LCD with shielding layer break detection function

Abstract

This invention provides an LCDI (Light Dependent Discharge Indicator) that has the function of detecting breaks in the shielding layer. It includes a live wire shielding layer, a neutral line shielding layer, a leakage current measuring unit, a drive mechanism, and a shielding layer break detection unit. Furthermore, a power cable shielding layer break detection unit is provided to the LCDI circuit in order to quickly detect whether the metallic braid shielding layer of a power cable has been broken, thereby reducing the risk of fire caused by misjudgment.

Description

LCDI with shield break detection function Technical Field

[0001] The present invention relates to the technical field of leakage current detection circuit breaker (LCDI), and in particular to an LCDI with a shielding layer fracture detection function. Background Art

[0002] A leakage current detection circuit breaker (LCDI), as the name suggests, detects leakage current between power lines. When it detects a leakage current exceeding a preset value, it immediately disconnects power to the load. An LCDI typically consists of a three-core power cord with a wire braided shield and a plug with a trip mechanism. The plug's dimensions conform to the US ANSI / NEMA WD 6 standard and incorporates a dual-contact electromagnetic trip mechanism. The power cord is a UL62-compliant SJT three-core power cord. The neutral and live insulation layers are each surrounded by a wire mesh shield. If the neutral or live insulation is damaged by twisting, squeezing, animal bites, or sharp objects, the neutral or live conductors of the power line may come into contact with the wire mesh shield. This triggers the plug's internal mechanism to immediately disconnect power. That is, if the leakage current between the neutral or live conductors and their metal shield exceeds a preset value, the LCDI will trip immediately, preventing the risk of fire caused by wire damage. The metal shielding layers wrapped around the wire insulation are not grounded. Once exposed, it must be treated as an electric shock hazard. They must not be grounded or connected to any exposed metal.

[0003] However, in existing technologies, the metal mesh shielding layers of power lines are in contact with each other, meaning there's no insulation layer between the L-line metal mesh shielding layer and the N-line metal mesh shielding layer. This can lead to the LCDI continuing to operate normally without being detected, potentially posing a fire hazard due to misjudgment. Therefore, there's an urgent need for an LCDI capable of detecting shielding layer breaks.

[0004] Summary of the Invention

[0005] To address the above-mentioned issues, the present invention aims to provide an LCDI with a shield break detection function. By adding a power line shield break detection unit to the LCDI circuit, it can promptly detect whether the metal mesh shielding layer of the power line is broken, thereby reducing the risk of fire caused by misjudgment.

[0006] To achieve the above objectives, the present invention provides an LCDI with a shielding layer breakage detection function, comprising a live wire shielding layer and a neutral wire shielding layer, a leakage current detection unit, an actuating mechanism, and a shielding layer breakage detection unit, wherein:

[0007] The actuating mechanism includes linkage switches respectively arranged on the AC live wire and the AC neutral wire, and solenoids J1 and J2 for controlling the actuation of the linkage switches;

[0008] The leakage current detection unit includes:

[0009] The anode of the thyristor Q1 is connected to the AC live wire through the solenoid J2, and the cathode is connected to the AC neutral wire through the positively connected diode D3;

[0010] The anode of the thyristor Q2 is connected to the AC neutral line through the solenoid J1, and the cathode is connected to the AC live line through the positively connected diode D4;

[0011] The control electrode of the thyristor Q1 is connected to the resistor R6 and the cathode of the diode D1 in sequence, the control electrode of the thyristor Q2 is connected to the resistor R4 and the cathode of the diode D2 in sequence, and the anode of the diode D1 and the anode of the diode D2 are connected to the AC live wire through the resistor R3, the cathode of the diode D5 and the resistor R8 connected in sequence;

[0012] The shielding layer fracture detection unit includes:

[0013] A resistor R8 and a positively connected diode D5 are connected in series between the AC live wire and the live wire shield, and the cathode of the diode D5 is connected to the live wire shield;

[0014] A resistor R9, a reverse-connected diode D6 and a normally closed switch are connected in series between the AC neutral wire and the neutral wire shielding layer, and the live wire shielding layer is electrically connected to the neutral wire shielding layer.

[0015] In one embodiment of the present invention, the linkage switch is provided on the AC input side.

[0016] In one embodiment of the present invention, a capacitor C1 and a resistor R1 are connected in parallel between the control electrode of the thyristor Q1 and the AC neutral line, and a capacitor C2 and a resistor R2 are connected in parallel between the control electrode of the thyristor Q2 and the AC live line.

