I. Causes of abnormal temperature rise in electrical contacts

1.1 The field environment is more complex than laboratory tests, and long-term field operation exhibits a cumulative temperature rise effect.

1.2 The expansion effect of different materials at the joint varies. Under the influence and restraint of stress during high-temperature expansion, plastic deformation occurs slowly, causing a minute gap to form at the joint.

1.3 Temperature changes cause oxidation corrosion at the joints, increasing contact resistance.

1.4 Repeated movement of the contact tip, improper pressure on the connecting bolt, leading to deformation of the contact surface, reduction of the contact area, and increase in resistance.

1.5 The purity of the conductor raw materials is insufficient, causing the electrical conductivity of the conductor material to not meet the requirements.

1.6 During the processing, connection, and installation of busbars, inadequate and uneven treatment of the busbar contact surfaces reduces the effective contact area, increases contact resistance, and generates heat.

To prevent equipment that transports electrical resources, such as transmission cables, transformers, and high-voltage switches, from suffering damage due to overheating in their connection parts, Acrel has developed a wireless temperature monitoring system to detect the operating conditions of high-voltage equipment components and promptly eliminate safety hazards. 

Keywords:Wireless temperature measurement system; high-voltage electrical equipment; temperature sensor; wireless temperature detector

II. Introduction to Acrel Temperature Online Monitoring System

2.1 Overview

The online temperature monitoring device for electrical contacts is used for temperature monitoring of equipment such as cable joints, circuit breaker contacts, disconnector switches, high-voltage cable terminations, dry-type transformers, and low-voltage high-current equipment within high and low-voltage switchgear. It prevents the formation of safety hazards caused by excessive heat generated due to high contact resistance resulting from factors like oxidation, loosening, and dust during operation, thereby improving equipment safety assurance, timely and continuously reflecting the equipment's operating status, and reducing the equipment accident rate. The Acrel-2000T wireless temperature monitoring system communicates directly with the equipment in the bay using an RS485 bus or Ethernet. The system design adheres to international transmission protocols such as Modbus-RTU and Modbus-TCP, enhancing its security, reliability, and openness. The system features functions for remote communication, remote measurement, remote control, remote adjustment, remote setting, event alarming, curves, bar charts, reports, and user management. It can monitor the operating status of equipment in wireless temperature monitoring systems, achieve rapid alarm response, and prevent the occurrence of serious failures.

2.2 Application Locations

Suitable for temperature monitoring of power equipment in enterprises such as ubiquitous power IoT, steel mills, chemical plants, cement plants, data centers, hospitals, airports, power plants, and coal mines, as well as in substations and distribution stations.

2.3 System Architecture

 

Temperature Online Monitoring System Structure Diagram 

2.4. System Hardware Configuration

The online temperature monitoring system mainly consists of temperature sensors and temperature acquisition/display units at the device layer, edge computing gateways at the communication layer, and the temperature measurement system host at the station control layer, achieving online temperature monitoring of key electrical parts in the distribution and power system.

2.5. System Functions 

Real-time monitoring

The Acrel-2000T wireless temperature monitoring system features a user-friendly interface that can intuitively display temperature data from each monitoring node, as well as related fault and alarm signals, in the form of a one-line distribution diagram.

Detailed temperature query

Historical temperature curve, real-time temperature curve query, real-time temperature data query

Real-time alarm

The Acrel-2000T wireless temperature monitoring system features real-time alarm functions, enabling the system to issue alerts for events such as temperature exceeding limits.

Historical Event Query

The Acrel-2000T wireless temperature monitoring system can store and manage high-temperature alarm event records, facilitating users in tracing system events and alarms, as well as performing query statistics and accident analysis. It allows for querying and sorting by time, type, and device.

 

III. Project Cases

Project Overview

A project for a chemical polymer synthesis plant in Shandong includes four distribution rooms: a high and low voltage distribution room for a future hydrogen energy utility plant, a modification of the Huanan R125 plant, a modification of the Huanan hydrogen fluoride refrigeration station, and a 35kV polymer plant. The entire distribution system consists of 10kV high-voltage distribution cabinets and 5 sets of 0.4kV low-voltage distribution cabinets, requiring the configuration of wireless temperature monitoring products for electrical connection points and high-current circuits within the distribution circuits.

Project Requirements and Configuration Plan

For this project, the wireless temperature measurement requires on-site display using a single cabinet, therefore ARTM-Pn was selected for both high and low voltage distribution rooms. Temperature sensors with CT induction power supply are required to be installed in the high and low voltage distribution rooms, and considering the limited space in the low voltage cabinets, the ATE400 model CT induction power supply sensor was selected.

On-site installation

IV. Conclusion

A wireless temperature measurement system consists of temperature sensors, a communication system, and a display system, and is connected to a host computer via a data cable or communication chip. It can achieve online monitoring and preprocessing of the temperatures of multiple high-voltage electrical equipment, helping staff promptly identify hidden dangers and ensure the performance of production equipment. Wireless transmission technology does not require external wires, which can effectively reduce capacitive and inductive coupling during the transmission process. It achieves electrical isolation between high-voltage environment detection equipment and secondary processing equipment, possesses high performance, and has broad application prospects in the field of high-voltage electrical equipment detection.