Insulation parameter detecting method for mine low-voltage cable

A technology of insulation parameters and low-voltage cables, applied in the field of parameter detection, can solve problems such as inability to realize online monitoring, difficulty in realization, large measurement error, etc., and achieve the effect of realizing the function of fault line selection

Inactive Publication Date: 2014-11-05
李磊 +1
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  • Application Information

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Problems solved by technology

These methods cannot realize online monitoring, and the measurement method is relatively passive. Only when an insulation fault occurs, can a conclusion be drawn through measurement
The measurement error of these methods is relatively large, and in practical application, the difficulty of realization is relatively large.

Method used

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  • Insulation parameter detecting method for mine low-voltage cable
  • Insulation parameter detecting method for mine low-voltage cable
  • Insulation parameter detecting method for mine low-voltage cable

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Embodiment Construction

[0015] The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0016] refer to figure 1 , under the action of low-frequency power supply, a low-frequency current will be generated on the three-phase lines of each branch. This low-frequency current is inversely proportional to the insulation resistance and proportional to the distributed capacitance. For low-frequency signals, the reactance introduced by the three-phase reactor is extremely small, which can be ignored compared with the insulation resistance of the low-voltage power grid. Then the equivalent circuit is simplified and regarded as an equivalent circuit composed of a voltage source, an equivalent resistance and an equivalent capacitance.

[0017] Such as figure 2 As shown, according to the equivalent circuit, we get

[0018] After paralleling R 1 ...

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Abstract

The invention discloses an insulation parameter detecting method for a mine low-voltage cable. The insulation parameter detecting method includes the steps that (1), the frequency of low-frequency signals is selected, according to the selecting principle, it is ensured that the injected low-frequency signals can not reduce insulation parameters of a power grid, the sensitivity of a protective device is improved, setting and filtering of a secondary circuit are facilitated, zero-sequence power-frequency signals and harmonic signals are finally filtered out, the injected low-frequency signals are reserved, and the anti-interference capacity is improved; (2), a low-frequency power source is output through an isolation transformer, enters the power grid through a three-phase electric reactor SK and is grounded through a ground capacitor and an insulation resistor of the power grid to form a low-frequency current circuit; (3), the low-frequency voltage signals and the low-frequency current signals are measured, phase difference exists between the voltage and the current, and a calculation formula of the insulation parameters is calculated and derived; (4), an insulation resistor formula is obtained; (5), a calculation formula of distributed capacitors is obtained.

Description

technical field [0001] The invention relates to a parameter detection method, in particular to a mine low-voltage cable insulation parameter detection method. Background technique [0002] The insulation resistance and capacitance of mine low-voltage grid to ground are important parameters related to the safe operation of the grid and must be measured frequently. This measurement should also be carried out when the power grid is in working condition, otherwise, it cannot reflect the actual situation of the power grid. Therefore, many methods for measuring the insulation resistance of the power grid have emerged. Divided into AC voltammetry, neutral point voltage displacement method, resonance measurement method, phase separation method of insulation resistance measurement. These methods cannot realize on-line monitoring, and the measurement method is relatively passive. Only when an insulation fault occurs, can a conclusion be drawn through measurement. The measurement err...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R27/16G01R27/26
Inventor 李磊李忠
Owner 李磊
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