Over-current quick-protection circuit for measurement instrument

Abstract

The invention relates to an over-current quick-protection circuit for a power analyzer, and belongs to the technical field of detection. The technical scheme is that: an electromagnet (3) is a coreless electromagnet; a reed switch penetrates through a coil of the electromagnet; a normally open contact (4) of the reed switch is connected with a coil (5) of a relay; a normally open contact (9) of the relay is bridged at the input end of a channel plate of the measurement instrument; the input end (2) of a panel of the measurement instrument is connected with the electromagnet; and whether the current input end of the measurement instrument has over-current or not is monitored by the coreless electromagnet and the reed switch which penetrates through the coil of the electromagnet. Whether the current input end of the measurement instrument has the over-current or not is monitored by the coreless electromagnet and the reed switch which penetrates through the coil of the electromagnet, so that the over-current quick-protection circuit has the advantages of no influence on the input impedance of the measurement instrument and no undesirable impact on the measurement accuracy of the measurement instrument, can be used for quick protection over alternating over-current or direct over-current, is wide in application range, quick in protection and high in current conveyance capability, and can effectively prevent the damage of instantaneous high current to a channel circuit of the measurement instrument.

Description

technical field [0001] The invention relates to a fast overcurrent protection circuit for a power analyzer, which is suitable for the fast overcurrent protection circuit of the power analyzer and belongs to the technical field of detection. Background technique [0002] Generally speaking, measuring instruments use overcurrent protection circuits, mainly using devices such as fuses and relays. When the current in the circuit is too large, the protected circuit will be disconnected, thus playing the role of overcurrent protection. However, in some special occasions, the above-mentioned over-current protection circuit is no longer applicable. For example, during the transformer no-load and load tests, the current input terminal of the measuring instrument is connected to the secondary side of the external current transformer. If the above-mentioned over-current protection circuit is used, when the protection function When it takes effect, it is equivalent to opening the second...

AI Technical Summary

Problems solved by technology

However, in some special occasions, the above-mentioned over-current protection circuit is no longer applicable. For example, during the transformer no-load and load tests, the current input terminal of the measuring instrument is connected to the secondary side of the external current transformer. If the above-mentioned over-current protection circuit is used, when the protection function When it takes effect, it is equivalent to opening the secondary side of the external current transformer, thereby generating high voltage on the secondary side of the external current transformer, which may damage the measuring instrument or even endanger personal safety

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