Most utilities and plants maintain electrical assets on a calendar: inspect every year, test every few years, replace on schedule. Predictive maintenance (PdM) does something better – it measures the actual condition of each asset and acts when the condition changes. For electrical assets – switchgear, transformers, cables, GIS – the condition signals are partial discharge, temperature, gas leakage and connection resistance. This guide sets out how to build a working PdM programme around those signals.
Step 1: Define the asset scope
Start with the assets where failure hurts most: critical switchgear, power transformers, cable circuits serving essential loads, and GIS bays. Rank them by criticality (consequence of failure) and failure likelihood. The programme begins with the top of the list.
Step 2: Select the instrument set
- Handheld PD detector (TEV + ultrasonic) – the workhorse for switchgear and panel surveys
- HFCT clamps – transformer and cable PD checks
- Infrared acoustic imager – thermal and acoustic one-pass surveys
- SF6 leak detector – for gas-insulated equipment
- Oscillating wave test set – for cable fleets
Choose instruments with quantitative output, English documentation and a training path – the programme depends on the engineers who use them daily.
Step 3: Establish baselines
The first survey cycle sets the baseline for every asset. Record readings per asset, per measurement point, with date and load. Without baselines, absolute numbers are hard to interpret; with them, trends drive decisions.
Step 4: Define the patrol schedule
Match frequency to risk and environment:
- Critical assets and harsh environments (tropical, desert, coastal): more frequent patrols
- Stable indoor assets: annual or per-utility schedule
- Post-event patrols: after storms, switching operations or alarms
Step 5: Set alarm rules
Alarm on change, not on absolute values alone:
- Rising PD trend on a specific asset – investigate, don’t wait
- Significant deviation from room background in TEV readings
- Hot-spot temperature above baseline in thermal surveys
- SF6 loss trend on any compartment
Step 6: Close the loop
Every alarm leads to a defined action: targeted inspection, repair planning, or escalation to permanent monitoring. Record the outcome so the programme learns – a defect found by PD testing and repaired becomes a data point that justifies the next patrol.
Step 7: Review and expand
Review the programme annually: which signals predicted failures correctly, which didn’t? Expand coverage as confidence grows.
About HUWOR
Zhuhai Huawang Technology Co., Ltd. (HUWOR) supplies the instruments behind predictive maintenance programmes – PD detectors, HFCT clamps, infrared acoustic imagers, SF6 leak detectors and cable test sets – with training support and OEM/ODM options for utilities and service companies worldwide. Contact the HUWOR sales team for programme planning support.