[0017] In one embodiment of the present invention, a capacitor C3 and a varistor MOV3 are connected in parallel between the anode of the thyristor Q1 and the AC neutral line, and a capacitor C4 and a varistor MOV2 are connected in parallel between the anode of the thyristor Q2 and the AC live line.

[0018] In one embodiment of the present invention, a transient diode is further connected between the connection point of the resistor R6 and the cathode of the diode D1 and the AC neutral line.

[0019] In one embodiment of the present invention, the AC live wire is further connected to the power neutral wire via a resistor R5, a light emitting diode, a normally closed switch, a diode D6 and a resistor R9.

[0020] In one embodiment of the present invention, a varistor MOV1 is further connected between the AC live wire and the AC neutral wire.

[0021] Compared with existing LCDIs, the LCDI with a shielding layer fracture detection function provided by the present invention has an additional shielding layer fracture detection function. It can promptly detect when a metal shielding mesh fracture occurs and cut off the power supply in a timely manner, thereby reducing the risk of fire caused by LCDI misjudgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] FIG1 is a circuit diagram of an embodiment of the present invention.

[0024] Explanation of the accompanying symbols: K1, K2 - linked switches; J1, J2 - solenoids; Q1, Q2 - thyristors; C1, C2, C3, C4 - capacitors; R1, R2, R3, R4, R5, R6, R8, R9 - resistors; D1, D2, D3, D4, D5, D6 - diodes; MOV1, MOV2, MOV3 - varistors; Test - normally closed switch; LED - light emitting diode; TVS - transient voltage diode. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0026] FIG1 is a circuit diagram of an embodiment of the present invention. As shown in FIG1 , this embodiment provides an LCDI with a shielding layer break detection function, including a live wire shielding layer and a neutral wire shielding layer, a leakage current detection unit, an actuating mechanism, and a shielding layer break detection unit, wherein:

[0027] The actuating mechanism includes linkage switches K1 and K2 respectively provided on the AC live wire L and the AC neutral wire N, and solenoids J1 and J2 for controlling the actuation of the linkage switches K1 and K2;

[0028] In this embodiment, the linkage switches K1 and K2 are arranged on the AC input side (the Input side in the figure).

[0029] The leakage current detection unit includes:

[0030] The anode of the thyristor Q1 is connected to the AC live wire L through the solenoid J2, and the cathode is connected to the AC neutral wire N through the positively connected diode D3;

[0031] The anode of the thyristor Q2 is connected to the AC neutral line N through the solenoid J1, and the cathode is connected to the AC live line L through the positively connected diode D4;

[0032] The control electrode of the thyristor Q1 is connected to the resistor R6 and the cathode of the diode D1 in sequence, the control electrode of the thyristor Q2 is connected to the resistor R4 and the cathode of the diode D2 in sequence, and the anode of the diode D1 and the anode of the diode D2 are connected to the AC live wire L through the resistor R3, the cathode of the diode D5 and the resistor R8 which are connected in sequence;

[0033] In this embodiment, a capacitor C1 and a resistor R1 are connected in parallel between the control electrode of the thyristor Q1 and the AC neutral line N, and a capacitor C2 and a resistor R2 are connected in parallel between the control electrode of the thyristor Q2 and the AC live line L, to form RC filter circuits respectively.

[0034] In this embodiment, a capacitor C3 and a varistor MOV3 are connected in parallel between the anode of the thyristor Q1 and the AC neutral line N, and a capacitor C4 and a varistor MOV2 are connected in parallel between the anode of the thyristor Q2 and the AC live line L.

[0035] The shielding layer fracture detection unit includes:

[0036] A resistor R8 and a positively connected diode D5 are connected in series between the AC live wire L and the live wire shield, and the cathode of the diode D5 is connected to the live wire shield;

[0037] A resistor R9, a reverse-connected diode D6 and a normally closed switch TEST are connected in series between the AC neutral line N and the neutral line shielding layer, and the live line shielding layer is electrically connected to the neutral line shielding layer.

[0038] In this embodiment, a transient voltage diode (TVS) is further connected between the connection point of the resistor R6 and the cathode of the diode D1 and the AC neutral line N to protect against lightning surges, that is, to absorb abnormally high voltage in the circuit.

[0039] In this embodiment, the AC live wire L is further connected to the power neutral wire N via the resistor R5 , the light emitting diode LED, the normally closed switch TEST, the diode D6 and the resistor R9 .

[0040] In this embodiment, a varistor MOV1 is further connected between the AC live wire L and the AC neutral wire N.

