Applicable Systems
MNS-MCC
Symptoms
The arc-flash detection system triggers a trip signal to the upstream breaker. The arc flash indicator LED turns solid red and the event log records light-plus-current coincidence. The compartment pressure relief flap may have deployed.
Possible Causes
- Internal arc fault due to tracking across busbar insulation
- Loose connection at a busbar joint creating ionized gas
- Foreign object left inside the switchgear during maintenance
- Contaminated or degraded solid insulation on bus supports
Troubleshooting Steps
- Step 1: Do not open the compartment. Wear full arc-flash PPE and ventilate the room for 30 minutes
O2 levels normal, no smoke or toxic gas detected by portable meter - Step 2: Inspect the pressure relief flap and door latches for signs of overpressure damage
Flap deployed correctly, no deformation of doors or hinges - Step 3: Use an endoscope or borescope camera through the inspection port to assess internal damage without opening
Visible busbars show no signs of melting or carbon tracking - Step 4: If internal damage is confirmed, de-energize and rack out the breaker, then engage a qualified technician for internal inspection
All energy sources locked out per OSHA 1910.147
How to Reset
The arc-flash system is self-resetting once the upstream breaker opens and the light/current coincidence condition clears. A manual event acknowledgment is required on the HMI before re-energization is permitted.
Common Replacement Parts
- 1VCF349767R8301: ABB TVOC-2 arc monitor sensor kit (Includes fiber-optic loop sensor and mounting hardware for SafeGear)
Frequently Asked Questions
- Q: Can the TVOC-2 system be tested without causing a trip?
Yes. Use the built-in LED test function which simulates light detection without injecting trip current. Refer to the commissioning manual.
- Q: What PPE category is required after an arc-flash event?
Minimum PPE Category 4 (40 cal/cm2) for internal inspection, per NFPA 70E. Do not rely on everyday coveralls.
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Source: ABB SafeGear Medium Voltage Switchgear Technical Guide, Publication 1VCP000287
Category: Electrical
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