CN214674340U - Automatic two safe neutral point resistance to ground cabinets of control - Google Patents
Automatic two safe neutral point resistance to ground cabinets of control Download PDFInfo
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- CN214674340U CN214674340U CN202120776324.XU CN202120776324U CN214674340U CN 214674340 U CN214674340 U CN 214674340U CN 202120776324 U CN202120776324 U CN 202120776324U CN 214674340 U CN214674340 U CN 214674340U
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Abstract
The utility model discloses an automatic two safe neutral point resistance cabinet that connects to ground of control, including three-phase grounding transformer, resistor, vacuum contactor, inductance coils, current transformer, infrared temperature sensor, microcomputer controller, three-phase grounding transformer's inlet wire end is connected with the system power, three-phase grounding transformer's neutral point is connected with the inlet wire end of resistor, vacuum contactor, inductance coils parallel connection are connected between the leading-out terminal of resistor and current transformer's inlet wire end, current transformer's leading-out terminal is connected with the earth. When the current and temperature of the resistor monitored by the microcomputer controller exceed the set values, the microcomputer controller sends a tripping command to break the vacuum contactor, and the neutral point current of the three-phase grounding transformer is grounded through the resistor and the inductance coil. The problem that the system loses the protection effect due to the fact that the resistor cabinet is burnt out in a through-flow mode for a long time is solved, so that more serious interphase short circuit accidents occur, and the safe operation of the system is protected.
Description
The technical field is as follows:
the utility model relates to an electric power system ground connection technical field especially relates to an automatic two safe neutral point resistance to ground cabinets of control.
Background art:
the neutral point grounding resistor cabinet is generally connected with the neutral point of a Z-type connection three-phase grounding transformer or the neutral point of a generator or the electrical equipment of a main transformer, the neutral point can effectively limit clearance arc grounding overvoltage, reduce system operation overvoltage, eliminate system resonance overvoltage, facilitate configuration of unidirectional grounding fault protection, and effectively cut off a fault circuit in a short time through a resistor grounding system, so that the insulation level of system equipment is reduced, the service life of the system equipment is prolonged, and the safety of system operation is improved, thereby being widely applied.
The resistor configured in the neutral point grounding resistor cabinet is generally made of metallic materials, and the like, and the power industry standard DL/T780 specifies the rated through-current time 10S of the stainless steel resistor, and the temperature rise is not more than 780K, which belongs to a short-time working system. The system with the neutral point grounded through the resistance cabinet is provided with zero sequence grounding protection, and when the system is in single-phase grounding, the zero sequence grounding protection device needs to act in time to cut off a fault line so as to protect the system and avoid the resistor from being burnt due to overhigh temperature.
In practical application, the neutral point grounding resistor cabinet is often subjected to burning accidents caused by overhigh temperature of the resistor, the system is changed from a small-resistance grounding system into an ungrounded system after the resistor is burnt out, the arc of the grounding point cannot be extinguished, the arc grounding overvoltage is generated, the amplitude of the arc grounding overvoltage is required to reach more than 3.5Pu under the continuous charging and discharging state of the capacitance current to the ground, meanwhile, the insulation of an adjacent line is damaged by the continuous burning of the arc of the grounding point, and other good phase insulation breakdown is caused under the double influence of high temperature and overvoltage, so that the serious accident of interphase short circuit is caused.
The utility model has the following contents:
the utility model discloses the purpose is solved and to break down when current zero sequence protection return circuit and can not in time amputate ground fault circuit, for avoiding the long-time through-flow of resistance cabinet to burn out and make the system lose the protection and lead to more serious occurence of failure, provides an automatic control's two safe neutral point ground resistance cabinets.
In order to achieve the above purpose, the utility model adopts the following technical scheme to realize:
the automatically-controlled double-safety neutral-point grounding resistance cabinet comprises a three-phase grounding transformer, a resistor, a vacuum contactor, an inductance coil, a current transformer, an infrared temperature measurement sensor and a microcomputer controller, wherein the wire inlet end of the three-phase grounding transformer is connected with a system power supply, the neutral point of the three-phase grounding transformer is connected with the wire inlet end of the resistor, the vacuum contactor and the inductance coil are connected between the wire outlet end of the resistor and the wire inlet end of the current transformer in parallel, and the wire outlet end of the current transformer is connected with the ground.
Further, the current transformer is secondarily connected with the microcomputer controller.
Furthermore, the infrared temperature measurement sensor is connected with the microcomputer controller.
Furthermore, the secondary switching-on and switching-off coil of the single-phase vacuum contactor is connected with a microcomputer controller.
The utility model provides an automatic two safe neutral point ground resistance cabinet of control has following beneficial effect:
when the system normally operates, the vacuum contactor is in a connection state, and the resistor is connected with the ground through the current transformer. When the system is in single-phase grounding, the neutral point generates displacement voltage and is added to the resistor, and the resistor enters a working state to limit single-phase grounding overvoltage and provide resistive current for tripping the zero-sequence protection device. Vacuum contactor and inductance coil are parallelly connected, because vacuum contactor contact resistance is very little, when the resistor through the electric current, all electric currents will be through vacuum contactor ground connection, and inductance coil only very little electric current is equivalent to the short circuit state.