[0041] In order to better understand the LCDI of the present invention, the working principle of the shielding layer fracture detection is described as follows:

[0042] Under normal circumstances, the voltage between the AC live wire L and the AC neutral wire N is stable, and a stable current flows through the resistor R9 and the diode D6. The product is intact. At this time, the control electrode of the thyristor Q1 is in a low voltage state and will not be triggered to conduct.

[0043] Since both the live wire shield and the neutral wire shield are metal shielding meshes, when the metal shielding mesh of the live wire shield or the neutral wire shield breaks, the voltage at the cathode end of diode D5 is raised, and current will flow through resistor R8, diode D5, resistor R3, diode D1, resistor R6 and resistor R1 in sequence. No current will flow through resistor R9 and diode D6. At this time, a voltage greater than the thyristor trigger voltage will be generated on the control electrode of the thyristor Q1, causing the thyristor Q1 to be triggered and turned on. Then, current will flow through the solenoid J2, causing its iron core to move, that is, the action mechanism will move to disconnect the linkage switches K1 and K2 (contacts), thereby achieving the purpose of cutting off the power supply.

[0044] Compared with existing LCDIs, the LCDI with a shielding layer fracture detection function provided by the present invention has an additional shielding layer fracture detection function. It can promptly detect when a metal shielding mesh fracture occurs and cut off the power supply in a timely manner, thereby reducing the risk of fire caused by LCDI misjudgment.

[0045] Those skilled in the art will appreciate that the accompanying drawings are merely schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0046] Those skilled in the art will appreciate that the modules in the apparatuses of the embodiments may be distributed in the apparatuses of the embodiments as described in the embodiments, or may be located in one or more apparatuses different from the embodiments with corresponding changes. The modules in the above embodiments may be combined into one module or further divided into multiple sub-modules.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LCDI with a shielding layer fracture detection function, characterized in that: It includes a live wire shielding layer and a neutral wire shielding layer, a leakage current detection unit, an action mechanism and a shielding layer break detection unit, wherein: The action mechanism includes linkage switches respectively arranged on the AC live wire and the AC neutral wire, and solenoids J1 and J2 for controlling the action of the linkage switches; The leakage current detection unit comprises: The anode of the thyristor Q1 is connected to the AC live wire through the solenoid J2, and the cathode is connected to the AC neutral wire through the forward-connected diode D3; The anode of the thyristor Q2 is connected to the neutral line of the AC power through the solenoid J1, and the cathode is connected to the live line of the AC power through the forward-connected diode D4; The control electrode of the thyristor Q1 is connected to the resistor R6 and the cathode of the diode D1 in sequence, the control electrode of the thyristor Q2 is connected to the resistor R4 and the cathode of the diode D2 in sequence, and the anode of the diode D1 and the anode of the diode D2 are connected to the AC live wire through the resistor R3, the cathode of the diode D5 and the resistor R8 connected in sequence; The shielding layer fracture detection unit comprises: A resistor R8 and a positively connected diode D5 are connected in series between the AC live wire and the live wire shielding layer, and the cathode of the diode D5 is connected to the live wire shielding layer; A resistor R9, a reverse-connected diode D6 and a normally closed switch are connected in series between the AC neutral line and the neutral line shielding layer, and the live line shielding layer is electrically connected to the neutral line shielding layer.

2. The LCDI with shielding layer fracture detection function according to claim 1, characterized in that: The linkage switch is arranged on the AC input side.

3. The LCDI with shielding layer fracture detection function according to claim 1, characterized in that: A capacitor C1 and a resistor R1 are connected in parallel between the control electrode of the thyristor Q1 and the neutral line of the alternating current, and a capacitor C2 and a resistor R2 are connected in parallel between the control electrode of the thyristor Q2 and the live line of the alternating current.

4. The LCDI with shielding layer fracture detection function according to claim 1, characterized in that: A capacitor C3 and a varistor MOV3 are connected in parallel between the anode of the thyristor Q1 and the AC neutral line, and a capacitor C4 and a varistor MOV2 are connected in parallel between the anode of the thyristor Q2 and the AC live line.

5. The LCDI with shielding layer fracture detection function according to claim 1, characterized in that: A transient diode is also connected between the connection point of the resistor R6 and the cathode of the diode D1 and the AC neutral line.

6. The LCDI with shielding layer fracture detection function according to claim 1, characterized in that: The AC live wire is also connected to the power neutral wire through resistor R5, a light emitting diode, a normally closed switch, a diode D6 and a resistor R9.

7. The LCDI with shielding layer fracture detection function according to claim 1, characterized in that: A varistor MOV1 is also connected between the AC live wire and the AC neutral wire.