Commissioning is the moment when a substation bay moves from construction to operation – and the best opportunity to prove equipment quality and establish the baselines that future maintenance will be measured against. Beyond routine electrical tests, a commissioning programme should include live-line detection checks that catch insulation defects, connection problems and gas-tightness issues before the asset is in service.
Why commissioning tests matter
- Defects are cheapest to fix now – repair before energisation beats failure in service.
- Baselines make trends possible – the commissioning measurement is the reference for every future patrol.
- Contractor quality is verified – a witnessed commissioning record holds the installer to the standard.
The live-line detection checklist
1. Switchgear and panels
- TEV survey of all panels to establish the PD baseline
- Ultrasonic check of compartments for audible discharge
- Thermal imaging during first load – hot connections appear within hours under load
2. Transformers
- HFCT PD measurement on grounding and neutral connections
- Ultrasonic PD scan of the tank surface at several heights
- Record oil sample for DGA baseline if not already done
3. GIS and gas equipment
- UHF PD sensor check where sensors are installed
- SF6 quantitative leak survey of joints, flanges and valves
- Confirm density monitor readings and gas pressure records
4. Cables
- Oscillating wave acceptance test for new cable circuits
- PD localisation recorded per circuit for future comparison
5. Surge arresters
- Leakage current measurement baseline where applicable
Building the commissioning record
Each measurement becomes a line in the asset register: asset identity, date, load, instrument, and the measured value. This register is what future patrols compare against, turning commissioning from a one-time event into the first point of an asset’s condition history.
Timing the tests
- Before energisation: cable acceptance, SF6 leak survey, gas pressure checks
- At energisation: initial thermal imaging during load build-up
- During the first weeks: repeat thermal survey to catch connection settlement, plus a TEV patrol to confirm stability
About HUWOR
Zhuhai Huawang Technology Co., Ltd. (HUWOR) manufactures the live-line detection instruments used in commissioning – handheld PD detectors, HFCT clamps, ultrasonic sensors, SF6 leak detectors, infrared acoustic imagers and cable test sets – and supports EPC contractors and utilities worldwide with OEM/ODM supply and application guidance. Contact the HUWOR sales team for a commissioning instrument set.