Latching relay for three phase electric energy meters


By Shicai Xie

Latching relay1

Figure 1 – Schematic of traditional
electric meter

Zhejiang Prestige Electronic Co., Ltd is a leader in the development of electric meter components in China. In the relay area, the company possesses an experienced R&D team, with the technical principal a senior expert who has been involved in latching relay research for 45 years. In order to develop a latching relay that meets the requirement of the three phase electric meter with high performance and to solve the technical problems, Prestige Electronics invested significant capital in the world’s first modularised magnetic latching relay, along with reserved intellectual property rights. The project was strongly supported through the product development stage by a leading electric power meter manufacturer in China. The performance, reliability and security achieve the level U3 of the standard IEC62055-31, as tested by the Chinese authoritative laboratory certification organisation. Advantages of the product include:

  • Switching current up to 200 A, continuously operable for extended periods
  • Short circuit current carrying capacity up to 3,000 A
  • Anti-interference from strong magnetic field.
Latching relay2

Figure 2 – Schematic of meter with
modularised magnetic latching relay

The latching relay, main circuit conductive bars and the terminal of the meter are designed as an independent entity, which is fixed in the base of the meter, and separated from the other circuit comprising the microelectronic components inside the meter (Figure 2). As a result the technical problems that occurred with earlier magnetic latching relays within electric meters are solved. This design also creates a neater and more attractive look and makes the assembly of the meter more convenient, thereby promoting production efficiency and a reduction in cost. Now this type of relay has been applied in many three phase electric meters and has been recognised by electric power departments.

In February 2008, the 1st World Meter Design Congress was organised by Smart Energy International in San José California, at which Zhejiang Prestige Electronic presented the design and development of the magnetic latching relay for electric meters and also displayed latching relays of ten styles with rated currents ranging from 60 A to 200 A.

Zhejiang Prestige Electronics intends to invest more capital in the innovation of its products. The company will also develop more new products to meet the increasing requirements of electric power meters worldwide. It is hoped also that more well-known electric meter manufacturers will make their requirements known to the company, which will design relays according to their special requirements in order to enhance the quality of their meters.