armature circuit interrupted

What does ACI mean?

This fault indicates an open circuit or very high resistance in the armature circuit of a DC motor, preventing current flow to the motor windings. This could be due to a loose connection, broken cable, or brush/commutator issue. By default, this critical condition triggers a full TRIP, inhibiting all ignition pulses and resetting the Ready signal, as the drive cannot control the motor without a complete armature circuit. Manual reset is required.

• Loose connection at DC motor armature terminals (A1, A2) or drive output terminals (e.g., T1, T2).
• Broken conductor within the DC motor armature cable due to repeated flexing or mechanical stress.
• Internal open circuit in the DC motor armature winding itself (e.g., commutator segment fault, broken winding wire).
• Blown armature circuit fuse or tripped armature circuit breaker (if present) preventing current flow.
• Excessive brush wear in the DC motor preventing proper electrical contact with the commutator.

Click steps to track your progress.

1. 1

   Perform a lockout/tagout procedure. Measure resistance across drive armature output terminals (e.g., T1, T2) with the motor disconnected; expect a low ohmic value (< 1 Ohm for many motors).

2. 2

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

3. 3

   Inspect DC motor brushes for wear; replace if length is below manufacturer's minimum specification (e.g., < 10mm).

4. 4

   Verify tightness of all armature circuit connections at the drive, motor, and any intermediate junction boxes (e.g., torque to 5 Nm).

5. 5

   Check for an open circuit on the armature winding by measuring resistance between commutator segments if accessible, or using a growler test.