The Grid Expansion Context
Qatar, Kuwait and Oman are all investing heavily in new transmission and distribution infrastructure. Qatar continues to expand network capacity after the major infrastructure build-out around the FIFA World Cup, driven by industrial zones and a growing permanent population. Kuwait is modernising aging substations and integrating new generation while shifting more of its grid underground. Oman’s grid operator is expanding across its governorates to support new industrial, tourism and residential developments. In all three countries, utilities are commissioning large numbers of new GIS substations while simultaneously trying to extend the life of older air-insulated switchgear and transformers.
This combination — a wave of new assets plus ageing legacy equipment — is exactly the environment where partial discharge monitoring pays for itself. New GIS installations can be fitted with UHF sensors at commissioning for a marginal cost. Legacy switchgear, which has no built-in monitoring, can be assessed with portable TEV and ultrasonic testing to prioritise refurbishment budgets.
Environmental Stress on Insulation
The Gulf environment is unusually harsh on insulation systems:
- Extreme heat accelerates ageing of epoxy, rubber and paper-based insulation.
- Dust and sand contaminate surfaces and cause tracking and surface discharge, particularly in air-insulated equipment and outdoor terminations.
- Coastal salt and humidity (in Qatar and Oman especially) attack cable terminations, bushing surfaces and switchgear compartments, creating leakage paths.
- Large temperature swings between day and night stress cable joints and terminations mechanically and thermally.
Surface discharge and tracking under dust and salt contamination are typically detectable by ultrasonic and TEV measurement long before a visible failure, which makes regular condition assessment valuable in this climate.
Where to Apply PD Monitoring
New GIS Substations: Commissioning Baseline and Online Sensors
New GIS is delivered with factory PD testing, but its condition can change during transport, assembly and energisation. A commissioning PD survey (UHF or acoustic) establishes a baseline; installing UHF sensors in bays where access is expensive creates a permanent early-warning layer. For utilities building many identical substations, standardising the sensor package at design stage is the most cost-effective approach.
Existing Switchgear and Transformers
Legacy air-insulated switchgear can be surveyed with a portable PD detector using TEV and ultrasonic probes — panel by panel, typically during a planned outage or, for many configurations, live. Transformers benefit from acoustic and electrical PD testing, with oil-filled units also monitored through dissolved gas analysis as a complementary technique. The goal is a risk-ranked list of panels that guides where to deploy permanent monitoring or plan replacement.
Cables and Outdoor Terminations
In Kuwait and Qatar, where significant distribution runs are underground, cable terminations and joints exposed to thermal cycling and humidity are common failure points. HFCT monitoring on critical feeders, combined with periodic offline testing, detects developing faults before they become outages. In Oman’s more overhead-heavy rural networks, ultrasonic detection of surface discharge on insulators and terminations is an effective field technique.
Deployment Guidance
- Standardise on one portable detector family for the whole maintenance team so data is comparable across sites and years.
- Add online sensors to new GIS at build time; retrofitting later is possible but costs more and may require outages.
- Rank assets by criticality and failure history before deciding where permanent monitoring goes; not every panel needs online sensors.
- Correlate PD readings with temperature and humidity, especially in coastal sites, to avoid acting on environmental noise rather than real defects.
- Keep a rolling database of survey results; trend analysis is what turns raw PD values into maintenance decisions.
FAQ
Should we install UHF sensors on all new GIS bays?
Not necessarily all, but the ones that are hard to access, critical to supply, or expensive to de-energise are the best candidates. Installing at commissioning is cheap; retrofitting later typically costs several times more.
Can TEV testing be done while the switchgear is energised?
Yes. TEV and ultrasonic measurements are non-intrusive and are routinely performed live on air-insulated switchgear. Only certain offline cable and transformer tests require de-energising.
How do dust and sand affect PD readings?
Surface contamination creates additional discharge activity, especially in dry dusty conditions. This shows up clearly in ultrasonic and TEV measurements. The key is interpretation: consistent readings during dry months may be contamination-driven, while sharp increases after humidity events suggest tracking and need closer inspection.
What is the difference between acoustic and electrical PD testing for transformers?
Acoustic testing locates discharge sources by their sound, which is useful for localising faults. Electrical methods (such as high-frequency current measurement) are more sensitive to small discharges but need a stable electrical reference. For transformers, combining acoustic location with electrical detection and DGA gives the most complete picture.