CN113675818A - System for be used for low pressure IT power supply system leakage protection - Google Patents
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- 238000000034 method Methods 0.000 description 12
- 238000002347 injection Methods 0.000 description 7
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
- H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
- H02H3/162—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems
- H02H3/165—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems for three-phase systems
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Abstract
The invention discloses a system for protecting the electric leakage of a low-voltage IT power supply system, which comprises a first relay, a second relay, a first nonlinear resistor, a second nonlinear resistor, a capacitor and an inductor, wherein the first relay is connected with the first nonlinear resistor; the coil of the first relay, the first switch of the first relay and the first nonlinear resistor form a first insulation monitoring circuit for insulation monitoring; the coil of the second relay, the first switch of the second relay and the second nonlinear resistor form a second insulation monitoring circuit for insulation monitoring; the capacitance and inductance are used to avoid series resonance of the distributed capacitance compensation to ground. The invention solves the problems of monitoring the insulation of the zero line to the ground, series resonance of a reactor to distributed capacitance compensation and generation of leakage current of zero line grounding leakage protection action under the condition of balanced three-phase-to-ground distributed capacitance, and solves the technical problems for widely expanding the application field of an IT system and popularizing a high-safety IT power supply system in the field of more complex low-voltage power supply.
Description
Technical Field
The invention belongs to the field of low-voltage power supply, and particularly relates to a system for leakage protection of a low-voltage IT power supply system.
Background
The low-voltage IT power supply system is a low-voltage power supply system with a non-grounded neutral point, and is characterized in that when a certain phase in a power supply circuit is grounded, the grounding current is extremely low and only a few milliamperes to tens of milliamperes, so that serious safety problems of human body electric shock, grounding arcing, short circuit tripping and the like can not be caused, and therefore, the low-voltage IT power supply system is generally also called as a high-reliability safety power supply. However, when the zero line is grounded, the low-voltage IT power supply system becomes an unstable TT system or TN system, and a large potential safety hazard exists. Therefore, in order to find out in as short a time as possible and eliminate the first fault between the phase conductor and the exposed conductive part (or ground), an insulation monitoring alarm device capable of emitting an acoustic or optical signal or the like must be installed in the low-voltage IT power supply system.
Currently, there are two main ways for insulation monitoring of low-voltage IT power supply systems: the first method is as follows: in a medical IT power supply system, such as the company bendell, siemens, etc., a signal injection method is used to monitor the insulation of a power supply circuit from ground by injecting a dc signal between a neutral point and ground. The method-signal injection method has high reliability for monitoring resistive grounding, but cannot sense a direct-current signal injection method for capacitive grounding, and an alternating signal injection method, namely a low-frequency signal injection method or a high-frequency signal injection method, is required to be adopted by a low-voltage IT power supply system. However, no matter which signal injection method is used, the following two limitations exist, namely, the structure of the original power supply loop is changed, other different power supply signals are added, the operation mode of compensating the neutral point and the ground by the inductance coil can be judged to be the neutral point grounding, and the normal grounding and the external fault grounding of the inductance coil are difficult to distinguish. Therefore, IT is difficult to apply the insulation monitoring device of companies such as bendell and siemens to a low-voltage IT power supply system with an inductor coil for compensating leakage current.
The second method comprises the following steps: the method for inducing voltage offset to ground utilizes the fact that tiny phase current imbalance is superposed between a zero line and ground to generate suspended potential voltage offset, and specifically judges whether to be in insulated grounding or not by monitoring A, B, C the voltage change to ground when insulated induction voltages of three phases and the zero line to ground are grounded in a certain phase (or the zero line) and are not grounded normally. The second mode is reliable in judgment of grounding of the live wire A, B, C, but in judgment of grounding of the zero wire, although a micro-voltage signal is added between the zero wire and the ground through an induced voltage shift method, the three-phase distributed capacitor is symmetrical, the zero wire is about 10-20V when not grounded, and when the ground resistance of the zero wire is lower than 20k omega, the ground voltage of the zero wire can be reduced to 2-5V. However, when the three-phase distributed capacitance is asymmetric, the zero line induced voltage to the ground is increased to nearly 50V, at this time, the voltage when the ground is grounded is reduced to 10-25V, and there is not much difference from the normal non-ground state, and the insulation judgment of the zero line ground is very unreliable because the low-voltage system three-phase distributed capacitance asymmetry appears randomly.
