ABB E-103: ABB MNS-MCC Error Code E-103

Symptoms

The temperature monitoring relay trips the feeder breaker and logs O/T. The PT100 sensor in the motor terminal box reads >130C. The red temperature alarm LED is illuminated.

Possible Causes

Motor ventilation blocked by debris or enclosed installation
Excessive number of starts per hour causing cumulative heating
Ambient temperature in the MCC room exceeds 40C design limit
Incorrect thermal protection curve selected for the motor duty cycle

Troubleshooting Steps

Step 1: Verify the motor cooling fan is intact and the ventilation channels are clear of dust or obstruction
Air flows freely through the motor cooling fins and fan cover
Step 2: Review the motor start count and running hours for the past 24 hours against the nameplate maximum
Start count is within the allowed starts per hour (typically 3-6 for standard motors)
Step 3: Measure ambient temperature inside the MCC enclosure with a digital thermometer
Ambient temperature is <40C or matches the design specification
Step 4: Verify the PT100 sensor wiring continuity and compare the relay trip threshold with the motor insulation class
Class F insulation allows 155C; trip threshold should be set 10-20C below this

How to Reset

Allow the motor to cool naturally for at least 30 minutes. Reset the temperature relay by pressing the reset button. Reclose the breaker only after confirming the temperature reading has dropped below the alarm threshold.

Common Replacement Parts

1SFA619510R1001: ABB CM-PFE temperature monitoring relay (Supports PT100/PT1000 and thermistor inputs)

Frequently Asked Questions

Q: Why does the motor overheat only during summer?
Ambient temperature rise in the MCC room or inadequate ventilation are the most common seasonal causes. Check HVAC operation.
Q: Should I reduce the trip threshold to protect the motor?
The threshold should match the motor insulation class and application. Too low causes nuisance trips; too high risks insulation damage.

ABB MNS-MCC Error Code E-103