A substation is not finished when it is built. It is finished when it is proven — and the proof is a record set that an inspecting authority, an insurer and the next maintenance crew can all read years later.
Primary equipment
- Transformer — turns ratio on every tap, winding resistance, magnetising current, insulation resistance and polarisation index, tan delta on windings and bushings, oil BDV and dissolved gas analysis as a commissioning baseline.
- Circuit breakers — contact resistance, closing and opening timing, simultaneity between poles, SF6 density and dew point where applicable.
- CTs and PTs — ratio, polarity, magnetising characteristic and burden verification. A reversed CT polarity that survives to charging is a differential trip waiting to happen.
- Isolators and earth switches — mechanical interlock proving, contact alignment, operating times.
Secondary systems
- Relay setting verification against the approved coordination study, not against the previous site's settings.
- Secondary injection on every protection element that will be live.
- End-to-end trip testing — relay to breaker, including lockout and breaker-failure paths.
- Annunciation, SCADA point-to-point and time synchronisation checks.
The earthing system
Earth grid resistance, continuity of every riser and touch-and-step potential measurements. This is the section that gets thinnest under schedule pressure and the one that matters most if something goes wrong.
What the client should receive
As-built drawings reflecting site changes rather than the tender drawings, the full test record set with instrument calibration certificates attached, relay setting files, O&M manuals, and a punch list with every item closed and signed. If a reading needs explaining two years later, this set is what explains it.
Have a project that needs this expertise?
We take substation work end to end — design, erection, testing, commissioning and the maintenance afterwards.
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