Application of Acrel Wireless Temperature Measurement in 35kV Substations

0 Introduction

With continuous improvement in automation and intelligence of power systems, 35kV substations serve as vital power supply units for industrial and mining enterprises as well as urban distribution networks, imposing increasingly stringent requirements on reliability of long-term uninterrupted operation. Abnormal overheating frequently occurs on equipment inside substations including high-voltage switchgears, transformers and line contact points due to equipment aging, poor contact and unbalanced load. Statistics indicate that approximately 40% of power accidents in China stem from abnormal heating of high-voltage equipment. Such faults may lead to equipment damage in mild cases, or severe incidents such as line short circuits and insulation failure in serious scenarios.

Conventional offline temperature measurement and periodic inspection suffer from delayed monitoring, numerous blind zones and insufficient precision, failing to meet the intelligent operation and maintenance demands of modern substations. Featuring superior insulation performance, high stability, strong real-time performance and convenient installation, Acrel wireless temperature measurement system stands out as the preferred solution for temperature monitoring in 35kV substations. Integrated with wireless sensing, IoT communication and big data analytics, the system realizes uninterrupted data collection, transmission, analysis and fault early warning for key temperature measuring points within substations, effectively overcoming drawbacks of traditional temperature monitoring methods. Based on operational features of 35kV substations, this paper conducts comprehensive research on field application of Acrel wireless temperature measurement technology, offering references for temperature monitoring retrofits of similar substations.

1 Necessity and Working Principle of Wireless Temperature Measurement Technology

1.1 Application Necessity

During operation of 35kV substations, equipment undergoes drastic load fluctuations under complex electromagnetic environments. Moving/static contacts inside switchgears and busbar connectors are high-risk locations for thermal faults. These positions are confined and difficult for routine inspection, making temperature deviations hard to detect in a timely manner. Targeting pain points in substation operation, Acrel wireless temperature measurement sensors boast compact size, strong anti-interference capability, high measuring accuracy and wireless wiring-free transmission. They can be directly mounted on live high-voltage components to achieve non-intrusive temperature monitoring.

Furthermore, the system supports multi-level fault early warnings. Alarms can be triggered via on-site audible & visual signals, SMS and platform push notifications once temperatures reach threshold values, winning precious time for fault disposal and greatly mitigating blackout risks induced by thermal failures. In addition, Acrel wireless temperature measurement system supports interconnection with existing substation monitoring systems to realize data sharing and integrated operation & maintenance. It reduces workload of manual patrol inspection and improves operational efficiency, conforming to the trend of intelligent and unattended power grids.

1.2 Core Working Principle

Acrel wireless temperature measurement system adopts a three-tier framework: temperature sensors – wireless data collectors – monitoring platform. Its operating mechanism is described as follows: wireless temperature sensors installed at key measuring points collect real-time temperature data and convert analog signals into digital signals. Sensors transmit data to nearby wireless collectors, which filter data and upload information to local substation monitoring platforms or the dedicated Acrel-2000T wireless temperature monitoring system via RS485 or Ethernet.

The platform realizes real-time data display, curve analysis and historical data storage. Automatic multi-level early warnings will be activated when temperatures exceed preset thresholds, with accurate fault positioning to guide maintenance crews for rapid troubleshooting. The temperature sensors adopt passive designs such as CT energy harvesting or battery power supply, requiring no external power supply. Direct installation on 35kV high-voltage equipment achieves reliable high-voltage isolation to guarantee safety of both facilities and personnel.

2 Architecture Design of Wireless Temperature Measurement System for 35kV Substations

According to equipment layout and temperature monitoring demands of 35kV substations, Acrel wireless temperature measurement system consists of three layers: front-end signal acquisition layer, middle-end data transmission layer and back-end analysis & diagnosis layer. The coordinated three-layer structure enables closed-loop full-process temperature monitoring. The architecture fits field working conditions of 35kV substations with balanced practicability and scalability.

2.1 Front-end Signal Acquisition Layer

The front-end signal acquisition layer acts as the perception terminal, mainly composed of Acrel wireless temperature sensors including ATE100 series and ATE400 series, which can be selected flexibly according to different measuring points.

Sensors are mounted on critical monitoring locations inside 35kV substations. Measuring points are deployed on phase A/B/C incoming terminals, outgoing terminals, moving and static contacts of each high-voltage switchgear. Additional sensors can be arranged on high/low voltage side connectors of transformers and lightning arrester leads to eliminate monitoring blind spots. Acrel temperature sensors feature a measuring range of -50℃ ~ 125℃ with accuracy up to ±1℃, satisfying precision requirements of 35kV substation monitoring. Sensor housings are made of high-temperature resistant and highly insulated engineering plastics with IP67 protection rating, adapting to harsh environments inside switchgears featuring humidity, high temperature and intensive electromagnetic fields.

2.2 Middle-end Data Transmission Layer

The middle-end data transmission layer serves as the data hub, consisting of Acrel wireless collectors and communication gateways responsible for aggregating, converting and uploading temperature data collected by front-end sensors.

