Anti-electric shock protection circuit for power transmission line

Abstract

The invention discloses an anti-electric-shock protection circuit for a power transmission line, belongs to the field of power transmission lines, and aims to solve the problems of existing anti-electric-shock protection measures for the power transmission line. The circuit comprises an AC contactor KM, a zero sequence current sensor TA, a start button SB, an intermediate relay KA, a resistor R1, a resistor R2, a resistor R3, a slide rheostat RP, a capacitor C1, an electrolytic capacitor C2, an electrolytic capacitor C3, a diode VD1, a diode VD2, an NPN triode VT1 and a PNP triode VT2. When an electric shock condition occurs, a human body, a rectifier bridge UR, a zero sequence sensor TA and the ground form a loop, a secondary side of the TA outputs zero sequence current, the zero sequence current is rectified through a VD1, so that a VT1 and a VT2 are turned to be conducted from cut-off, and a KA coil is electrified; and if the power is off, the normally closed contact KA-1 is switched off, the power supply loop of the KM coil is cut off, the KM coil loses power, the KM main contact KM-1 is switched off, power supply to the user is stopped, and the personal safety is protected by cutting off the power supply.

Description

Technical Field

[0001] The invention relates to an anti-electric shock protection circuit and belongs to the field of power transmission lines. Background Art

[0002] The transmission line is realized by using a transformer to step up the voltage of the electric energy generated by the generator, and then connecting it to the transmission line through control equipment such as circuit breakers. In terms of structural form, the transmission line is divided into overhead transmission lines and cable lines.

[0003] When a fault occurs, the cable lines located in factories and urban areas are the objects of operation by maintenance personnel. Electric shock accidents must be avoided during the maintenance process. However, the existing anti-electric shock measures are too complicated and often rely on processor control. The feedback is not direct and is prone to misjudgment. Summary of the invention

[0004] In view of the problems existing in the existing protection measures against electric shock of power transmission lines, the present invention provides an anti-electric shock protection circuit for power transmission lines.

[0005] The electric shock protection circuit for power transmission lines of the present invention comprises an AC contactor KM, a zero-sequence current sensor TA, a start button SB, an intermediate relay KA, a resistor R1, a resistor R2, a resistor R3, a sliding rheostat RP, a capacitor C1, an electrolytic capacitor C2, an electrolytic capacitor C3, a diode VD1, a diode VD2, an NPN transistor VT1 and a PNP transistor VT2;

[0006] The main normally open contact KM-1 of the AC contactor KM is arranged on the transmission line between the zero-sequence current sensor TA and the AC power supply;

[0007] The primary coil of the zero-sequence current sensor TA is arranged on three live wires and a neutral wire N of the transmission line, one end of the secondary coil of the zero-sequence current sensor TA is connected to the cathode of the diode VD1, one end of the capacitor C1 and the base of the NPN transistor VT1, the other end of the secondary coil of the zero-sequence current sensor TA is connected to the other end of the capacitor C1 and the sliding end of the sliding rheostat RP, a fixed end of the sliding rheostat RP is simultaneously connected to the anode of the diode VD1, the emitter of the NPN transistor VT1, the cathode of the diode VD2, the negative electrode of the electrolytic capacitor C2, the negative electrode of the electrolytic capacitor C3 and one end of the coil of the intermediate relay KA and is grounded; the other fixed end of the sliding rheostat RP is simultaneously connected to the anode of the diode VD2 and one end of the resistor R3, the other end of the resistor R3 is simultaneously connected to the positive electrode of the electrolytic capacitor C2, one end of the resistor R2, the emitter of the PNP transistor VT2 and the DC power supply;

[0008] The collector of NPN transistor VT1 is connected to one end of resistor R1 and the other end of resistor R2 at the same time, the other end of resistor R1 is connected to the base of PNP transistor VT2, and the collector of PNP transistor VT2 is connected to the positive electrode of electrolytic capacitor C3 and the other end of the coil of intermediate relay KA at the same time;

[0009] The start button SB and the coil of the AC contactor KM are connected in series between two points of the live wire L3. The normally open auxiliary contact KM-2 of the AC contactor KM and the normally closed contact KA-1 of the intermediate relay KA are connected in series and then in parallel at both ends of the start button SB.

