CN111478274A - Circuit for solving residual current protection device misoperation caused by large motor starting - Google Patents
Circuit for solving residual current protection device misoperation caused by large motor starting Download PDFInfo
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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
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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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
- H02H3/34—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 of a three-phase system
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/02—Details of starting control
- H02P1/022—Security devices, e.g. correct phase sequencing
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Abstract
The invention discloses a circuit for solving the problem of residual current protection device misoperation caused by large motor starting, which comprises a residual current detection circuit, a load current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and a calculation function inside a single chip microcomputer. This solve big motor start and arouse circuit of residual current protection device malfunction, can realize through the big or small change curve according to three-phase return circuit load current, the size of phase place and leakage current, phase place and rate of change contrast in real time, judge whether normal leakage current or the capacitor charging current between large capacity motor starting current and the ground, large capacity motor normal boot has been realized, residual current protection device's sensitivity has been ensured simultaneously, the safe operation for high power motor use occasion provides technical guarantee, through hundreds of high power motor field installations, the operation is stable effective.
Description
Technical Field
The invention relates to the technical field of power protection, in particular to a circuit for solving the problem of residual current protection device misoperation caused by the starting of a large motor.
Background
IN a three-phase four-wire system TN-S power supply system, generally, residual current protection devices are required to be installed on a main circuit outgoing line and an important branch circuit, the basic principle of the residual current protection devices enables a three-phase lead and an N line (a three-phase equipment circuit has no zero line) to pass through a zero sequence C.T together to obtain a current vector sum Ion of the three-phase lead and a neutral line N, wherein the current vector sum Ion is IA + IB + IC + IN, and when no single-phase ground fault occurs and no leakage current exists between the line and the equipment, the vector sum Ion is zero; when a certain phase ground fault occurs, the fault current passes through the protection line PE and a metal component associated with the ground, i.e., IA + IB + IC + IN ≠ 0, and then the value Ion is the ground fault current Id plus the normal leakage current. When the vector sum Ion reaches a preset protection value I delta n, the device gives an alarm or performs brake opening, and the purpose of protecting line equipment and personal safety is achieved.
In practical application, the situation that the residual current protection device acts during starting almost all exist in a high-power motor loop, and in addition, after the starting is finished, the residual current protection device is put into the high-power motor loop, so that the high-power motor loop can normally work.
The condition detection motor has the advantages that the insulation of the motor is up to the standard, the circuit condition is good, and the residual current protection device is qualified. And the industry often analyzes as:
1. and if the distance between a power line and a far line is small, voltage reduction is serious during starting, and the voltage-loss protection action is caused.
2. The capacity of the protection device is small, and overcurrent protection is tripped during starting.
3. The unbalance degree of three-phase current is large.
Because the reason analysis is deviated and the problem cannot be solved, a plurality of large-capacity motors are not provided with residual current protection devices, and serious potential safety hazards are left.
When a large-capacity motor is started, the starting current is usually 5-15 times of the working current, and through professional detection, in fact, the reason that the residual current protection device really causes the residual current protection device is that a large current forms an alternating current loop through equipment and a capacitor between a power supply cable and a shell (the ground), and because of the inconsistency of relative positions of the shell and the ground relative to a motor winding, a motor incoming line cable and the like, the three phases of charging currents relative to the ground are unequal in size, vector sum is generated, and the residual current is formed for the residual current protection device.
For normal design load current, the shunt of the load current through the distributed capacitor is very small, the formed capacitor charging current vector sum is only tens of milliamperes at most, particularly, after the large motor is started and enters a normal running state, the three-phase current tends to be balanced, so that the charging current vector sum generated by the distributed capacitor to ground is smaller, and even reaches a zero value.
In order to install a residual current protection device on a high-capacity motor loop without influencing the normal starting of the high-capacity motor loop, the invention designs an intelligent identification system circuit based on the principle of the residual current protection device according to the actual running condition of the motor, thereby solving the defects of the current industry.
The circuit compares the magnitude change curve of the three-phase loop load current, the magnitude of the phase and the leakage current, the phase and the change rate in real time, judges whether the leakage current is normal or the capacitor charging current between the large-capacity motor starting current and the ground, and realizes the stripping of the large-current ground capacitor charging in the residual current and the extraction of the normal leakage current through the circuit, thereby realizing the normal starting of the large-capacity motor and simultaneously ensuring the sensitivity of the residual current protection device.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a dynamic tracking comparison circuit for parameters such as the current values, the phases and the like of three-phase residual current and three-phase load current, so as to solve the contradiction between the sensitivity of a residual current protection device in a three-phase four-wire system and three-phase three-wire system and the misoperation of the residual current protection device caused by the charging current of a ground distributed capacitor when loads such as a large-capacity motor and the like are started.
