An intelligent AC contactor based on breaking phase control and its operation method

Abstract

The invention provides a switch-off phase control based intelligent alternating current contactor. The intelligent alternating current contactor comprises an electromagnetic type alternating current contactor and an intelligent controller consisting of a signal collection module, a main control module, a power supply module, a coil current control module and the like; the signal collection module collects current of any one phase of the alternating current contactor and sends the current to the main control module; the power supply module converts the alternating current generated by the coil on the alternating current contactor into direct current and sends the direct current to the main control module; when the main control module detects that the direct current voltage value is less than a preset numerical value, a switch-off instruction is output after the current collected by the signal collection module achieves a phase angle with the minimum switch-off energy sum, and the coil current control module controls the switch off of the coil current; or when the main control module detects that the direct current voltage value is greater than or equal to the preset numerical value, a switch-on instruction is output, and the coil current control module controls the switch-on of the coil current. By the implementation of the switch-off phase control based intelligent alternating current contactor, the switch-off electric arc energy can be reduced by changing the switch-off policy, so that lower switch-off electric arc energy can be obtained, and the service life of the intelligent alternating current contactor can be prolonged.

Description

technical field [0001] The invention relates to the technical field of intelligent switching appliances, in particular to an intelligent AC contactor based on breaking phase control and an operating method thereof. Background technique [0002] Electromagnetic AC contactors are widely used in power distribution systems and industrial production. They are generally three-phase three-wire systems, and control the on-off of the main current circuit through the conduction or disconnection of the built-in coil circuit. [0003] At present, the life of the electromagnetic AC contactor mainly depends on the life of the electric contact, but the ablative arc generated on the electric contact during the breaking process is the main factor leading to the loss of the life of the electric contact. Because electrical contacts are usually copper-based, the surface is covered with high-hardness, anti-welding silver oxide (such as silver chromium oxide AgCdO or silver tin oxide AgSnO 2 ), ...

AI Technical Summary

Problems solved by technology

[0003] At present, the life of the electromagnetic AC contactor mainly depends on the life of the electric contact, but the ablative arc generated on the electric contact during the breaking process is the main factor leading to the loss of the life of the electric contact

Because electrical contacts are usually copper-based, the surface is covered with high hardness, anti-welding silver oxide (such as silver chromium oxide AgCdO or silver tin oxide AgSnO 2 ), during the breaking process of the electrical contacts, regardless of whether the air between the moving and static contacts is ionized or not, due to the existence of current, it will move in the air to generate a lot of heat, and further due to the short time, it cannot dissipate heat, making the movement and static Contact surface temperature rises sharply and is ablated

In particular, when the silver oxide on the surface of the dynamic and static contacts is ablated to a certain extent, the copper matrix contained in the two will be in direct contact, which is likely to cause serious electrical accidents at high temperatures

[0004] In the prior art, there are two methods for prolonging the life of electromagnetic AC contactors: 1. Use contact covering materials with better welding resistance, but it is impossible to obtain better cost-effective materials than existing materials; 2. To reduce the energy of the breaking arc by changing the breaking strategy, the three phases need to be broken at different times to ensure that the breaking phase angle of each phase is slightly earlier than the current zero crossing point, but in actual manufacturing, the process accuracy is often not guaranteed

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