Disclosure of Invention
The invention aims to provide a system for leakage protection of a low-voltage IT power supply system, which can ensure leakage protection action of the IT power supply system, can be applied to a low-voltage IT power supply circuit with an inductor for compensation, and can accurately eliminate hidden danger of zero line grounding.
The system for the low-voltage IT power supply system leakage protection comprises a first relay, a second relay, a first nonlinear resistor, a second nonlinear resistor, a capacitor and an inductor, wherein the first relay is connected with the first relay; the live wire is sequentially connected in series with the first nonlinear resistor and the coil of the first relay and then grounded; one end of a first switch of the first relay is connected with one end of the first nonlinear resistor, and the other end of the first switch of the first relay is connected with the other end of the first nonlinear resistor; the live wire is also sequentially connected in series with a second switch of the first relay and the capacitor and then grounded; the zero line is connected with the second nonlinear resistor and a coil of the second relay in sequence and then is grounded; one end of a first switch of the second relay is connected with one end of the second nonlinear resistor, and the other end of the first switch of the second relay is connected with the other end of the second nonlinear resistor; the zero line is also sequentially connected in series with a second switch of a second relay and an inductor and then grounded;
the coil of the first relay, the first switch of the first relay and the first nonlinear resistor form a first insulation monitoring circuit for insulation monitoring; the coil of the second relay, the first switch of the second relay and the second nonlinear resistor form a second insulation monitoring circuit for insulation monitoring; the nonlinear resistor is used for improving the power frequency impedance of a normally insulated coil loop, reducing the bearing voltage of a coil of the relay connected in series with the nonlinear resistor, and enabling the corresponding relay to act when the nonlinear resistor is grounded in an insulated mode;
when the live wire is grounded, a coil of the second relay is electrified, and the electrifying action of the second relay outputs a live wire grounding alarm signal to the outside; when the zero line is grounded, the coil of the first relay is electrified, and the contact point of the first relay acts to output a live wire grounding alarm signal to the outside.
The first relay and the second relay adopt relays with action time not more than 20 ms.
The first relay and the second relay comprise MY4N-GS and AC220V intermediate relays.
The inductor adopts an adjustable inductor; the capacitor and the inductor are used for avoiding series resonance of ground distributed capacitance compensation; when the relay is in normal operation, the coil of the second relay is not electrified, and the second switch of the second relay is not conducted; when the inductor works normally, the inductor and the capacitor do not form a series resonance circuit; when the line A, the line B or the line C are grounded, the line PE is communicated with a grounded live wire in a low-resistance mode, the voltage between the line N and the line PE is increased to AC220V, a coil of the second relay is electrified, and a second switch of the second relay is conducted; at the moment, the inductor and the capacitor are connected in parallel, and because the inductor is not connected with a zero line in normal operation, series resonance does not occur in full compensation, under compensation and over compensation.
The ground resistance was set to 20k Ω for zero line to ground insulation monitoring.
The system for the leakage protection of the low-voltage IT power supply system utilizes the relay and the nonlinear resistor to form an insulation monitoring circuit for insulation monitoring, and systematically solves the problem of monitoring the insulation of a zero line to the ground; the series resonance of the ground distributed capacitance compensation is avoided by adopting the capacitor and the inductor; meanwhile, the problem of generation of leakage current of zero line grounding leakage protection action under the condition of balanced three-phase ground distributed capacitance is solved, and the leakage state of the zero line is accurately judged.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention.
Fig. 2 is a schematic diagram of the three-phase earth leakage current vector relationship synthesized N line pair earth leakage current in the embodiment of the present invention.
Fig. 3 is a schematic diagram of a circuit operating condition of the N-wire grounding according to the embodiment of the present invention.
Fig. 4 is a schematic diagram of a circuit operating condition of line a grounded according to an embodiment of the present invention.
Fig. 5 is a schematic diagram of a circuit operating condition of the B-line ground according to the embodiment of the present invention.