(II) technical scheme
In order to achieve the purpose, the invention is realized by the following technical scheme: a circuit for solving the problem of residual current protection device misoperation caused by the starting of a large motor comprises a residual current detection circuit, a load (compatible with zero line) current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and a calculation function in a single chip microcomputer.
The residual current detection circuit: the main winding of the zero-sequence transformer IS4 IS sampled by Ri15, filtered by C35, limited by CW1, and connected to the 13-pin signal input end of the operational amplifier A5 by Ri16, after amplification, the signal IS connected to the 11-pin of the MCU singlechip by the 14-pin signal output end of the operational amplifier A5 through R99.
The load current detection circuit: the A phase current IS obtained by a mutual inductor IS1, full-wave rectification IS carried out through BR1, a negative electrode signal IS grounded through sampling resistors Ri1 and Ri1b, a current value signal IS input to a signal input end of an operational amplifier A1 through Ri2, and the amplified current value signal IS input to a pin 1 of the MCU singlechip through R90 by the operational amplifier AI.
The phase B current IS obtained by a mutual inductor IS2, full-wave rectification IS carried out through BR2, a negative electrode signal IS grounded through sampling resistors Ri5 and Ri5B, a current value signal IS input to a signal input end of an operational amplifier A2 through Ri6, and the amplified current value signal IS input to a pin 3 of the MCU singlechip through an operational amplifier A2 and R91.
The phase C current IS obtained by a mutual inductor IS3, full-wave rectification IS carried out through BR3, a negative electrode signal IS grounded through sampling resistors Ri9 and Ri9b, a current value signal IS input to a signal input end of an operational amplifier A3 through Ri10, and the amplified current value signal IS input to a pin 5 of the MCU singlechip through an operational amplifier A3 and R92.
The N-phase current IS obtained by a mutual inductor IS4, IS subjected to full-wave rectification by BR4, a negative electrode signal IS grounded by sampling resistors Rin and Rinb, a current value signal IS input to a signal input end of an operational amplifier A4 through Rn1, and the amplified current value signal IS input to a pin 7 of the MCU singlechip through an operational amplifier A4 and R95.
The starting current trigger circuit is formed by connecting the anodes of A/B/C/N, 4 groups (3 groups on the occasion without zero line) of current signal rectification circuits in parallel to a trigger circuit mainly composed of Q4.
Preferably, the residual current phase detection signal IS input to the MCU singlechip 9 pin through an IS4 secondary winding and R98 to capture the phase of the residual current signal.
Preferably, the a-phase current value signal is used as both a measurement of the magnitude of the a-current and a determination of the phase of the a-phase current, and the B-phase current value signal is used as both a measurement of the magnitude of the B-current and a determination of the phase of the B-phase current.
Preferably, the C-phase current value signal is used as a measure of the magnitude of the C-current and is also used for determining the phase of the C-phase current, and the N-phase current value signal is used as a measure of the magnitude of the N-current and is also used as a basis for calculating the phase shift of the center point of the a/B/C three phases.
Preferably, the specific principle of the starting current trigger loop is as follows: when the load current of a certain phase or multi-phase main loop reaches a certain threshold value, the R61/ZD1/R62 series loop is triggered to break down, at the moment, a voltage value proportional to the load current is formed on the R62, for the triode Q4, a base input signal is amplified through the Q4, a Q4 emitter resistor R60 generates a voltage signal synchronous with the load current, the signal is input into a pin 2 of the MCU singlechip through the R65, and the MCU singlechip starts an internal phase and amplitude comparison function according to a preset threshold value.
Preferably, in order to take the three-phase three-wire and three-phase four-wire systems into consideration, the A phase is connected in series with R1/R2/R3, the B phase is connected in series with R4/R5/R6, and the C phase is connected in series with R7/R8/R9 and then is connected with the system ground, so as to finish the A/B/C three-phase of the main circuit to form a virtual central point separated from the zero line, then the virtual central point is input to the + input end of the A0 operational amplifier from the signal end of the A phase R3, a zero-cross pulse square wave completely synchronous with the A phase is formed at the output end of the A0 operational amplifier, the square wave is used as the phase reference of the whole system and is sent to the 4 pin of the MCU by R22, the A/B/C three-phase voltage value is respectively sent to the 6/8/10 pin of the MCU through R3/R6/R9, and simultaneously, the phase of the A/B/, and the MCU singlechip completes detection calculation through internal functions.
