Guides

A multi-channel partial discharge diagnosis system acquires many sensors at the same time and locates defects by comparing arrival times across channels. This article explains how the HMJ9041 works and when a multi-channel system is the right investment.

A portable integrated cable tester verifies cable length, cross-sectional area and material type on site, without laboratory equipment. This article explains how the HMJ9030 works and how field teams use it for acceptance and troubleshooting.

Metal-oxide surge arresters age slowly and fail suddenly. Monitoring the leakage current and its resistive component reveals varistor degradation early, and a lightning strike counter records every event. This article explains how the HMJ1011-WB leakage current sensor works.

Acoustic imaging locates partial discharge and pressurised gas leaks by overlaying the sound source on a live image. This article explains how the technology works and how a handheld detector with a digital microphone array shortens inspection time in substations and on overhead lines.

Oil-filled and cross-linked polyethylene cables degrade before they fail, releasing hydrogen, acetylene, methane and carbon monoxide into cable tunnels and ducts. This article explains why cable gas monitoring works, which gases matter, and how the HMJ1012-WLQ sensor detects them with ±1 ppm accuracy.

Choosing the right partial discharge sensor depends on the equipment type and the defect to be found. This guide compares TEV, UHF, HFCT and ultrasonic (AE) coupling methods, maps each to switchgear, GIS, cables and transformers, and explains when a combined sensor is the better investment.

Built-in UHF PD sensors (e.g. HMJ1010-WGN) couple to the dielectric ports of GIS and transformers for continuous online partial discharge monitoring. This article explains how they work, their 300-1500 MHz detection band, installation requirements and how they compare with external UHF sensors.