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DC leakage current detection and protection circuit and detection and protection method

A technology for DC leakage and protection circuits, applied in emergency protection circuit devices, measuring current/voltage, circuit devices, etc., can solve problems such as inconvenient on-site debugging, affecting detection accuracy and stability, and ripple interference in the relative position of sensor wires. Achieve the effect of ensuring anti-interference ability, simple installation and strong anti-interference ability

Inactive Publication Date: 2014-05-07
朱志伟
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the actual application process, these methods have deficiencies. The main problems are that the sensor is affected by the distributed capacitance, the influence of the change of residual magnetism, the influence of the relative position of the wires, the environmental electromagnetic interference and the ripple interference in the measured DC current, etc. Thus affecting the accuracy and stability of the detection, bringing great inconvenience to the on-site debugging

Method used

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  • DC leakage current detection and protection circuit and detection and protection method

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Effect test

Embodiment 1

[0041] Embodiment 1: The way to cut off the power supply

[0042] use figure 1 The wiring method is that the load is connected to the relay RL1, and the relay RL1 is used as the power switch of the load.

[0043] A DC leakage current detection and protection circuit, including a measuring resistance, an amplification circuit, a comparison circuit, and a control circuit;

[0044] The measuring resistance includes a first measuring resistance R1 and a second measuring resistance R3; one end of R1 is connected to the positive end of the main power supply, and the other end of R1 is marked as the M end through the normally open contact of the relay RL1 and the first end of the load connected, that is, the normally closed contact of RL1 is suspended, and the normally open contact of RL1 is connected to the first end of the load. One end of R3 is grounded, and the other end of R3 is marked as the N end and connected to the second end of the load;

[0045] The amplification and co...

Embodiment 2

[0063] Embodiment 2: The way of not cutting off the power supply.

[0064] Connect the load between the sampling resistor R1 and the test key K3, so that when there is a leakage, the power supply of the load is not cut off, and only the light-emitting diode D2 lights up to alarm. Other parts of the circuit are the same as embodiment 1.

[0065] The specific structure description of the circuit:

[0066] A DC leakage current detection and protection circuit, including a measurement resistance, an amplification and comparison circuit, and a control circuit;

[0067] The measuring resistance includes a first measuring resistance R1 and a second measuring resistance R3; one end of R1 is connected to the positive end of the main power supply, and the other end of R1 is recorded as the M end and is directly connected to the first end of the load [when there is leakage at this time , only alarm, and the load is continuously powered]; one end of R3 is grounded, and the other end of ...

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Abstract

The invention discloses a DC leakage current detection and protection circuit and a detection and protection method. A detection circuit used for detecting a difference value between an output current and an input current of a DC power supply, a difference value signal amplification and comparison circuit, a relay interlocking and thyristor (SCR) control protection circuit and a DC leakage protection testing circuit are adopted. According to the DC leakage current detection and protection circuit and the detection and protection method, the leakage current is detected by adopting the method of measuring the sampling resistance drop difference value, so the anti-interference capability of the circuit is guaranteed; the voltage drop difference value is amplified through a differencing circuit formed by an operational amplifier, and a leakage protection control signal is outputted through a comparison circuit formed by a precise stabilized power supply TL431. When the leakage current exceeds the maximum allowable value, power supply of a load is cut off through a relay and a thyristor. The DC leakage current detection and protection circuit and the detection and protection method integrate the functions of DC leakage current detection and open circuit protection, and have the advantages of being high in precision and reliability, strong in anti-interference capability, easy to install, convenient to debug, and the like.

Description

technical field [0001] The invention relates to a DC leakage current detection and protection circuit and a detection and protection method. Background technique [0002] Currently, DC power supplies are widely used. The DC leakage detection and protection circuit can ensure the safety of equipment and personnel when leakage occurs in the DC circuit. DC screen is the abbreviation of DC operating power system. Simply put, a DC screen is a device that provides a stable DC power supply. The power operating power supplies in power plants and substations are all DC power supplies today, which provide power for control loads, power loads, and DC accident lighting loads, and are the basis for control and protection of contemporary power systems. DC leakage is one of the common faults of DC operating power supplies in power systems, which may cause malfunctions of signaling devices, control circuits, and relay protection devices, or trip circuit breakers. Therefore, it is necess...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H3/32H02H3/04G01R19/10
Inventor 朱志伟刘琼
Owner 朱志伟
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