field current limit (e.g., P5-02) preventing proper field excitation.

Click steps to track your progress.

1. 1

   Perform a lockout/tagout procedure. Measure resistance across the DC motor field winding terminals (F1, F2) with the field cable disconnected; expect tens to hundreds of Ohms (refer to motor nameplate).

2. 2

   Measure continuity of each conductor in the field cable from drive output to motor terminals using a multimeter; expect < 0.1 Ohm.

3. 3

   Verify tightness of all field circuit connections at the drive, motor, and any intermediate junction boxes (e.g., torque to 2 Nm).

4. 4

   Check for a blown fuse or tripped circuit breaker in the field excitation circuit (if installed).

5. 5

   With the drive powered and safe, measure the actual field voltage (e.g., P5-01) and current output at the drive's field terminals and compare to motor nameplate data.