When the zero sequence protection tripping circuit has a problem and can not cut off a grounding fault line in time, when the current and the temperature of the resistor monitored by the microcomputer controller exceed a set value, the microcomputer controller sends a tripping command to break the vacuum contactor, at the moment, the neutral point current of the three-phase grounding transformer is grounded through the resistor and the inductance coil, the inductance coil generates inductance current to compensate the capacitance current of the system, the current of the grounding fault point is reduced to automatically quench the arc, the problem that the system loses the protection effect due to long-time through-flow burning of the resistor cabinet is solved, and therefore more serious interphase short circuit accidents occur, and the safe operation of the system is protected. The three-phase grounding transformer has the advantages that the current and the temperature of the resistor are greatly reduced after the neutral point of the three-phase grounding transformer is grounded through the resistor and the inductance coil, the problem that the resistor is burnt due to overhigh temperature is solved, the grounding mode that the resistor is connected with the inductance coil in series is adopted, the condition that the system resonates is avoided due to the damping effect of the resistor, and the safe operation of the system and the resistor is guaranteed.
Description of the drawings:
the following detailed description of embodiments of the present invention is provided with reference to the accompanying drawings:
fig. 1 is a schematic structural diagram of the automatic control dual-safety neutral grounding resistor cabinet of the present invention.
The reference numbers in the figures illustrate: the device comprises a 1-three-phase grounding transformer, a 2-resistor, a 3-single-phase vacuum contactor, a 4-current transformer, a 5-inductance coil, a 6-infrared temperature measurement sensor and a 7-microcomputer controller.
The specific implementation mode is as follows:
it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that the position of all the mounting elements in the embodiments of the present invention is only illustrated for explaining the relative position relationship between the components in a specific posture (as shown in the drawings), and if the specific position is changed, the connection of the components is changed accordingly.
As shown in fig. 1, an automatically controlled dual-safety neutral grounding resistor cabinet comprises a three-phase grounding transformer 1, wherein an incoming line end of the three-phase grounding transformer 1 is connected with a system power supply, a neutral point of the three-phase grounding transformer 1 is connected with an incoming line end of a resistor 2, an inductive coil 4 of a vacuum contactor 3 is connected between an outgoing line end of the resistor 2 and an incoming line end of a current transformer 4 in parallel, an outgoing line end of the current transformer 4 is connected with the ground, an on-off coil of the vacuum contactor 3 is connected with a microcomputer controller 7, a secondary line of the current transformer 4 is connected with the microcomputer controller 7, and an infrared temperature measuring sensor 6 is connected with the microcomputer controller 7.
Specifically, the vacuum contactor 3 is in a closing on state during normal operation.
Specifically, the vacuum contactor 3 and the inductance coil 5 are connected in parallel between the outlet end of the resistor 2 and the current transformer 4.
Specifically, the microcomputer controller 7 collects a secondary current signal of the current transformer 4.
Specifically, the microcomputer controller 7 collects a temperature signal of the infrared temperature measurement sensor 5.
By adopting the technical scheme, when the three-phase grounding transformer is used, the microcomputer controller 7 sends an action command to break the single-phase vacuum contactor 3 through the secondary current signal of the current transformer 4 and the temperature signal of the infrared temperature measurement sensor 6 which are monitored in real time, when the current signal and the temperature signal exceed set values, the neutral point current of the three-phase grounding transformer is grounded through the resistor and the inductance coil, and the resistor is prevented from being burnt due to long-time through-current.
The foregoing shows and describes the general principles, essential features, and features of the invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the description of the above embodiments and the description is only illustrative of the principles of the present invention, and that various changes and modifications may be made without departing from the spirit and scope of the present invention, and these changes and modifications are all within the scope of the present invention as claimed. The scope of the invention is to be protected by the following claims and their equivalents.
Claims (5)
1. The utility model provides an automatic two safe neutral point resistance to earth cabinet of control, its characterized in that, includes three-phase grounding transformer (1), resistor (2), single-phase vacuum contactor (3), current transformer (4), inductance coil (5), infrared temperature sensor (6) and microcomputer control ware (7), the inlet wire end of three-phase grounding transformer (1) is connected with the system power, the neutral point of three-phase grounding transformer (1) is connected with the inlet wire end of resistor (2), single-phase vacuum contactor (3), inductance coil (5) are connected in parallel between the outlet wire end of resistor (2) and the inlet wire end of current transformer (4), the outlet wire end of current transformer (4) is connected with the ground, single-phase vacuum contactor (3) closes the separating brake coil and is connected with microcomputer control ware (7).
2. The automatically controlled double safety neutral grounding resistor cabinet of claim 1, wherein: and the secondary line of the current transformer (4) is connected with a microcomputer controller (7).
3. The automatically controlled double safety neutral grounding resistor cabinet of claim 1, wherein: the infrared temperature measuring sensor (6) is connected with the microcomputer controller (7).
4. The automatically controlled double safety neutral grounding resistor cabinet of claim 1, wherein: the secondary on-off coil of the single-phase vacuum contactor (3) is connected with a microcomputer controller (7).
5. The automatically controlled double safety neutral grounding resistor cabinet of claim 1, wherein: when the equipment normally operates, the single-phase vacuum contactor (3) is in a closing connection state, when the temperature and the current of the resistor exceed set values, the single-phase vacuum contactor (3) is switched off through the microcomputer controller (7), and the neutral point current of the three-phase grounding transformer (1) is grounded through the resistor (2) and the inductance coil (5).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120776324.XU CN214674340U (en) | 2021-04-16 | 2021-04-16 | Automatic two safe neutral point resistance to ground cabinets of control |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120776324.XU CN214674340U (en) | 2021-04-16 | 2021-04-16 | Automatic two safe neutral point resistance to ground cabinets of control |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214674340U true CN214674340U (en) | 2021-11-09 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120776324.XU Active CN214674340U (en) | 2021-04-16 | 2021-04-16 | Automatic two safe neutral point resistance to ground cabinets of control |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214674340U (en) |
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2021
- 2021-04-16 CN CN202120776324.XU patent/CN214674340U/en active Active
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