CN220421423U - Three-phase four-wire system neutral line broken wire detection protection circuit - Google Patents
Three-phase four-wire system neutral line broken wire detection protection circuit Download PDFInfo
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- CN220421423U CN220421423U CN202321991467.8U CN202321991467U CN220421423U CN 220421423 U CN220421423 U CN 220421423U CN 202321991467 U CN202321991467 U CN 202321991467U CN 220421423 U CN220421423 U CN 220421423U
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Abstract
The utility model discloses a three-phase four-wire neutral line break detection protection circuit, which relates to the technical field of neutral line break detection and comprises a circuit breaker, a contactor, a load assembly, a relay and a neutral line, wherein the circuit breaker comprises a first circuit breaker switch, a second circuit breaker switch and a third circuit breaker switch, the contactor comprises a first contact, a second contact, a third contact and a coil, the load assembly comprises a first load, a second load and a third load, one end of the first circuit breaker switch is electrically connected with a first phase line, and the other end of the first circuit breaker switch is sequentially electrically connected with the first contact and the first load; the utility model realizes the functions of detecting and protecting the broken neutral line of the three-phase four-wire system with lower cost, effectively simplifies the circuit for detecting and protecting the broken neutral line, does not need complex algorithm, can solve the problem of burning out the single-phase load caused by the broken neutral line, and practically improves the safety of equipment.
Description
Technical Field
The utility model relates to the technical field of neutral line breakage detection, in particular to a three-phase four-wire neutral line breakage detection protection circuit.
Background
When three-phase four-wire system is used for supplying power, three coils of the three-phase alternating current power supply are connected together by adopting a star-shaped (Y-shaped) connection method, namely, the tail ends X, Y, Z of the three coils are connected together to form a common point of the three coils, which is commonly called a midpoint or zero point. When power is supplied, the wire led out from the middle point is called a neutral wire N, and three wires led out from the head ends of the three coils are collectively called phase wires, and are generally named as a first phase wire, a second phase wire and a third phase wire respectively.
In the case of three-phase four-wire power supply, a plurality of single-phase loads should be connected to the three-phase circuits in an as balanced manner as possible, without concentrating them in one phase of the three circuits. If the impedance and properties of the load connected to each of the three-phase circuits are the same, the loads in the three circuits are said to be symmetrical. Under the condition of symmetrical load, the phase positions of the currents of all phases are mutually different by 120 degrees, so that the sum of the currents flowing through the neutral line at each moment is zero, the neutral line is removed, and three-phase three-wire system power supply is possible.
However, a three-phase load constituted by connecting a plurality of single-phase loads to a three-phase circuit may not be completely symmetrical. In this case, the neutral line is particularly important, and the voltage across the load of each phase of the neutral line is always equal to the phase voltage of the power supply, and will not change due to the asymmetry of the load and the change of the load, so that each load can work normally just as if each phase of the power supply is used for supplying power to the load of each phase individually.
In the neutral line break accident, the voltage of one phase with large load can be reduced, so that the single-phase load can not be started, and the voltage of one phase with small load can be increased to greatly exceed the rated voltage of the household appliance, so that the single-phase load can be burnt out. Therefore, it is important to make corresponding precautionary measures to solve the problem of disconnection of the neutral line in time.
The realization of the existing three-phase four-wire neutral line disconnection detection is generally divided into the following steps:
1. detecting the unbalanced three-phase voltage and current to judge whether the neutral line is broken, however, the three-phase detection circuit is relatively complex because the three-phase voltage and current are detected, and the cost is increased;
2. the neutral line is connected with the piezoresistor in parallel, when the neutral line is disconnected, the phase line is grounded through the piezoresistor, and when the neutral line is disconnected, the unidirectional load can be protected from being burnt out, but a load circuit is not actually cut off;
3. the voltage stabilizing circuit is added to ensure that the rear-end single-phase voltage is kept in a proper interval, and the added voltage stabilizing circuit has high safety and stability, but has higher cost and is not suitable for large-scale popularization and use.
Disclosure of Invention
The utility model aims to provide a three-phase four-wire neutral line breakage detection protection circuit, which realizes the three-phase four-wire neutral line breakage detection and protection function at lower cost, effectively simplifies the neutral line breakage detection and protection circuit, does not need a complex algorithm, can solve the problem of single-phase load burnout caused by neutral line breakage, and practically improves the safety of equipment.
