Rheostat circuit for eliminating contactor coil surge in switch cabinet

A technology of contactors and rheostats, which is applied in the direction of emergency protection circuit devices, electrical components, and protection against overvoltages. It can solve problems such as damage to electronic components, interference signal interference, and damage to contactors, so as to eliminate overvoltages, The effect of increasing safety

CN104821558AInactive Publication Date: 2015-08-05SOLVE AIR HEFEI
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2015-08-05
Estimated Expiration
Not applicable · inactive patent

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Abstract

A rheostat circuit for eliminating contactor coil surge in a switch cabinet relates to the technical field of a switch cabinet control circuit. The rheostat circuit is characterized in that the rheostat circuit comprises a rheostat (1) and a contactor (2), wherein the rheostat (1) is connected in parallel to the two ends of the contactor (2). The rheostat circuit is simple in structure and can effectively eliminate overvoltage generated by a contactor coil in the on and off process, and thus circuit safety, stability and continuity are enhanced.
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Description

technical field

[0001] The invention relates to the technical field of switch cabinet control circuits, in particular to a rheostat circuit for eliminating contactor coil surges in a switch cabinet. Background technique

[0002] When the switchgear control circuit contactor is disconnected, there will be an overvoltage due to the inductance of the coil trying to maintain the current passing through it during the disconnection process. However, the circuit will be closed by the capacitance of the magnetic coil itself; if the circuit has enough power, the current And the voltage will flow through the coil in the way of damping vibration. Due to the dynamic impedance when the coil is turned off, the voltage amplitude will be in the range of several thousand volts and rise at a speed of about 1kv / us, so it is necessary to eliminate the contactor coil in the switch Overvoltage generated during the process, increase the protection circuit.

[0003] In the process of using AC cont...

Examples

Embodiment Construction

[0013] refer to figure 1 , The present invention includes a varistor 1 and a contactor 2, and the varistor 1 is connected to both ends of the contactor 2 in parallel.

[0014] refer to figure 2 , this figure is a switch overvoltage condition of a contactor coil without any optimized circuit connected, it shows that the "instantaneous discharge" damped vibration caused by the energy down cycle of the contactor control magnetic coil will appear at the peak value of 3.5kv, and the instantaneous discharge will In addition, due to the steep voltage waveform of the capacitor path, it will cause signal interference to adjacent electrical and electronic equipment, capacitive coupling, and other electrical malfunctions.

[0015] refer to image 3 , this picture is a 275V rheostat circuit contactor control magnetic coil (230V, 50HZ, 10VA) switching overvoltage (initial range: about 3ms voltage drop to zero), the optimized circuit, although it can not reduce the voltage rise Steepnes...