MV switchgear performs critical switching and protection functions. Maintenance includes more than cleaning: breakers, busbars, cable terminations, interlocks, auxiliary supplies and protection must be considered together.
This guide is general information. HV/MV intervention and testing must be carried out by qualified personnel under the equipment manual and facility safety procedures.
Physical and mechanical checks
Look for arc traces, moisture, contamination, loose connections and wear. Verify breakers, disconnectors, door interlocks and earthing switches according to the equipment manual. Intrusive work requires secure isolation.
- Busbars and cable terminations
- Breaker and disconnector mechanisms
- Mechanical interlocks and earthing
- Auxiliary supply and control wiring
Electrical tests
Depending on design, tests can include insulation resistance, contact resistance, breaker timing and relay functions. Secondary injection assesses protection settings and trip circuits. Primary injection is not automatically required or suitable for every installation.
Intervals and records
Manufacturer instructions, operation count, environmental severity and past findings influence frequency. Abnormal operation or a fault trip may call for an unscheduled inspection. Record equipment identity, test conditions, findings and actions.
Match inspection and tests to the switchgear type
The breaker, isolator, earthing device, busbar and protection circuit form one system. Interlock checks verify the correct sequence of operation. Insulation and contact tests must follow the manufacturer's limits and connection instructions. Functional relay testing is more than reading the displayed setting: where appropriate, the trip chain and breaker response are checked. Findings should be recorded against the exact panel identity.
Decision checklist
- Panel type and breaker technology
- Interlocks and earthing arrangement
- Need for insulation, contact and timing tests
- Relay settings and trip-chain verification
Related service
MV Switchgear Maintenance and Repair →
Request technical support →Frequently asked questions
Must MV switchgear be de-energized for maintenance?
Internal inspection and contact work require safe isolation and voltage-absence verification.
Does every panel get the same tests?
No. The panel, breaker and protection design determine the test plan.
Is primary injection mandatory for every panel?
No. The test depends on circuit design, equipment type and the problem under investigation.