Wireless collectors are installed in low-voltage areas adjacent to switchgears. Each collector connects multiple wireless temperature sensors and transmits data over RS485 interface following Modbus protocol, matching equipment layout of 35kV substations. Interconnection with local substation monitoring platforms and Acrel cloud platform ensures compatibility and stability of data transmission.

2.3 Back-end Analysis & Diagnosis Layer

The back-end analysis & diagnosis layer functions as the core control and decision unit, comprising the Acrel-2000T wireless temperature monitoring system, servers and display terminals deployed in the substation control room.

Specially developed by Acrel for power equipment temperature monitoring, the monitoring software supports Windows and Linux operating systems. It integrates functions including real-time temperature display, measuring point status monitoring, temperature curve analysis, historical data query, fault early warning and report generation. Visualized management of all measuring points is available, displaying phase A/B/C temperature data grouped by each switchgear with real-time value refresh. Temperature trend curves of single or multiple measuring points can be plotted to facilitate analysis of thermal variation rules of equipment. Historical data can be stored for more than one year and retrieved by time, cabinet number or measuring point type, providing data support for equipment condition assessment.

Customizable multi-level temperature thresholds (warning value, alarm value and tripping value) can be configured in the system. Audible and visual warnings will be triggered once readings hit warning values. When reaching alarm values, besides on-site alerts, notifications will be sent to maintenance staff via SMS and WeChat Official Account. If temperatures reach tripping thresholds, linkage with substation relay protection devices can be activated for automatic circuit breaking to prevent accident escalation. The system supports fault positioning, highlighting faulty cabinets and measuring points upon alarms to accelerate troubleshooting.

3 Hardware & Software Configuration and Installation of Acrel Wireless Temperature Measurement System

3.1 Hardware Configuration and Model Selection

Hardware selection of Acrel wireless temperature measurement system follows principles of good adaptability, high reliability and easy installation. Targeting temperature monitoring demands covering 5 sets of high-voltage switchgears in a 35kV substation, the hardware list is shown below:

3.2 Software Configuration and Functions

Acrel-2000T wireless temperature monitoring system communicates directly with bay-level devices via RS485 bus or Ethernet. The system complies with international standards including Modbus-RTU and Modbus-TCP protocols, achieving improved security, reliability and openness. It realizes remote signaling, remote measuring, remote control, remote adjustment, parameter remote setting, event alarming, curve display, bar charts, report generation and user management. The system monitors operating status of the whole wireless temperature measurement system, enables rapid alarm response and prevents severe failures.

It is applicable to temperature monitoring of power equipment in ubiquitous power Internet of Things, steel plants, chemical factories, cement plants, hospitals, airports, power plants, coal mines, industrial enterprises and distribution substations.

3.2.1 Temperature Display: Show real-time readings of all measuring points within power distribution systems; remote data access via WEB browser or mobile APP is supported.

3.2.2 Temperature Curve: Query temperature trend curves of individual measuring points.

3.2.3 Operation Reports: Retrieve and print historical temperature data of measuring points by time segment.

3.2.4 Real-time Alarm: The system generates alarms upon abnormal temperatures. Built-in voice alarm function is available alongside pop-up reminders. Alarm notifications can be pushed via SMS and mobile APP to notify on-duty personnel timely.

3.2.5 Historical Event Query: Store and manage temperature over-limit records to support event review, statistical analysis and post-accident investigation

3.3 Key On-site Installation Guidelines

3.3.1 Sensor Installation: Passive sensors are fixed onto moving/static contacts and busbar connectors via buckles or bolts. Tight contact between sensors and measured surfaces shall be guaranteed to avoid measurement errors caused by gaps. Sensors shall be kept away from strong electromagnetic interference sources to secure stable wireless communication. 3.3.2 Collector Installation: Collectors are mounted inside low-voltage cabinets adjacent to switchgears. The wireless transmission distance between collectors and sensors shall not exceed 150 meters. Reliable earthing of collectors is required to suppress static interference. 3.3.3 Communication Wiring: RVSP 2×1.5 shielded twisted pair cables are adopted for wiring between collectors and gateways. The shielding layer shall be grounded at single end to reduce electromagnetic interference. Ethernet connection is deployed between gateways and servers to guarantee transmission speed. 3.3.4 System Commissioning: After installation, address assignment and parameter configuration for sensors and collectors shall be completed through configuration software. Test wireless signal strength and data transmission stability, and calibrate temperature measurement accuracy point by point.

4 Conclusion

With continuous intelligence upgrading of power systems, Acrel wireless temperature measurement system can be further integrated with artificial intelligence and big data analytics to realize early prediction and trend analysis of thermal faults, providing data foundation for condition-based maintenance and full-life cycle management of 35kV substation equipment. The application scheme delivers high promotion value for temperature monitoring retrofits of 35kV substations deployed in industrial, mining and urban distribution networks, offering solid technical support for intelligent operation and maintenance of power grids.