FIG. 6 is a schematic diagram of the circuit operating condition of line C to ground according to the embodiment of the present invention,
Detailed Description
Generally, in a low-voltage IT power supply system without distributed capacitance compensation, if a certain phase live line grounding occurs, a certain amount of grounding leakage current exists more or less. After phase capacitance balance and compensation are carried out, the earth leakage current of each phase can be controlled to be a small value, so that the earth leakage current is guaranteed not to hurt people (lower than 30mA), and can be used for the leakage protection action (larger than 6mA) of a special IT power supply system, generally about 10mA, and a circuit part with the first-time grounding hidden trouble is reliably eliminated. However, when the zero line is grounded, the capacitance is balanced with respect to the ground (refer to patent application number: 202110510711.3), and when the zero line is grounded, the leakage current is zero, so that an unbalanced leakage current is required to be added when the zero line is grounded, the leakage current when the zero line is grounded is controlled to be about 10mA, the special IT power supply system leakage protection action is realized, and the circuit part with the hidden danger of the grounding of the zero line is accurately and timely eliminated.
The present invention is a circuit system that incorporates the implementation of the patent (application No. 202110510711.3) to solve the following three problems: 1) the low-voltage IT power supply system monitors the ground insulation, particularly the judgment accuracy of zero line grounding; 2) the problem of series resonance with distributed capacitance compensation to ground; 3) when the neutral line, namely the zero line is grounded, leakage current of a zero line grounding signal is generated to ensure the reliable action of the leakage protection of the IT power supply system and accurately and timely eliminate the circuit part with the hidden danger of zero line grounding.
FIG. 1 is a schematic structural diagram of the system of the present invention: the system provided by the invention comprises a first relay ZJ0, a second relay ZJ1, a first nonlinear resistor R0 and a second nonlinear resistor R0Two nonlinear resistors R1 and a capacitor CΔAnd an inductance L; the C line is sequentially connected with the first nonlinear resistor and a coil of the first relay in series and then is grounded (PE line); one end of a first switch ZJ01 of the first relay is connected with one end of the first nonlinear resistor, and the other end of the first switch of the first relay is connected with the other end of the first nonlinear resistor; the line C is also sequentially connected with a second switch ZJ02 of the first relay and the capacitor in series and then grounded; the N line is connected with the second nonlinear resistor and a coil of the second relay in sequence and then is grounded; one end of a first switch ZJ11 of the second relay is connected with one end of the second nonlinear resistor, and the other end of a first switch ZJ11 of the second relay is connected with the other end of the second nonlinear resistor; the N line is also sequentially connected in series with a second switch ZJ12 of the second relay and the inductor and then grounded;
the coil of the first relay, the first switch of the first relay and the first nonlinear resistor form a first insulation monitoring circuit for insulation monitoring; the coil of the second relay, the first switch of the second relay and the second nonlinear resistor form a second insulation monitoring circuit for insulation monitoring; the nonlinear resistor is used for improving the power frequency impedance of a normally insulated coil loop, reducing the bearing voltage of a coil of the relay connected with the nonlinear resistor in series, and meanwhile, ensuring that the corresponding relay acts when the relay is grounded in an insulated mode. In this embodiment, the first nonlinear resistor corresponds to the first relay; the second nonlinear resistor corresponds to the second relay.
In a specific implementation process, the system of the invention adopts a relay with the action time not more than 20ms, the embodiment adopts an ohm dragon MY4N-GS and AC220V intermediate relay, the power frequency impedance of a coil of the relay is 45k omega, and because the first relay and the second relay are connected in series between a C line and an N line through a PE line, the partial voltage of each coil is AC 115V; after the nonlinear resistors are connected in series, the total power frequency impedance of the AC230V added on the two serially connected branches is 170k omega, the voltage of the coil of the first relay and the coil of the second relay is AC60V, no action is carried out, and the leakage current of the coils is small; when the resistance of N line or live line (including A line, B line and C line) to ground is below 20k omega, the initial voltage applied on the coil of the corresponding relay is above AC180V, the relay acts, and the first switch of the corresponding relay is self-locked; after the first switch of the first relay or the first switch of the second relay is self-locked, AC186V-AC220V voltage is stably applied to the coil of the actuated relay, and the insulation condition of the N line or the fire line to the ground is accurately reflected.