[0010] Preferably, the DC power supply includes a single-phase transformer T and a rectifier bridge UR, the two ends of the primary coil of the single-phase transformer T2 are respectively connected to any live wire and a neutral wire N, the two ends of the secondary coil of the single-phase transformer T are respectively connected to two AC input ends of the rectifier bridge UR, the negative power output end of the rectifier bridge UR is grounded, and the positive power output end of the rectifier bridge UR serves as the positive output end of the DC power supply.

[0011] Beneficial effects of the present invention: The present invention provides an anti-electric shock protection circuit constructed by an analog circuit. When an electric shock accident occurs, the reaction is direct and rapid, and the circuit can be disconnected in time to protect the safety of maintenance personnel. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the anti-electric shock protection circuit for power transmission lines according to the present invention. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0015] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0016] Specific implementation method 1: The following is combined Figure 1The present embodiment is described. The electric shock protection circuit for power transmission lines described in the present embodiment includes an AC contactor KM, a zero-sequence current sensor TA, a start button SB, an intermediate relay KA, a resistor R1, a resistor R2, a resistor R3, a sliding rheostat RP, a capacitor C1, an electrolytic capacitor C2, an electrolytic capacitor C3, a diode VD1, a diode VD2, an NPN transistor VT1, and a PNP transistor VT2;

[0017] The main normally open contact KM-1 of the AC contactor KM is arranged on the transmission line between the zero-sequence current sensor TA and the AC power supply;

[0018] The primary coil of the zero-sequence current sensor TA is arranged on three live wires and a neutral wire N of the transmission line, one end of the secondary coil of the zero-sequence current sensor TA is connected to the cathode of the diode VD1, one end of the capacitor C1 and the base of the NPN transistor VT1, the other end of the secondary coil of the zero-sequence current sensor TA is connected to the other end of the capacitor C1 and the sliding end of the sliding rheostat RP, a fixed end of the sliding rheostat RP is simultaneously connected to the anode of the diode VD1, the emitter of the NPN transistor VT1, the cathode of the diode VD2, the negative electrode of the electrolytic capacitor C2, the negative electrode of the electrolytic capacitor C3 and one end of the coil of the intermediate relay KA and is grounded; the other fixed end of the sliding rheostat RP is simultaneously connected to the anode of the diode VD2 and one end of the resistor R3, the other end of the resistor R3 is simultaneously connected to the positive electrode of the electrolytic capacitor C2, one end of the resistor R2, the emitter of the PNP transistor VT2 and the DC power supply;

[0019] The collector of NPN transistor VT1 is connected to one end of resistor R1 and the other end of resistor R2 at the same time, the other end of resistor R1 is connected to the base of PNP transistor VT2, and the collector of PNP transistor VT2 is connected to the positive electrode of electrolytic capacitor C3 and the other end of the coil of intermediate relay KA at the same time;

[0020] The start button SB and the coil of the AC contactor KM are connected in series between two points of the live wire L3. The normally open auxiliary contact KM-2 of the AC contactor KM and the normally closed contact KA-1 of the intermediate relay KA are connected in series and then in parallel at both ends of the start button SB.

[0021] The DC power supply includes a single-phase transformer T and a rectifier bridge UR. The two ends of the primary coil of the single-phase transformer T2 are respectively connected to any live wire and a neutral wire N, the two ends of the secondary coil of the single-phase transformer T are respectively connected to two AC input ends of the rectifier bridge UR, the negative power output end of the rectifier bridge UR is grounded, and the positive power output end of the rectifier bridge UR serves as the positive output end of the DC power supply.

