Project Background
With the rapid integration of urban rail transit, substation automation and unmanned operations have become standard configurations for modern metro power systems. As the backbone of Suzhou’s transit network, Suzhou Metro Line 7 and Line 8 will form a vital “combined loop line” upon completion, holding significant strategic importance.
Project Challanges
However, metro power distribution systems operate in high-load underground environments. The moving/fixed contacts of circuit breakers, busbar connections, and dense cable joints inside high/medium/low voltage switchgears are highly susceptible to severe overheating caused by aging, vibration, or excessive contact resistance over long-term operations. Since conventional infrared inspections cannot penetrate enclosed cabinets, these thermal risks remain hidden. If an undetected hot spot leads to melted contacts or equipment damage, it will trigger immediate power interruptions. Therefore, implementing a continuous and accurate wireless temperature online monitoring system for switchgear contacts and cable joints is an absolute necessity to safeguard the lifeblood of metro operations.
Customer Requirements & Technical Standards
For critical equipment in the power distribution rooms, including incoming and outgoing cabinets, the client established rigorous technical benchmarks:
- Maintenance-Free & Low Power: Sensors must utilize CT induction power-harvesting technology, completely eliminating the limitations of battery lifespans for a long lifecycle.
- Measurement Range & High Precision: The temperature range must cover $-50^\circ\text{C}$ to $+125^\circ\text{C}$, with an accuracy of $\pm 1^\circ\text{C}$.
- Precise Monitoring Layout: Provide dead-zone-free monitoring for high-risk heat areas inside the switchgears, such as cable joints and contacts.
- Local Display & Data Uplink: Thermal metrics of electrical contacts and cable joints must be displayed locally on the panel, while supporting data uplink via standard industrial protocols.
Acrel Intelligent Wireless Monitoring Solution
To overcome industrial environment challenges, Acrel deployed a tailored ARTM Series Wireless Temperature Local Monitoring Scheme. This solution focuses strictly on the safety of high/medium/low voltage switchgears and cable joints (not applicable to gas-insulated substations GIS).
Core Hardware Configuration
- ATE400 CT-Powered Wireless Temperature Sensor： Engineered explicitly for hot spot monitoring on switchgear contacts, busbars, and cable joints. Driven by advanced CT energy-harvesting technology with a low startup current ($\ge 5\text{A}$), it aligns perfectly with metro load fluctuations. Its ultra-compact design ($25.82\times20.42\times12.8\text{mm}$) utilizes durable alloy strips for local fixing, delivering easy installation and robust dielectric insulation. Utilizing $470\text{MHz}$ wireless telemetry, it supports an open-air transmission range of up to 150 meters, flawlessly penetrating metal enclosures.
- ARTM-Pn Wireless Temperature Display Meter：Flush-mounted on the switchgear panel faceplate (cutout size: $92\times92\text{mm}$), it aggregates real-time data from up to 60 wireless sensors simultaneously. Beyond its local high-definition LCD display, it incorporates an upstream RS485 Modbus-RTU communication interface to stream field-level thermal data.
System Architecture
- Thermal metrics captured from cable joints and contacts are transmitted wirelessly to the ARTM-Pn display meters, then routed via RS485 fieldbus to the central Acrel-2000/T Wireless Temperature Monitoring Software Platform for $24/7$ continuous visibility and over-temperature alarming.
Project Results & Industrial Applications
Currently, the complete wireless temperature monitoring solution has been successfully integrated into the Suzhou Metro power facilities.
- Elimination of Blind Spots: By establishing real-time oversight across key switchgear contacts and cable joints, the system effectively prevents overheating incidents caused by poor contact or aging.
- Maintenance-Free Efficiency: The self-powered sensors replace manual infrared patrols, greatly reducing operational and labor costs.
- Broad Application Scenarios: Specially tailored for high/medium/low voltage switchgears and cable joints, this solution is widely applicable not only to mass transit but also to metallurgy, petrochemicals, large-scale data centers, and general industrial facilities.
Conclusion & Industrial Applications
Efficient thermal tracking across cable connections, circuit breaker contacts, and busbars within high/low-voltage switchgears has become a definitive benchmark for enhancing grid stability and minimizing critical failure rates. The successful implementation of Acrel’s wireless temperature monitoring solutions in the Suzhou Metro Project underscores our leading technical expertise in smart microgrids and electrical hazard prevention.
This versatile solution is tailor-made not only for mass transit but also for metallurgy, petrochemicals, large-scale data centers, and critical commercial complexes worldwide, safeguarding global energy assets.
Acrel – Your Trusted Partner for Power Safety