Therefore, when the A wire, the B wire or the C wire are grounded through metal or nonmetal, and the grounding resistance is lower than 20k omega, the coil of the second relay is electrified, and the power connection action of the second relay outputs a live wire grounding alarm signal to the outside; when the N line is grounded through metal or nonmetal, and the grounding resistance is lower than 20k omega, the coil of the first relay is electrified, and the contact action of the first relay outputs a live wire grounding alarm signal to the outside.
The capacitor and the inductor are used for avoiding series resonance of ground distributed capacitance compensation; the inductor adopts an adjustable inductor; in normal operation, because the voltage between the N line and the PE line is very low, the coil of the second relay ZJ1 is not electrified, and the second switch ZJ12(ZJ12 is a normally open switch) of the second relay is not conducted; at this time, the inductor L will not be connected to the capacitor C during normal operationΔA series resonance circuit is formed, namely series resonance can not occur; when any live wire of the A wire, the B wire or the C wire is grounded, the PE wire (ground wire) is communicated with the low resistance (the low resistance is lower than 20k omega) of the grounded live wire, the voltage between the N wire and the PE wire is increased to AC220V, a coil of the second relay is electrified, and a second switch of the second relay is conducted; at the moment, the inductor and the capacitor are connected in parallel, the compensation difference value is the current flowing into the earth through the grounding point, and because the inductor is not connected with a zero line in normal operation, series resonance does not occur in full compensation, under compensation and over compensation.
The embodiment can generate 6-15mA leakage protection action current by grounding the N line under the condition of three-phase balance of the distributed capacitance to the ground. Fig. 2 is a schematic diagram of the three-phase leakage current vector relationship synthesized into the N line pair leakage current in the embodiment of the present invention. When A, B, C three distributed capacitors (converted into current) to earth are all 30mA, the synthesized N line distributed capacitor (converted into current) to earth is 0mA, and a zero line grounding additional capacitor C is added between C phase and earthΔWhen the current is converted to 10mA, N line pair is synthesized to distribute electricity to the groundThe capacity (converted to current) was 10 mA. After the zero line earth leakage current is grounded on the zero line, because the insulation resistance value of the N and the PE wire is reduced to be below 20k omega, the coil of the first relay ZJ0 is electrified, the second switch ZJ02 (normally open switch) of the first relay is closed, and the additional capacitor C is connectedΔThe leakage protection switch is connected between the C phase and the PE phase, leakage current of about 10mA is guaranteed to exist when the zero line is grounded, the leakage protection switch can be started to remove a circuit with hidden danger of zero line grounding, and meanwhile, personnel cannot be injured by electric shock.
The principle of the leakage protection is as follows: for the IT power supply system, as the neutral point is not grounded, the leakage current is very small, after the IT power supply system is loaded, the value of the grounding leakage current is usually determined by the sum of the distributed capacitance currents of the three-phase conductor to the ground, and under the normal condition, the value of the grounding leakage current of the low-voltage IT system cannot exceed 1000 mA. However, even with such a small current, when the electric shock current of a person reaches 100mA or more, the time exceeding 1S is likely to cause irreversible physical function damage or even death by electric shock. When the ground leakage current is less than 500mA, the ground arc does not cause a fire, and the dangerous leakage current value that may cause a fire is generally defined as 1A or more. According to the prior art, when the current flowing through the human body is not more than 30mA, there is no time limit, and organ injury is not usually caused. In addition, for the leakage current exceeding 30mA, if the product of the leakage current acting on the human body and the time does not exceed 30mA · S, the human body is not damaged by electric shock. Therefore, if the relay operation time is not more than 0.02S (i.e. 1 cycle) when an electric shock occurs, even if the leakage current before compensation reaches 1000mA, the integrated value of the current time acting on the human body is only 20mA · S, and a reactor close to full compensation is preset within 1 cycle (normally, in order to eliminate the potential ground hazard, a compensation margin of about 10mA is left to ensure reliable operation of the IT system-dedicated leakage protection switch).
