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Low-voltage switch system based on double current transformers

A current transformer and low-voltage switch technology, which is applied in the field of low-voltage switch systems, can solve the problems of unsuitable for metering and sampling, unreachable metering accuracy, and low accuracy, so as to achieve wide-range current measurement, realize line selective protection, and realize The effect of precision metering

Inactive Publication Date: 2021-03-26
STATE GRID TIANJIN ELECTRIC POWER +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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

Method used

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  • Low-voltage switch system based on double current transformers
  • Low-voltage switch system based on double current transformers
  • Low-voltage switch system based on double current transformers

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] See attached figure 1 , a low-voltage switch system based on dual current transformers. There are two sets of current transformers in the low-voltage switch body. The output signals of the first set of current transformers are connected to the sampling operational amplifier circuit, and then connected to the sampling operational amplifier circuit after processing. The output signal of the second group of current transformers is connected to the sampling circuit, and after being processed by the sampling circuit, it is connected to the current sampling pin of the metering chip to realize the metering function. The chip is connected with the microprocessor, so that the microprocessor can obtain the data of the metering chip.

[0031] The first group of current transformers is mainly used for protection and has a wide measurement range, preferably >10 times the rated current.

[0032] The second group of current transformers is mainly used for metering, with high precisio...

Embodiment 2

[0037] See attached figure 2 , taking a 3-phase 4-wire low-voltage switch as an example, specifically introducing the intelligent low-voltage switch with a double current transformer structure. Two sets of current transformers 1 and 2 are arranged in the low-voltage switch body.

[0038] The first group of current transformers 1 includes 3 current transformers, and the 3 current transformers are respectively connected to the A, B, and C three-phase lines in the low-voltage switch, and are used to detect the current signals of the A, B, and C three-phase lines ; The secondary side current signal output terminals of the first group of A, B, and C three-phase 3 current transformers are respectively connected to the sampling op-amp processing circuit module, and are connected to the microprocessor after being processed by the sampling op-amp processing circuit module AD pin.

[0039] Specifically, see the attached image 3 , 4 , 5, are respectively corresponding sampling oper...

Embodiment 3

[0044] Furthermore, the microprocessor uses the STM32F207 chip, and the metering chip ATT7022 communicates with the microprocessor STM32F207 through the SPI bus.

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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 ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/52G01R31/58G01R19/25G01R19/165H02H7/26
CPCG01R31/52G01R31/58G01R19/25G01R19/16571H02H7/263
Inventor 刘滨贾嘉聂玮马涛孙继科谢佳高伟张婕翟雨茜臧依璨
Owner STATE GRID TIANJIN ELECTRIC POWER
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