Voltage transformer excitation surge current free idle-loaded switching-on controller

Abstract

The invention discloses a voltage transformer excitation surge current free idle-loaded switching-on controller which is composed of a primary switch, an auxiliary switch and a voltage regulator. The auxiliary switch and the voltage regulator are connected in series, then are connected parallelly with the primary switch at the input end of the voltage transformer, and the primary switch and the auxiliary switch are mutually locked. When the voltage transformer is put into operation and the auxiliary switch is conducted, the voltage regulator regulates the primary lateral input voltage of the voltage transformer by a certain gradient, so that the starting process of the power transformer can be controlled, avoiding large excitation surge current caused by overlarge primary lateral voltage; after the voltage transformer is stared normally, the auxiliary switch is cut off and synchronously the primary switch is conducted, the power transformer can run normally while the voltage transformer is withdrawn. The invention can realize the soft starting control of the voltage transformer idle-loaded switching-on, radically avoid the excitation surge current from impacting the power transformer and surrounding electric equipments, reduce the false operation rate of a protective relaying device and enhance the success ratio of the idle-loaded switching-on of the power transformer.

Description

technical field [0001] The invention relates to a transformer non-excitation inrush current no-load closing control. Background technique [0002] Under normal operating conditions of the power transformer, the iron core works in an unsaturated state, the relative magnetic permeability is large, and the excitation inductance of the winding is also large, so the excitation current is very small. When the transformer is turned on without load or the voltage recovers after the external fault is removed, it is easy to cause saturation of the iron core, the relative magnetic permeability of the iron core is close to 1, and the inductance value of the winding is reduced, so that a large value of excitation current will appear in the winding. The damage caused by the excitation inrush current is multi-faceted: (1) the relay protection device of the transformer is caused to malfunction when the transformer is put into operation, and the operation of the transformer fails frequently;...

AI Technical Summary

Problems solved by technology

[0004] In order to solve the common technical problem that the power transformer cannot avoid the excitation inrush current when it is switched on without load, the invention provides a non-excited inrush current no-load switch-on control device

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