[0022] Working principle:

[0023] Press the start button SB, the KM coil is energized, the KM main contact KM-1 is closed, the transmission line supplies power to the user, and the KM auxiliary contact KM-2 is closed and self-locked to maintain the energized state of the KM coil.

[0024] When maintenance personnel are operating on the transmission line and no electric shock occurs to the human body, there is no zero-sequence current output on the secondary side of the zero-sequence current transformer TA, that is, the secondary output current is zero, VT1 is cut off, VT2 is cut off, and the coil of the intermediate relay KA is not energized; then KA-1 remains closed and the transmission line is powered normally.

[0025] When electric shock occurs, the human body, rectifier bridge UR, zero-sequence sensor TA and the earth form a loop. The secondary output of TA is zero-sequence current, which is rectified by VD1 to make VT1 and VT2 flip from cut-off to conduction, so that the KA coil is energized; then the normally closed contact KA-1 is disconnected, cutting off the power supply circuit of the KM coil, the KM coil loses power, the KM main contact KM-1 is disconnected, and the power supply to the user is stopped. Personal safety is protected by cutting off the power supply.

[0026] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. An anti-electric shock protection circuit for a power transmission line, characterized in that: It includes an AC contactor KM, a zero-sequence current sensor TA, a start button SB, an intermediate relay KA, a resistor R1, a resistor R2, a resistor R3, a sliding rheostat RP, a capacitor C1, an electrolytic capacitor C2, an electrolytic capacitor C3, a diode VD1, a diode VD2, an NPN transistor VT1 and a PNP transistor VT2; The main normally open contact KM-1 of the AC contactor KM is arranged on the transmission line between the zero-sequence current sensor TA and the AC power supply; The primary coil of the zero-sequence current sensor TA is arranged on three live wires and a neutral wire N of the transmission line, one end of the secondary coil of the zero-sequence current sensor TA is connected to the cathode of the diode VD1, one end of the capacitor C1 and the base of the NPN transistor VT1, the other end of the secondary coil of the zero-sequence current sensor TA is connected to the other end of the capacitor C1 and the sliding end of the sliding rheostat RP, a fixed end of the sliding rheostat RP is simultaneously connected to the anode of the diode VD1, the emitter of the NPN transistor VT1, the cathode of the diode VD2, the negative electrode of the electrolytic capacitor C2, the negative electrode of the electrolytic capacitor C3 and one end of the coil of the intermediate relay KA and is grounded; the other fixed end of the sliding rheostat RP is simultaneously connected to the anode of the diode VD2 and one end of the resistor R3, the other end of the resistor R3 is simultaneously connected to the positive electrode of the electrolytic capacitor C2, one end of the resistor R2, the emitter of the PNP transistor VT2 and the DC power supply; The collector of NPN transistor VT1 is connected to one end of resistor R1 and the other end of resistor R2 at the same time, the other end of resistor R1 is connected to the base of PNP transistor VT2, and the collector of PNP transistor VT2 is connected to the positive electrode of electrolytic capacitor C3 and the other end of the coil of intermediate relay KA at the same time; The start button SB and the coil of the AC contactor KM are connected in series between two points of the live wire L3. The normally open auxiliary contact KM-2 of the AC contactor KM and the normally closed contact KA-1 of the intermediate relay KA are connected in series and then in parallel at both ends of the start button SB.

2. The anti-electric shock protection circuit for power transmission lines according to claim 1, characterized in that: The DC power supply includes a single-phase transformer T and a rectifier bridge UR. The two ends of the primary coil of the single-phase transformer T2 are respectively connected to any live wire and a neutral wire N, the two ends of the secondary coil of the single-phase transformer T are respectively connected to two AC input ends of the rectifier bridge UR, the negative power output end of the rectifier bridge UR is grounded, and the positive power output end of the rectifier bridge UR serves as the positive output end of the DC power supply.

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