Non-arc power-off protection switch control circuit

Abstract

The invention discloses a non-arc power-off protection switch control circuit. The control circuit comprises a first switch, a second switch, a first time delay circuit, a first controllable switch, a second controllable switch, a second time delay circuit and a thyristor circuit, wherein one end of the first switch is connected to a live wire of a power supply, and the other end of the first switch is connected with a load; the first time delay circuit is used for rectifying output of the power supply and controlling on and off of the second controllable switch; the second time delay circuit is used for controlling on and off of the first controllable switch; the time constant of the second time delay circuit is smaller than the time constant of the first time delay circuit; the second switch is connected between a second input end of the second time delay circuit and a null wire; the thyristor circuit is in circuit connection between the live wire of the power supply and the load. The non-arc power-off protection switch control circuit has the characteristics of long life, simple structure and low cost.

Description

technical field [0001] The invention belongs to the field of electric switches, and in particular relates to a control circuit for a non-arc power failure protection switch. Background technique [0002] At present, AC contactors generally use capacitors connected in parallel in the line as power factor compensation. This type of AC contactor has arcing and high surge current, and the compensation circuit is easy to break down, the service life is short, and the long-term operation cost is high. [0003] Thyristor capacitor switching switch has the advantages of no surge when connecting the capacitor and no arc when breaking the capacitor. However, due to the problems of large conduction voltage drop, temperature rise, and large harmonic pollution, it has appeared on the market for this reason. A capacitive switching switch called a compound switch with a parallel structure of a thyristor and a mechanical contact has been introduced. It has the advantages of reduced voltage ...

AI Technical Summary

Problems solved by technology

Since there is a certain and uncertain value of the disconnection delay of the mechanical contactor, in order to ensure reliable disconnection without arcing, it is necessary to keep the thyristor on for a long period of time after the mechanical contacts are separated. , there is a shortcoming that the thyristor needs to be turned on for a long time when it is disconnected, resulting in a shortened service life

And the control circuit needs to be energized for a long time, and a microprocessor needs to detect the state of the switch to make correct judgments. Using this circuit to realize the function of arc-free power-off protection is costly and complicated.

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