ct open circuit protection device

Abstract

The invention discloses a CT open-circuit protection device. The device mainly comprises two field-effect triodes, a rectification filter circuit, a detection driving circuit and a protection circuit, wherein sources of the two field-effect triodes are both connected to a DC output negative electrode of the rectification circuit, drains of the two field-effect triodes are separately connected to two input ends of the protection device, gates of thee two field-effect triodes are both connected to the output end of the driving circuit, an AC input end of the rectification circuit is connected to the two input ends of the protection device, positive electrodes of two diodes of the protection circuit are separately connected with the sources of the two field-effect triodes, and negative electrodes of the two diodes are connected, are then connected in series with a pressure sensitive component and are connected with the gates of the two field-effect triodes. The CT open-circuit protection device has the advantages of working reliability, small size and low power consumption.

Description

technical field [0001] The invention relates to a protection device, in particular to a CT open circuit protection device for a power system. Background technique [0002] The CT of the power system, that is, the current transformer, its secondary side is open circuit during operation, which may cause the voltage on the secondary coil to rise to several thousand volts, or even tens of thousands of volts, which will seriously threaten personal safety and equipment safety, therefore, in order to prevent the harm caused by CT secondary open circuit, various CT open circuit protection devices have appeared, but all have their own disadvantages. Chinese patent publication CN204858552U discloses a current transformer open circuit protection device , two anti-series field effect transistors and their drive circuits are connected in parallel on the secondary side of the current transformer. When the rectifier circuit, filter circuit, detection circuit and drive circuit of the protec...

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Problems solved by technology

[0002] The CT of the power system, that is, the current transformer, its secondary side is open circuit during operation, which may cause the voltage on the secondary coil to rise to several thousand volts, or even tens of thousands of volts, which will seriously threaten personal safety and equipment safety, therefore, in order to prevent the harm caused by CT secondary open circuit, various CT open circuit protection devices have appeared, but all have their own disadvantages. Chinese patent publication CN204858552U discloses a current transformer open circuit protection device , two anti-series field effect transistors and their drive circuits are connected in parallel on the secondary side of the current transformer. When the rectifier circuit, filter circuit, detection circuit and drive circuit of the protection device detect high voltage in CT open , driving two anti-series field effect transistors to conduct, suppressing the possible dangerous high voltage, the protection device is small in size and low in cost, but the device does not conduct the two field effect transistors during the detection period At this time, the secondary voltage of the CT is limited by the bidirectional TVS diode connected in parallel on the secondary side of the CT, and the two field effect transistors and other components are protected at the same time. Due to the limitation of the performance of the bidirectional TVS diode itself, when the CT secondary When the secondary current is large, it is easy to damage the bidirectional transient suppression diode itself and the field effect transistor

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