In order to achieve the above purpose, the utility model discloses a three-phase four-wire neutral line break detection protection circuit, which comprises a breaker, a contactor, a load assembly, a relay and a neutral line, wherein the breaker comprises a first break switch, a second break switch and a third break switch, the contactor comprises a first contact, a second contact, a third contact and a coil, the load assembly comprises a first load, a second load and a third load, one end of the first break switch is electrically connected with a first phase line, the other end of the first break switch is electrically connected with the first contact and the first load in sequence, one end of the second break switch is electrically connected with a second phase line, the other end of the second break switch is electrically connected with the second contact and the second load in sequence, one end of the third break switch is electrically connected with the third phase line, the other end of the third break switch is electrically connected with the third contact and the third load in sequence, one end of the first load far away from the first contact, one end of the second load far away from the second contact, one end of the third load far from the third contact is connected with the third contact in parallel, one end of the third load far away from the third contact is electrically connected with the first end of the third contact, and the other end of the third contact is far from the third contact through the relay is electrically connected with the second end of the third contact, and the other end of the third break switch is far from the third contact.
Preferably, the relay is a voltage relay.
Preferably, the contactor is an ac contactor.
Preferably, the first load, the second load and the third load are real loads corresponding to phase lines.
Preferably, the circuit breaker further comprises a circuit breaking control switch, wherein the circuit breaking control switch is used for controlling the on-off of the first circuit breaking switch, the second circuit breaking switch and the third circuit breaking switch.
Preferably, the first load, the second load and the third load are symmetrically arranged.
Preferably, the first load, the second load and the third load are asymmetrically arranged.
Preferably, the first load, the second load and the third load are not completely symmetrically arranged.
Compared with the prior art, the utility model realizes the three-phase four-wire neutral wire breakage detection and protection function with lower cost, effectively simplifies the neutral wire breakage detection and protection circuit, does not need complex algorithm, can solve the problem of single-phase load burnout caused by neutral wire breakage, and practically improves the safety of equipment.
Drawings
Fig. 1 is a circuit diagram of a three-phase four-wire neutral wire breakage detection protection circuit of the present utility model.
Detailed Description
In order to describe the technical content, the constructional features, the achieved objects and effects of the present utility model in detail, the following description is made in connection with the embodiments and the accompanying drawings.
Referring to fig. 1, the three-phase four-wire system neutral line breakage detection protection circuit of the present embodiment includes a circuit breaker 10, a contactor, a load assembly, a relay 40 and a neutral line N, wherein the three-phase four-wire system is a power supply mode in which a power grid is a power supply, and has a first phase line L1, a second phase line L2, a third phase line L3 and a neutral line, wherein the neutral line is the neutral line N to be detected in the present embodiment. Preferably, the contactor is an ac contactor and the relay 40 is a voltage relay.
The circuit breaker 10 comprises a first circuit breaker 11, a second circuit breaker 12 and a third circuit breaker 13, and the contactor comprises a first contact 21, a second contact 22, a third contact 23 and a coil 24.
The load assembly includes a first load 31, a second load 32, and a third load 33, and preferably, the first load 31, the second load 32, and the third load 33 are real loads corresponding to phase lines, and the first load 31, the second load 32, and the third load 33 may be symmetrical loads, asymmetrical loads, or incomplete symmetrical loads.
One end of the first circuit breaker 11 is electrically connected to the first phase line L1, the other end is electrically connected to the first contact 21 and the first load 31 in sequence, one end of the second circuit breaker 12 is electrically connected to the second phase line L2, and the other end is electrically connected to the second contact 22 and the second load 32 in sequence.
One end of the third cut-off switch 13 is electrically connected to the third phase line L3, and the other end is electrically connected to the third contact 23 and the third load 33 in sequence. The end of the first load 31 far away from the first contact 21, the end of the second load 32 far away from the second contact 22 and the end of the third load 33 far away from the third contact 23 are connected in parallel and then grounded through the relay 40, the end of the first load 31 far away from the first contact 21, the end of the second load 32 far away from the second contact 22 and the end of the third load 33 far away from the third contact 23 are connected in parallel and then electrically connected with the neutral line N, one end of the coil 24 is connected between the first disconnecting switch 11 and the first contact 21, and the other end is connected between the third disconnecting switch 13 and the third contact 23 through the normally closed contact 41 of the relay 40.
Preferably, the circuit breaker 10 further includes a circuit breaking control switch for controlling the on/off of the first, second and third circuit breakers 11, 12 and 13. Specifically, the break control switch can independently control the on-off of each break switch and can also simultaneously control the on-off of all the break switches.
