What Are the Common Failure Points in ABB VD4 Breakers After Years of Service?

Does Your Plant Use ABB VD4 Breakers?Despite the VD4's proven reliability in global markets, no equipment is immune to faults with prolonged use. Below, we’ve compiled common VD4 faults and their solutions—hopefully this helps you in daily maintenance!

Fault 1: Energy Storage Mechanism Failure

Symptom:
Motor cannot store energy, but manual storage works.

Possible Causes & Solutions:

1. Power Not Connected

Check if power is reaching the terminal block in the switchgear and confirm that the control power switch 2ZK in the storage circuit is in the closed position.

2. Faulty Energy Storage Limit Switch (S1)

The S1 limit switch in the VD4-12 controls motor start/stop and signal circuits. Two normally closed (NC) contacts in series control the motor: when the spring is fully charged, S1 actuates mechanically, opening the NC contacts and cutting power to the motor. When the spring is released or uncharged, the NC contacts close to allow recharging.

• Unplug the aviation connector and measure the resistance between pins 25# and 35#.

• If abnormal, check NC contacts 31–32 and 41–42. Burnt contacts indicate S1 failure—replace the S1 switch.

• After replacement, adjust the S1 drive rod gap to 2.5–2.8 mm after full charging.

3. Worn Motor Brushes

Severe brush wear prevents normal motor operation. Replace the carbon brushes.

4. Burnt Storage Motor (MO)

If the control circuit is intact but resistance is abnormal, the motor may be burnt.

• Disconnect wiring, remove the three mounting bolts, and replace the motor.

Fault 2: Breaker Fails to Close

Symptoms:

• Electrical close fails; closing solenoid (trip coil) does not actuate.

• Electrical close fails due to weak solenoid action, but manual close succeeds.

• Electrical and manual closing both fail.

For Symptom 1 (Solenoid Not Actuating):

1. Drawer Unit Not Fully Seated
If the withdrawable unit is not fully racked in, two limit switches in the chassis won’t close the interlock coil circuit, preventing closing.

• Check the position indicator on the switchgear.

• Ensure the unit is correctly positioned in either "Service" or "Test" position.

2. Faulty Closing Interlock Solenoid (Y1) or Microswitch (S2)
A faulty Y1 solenoid or improperly actuated S2 microswitch can interrupt the closing circuit.

• Measure Y1 coil resistance. If abnormal (shorted or open), replace the Y1 module.

• If resistance is normal, check S2 actuation. Use needle-nose pliers to gently bend the S2 spring contact outward by 1–2 mm. Manually operate the Y1 plunger and listen for a click from S2.

3. Faulty Auxiliary Switch (S3) or Aviation Plug Pin Dropout
Open contacts in S3 or loose pins in the aviation connector will interrupt the closing circuit.

• In the open position, if S3’s NC contact fails to close, adjust the S3 drive rod gap.

• If pins are damaged or loose, replace the aviation connector.

For Symptom 2 (Weak Solenoid, Manual Close Works):
Likely due to low closing voltage or faulty closing coil rectifier bridge.

• Check power supply voltage.

• Test output of the rectifier bridge; replace the closing coil module if faulty.

For Symptom 3 (Both Electrical and Manual Close Fail):
Usually caused by the mechanical interlock plate in the spring mechanism being stuck or not resetting after racking in, preventing the closing pawl from releasing.

• Inspect the interlock plate carefully.

• If deformed, replace the entire actuator module.

⚠️ Prolonged energizing of the closing coil in this state may cause coil burnout.

Fault 3: Breaker Fails to Trip (Trip Rejection)

This is a critical emergency fault.

Symptoms:

• Electrical trip fails; trip solenoid (Y2) does not actuate.

• Electrical trip fails due to weak solenoid action, but manual trip succeeds.

For Symptom ① (Solenoid Not Actuating):

1. Faulty Trip Solenoid (Y2)

Measure the resistance of Y2 coil. If abnormal, replace the trip coil.

2. Poor Contact in Auxiliary Switch (S4)

After closing, S4’s normally open (NO) contact must close to complete the trip circuit. After tripping, it must open quickly to prevent prolonged coil energization. Frequent operation can damage S4 contacts.

• For minor damage, adjust the S4 drive rod gap.

• For severe damage, replace the S4 auxiliary switch.

3. Loose Wiring or Aviation Plug Pin Dropout

Loose connections or broken pins in the secondary control circuit will prevent tripping.

• Inspect and tighten loose wires.

• Replace the aviation connector if pins are damaged or missing.