Since the three-phase grounding distributed capacitance of the system is pre-balanced, see the patent application number: 202110510711.3, the leakage current is zero when the zero line is grounded. At this time, in order to eliminate the hidden danger of zero line grounding, leakage current of about 10mA is artificially increased to ensure the reliable action of the special leakage protection switch for the IT system, and a loop with the hidden danger of zero line grounding is cut off from the power supply system to ensure the stability and the integrity of the IT power supply system. In addition, whether the zero line is grounded or not is judged simply and reliably through the action of the relay.
FIG. 3 is a schematic diagram of the circuit operating condition of the N-wire grounding according to the embodiment of the present invention, in which the coil of the first relay ZJ0 is powered on, the inductor L is disconnected, and the capacitor C is connected to groundΔAnd conducting. FIG. 4 is a schematic diagram of the circuit operating condition of line A grounded according to the embodiment of the present invention, in which the coil of the second relay ZJ1 is powered on, the inductor L is turned on, and the capacitor C is turned onΔAnd (5) disconnecting. FIG. 5 is a schematic diagram of the circuit operating condition of the B-line grounding according to the embodiment of the present invention, in which the coil of the second relay ZJ1 is powered on, the inductor L is turned on, and the capacitor C is turned onΔAnd (5) disconnecting. FIG. 6 is a schematic diagram of the circuit operating condition of the C-line ground according to the embodiment of the present invention, in which the coil of the second relay ZJ1 is powered on, the inductor L is turned on, and the capacitor C is turned onΔAnd (5) disconnecting.
For a low-voltage IT power supply system, metallic grounding cannot cause short circuit blasting of a cable, nonmetallic grounding cannot cause fire of the cable, however, the system structure is changed, the IT power supply system is changed into an unstable TT system, and at the moment, insulation grounding alarming is needed and the protection of a loop with grounding hidden danger is separated. When accidental electric shock occurs, a reactor which is preset according to the system ground distribution capacitance is quickly put into the electric shock device in a very short time, and the grounding leakage current is controlled to be about 10mA, so that the safety of a human body is ensured. In a dry environment, the general body resistance is about 2k omega; when the skin sweats, the skin is about lk omega; when the skin has a wound, the wound is about 800 omega. Therefore, if only the compensation of human body electric shock is considered, the relay with the insulation resistance of zero line to ground lower than 5k omega can reliably operate, but the relay with the operation value of the insulation resistance below 20k omega operates in consideration of the insulation monitoring of zero line to ground.
Through the system for the leakage protection of the low-voltage IT power supply system, the problems of monitoring the zero line insulation to the ground, series resonance of a reactor to distributed capacitance compensation and generation of leakage current of zero line grounding leakage protection action under the balanced condition of three phase-to-ground distributed capacitance are solved, and a certain foundation is laid for comprehensively solving the technical bottleneck of application and popularization of the low-voltage IT power supply system. Meanwhile, the problem of monitoring the insulation of the zero line to the ground, the problem of series resonance of a reactor to distributed capacitance compensation and the problem of generation of leakage current of zero line grounding leakage protection action under the condition of balanced three-phase-to-ground distributed capacitance are solved, and the technical problem of popularizing a high-safety IT power supply system in the field of more complex low-voltage power supply is solved for widely expanding the application field of the IT system.
Claims (5)
1. A system for low-voltage IT power supply system leakage protection is characterized by comprising a first relay, a second relay, a first nonlinear resistor, a second nonlinear resistor, a capacitor and an inductor; the live wire is sequentially connected in series with the first nonlinear resistor and the coil of the first relay and then grounded; one end of a first switch of the first relay is connected with one end of the first nonlinear resistor, and the other end of the first switch of the first relay is connected with the other end of the first nonlinear resistor; the live wire is also sequentially connected in series with a second switch of the first relay and the capacitor and then grounded; the zero line is connected with the second nonlinear resistor and a coil of the second relay in sequence and then is grounded; one end of a first switch of the second relay is connected with one end of the second nonlinear resistor, and the other end of the first switch of the second relay is connected with the other end of the second nonlinear resistor; the zero line is also sequentially connected in series with a second switch of a second relay and an inductor and then grounded;
the coil of the first relay, the first switch of the first relay and the first nonlinear resistor form a first insulation monitoring circuit for insulation monitoring; the coil of the second relay, the first switch of the second relay and the second nonlinear resistor form a second insulation monitoring circuit for insulation monitoring; the nonlinear resistor is used for improving the power frequency impedance of a normally insulated coil loop, reducing the bearing voltage of a coil of the relay connected in series with the nonlinear resistor, and enabling the corresponding relay to act when the nonlinear resistor is grounded in an insulated mode;
when the live wire is grounded, a coil of the second relay is electrified, and the electrifying action of the second relay outputs a live wire grounding alarm signal to the outside; when the zero line is grounded, the coil of the first relay is electrified, and the contact point of the first relay acts to output a live wire grounding alarm signal to the outside.
