Direct current contactor moving contact system capable of improving short-time current withstanding capacity

Abstract

The invention discloses a direct current contactor moving contact system capable of improving short-time current withstanding capacity. The system comprises N groups of moving contact fingers, a resetspring and a contact supporting element, wherein the N groups of moving contact fingers are connected in parallel and are installed in the contact supporting element; each group of moving contact fingers is independently provided with contact springs which are mutually independent; the reset spring is fastened and installed on the upper part of the contact supporting element; each group of movingcontact fingers comprises a moving contact bridge and two contact points, wherein the two contact points are independently welded to the lower parts of two ends of the moving contact bridge; and thecontact supporting element is a frame, and a plurality of clapborads are arranged at equal intervals in the frame to divide the internal space of the frame into N pieces of spaces with equal width. Byuse of the system, multiple groups of moving contact fingers are connected in parallel and are independently provided with the independent contact spring, so that total Holm force borne by the movingcontact system is greatly lowered, an electric arc generated in a moving contact finger bouncing process is reduced, the overcurrent withstanding capacity of the direct current contactor and the short circuit current withstanding capacity of the direct current contactor are improved, and 50KA overcurrent can be withstood in short time.

Description

technical field [0001] The invention relates to a DC contactor, in particular to a moving contact system of a DC contactor which improves short-time withstand current capability. Background technique [0002] The DC power distribution system has the advantages of low line cost, large capacity, small active power loss, rapid adjustment, and reliable operation. It has been widely used in urban rail transit and ships in recent years. As a necessary equipment for the operation control of the DC system, the contactor in the DC system must have the ability to reliably connect, break and carry the current under normal circuit operation conditions and the ability to carry a certain period of time under the specified abnormal circuit (such as short circuit). ability. [0003] When a short-circuit fault occurs in the medium-voltage DC system, the peak value of the short-circuit current can often reach hundreds of thousand amperes. Such a large current flows through the conductive cir...

AI Technical Summary

Problems solved by technology

[0003] When a short-circuit fault occurs in the medium-voltage DC system, the peak value of the short-circuit current can often reach hundreds of thousand amperes. Such a large current flows through the conductive circuit of the contactor, which will generate a large electrodynamic repulsion between the moving and static contacts (Holm Holm force), if the contact system of the contactor cannot provide enough contact pressure, the moving and static contacts will be repelled under the action of electric repulsion, and an arc will be generated between the moving and static contacts. The arcing capacity under short-circuit current is Far beyond the rated breaking capacity of the contactor, the contact system of the contactor will be permanently damaged or even burned

[0004] The existing DC contactors mainly follow the national standard "GB 14048.4-2010 Low-voltage switchgear and control equipment Part 4-1: Contactors and motor starters Electromechanical contactors and motor starters (including motor protectors)", while With the rapid development of my country's rail transit industry, DC contactors are also widely used in the ground equipment of the rail transit industry. Part 3: Indoor DC Isolating Switches, Load Switches and Earthing Switches", among which, there is a big difference in the verification of the product's ability to withstand overload current, "GBT 25890.3-2010 Rail Transit Ground Installation DC Switchgear Part 3: Indoor DC isolating switches, load switches and grounding switches" standard requires that the rated short-time withstand current often reach 50KA or higher, and the electric stability of conventional DC contactors can hardly meet this requirement ("GB 14048.4-2010 Low Voltage Switchgear and controlgear Part 4-1: Contactors and motor starters Electromechanical contactors and motor starters (including motor protectors) "The maximum overload requirement in the standard is only 8 times the rated current)

[0005] Most of the existing DC contactor products that can withstand short-term overload currents of 50KA are designed with a very large contact pressure to resist the electric repulsion generated when the overload current flows through the contacts and prevent the contacts from being bounced off. The electromagnet of a product with a large contact pressure needs a large starting power (nearly 1KW) to make the product operate normally, and because the contact pressure is too large, the contact collision of the product when it is turned on is also violent, and the acceleration Reduce the wear of the contacts and indirectly reduce the mechanical life of the product

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