Energy accumulation type DC suction and DC keeping circuit for AC contactor

Abstract

The invention relates to a circuit used for energy storage type direct current attracting and direct current keeping of an alternating current contactor. The circuit is formed as follows: a first capacitor is connected with the positive pole of a first diode and the negative pole of a third diode, the negative pole of the first diode is connected with the negative pole of a second diode, the positive pole of the second diode is connected with the negative pole of a fourth diode, and the positive pole of the fourth diode is connected with the positive pole of the third diode; the positive pole of a second capacitor is connected with the negative pole of the first diode, the negative pole of the second diode, and one end of a relay; the other end of the relay is connected with a contactor and the negative pole of a fifth diode, and at the same time the contactor is connected with the positive pole of the third diode, the positive pole of the fourth diode, the negative pole of the second capacitor, and one end of a resistance; and the other end of the resistance is connected with the positive pole of the fifth diode. The circuit has a simple structure, the regulation is convenience, no auxiliary contact is needed, the voltage for attracting and keeping is stable, the circuit is suitable for various alternating current contactors, and the reliability of the action of the built-in alternating current contactor of a soft starter can be efficiently improved.

Description

technical field [0001] The invention relates to a soft starter device, in particular to an energy storage type DC pull-in and DC hold circuit for an AC contactor. Background technique [0002] There are two types of AC contactors in low-voltage electrical, one works in 220V AC circuits, and the other works in 380V AC circuits. Most of the commercially available ones belong to the first category, and in order to simplify the design in the soft starter, the contactor action must be powered from two of the three phases, so it must work at 380V AC voltage. [0003] The existing contactor coil directly obtains voltage from 220V AC or 380V AC, the circuit is simple and the cost is low, but the power factor is obviously reduced due to the influence of magnetic hysteresis and eddy current loss in the iron core. When the low voltage (such as 70% of the nominal voltage value) can operate, the high voltage (such as greater than or equal to 15% of the nominal value) is prone to overhea...

AI Technical Summary

Problems solved by technology

[0007] 2. The control circuit must be isolated from the switching circuit through photoelectricity

Although this circuit is theoretically feasible, due to the half-wave pull-in and half-wave hold, the contacts are prone to jitter in the half-wave state, and its reliability is not good, and this scheme requires two auxiliary contacts of the contactor. It has certain limitations, especially for the contactor of our company, the structure changes too much, it is too complicated, and it is difficult to implement

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