ABB MNS-MCC Error Code E-106

ABB Electrical Critical Overcurrent

Model: MNS-MCC | Code: E-106

Applicable Systems
MNS-MCC

Symptoms

The motor protection relay has tripped on overcurrent. The circuit breaker opened and the motor stopped. The relay display shows phase current exceeded 115% of FLA.

Possible Causes

  • Motor overload due to mechanical load exceeding the rated torque
  • Shorted motor winding causing excessive current draw
  • Low supply voltage causing the motor to draw more current to maintain power output
  • Phase imbalance or single-phasing causing uneven current distribution

Troubleshooting Steps

  1. Step 1: Check the motor protection relay trip log for the fault current and duration
    Record the phase currents and compare to the motor FLA on the nameplate
  2. Step 2: Inspect the motor for signs of overheating, burning smell, or winding discoloration
    If damage is visible, perform a winding resistance and insulation test before restarting
  3. Step 3: Measure the three-phase supply voltage and verify balance within 3%
    If voltage imbalance exceeds 3%, investigate the supply transformer and connections
  4. Step 4: Disconnect the motor from the load and perform a no-load test run
    No-load current should be 30-50% of FLA; if higher, the motor may have internal issues

How to Reset

Reset: After correcting the root cause, manually close the motor protection relay and reset the circuit breaker. The motor can then be restarted.

Common Replacement Parts

  • Motor protection relay: Electronic type, 0.5-5A range (Set to motor FLA and trip class 10 or 20)
  • Circuit breaker: Motor-rated, 3-pole, 25kA interrupting (Match frame size to motor full-load current)

Frequently Asked Questions

  • Q: What is motor FLA?

    Full-Load Amperage is the current the motor draws at rated voltage and rated load. It is printed on the motor nameplate.

  • Q: How do I test for a shorted winding?

    Measure winding resistance between all three phases. Readings should be within 5% of each other. A low reading indicates a short.

  • Q: What is single-phasing?

    Loss of one phase in a three-phase system. The motor continues running on two phases but draws excessive current, leading to rapid overheating.

Related ABB Fault Codes

Source: OEM Technical Manual

Category: Electrical