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Current mutual inductor and current transformer for protecting frequency-adjusting electromotor

A technology for current transformers and motors, applied in the design of current transformers, frequency modulation motor current transformers, and relay protection fields

Active Publication Date: 2011-03-30
BEIJING SIFANG JIBAO AUTOMATION +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0031] The current variable transformer in the conventional microcomputer protection device, like the conventional current transformer, is designed to operate in the power frequency environment, and cannot work normally in the frequency modulation motor system

Method used

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  • Current mutual inductor and current transformer for protecting frequency-adjusting electromotor
  • Current mutual inductor and current transformer for protecting frequency-adjusting electromotor
  • Current mutual inductor and current transformer for protecting frequency-adjusting electromotor

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Embodiment Construction

[0077] The technical solution of the present invention will be described in further detail below in conjunction with the accompanying drawings.

[0078] The invention discloses a current transformer of a frequency modulation motor, which adopts OD170 / 120-40 ultrafine crystal material to make an iron core. The first secondary winding and the second secondary winding are wound on the iron core with 300 turns, the two secondary windings can be used in series or in parallel, the primary winding is 1 turn or 2 turns, the primary The transformation ratios of the current transformer under the combination of the winding turns and the two secondary windings in series and parallel are 600A / 1A, 300A / 1A and 150A / 1A. The number of turns of the secondary winding and the series-parallel relationship between the two secondary windings under the three transformation ratios are shown in Table 3:

[0079] Table 3 Three transformation ratios, the number of turns of the secondary winding and the ...

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Abstract

The invention relates to a current mutual inductor and a current transformer for a frequency-adjusting electromotor, which can normally run in the adjustment range of the working frequency of the frequency-adjusting electromotor. Frequency-adjusting reformation of a large-scale asynchronous electromotor is an important energy-saving measure. After frequency-adjusting reformation, because no current mutual inductor or current transformer suitable for a frequency-adjusting system is available, the longitudinal differential protection of the frequency-adjusting electromotor cannot put into practice. An ultracrystalline iron core with excellent electromagnetic performance is used for protecting the current mutual inductor and the current transformer, and a computational formula of net sectional areas of the current mutual inductor and the current transformer for protection is deduced, thereby the technical difficult problem is solved.

Description

technical field [0001] The invention belongs to the technical field of electric power system, and more specifically relates to the design of relay protection, frequency modulation motor current transformer and current variable transformer. Background technique [0002] Ordinary motors that drive large feedwater pumps, induced draft fans, etc., cannot adjust the speed, so mechanical equipment such as water gates and dampers need to be installed. In essence, the flow is controlled by the method of consuming energy. [0003] Ordinary large-scale motors are equipped with a set of current transformers at the power switch cabinet and the tail end of the motor to form a "circular current differential protection". [0004] Drive the frequency modulation motor of the large feed water pump and the induced draft fan, automatically adjust the output of the load by changing the working frequency, and do not need to control the flow by the method of consuming energy. [0005] Large async...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F38/28H01F27/24H01F27/28H02H7/08
Inventor 袁伯诚赵玉才屠黎明
Owner BEIJING SIFANG JIBAO AUTOMATION