Gas-insulated switchgear (GIS) is widely used across the Middle East because its compact, sealed design suits desert substations – but GIS still has two principal failure modes that maintenance teams must watch: insulation defects that produce partial discharge (PD), and SF6 gas loss that degrades insulation and quenching performance. Both are detectable online.
How the desert stresses GIS
Sand and dust ingress
Despite sealing, sand can enter enclosures through joints, bushing interfaces and access covers over many years of operation. Deposits on insulator surfaces reduce creepage strength and promote surface discharge. Monitoring verifies that the seal and insulation integrity are holding, rather than waiting for a failure to prove otherwise.
Heat cycling
Desert day-night temperature swings stress the enclosure, gas pressure and mechanical interfaces. Thermal expansion and contraction can loosen contacts and stress insulation, and temperature affects SF6 pressure – which is why SF6 density and PD should be watched together.
Conductor defects from assembly and operation
PD in GIS originates from protrusions, free particles, floating electrodes and contamination left after assembly or developed in service. The electromagnetic pulses propagate inside the enclosure and are most sensitively detected with UHF couplers.
Why UHF is the standard approach for GIS
- High sensitivity – UHF sensors detect picocoulomb-level PD with good signal-to-noise ratio inside the gas compartment.
- Retrofit-friendly – sensors install on dielectric windows or via existing ports without taking the bay out of service.
- Localisation – multi-sensor configurations can localise the discharge source along the bay, focusing inspection effort.
- Noise immunity – the enclosure screens external noise, so UHF measurements inside GIS are relatively clean.
Combining PD with SF6 monitoring
SF6 gas loss and PD are the two complementary signals of GIS health. A complete desert-GIS monitoring deployment combines:
- UHF PD sensors on critical bays, busbar sections and cable/transformer connections
- SF6 density monitors that alarm on gas loss
- An IoT gateway collecting both data streams
- A platform that trends PD amplitude, discharge rate and gas density together
When both signals are watched, a developing defect is caught early – PD rising while SF6 density is stable points to an insulation issue; SF6 falling with normal PD points to a gas leak; both changing together suggests a compartment fault.
Practical deployment for utilities in the region
Phased rollout
Start with the bays that supply critical loads or have known installation histories, then extend monitoring to the rest of the substation.
Baseline and thresholds
Record a baseline during commissioning of the monitoring system, then set alarm thresholds on trend rather than absolute values – desert heat causes background variations that trend-based alarming handles correctly.
Integration
Feed PD and SF6 data into the substation automation or asset management system so operations teams see GIS condition alongside other asset data.
About HUWOR
Zhuhai Huawang Technology Co., Ltd. (HUWOR) supplies UHF PD sensors, SF6 monitoring instruments, IoT gateways and online monitoring platforms for GIS applications, with export and service coverage in Saudi Arabia, the UAE and the wider GCC. The company supports OEM/ODM supply and project-based deployment. Contact the HUWOR sales team.