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Combined detector and combined detecting method for switch state of DC ground resistance

A combined detection and DC grounding technology, applied in the direction of fault location, etc., can solve the problems of difficult batch production, undetectable, cumbersome production process, etc., to reduce production cost and maintenance cost, facilitate production and maintenance, and have good instrument consistency Effect

Inactive Publication Date: 2005-10-26
NANJING NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The advantage of this method is that the branch detection sensor is cheap, but the disadvantages are: AC signal generating circuit is required, and the system is more complicated; the detection result is affected by the distributed capacitance of the system, and when the value of the distributed capacitance is large, it is almost impossible to detect; The 20V AC signal is an interference quantity with a relatively large amplitude, which has adverse effects on the DC system
The disadvantage is that the detection accuracy is not high, and the detection sensitivity and range are limited
Its shortcoming is that nonlinear detection components are used, and the dispersion of nonlinear detection components is extremely large. In order to accurately detect the value of grounding resistance, it is necessary to measure the characteristics of nonlinear components one by one and perform curve fitting. Therefore, the production process is very difficult. It is cumbersome, the replacement of components on the detection instrument is poor, it is not conducive to maintenance, it is difficult to mass produce, and the nonlinear components also limit the further improvement of detection accuracy

Method used

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  • Combined detector and combined detecting method for switch state of DC ground resistance
  • Combined detector and combined detecting method for switch state of DC ground resistance
  • Combined detector and combined detecting method for switch state of DC ground resistance

Examples

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Embodiment 1

[0036] Embodiment 1: attached figure 2 As one of the embodiments, the first controllable electronic switch S1 and the second controllable electronic switch S2 adopt two photoelectrically isolated semiconductor switches (also known as photoelectric relays), and the control signals P1 and P2 are from CPU or other control circuits. Control signal; the voltage of the voltage sampling point U passes through the absolute value circuit and the sign judgment circuit, and is input into the analog input port and the digital input port of the microcomputer; the control signal P1 is high level, and the control signal P2 is low level, then the first The first controllable electronic switch S1 is turned on, and the second controllable electronic switch S2 is turned off; when the control signal P2 is at a high level and the control signal P1 is at a low level, the second controllable electronic switch S2 is turned on, and the first controllable electronic switch S2 is at a low level. The el...

Embodiment 2

[0039] Embodiment 2: attached image 3 It is the second embodiment of the present invention, the difference is that the first controllable electronic switch S1 and the second controllable electronic switch S2 are realized by relays. The control signals P1 and P2 are control signals from the CPU or other control circuits; the voltage of the voltage sampling point U passes through the absolute value circuit and the symbol judgment circuit, and then input to the analog input port and the digital input port of the microcomputer; the control signal P1 is low level, the control signal P2 is high level, the first controllable electronic switch S1 is turned on, and the second controllable electronic switch S2 is turned off; the control signal P1 is high level, and the control signal P2 is low level, then the second The second controllable electronic switch S2 is turned on, and the first controllable electronic switch S1 is turned off; when the control signals P1 and P2 are both at low...

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Abstract

The combinational detecting device and detecting method of DC earth resistance switch-status is one of high degree of accuracy online detecting method for earth resistance of electric power system DC power plus-minus busbar and branch wire. The device includes first current-limiting resistance (R1), second current-limiting resistance (R2), sampling resistance (R3), and first controllable electronic switch (S1), (S2). The first current-limiting resistance connects to system positive pole (KM+) and first controllable electronic switch which connect to second current-limiting resistance and sampling resistance in the other end, as voltage sampling point (U). The other end of sampling resistance put to earth. The other end of the second controllable electronic switch connects to the second current-limiting resistance in one end and to system minus pole (KM-) in other end.

Description

technical field [0001] The invention relates to a high-precision on-line detection method for realizing the insulation resistance of positive and negative busbars and branch cables to ground of a DC operating power supply in a power system, and belongs to the technical field of fault detection in power systems. Background technique [0002] DC grounding is one of the common faults of DC operating power supplies in power systems. When a point ground fault occurs in the DC system (directly grounded or the insulation resistance to the ground is reduced), there will generally not be immediate harmful consequences, but if two points are grounded at the same time, it may cause damage to the signal device, control circuit and relay protection device. The malfunction of the circuit breaker will cause the trip of the circuit breaker, or directly cause the short circuit of the DC operating power supply, thus causing serious power system accidents. Therefore, the DC system is not allo...

Claims

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Application Information

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IPC IPC(8): G01R31/08
Inventor 费万民张艳莉
Owner NANJING NORMAL UNIVERSITY
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