Guarding 35kV high-voltage environments: Ankure’s wireless temperature‑measurement technology provides dual protection for equipment

 

Introduction

As the electricity market places ever-increasing demands on power system stability, higher standards are being set for the quality and reliability of power supply. The widespread adoption of new technologies and manufacturing processes in switchgear has significantly enhanced its reliability. Sulfur hexafluoride gas, with its excellent insulating and arc-quenching properties, is extensively used in high-voltage switchgear. However, fully enclosed high-voltage switchgear suffers from poor heat dissipation under prolonged heavy loads, leading to thermal buildup; rising temperatures can adversely affect the insulation performance of electrical components. Moreover, such switchgear does not allow visual monitoring of the connection between moving contacts and stationary contacts inside the cabinet, nor does it enable observation of the opening and closing status of earthing switches, and it lacks internal temperature measurement capabilities, posing substantial safety risks. By directly monitoring busbars and cable joints in high-voltage switchgear, it is possible to effectively mitigate fire hazards and large-scale power outages caused by overheating.

 

Significance of Wireless Temperature Measurement Technology in High-Voltage Switchgear

Loose conductive connections in electrical equipment, as well as loose contacts in disconnect switches and circuit breakers, can lead to localized temperature buildup, degrading the performance of affected components and potentially causing wire melting and insulation breakdown—serious threats to grid safety. With the continuous growth of the steel industry, unmanned substations are expected to see widespread adoption, necessitating stricter control over various types of substation data. However, current temperature monitoring of key equipment remains at an early stage, with limited coverage; in particular, temperature monitoring within enclosed equipment is virtually unaddressed, representing a significant oversight, and the underlying technology is relatively underdeveloped. At present, high-voltage equipment in substations is predominantly enclosed, making conventional temperature‑measurement methods impractical. Some systems resort to drilling holes or employing infrared thermometers, but these approaches suffer from the inability to collect and transmit data in real time and impose stringent requirements on the insulation performance of power systems.It cannot be directly attached to high-voltage energized equipment; its low accuracy requires regular inspection, and it only works effectively when personnel are present on site. However, this model offers higher safety. Traditional temperature measurement methods fail to meet the requirements of unattended substations for real-time monitoring at critical locations of major equipment. Developing a temperature‑monitoring system that is widely applicable, safe, and reliable—capable of providing real-time temperature surveillance at key points of important equipment, especially enclosed devices—can promptly detect potential faults, enable timely corrective actions, and prevent further escalation of incidents, thereby playing a crucial role in ensuring the secure operation of the power grid.

 

Principles and Technical Characteristics of Several Commonly Used Wireless Temperature Sensors for 35kV High-Voltage Switchgear

 

(1) Principle of Wireless Temperature Measurement

Wireless temperature measurement primarily employs sensors such as thermistors, infrared, semiconductor, surface‑mounted, and passive wireless types, each with its own distinct core principle:

Thermal sensors measure temperature by detecting changes in resistance with temperature; they offer high sensitivity but suffer from nonlinear resistance characteristics and limited lifespan.

Infrared sensors are non‑contact, do not interfere with the measured object, but are easily affected by environmental factors.

Semiconductor sensors provide high precision, reliability, and safety, though their response speed is relatively slow.

Passive wireless sensors use passive temperature measurement and wireless transmission; they are compact and low‑power, but have a short transmission range and are susceptible to obstacles and displacement/vibration.

Passive wireless sensors harvest energy through energy harvesting, eliminating the need for batteries or conventional CT‑based power extraction, and employ equipotential methods to ensure the safety of high‑voltage power grids—making them a key direction for future development.

 

(2) Core Technical Features

Energy Self-Sufficiency: Utilizes the alternating magnetic field generated by busbar AC current, collecting energy via specialized metal strips and coils to power the MCU. This battery-free design offers a service life exceeding 10 years and requires no maintenance.

Safe and Stable: Employs a special alloy that saturates easily in the magnetic field, eliminating eddy current and thermal‑rise risks; its compact size does not compromise insulation clearances or the safety of electrical equipment.

High Precision: Equipped with high‑precision imported contact-type digital sensing elements, delivering fast response and exceptional accuracy, with data transmission verified to eliminate errors.

Easy installation: Compatible with multiple components such as moving contacts and stationary contacts, supports the installation of multiple sensors, features a fixed factory serial number, and ensures simple matching without prior coordination.

Strong compatibility: Utilizes frequency-division multiple access technology, allowing it to share a receiving device with other sensors like temperature and humidity sensors; integrates various standard communication interfaces, supporting multi-platform data sharing and centralized display.

Wide-temperature compatibility: operating temperature range -45~125℃, with plans to extend it to -45~135℃ in the future.

 

Acrel Wireless Temperature Measurement System

 

(1) System Architecture

The Acrel-2000T wireless temperature monitoring system communicates directly with devices at the bay level via RS485 bus or Ethernet. The system design adheres to international standards such as Modbus-RTU and Modbus-TCP transmission protocols, significantly enhancing its security, reliability, and openness. This system offers functions including remote signaling, remote measurement, remote control, remote adjustment, remote configuration, event alarms, trend curves, bar graphs, reports, and user management. It enables monitoring of the operating status of wireless temperature‑monitoring equipment, facilitates rapid alarm response, and helps prevent serious failures.

Suitable for temperature monitoring in ubiquitous power IoT applications, steel plants, chemical facilities, cement factories, hospitals, airports, power plants, coal mines, and other industrial enterprises, as well as substations and distribution stations.

Online Temperature Monitoring System Architecture Diagram

 

(2) System Functions

The Acrel-2000T temperature monitoring system host is installed in the duty control room and can remotely monitor the operating temperature status of all switchgear within the system. The system has the following main functions:

Temperature display: Shows the real-time values at each temperature measurement point in the distribution system, and also enables remote data access via computer web interface or mobile app.

Temperature Curve: View the temperature trend curve for each measurement point.

Run Report: Query and print temperature data for each temperature measurement point over time.

Real-time Alerts: The system can issue alerts for abnormal temperatures at each monitoring point. It features real-time voice alarms and can generate voice notifications for all events, with alert methods including pop-up windows and voice prompts. Additionally, it supports sending alert messages via SMS or app push notifications to promptly notify on-duty personnel.

Historical Event Query: Enables the storage and management of event records such as temperature exceedance alerts, facilitating users to trace system events and alarms over time, perform query and statistical analysis, and conduct incident investigations.

(3) System Hardware Configuration

The temperature online monitoring system mainly consists of temperature sensors and a temperature acquisition/display unit at the device level, an edge computing gateway at the communication level, and a temperature measurement system host at the station control level, enabling online temperature monitoring of critical electrical components in the power distribution system.

Conclusion

Currently, conventional wireless temperature‑measurement technology struggles to meet the requirements for 35 kV high‑voltage switchgear. As a critical component of the power system, any failure can have significant consequences. Employing wireless temperature‑measurement technology in 35 kV switchgear offers convenient installation and rapid data acquisition, aligning better with today’s rapid technological advancements. In future temperature‑measurement technologies, it will be essential to integrate practical application conditions, summarize and analyze issues encountered during use, and continuously refine the temperature‑measurement system through ongoing learning and experimentation.