Low-voltage switch system based on double current transformers

Abstract

The invention discloses a low-voltage switch system based on double current transformers, which is characterized in that two groups of current transformers with different transformation ratios are arranged in a low-voltage switch body, output signals of the first group of current transformers are connected to a sampling operational amplifier circuit, and the output signals are connected to an AD pin of a microprocessor after being processed by the sampling operational amplifier circuit; output signals of the second group of current transformers are connected to the sampling circuit and are connected to a current sampling pin of the metering chip after being processed by the sampling circuit, and the metering chip is connected with the microprocessor, so that the microprocessor can acquiredata of the metering chip. According to the invention, wide-range current measurement and line selective protection can be realized, and high-precision metering can also be realized.

Description

technical field [0001] The invention belongs to the technical field of electric switches, and in particular relates to a low-voltage switch system based on double current transformers. Background technique [0002] In the body of ordinary intelligent low-voltage switches, most of them only have a set of current transformers, which are used to measure the current in the line. Value comparison, to determine what type of fault, and after a delay, to make the corresponding action (alarm or trip), to achieve current three-stage protection. However, in the construction process of the ubiquitous power Internet of Things, the lean management requirements of the low-voltage distribution network continue to increase. Among them, the improvement of the leanness of line loss management and anti-theft management requires that low-voltage switchgear not only have traditional protection functions, but also add power metering functions, and the metering accuracy requirements are high. If ...

AI Technical Summary

Problems solved by technology

If the transformation ratio of a group of current transformers of ordinary intelligent low-voltage switches is too large, the protection function can be realized normally, and the measurement accuracy cannot be achieved; if the transformation ratio is too small, the measurement accuracy can be achieved, but the circuit selective protection cannot be achieved; therefore Ordinary intelligent low-voltage switches only have one set of current transformers, the accuracy is not high, and the measurement range is wide, so it is not suitable for metering and sampling

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