Preferably, the comparison of real-time phases of residual current, three-phase load current and three-phase incoming line voltage is carried out respectively, and the judgment is carried out through the calculation of related functions in the MCU singlechip, in the very accurate judgment of the residual current value, which signals are formed by load non-running current, namely starting current, and which are leakage current signals generated by safety insulation and the like, the MCU singlechip executes alarm reminding and fault tripping according to the gear set by a user, the alarm signal is output by a pin 24 of the MCU singlechip and is driven to be executed by a Q9 driven by R81, the fault tripping signal is output by a pin 27 of the MCU singlechip and is driven to be executed by a Q1 driven by R42.
Preferably, a circuit for solving the problem of residual current protection device misoperation caused by the starting of a large motor is implanted into the residual current protection device for application, wherein the circuit comprises a zero sequence current CT, an A/B/C three-phase (capable of being compatible with an N zero line) load current CT, a residual current detection circuit, a load (compatible with a zero line) current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and an MCU singlechip basic circuit integrating sampling, calculating, storing and driving output.
(III) advantageous effects
The invention provides a circuit for solving the problem of residual current protection device misoperation caused by large motor starting. Compared with the prior art, the method has the following beneficial effects: the circuit for solving the problem of residual current protection device misoperation caused by the starting of the large motor comprises a residual current detection circuit, a load (compatible with zero line) current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and a calculation function in a single chip microcomputer, can realize the real-time comparison according to the magnitude change curve of the load current of a three-phase circuit, the magnitude of the phase and the leakage current, the phase and the change rate, judge whether the current is normal leakage current or the capacitor charging current between the starting current of the large-capacity motor and the ground, realize the stripping of the large-current ground capacitor charging of the motor starting in the residual current and the extraction of the normal leakage current through the circuit, realize the normal starting of the large-capacity motor, ensure the sensitivity of the residual current protection device and solve the fundamental technical problem that the large-power motor cannot use the residual current protection device, the technical guarantee is provided for the safe operation of the use occasions of the high-power motors, and the operation is stable and effective after hundreds of high-power motors are installed on site.
Drawings
Fig. 1 is a circuit diagram of the operation of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the present invention provides a technical solution: a circuit for solving the problem of residual current protection device misoperation caused by the starting of a large motor comprises a residual current detection circuit, a load (compatible with zero line) current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and a calculation function in a single chip microcomputer.
Residual current detection circuit: sampling by an IS4 main winding of the zero-sequence transformer through Ri15, filtering by C35, amplitude limiting by CW1, connecting Ri16 to a 13-pin signal input end of an operational amplifier A5, amplifying, connecting a signal to an 11-pin MCU singlechip through R99 by a 14-pin signal output end of an operational amplifier A5, inputting a residual current phase detection signal to a 9-pin MCU singlechip through R98 by an IS4 auxiliary winding, and capturing the phase of the residual current signal.
Load current detection circuit: the A-phase current IS obtained by a mutual inductor IS1, full-wave rectification IS carried out through BR1, a negative electrode signal IS grounded through sampling resistors Ri1 and Ri1b, a current value signal IS input to a signal input end of an operational amplifier A1 through Ri2, the amplified current value signal IS input to a pin 1 of the MCU singlechip through R90 by the operational amplifier AI, and the A-phase current value signal IS used for measuring the magnitude of the A current and also used for judging the phase of the A-phase current.
The phase B current IS obtained by a mutual inductor IS2, full-wave rectification IS carried out through BR2, a negative electrode signal IS grounded through sampling resistors Ri5 and Ri5B, a current value signal IS input to a signal input end of an operational amplifier A2 through Ri6, the amplified current value signal IS input to a pin 3 of the MCU singlechip through R91 through an operational amplifier A2, and the phase B current value signal IS used for measuring the magnitude of the phase B current and judging the phase of the phase B current.
The C phase current IS obtained by a mutual inductor IS3, full-wave rectification IS carried out through BR3, a negative electrode signal IS grounded through sampling resistors Ri9 and Ri9b, a current value signal IS input to a signal input end of an operational amplifier A3 through Ri10, and the amplified current value signal IS input to a C phase current value signal of a pin 5 of the MCU singlechip microcomputer through an operational amplifier A3 and R92 to be used as measurement of the magnitude of the C current and judgment of the phase of the C phase current.
The N-phase current IS obtained by a mutual inductor IS4, full-wave rectification IS carried out through BR4, a negative electrode signal IS grounded through sampling resistors Rin and Rinb, a current value signal IS input to a signal input end of an operational amplifier A4 through Rn1, the amplified current value signal IS input to a pin 7 of the MCU singlechip through an operational amplifier A4 and R95, and the N-phase current value signal IS used as measurement of the magnitude of the N current and IS also used as a calculation basis for phase deviation of a central point of an A/B/C three-phase.