When the neutral line N is not broken, the voltage (UN) of the neutral line N is approximately equal to zero, the relay 40 does not act, the normally closed contact is closed, the main contact of the contactor is closed, at the moment, the first break switch 11, the second break switch 12 and the third break switch 13 are closed at the same time, and the power grid operates normally;
when the neutral line N is disconnected, the neutral line N voltage (UN) is not equal to 0, when the value of the neutral line N voltage (UN) is greater than the setting value of the relay 40, the relay 40 acts, the normally closed contact thereof is opened, the contactor loses electricity, the main contact of the contactor is disconnected, at this time, the first disconnection switch 11, the second disconnection switch 12 and the third disconnection switch 13 are simultaneously disconnected, and the power supply of the power grid is disconnected, so that the three-phase power supply is disconnected, and the load corresponding to each phase line is effectively included.
With reference to fig. 1, the utility model realizes the three-phase four-wire system neutral line N disconnection detection and protection function at lower cost, effectively simplifies the neutral line N disconnection detection and protection circuit, does not need complex algorithm, can solve the problem of single-phase load burnout caused by neutral line N disconnection, and practically improves the safety of equipment.
The foregoing description of the preferred embodiments of the present utility model is not intended to limit the scope of the claims, which follow, as defined in the claims.
Claims (8)
1. A three-phase four-wire system neutral line broken wire detection protection circuit is characterized in that: including circuit breaker, contactor, load subassembly, relay and neutral, the circuit breaker includes first circuit breaker, second circuit breaker and third circuit breaker, the contactor includes first contact, second contact, third contact and coil, load subassembly includes first load, second load, third load, first circuit breaker's one end electricity is connected first phase line, and the other end is electric connection in proper order first contact and first load, second circuit breaker's one end electricity is connected second phase line, and the other end is electric connection in proper order second contact and second load, third circuit breaker's one end electricity is connected third phase line, and the other end is electric connection in proper order third contact and third load, first load is kept away from first contact's one end the second load is kept away from after the one end of third contact connects in parallel through the relay ground, first load is kept away from first contact's one end, second load is kept away from the second contact, the other end is kept away from between the third contact and the neutral connection in parallel connection between the third contact of third load and the other end of third circuit breaker.
2. The three-phase four-wire neutral wire breakage detection and protection circuit according to claim 1, wherein: the relay is a voltage relay.
3. The three-phase four-wire neutral wire breakage detection and protection circuit according to claim 1, wherein: the contactor is an alternating current contactor.
4. The three-phase four-wire neutral wire breakage detection and protection circuit according to claim 1, wherein: the first load, the second load and the third load are real loads corresponding to phase lines.
5. The three-phase four-wire neutral wire breakage detection and protection circuit according to claim 1, wherein: the circuit breaker further comprises a circuit breaking control switch, wherein the circuit breaking control switch is used for controlling the on-off of the first circuit breaking switch, the second circuit breaking switch and the third circuit breaking switch.
6. The three-phase four-wire neutral wire breakage detection and protection circuit according to claim 1, wherein: the first load, the second load and the third load are symmetrically arranged.
7. The three-phase four-wire neutral wire breakage detection and protection circuit according to claim 1, wherein: the first load, the second load and the third load are asymmetrically arranged.
8. The three-phase four-wire neutral wire breakage detection and protection circuit according to claim 1, wherein: the first load, the second load and the third load are arranged in an incompletely symmetrical manner.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321991467.8U CN220421423U (en) | 2023-07-26 | 2023-07-26 | Three-phase four-wire system neutral line broken wire detection protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321991467.8U CN220421423U (en) | 2023-07-26 | 2023-07-26 | Three-phase four-wire system neutral line broken wire detection protection circuit |
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| CN220421423U true CN220421423U (en) | 2024-01-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202321991467.8U Active CN220421423U (en) | 2023-07-26 | 2023-07-26 | Three-phase four-wire system neutral line broken wire detection protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118300054A (en) * | 2024-06-05 | 2024-07-05 | 深圳市移速科技有限公司 | Power supply control circuit and charging pile |
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2023
- 2023-07-26 CN CN202321991467.8U patent/CN220421423U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118300054A (en) * | 2024-06-05 | 2024-07-05 | 深圳市移速科技有限公司 | Power supply control circuit and charging pile |
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