The tests that stand between "built" and "energized."

Commissioning is where construction becomes an operating asset. Over roughly 4 to 8 weeks, every piece of primary and secondary equipment is proven individually, then as a system, then under real voltage — in that order. Skipping steps is how latent faults survive into service.

The sequence, stage by stage

1. Individual equipment tests

• Insulation resistance & dielectric tests on transformers, cables, breakers and busbars.
• Breaker timing and contact resistance — the interrupter must open and close within its rated milliseconds.
• Transformer ratio, vector group and winding resistance — verifying the unit matches its nameplate.
• CT/VT ratio and polarity — the measurement chain every protection decision depends on.

2. System tests

• Secondary injection — simulated fault signals fed into each protection relay.
• Primary injection — real current driven through the primary circuit end-to-end.
• SCADA point-to-point — every alarm, status and control command verified.
• Interlock and tripping matrix checks — confirming every fault trips exactly the breakers it should.

3. Staged energization

Energization is never a single switch-on. The bus is energized first and held, then each transformer is energized from the HV side and monitored, then load is picked up feeder by feeder.

The commissioning file — test sheets, relay settings, as-built drawings — is as much a deliverable as the substation itself.

Powerst executes commissioning with dedicated test engineers as the final phase of every substation scope, handing over energized, in-service facilities with complete documentation.