Single-phase source leakage detection circuit for isolated neutral system

A technology of ungrounded neutral point and single-phase power supply, which is applied in the direction of circuit devices, emergency protection circuit devices, measuring power, etc., and can solve problems such as misoperation and refusal of protectors

Active Publication Date: 2013-04-24
CHANGZHOU LIANLI AUTOMATION TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

resulting in a multiplied error
May cause the protector to malfunction or refuse to operate when leakage or insulation degradation occurs

Method used

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  • Single-phase source leakage detection circuit for isolated neutral system
  • Single-phase source leakage detection circuit for isolated neutral system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0020] Such as figure 1 As shown, the two poles of the single-phase power supply 1 described in the one-way power supply leakage detection circuit of the neutral point ungrounded system of the present invention are respectively connected with a rectifier diode, namely figure 1 Middle rectifier diodes V1 and V2, single-phase power supply 1 adopts underground 127V general AC power supply. A sampling unit 2 is connected between the two rectifier diodes V1 and V2 and the ground, and the sampling unit includes a series circuit of a sampling resistor R4 and a voltage dividing resistor. Here, in order to obtain the required resistance value, the voltage dividing resistor is resistor R3 and The series resistor of R31. A filter capacitor is connected in parallel at both ends of the sampling resistor R4, and the filter capacitor is a parallel capacitor group of electrolytic capacitors C9 and C10, and the connection point between the sampling resistor R4 and the resistor R31 is a sampli...

Embodiment approach 2

[0029] Such as figure 2 As shown, the single-phase power supply of the single-phase power supply leakage detection circuit of the present invention may be connected to multiple outputs, so that each output branch can be controlled to be disconnected when leakage is detected. The other parts of embodiment two are the same as embodiment one, and the difference is that the output end of the trigger holding unit 4 is connected in parallel with a plurality of holding units, each holding unit is connected with a relay trigger unit, and the output end of each holding unit is connected to the relay. The bases of the switching transistors of the trigger unit are connected to each other.

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Abstract

The invention relates to a leakage detection circuit, in particular to a single-phase source leakage detection circuit applied to an isolated neutral system. Two electrodes of a single-phase source are respectively connected with a commutation diode, and a sampling unit is connected between the two commutation diodes and the ground. The output end of the sampling unit is connected with a comparison output unit. The comparison output unit is connected with a relay triggering unit. Through the adoption of the structure, a detection mutual inductor is saved, a voltage drive logic circuit of a leakage resistance in a half-wave rectifying circuit is utilized to achieve detection when a power source leaks electricity, and therefore cost is saved. In addition, misoperation caused by voltage floating is reduced, and the safety of mine power supply is improved.

Description

technical field [0001] The invention relates to a leakage detection circuit, in particular to a leakage detection circuit suitable for a one-way power supply of a neutral point ungrounded system. Background technique [0002] Underground coal mine 127V power supply is used for lighting and communication equipment power supply. Due to the harsh underground environment, cable insulation reduction or leakage accidents are prone to occur and endanger personal safety. Therefore, the detection performance requirements of the integrated protector are getting higher and higher, especially when the grid voltage changes in the range of -25%~+20%, the protector is required to still supply power normally, and the protector can operate normally when a fault occurs. [0003] Most of the existing 127V leakage protectors use the detection transformer to detect the zero-sequence variation generated when the insulation is reduced or leakage, and then send the variation to the logic judgment o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H3/14G01R31/02
Inventor 林冬伟
Owner CHANGZHOU LIANLI AUTOMATION TECH
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