A 110kV substation in Jiangxi, China, has deployed an online monitoring system for its GIS equipment to support long-term insulation condition monitoring.
For this project, Zhuhai Huawang Technology installed smart UHF sensors and contact ultrasonic sensors at selected monitoring points on the GIS equipment.
The two sensing technologies collect different types of signals generated by partial discharge (PD), providing complementary information for evaluating the insulation condition of GIS equipment during operation.
Two Sensors for Different PD Signals
The monitoring system in this project combines smart UHF sensors and contact ultrasonic sensors.
UHF sensors detect the high-frequency electromagnetic signals generated by partial discharge inside GIS equipment. This method is particularly suitable for GIS because the metal enclosure provides a relatively shielded environment against external electromagnetic interference.
The contact ultrasonic sensor works differently. When partial discharge occurs inside GIS, it can generate acoustic emission (AE) signals. These ultrasonic signals propagate through the equipment structure and reach the GIS enclosure.
A contact sensor mounted directly on the enclosure can pick up these acoustic signals for further monitoring and analysis.
Using both methods gives maintenance personnel another reference when evaluating an abnormal monitoring point.
Contact Ultrasonic Sensor for GIS Monitoring
The project uses the HMJ1010-WAEA Smart Contact Ultrasonic Sensor for collecting AE ultrasonic signals from GIS equipment.
The sensor integrates a high-precision amplification circuit, a low-power LoRa communication module, and an industrial-grade lithium battery.
With a frequency range of 30 kHz to 200 kHz and a resonant frequency of 40 kHz, the sensor is designed to detect ultrasonic signals associated with partial discharge.
Its contact installation method allows the sensor to directly couple with the GIS enclosure. This helps reduce the influence of ambient noise and signal attenuation that can occur with air-coupled measurement.
The sensor can be supplied in either a wireless or wired configuration:
- Wireless: LoRa communication + built-in lithium battery
- Wired: RS485 communication + DC24V power supply
For retrofit applications, the wireless configuration can also reduce the amount of additional cabling required around existing GIS equipment.
Designed for Complex Substation Environments
Substations contain many electrical devices and can have complex electromagnetic conditions.
The ultrasonic measurement principle does not require a direct connection to the electrical circuit. Instead, the sensor receives acoustic signals transmitted through the equipment structure.
This gives contact ultrasonic monitoring a useful advantage when it is applied alongside electromagnetic PD detection methods.
The HMJ1010-WAEA provides a sensitivity of ≥120 dB and a dynamic range of ≥40 dB, supporting the detection of relatively weak ultrasonic signals generated by partial discharge.
The sensor is also designed for harsh operating environments, with an operating temperature range of -40°C to +85°C and an operating humidity range of 5% to 95% RH.
From Periodic Inspection to Continuous Observation
Traditional PD testing is often carried out during scheduled inspections or specific diagnostic activities.
Online monitoring takes a different approach: sensors remain installed on the equipment and collect relevant signals while the GIS is in normal operation.
In this Jiangxi project, data from the UHF and ultrasonic sensors is transmitted through the monitoring system for centralized management and observation.
If an abnormal signal or significant change is detected, maintenance personnel can use the monitoring information as a reference for further field inspection or diagnostic testing.
Online monitoring therefore works as an additional layer between routine operation and detailed diagnostic testing.
Project Application
The Jiangxi 110kV GIS online monitoring project demonstrates the practical application of combining UHF electromagnetic detection and contact ultrasonic AE detection for GIS equipment.
The UHF sensors monitor electromagnetic PD signals, while the contact ultrasonic sensors monitor acoustic emission signals. The two methods provide different perspectives on the same equipment and can be used together when evaluating abnormal conditions.
For substations with critical GIS equipment, this type of monitoring can provide useful operating data for condition-based maintenance and help maintenance teams make better-informed decisions about further inspection.
Zhuhai Huawang Technology provides partial discharge monitoring products and solutions for GIS, transformers, switchgear and other electrical equipment, including UHF sensors, ultrasonic sensors, HFCT sensors, PD monitoring systems and related condition monitoring solutions.