The small dc contactor used in batteries has a history of 70 or 80 years. Widely used in communications,transportation and lifting industries, it is also used in military fields such as aviation and tanks. In the 1960s, for important areas of aviation and the military, small sealed dc relays have been developed, and even sealed air-filled products have been developed to meet the requirements of reliability and miniaturization. But the voltage of these products does not exceed 48V. In the initial stage, using the military standard and relay standard of four machine department (electronic industry department). As the use of products expanded in industry, Promotion of GB14048.4 standard, Some of the products are starting to adopt common standard of GB14048.4, and according to the DC1 load assessment.
The dc contactor used in industry requires high voltage, the applicable of load is wide, and the condition of on-off is harsh, the requirements for cost performance are relatively high, while the requirements for space are not too strict. Considering the reliability of arc extinguishing, arc extinguishing system volume is relatively large, the volume is relatively large.
With the advent of the green revolution, the development of non-traditional fuel vehicles has been advanced rapidly. Whether it is a hybrid or a pure electric vehicle, Higher voltage is required for small dc contactor, The bulky industrial dc contactors could not meet the demand. So some companies have combined relay and vacuum to develop small high-voltage dc contactors. The structural features of this small high voltage direct current contactor is the whole electromagnetic operating system and arc extinguishing system are all encapsulated in one shell (traditional small dc contactor adopts this structure), the shell is fully sealed and filled with nitrogen or hydrogen, With this structure, the contactor has simple internal structure, stable contact and reliable arc extinguishing, can be miniature.
As soon as the product was launched, it was widely used in the automobile industry and gradually spread to other areas. With the rapid development of electric vehicle industry in China, some domestic enterprises (most of the first entrants are relay and vacuum device manufacturers) began to produce small high-voltage direct current contactors.