Metal-oxide surge arresters protect transformers, switchgear and cable terminations from lightning and switching surges – threats that are frequent across Indonesia, Malaysia, Vietnam and the Philippines. When an arrester ages or absorbs moisture, its protective characteristics change and the protected equipment is left exposed. Portable leakage current testing instruments let field teams check arrester condition quickly during routine patrols, without taking the line out of service.
Why arresters deserve attention in the tropics
Frequent surge duty
High thunderstorm activity means arresters absorb more surge energy and see more operations than in temperate regions, accelerating ageing of the metal-oxide blocks.
Humidity, salt and pollution
Coastal salt and tropical humidity deposit on arrester housings, increasing surface leakage current. Seals that fail under temperature cycling allow moisture ingress – the most common hidden failure path.
How portable leakage current testing works
A portable instrument measures the arrester’s total leakage current while it is in service, and separates the capacitive and resistive components:
- Resistive leakage current – a rising resistive component indicates block deterioration and possible moisture ingress.
- Third-harmonic current – correlates with block ageing and is a sensitive trending indicator.
- Surface current – increases caused by contamination on the housing.
The measurement is taken with a clamp sensor on the arrester’s earth lead or ground strap, so no disconnection is required.
Building a field testing programme
- Baseline – measure every arrester once to establish the population’s normal range.
- Periodic patrols – re-measure on a schedule matched to pollution levels and surge activity in each area.
- Trending – record results against time and weather so a rising resistive component triggers investigation.
- Follow-up – arresters with confirmed deterioration are replaced before failure, and suspected failures are verified with laboratory or HV tests.
Instrument selection for tropical field use
- Portable and battery-powered – suitable for ladder and pole work.
- Clamp-style sensing – no outage, no disconnection, quick measurements on live installations.
- Recording and export – on-board logging so field data can be trended in the office.
- Rugged construction – rated for outdoor tropical conditions including heat and humidity.
About HUWOR
Zhuhai Huawang Technology Co., Ltd. (HUWOR) is a Chinese manufacturer of live-line detection instruments, including portable surge arrester leakage current testers, PD detectors and cable test sets. The company supplies field teams, utilities and service providers across Southeast Asia, with OEM/ODM support. Contact the HUWOR sales team for instrument specifications.