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IEC 60298: AC Metal-Enclosed Switchgear — Internal Arc Protection and LSC Classification
An LSC2B Switchgear Limits Arc Propagation to a Single Compartment — Protecting Operators and Maintaining Supply
IEC 60298 specifies AC metal-enclosed switchgear for 1–52 kV (superseded by IEC 62271-200, but remains foundational for in-service equipment). Internal Arc Classification (IAC) and Loss of Service Continuity (LSC) are the core of safety design.
| LSC | Isolation Level | Single-Fault Impact | Operator Safety |
|---|---|---|---|
| LSC1 | No internal compartments | Entire switchgear de-energized | Lowest — but lowest cost |
| LSC2A | Busbar compartment separated from CB compartment | Only faulted compartment de-energized | Moderate — most common |
| LSC2B | All HV parts in independent compartments | Only faulted compartment; remainder stays operational | Highest — for critical loads |
IAC test: A three-phase arcing fault is deliberately initiated inside the switchgear to verify the enclosure can withstand overpressure (>0.5 MPa instantaneous), extreme temperature (>1,000 °C), and intense light without endangering external personnel. Key pass criteria: (1) doors must not open; (2) no hole >50 mm in the enclosure; (3) indicators (cotton cloth simulating operator clothing) must not ignite; (4) earth continuity maintained throughout.
TN Lab — The IAC level of metal-enclosed switchgear is the last line of defense for operator life safety.