2. The system of claim 1, wherein the first relay and the second relay are relays having an actuation time of no more than 20 ms.
3. A system for leakage protection of a low voltage IT power supply system according to claim 2 wherein said first and second relays comprise MY4N-GS, AC220V intermediate relay.
4. A system for leakage protection of a low voltage IT power supply system according to any of claims 1 to 3, wherein said inductor is an adjustable inductor; the capacitor and the inductor are used for avoiding series resonance of ground distributed capacitance compensation; when the relay is in normal operation, the coil of the second relay is not electrified, and the second switch of the second relay is not conducted; when the inductor works normally, the inductor and the capacitor do not form a series resonance circuit; when the line A, the line B or the line C are grounded, the line PE is communicated with a grounded live wire in a low-resistance mode, the voltage between the line N and the line PE is increased to AC220V, a coil of the second relay is electrified, and a second switch of the second relay is conducted; at the moment, the inductor and the capacitor are connected in parallel, and because the inductor is not connected with a zero line in normal operation, series resonance does not occur in full compensation, under compensation and over compensation.
5. The system according to claim 4, wherein the ground resistance is set to 20 kq for zero line to ground insulation monitoring.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2684433Y (en) * | 2003-05-05 | 2005-03-09 | X-L新纳基有限责任公司 | A conductor creepage detection and circuit breaking apparatus in distribution system |
| CN201210614Y (en) * | 2008-05-23 | 2009-03-18 | 陈家斌 | Residual current controlling and monitoring protector |
| CN102780215A (en) * | 2012-07-02 | 2012-11-14 | 太原理工大学 | Mine low voltage power network capacitative current automatic compensation device |
| CN105186694A (en) * | 2015-10-09 | 2015-12-23 | 北京航天发射技术研究所 | Commercial power switching control apparatus |
| CN105610138A (en) * | 2014-11-14 | 2016-05-25 | 本德尔有限两合公司 | Electrical protective device and method for selective disconnection of subsystem in case of second fault in IT power supply system |
| CN107104426A (en) * | 2017-06-02 | 2017-08-29 | 中国水利水电第五工程局有限公司 | WR and hydropower construction earthing protecting method |
| CN112003275A (en) * | 2020-08-17 | 2020-11-27 | 深圳弘德智能有限公司 | Safe power supply system and method |
-
2021
- 2021-08-18 CN CN202110950841.9A patent/CN113675818B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2684433Y (en) * | 2003-05-05 | 2005-03-09 | X-L新纳基有限责任公司 | A conductor creepage detection and circuit breaking apparatus in distribution system |
| CN201210614Y (en) * | 2008-05-23 | 2009-03-18 | 陈家斌 | Residual current controlling and monitoring protector |
| CN102780215A (en) * | 2012-07-02 | 2012-11-14 | 太原理工大学 | Mine low voltage power network capacitative current automatic compensation device |
| CN105610138A (en) * | 2014-11-14 | 2016-05-25 | 本德尔有限两合公司 | Electrical protective device and method for selective disconnection of subsystem in case of second fault in IT power supply system |
| CN105186694A (en) * | 2015-10-09 | 2015-12-23 | 北京航天发射技术研究所 | Commercial power switching control apparatus |
| CN107104426A (en) * | 2017-06-02 | 2017-08-29 | 中国水利水电第五工程局有限公司 | WR and hydropower construction earthing protecting method |
| CN112003275A (en) * | 2020-08-17 | 2020-11-27 | 深圳弘德智能有限公司 | Safe power supply system and method |
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