The starting current trigger circuit is formed by connecting the positive electrodes of A/B/C/N, 4 groups (3 groups on the occasion without zero line) of current signal rectification circuits in parallel to a trigger circuit mainly composed of Q4, and the specific principle of the starting current trigger circuit is as follows: when the load current of a certain phase or multi-phase main loop reaches a certain threshold value, the R61/ZD1/R62 series loop is triggered to break down, at the moment, a voltage value proportional to the load current is formed on the R62, for the triode Q4, a base input signal is amplified through the Q4, a Q4 emitter resistor R60 generates a voltage signal synchronous with the load current, the signal is input into a pin 2 of the MCU singlechip through the R65, and the MCU singlechip starts an internal phase and amplitude comparison function according to a preset threshold value.
The reference time base generation circuit is characterized in that a phase A is connected in series with R1/R2/R3, a phase B is connected in series with R4/R5/R6, a phase C is connected in series with R7/R8/R9 and then is connected with a system ground, the A/B/C three phases of the main circuit are completed, a virtual central point separated from a zero line is formed, a signal end of the phase A R3 is input to a + input end of an A0 operational amplifier, a zero-crossing pulse square wave completely synchronous with the phase A is formed at an output end of the A0 operational amplifier, the square wave is used as a phase reference of the whole system and is sent to A4 pin of a MCU singlechip through R22, the three-phase values of A/B/C are respectively sent to a 6/8/10 pin of the singlechip through R3/R6/R9, and simultaneously, the phase of the three-phase voltage signals of A/B/C, and the MCU singlechip completes detection calculation through internal functions.
The invention compares the real-time phases of the residual current, the three-phase load current and the three-phase incoming line voltage respectively, judges through the calculation of related functions in the MCU singlechip, and in the value of the residual current, judges accurately which signals are formed by the non-running current of the load, namely the starting current, and which are leakage current signals generated by safety insulation and the like, and executes alarm reminding and fault opening according to the gear set by a user by the MCU singlechip, wherein the alarm signals are output by a pin 24 of the MCU singlechip and drive a Q9 to execute through R81, and the fault opening signals are output by a pin 27 of the MCU singlechip and drive a Q1 to execute through R42.
The invention implants the circuit for solving the problem of residual current protection device misoperation caused by the starting of a large motor into the residual current protection device comprising a zero sequence current CT, an A/B/C three-phase (compatible with N zero line) load current CT, a residual current detection circuit, a load (compatible with zero line) current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and an MCU singlechip basic circuit integrating sampling, calculating, storing and driving output for application.
In conclusion, the invention can judge whether normal leakage current or large-capacity motor starting current is the capacitor charging current between the large-capacity motor starting current and the ground by comparing the magnitude change curve of the three-phase loop load current, the magnitude of the phase and the leakage current, the phase and the change rate in real time, and realizes the stripping of the large-capacity motor starting current in the residual current to the ground capacitor charging and the extraction of the normal leakage current by the circuit, thereby realizing the normal starting of the large-capacity motor, ensuring the sensitivity of the residual current protection device, solving the fundamental technical problem that the large-power motor can not use the residual current protection device, providing technical support for the safe operation of the large-power motor using occasions, and realizing the stable and effective operation by the field installation of hundreds of large-power motors.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (8)
1. The utility model provides a solve big motor and start circuit that causes residual current protection device maloperation which characterized in that: the system comprises a residual current detection circuit, a load current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and a calculation function inside a single chip microcomputer;
the residual current detection circuit: sampling a main winding of the zero-sequence transformer IS4 through Ri15, filtering through C35, amplitude limiting through CW1, connecting Ri16 to a 13-pin signal input end of an operational amplifier A5, and after amplification, connecting a signal to an 11 pin of an MCU singlechip through R99 from a 14-pin signal output end of an operational amplifier A5;
the load current detection circuit: the phase A current IS obtained by a mutual inductor IS1, full-wave rectification IS carried out through BR1, a negative electrode signal IS grounded through sampling resistors Ri1 and Ri1b, a current value signal IS input to a signal input end of an operational amplifier A1 through Ri2, and the amplified current value signal IS input to a pin 1 of the MCU singlechip through R90 by the operational amplifier AI;
the phase B current IS obtained by a mutual inductor IS2, full-wave rectification IS carried out through BR2, a negative electrode signal IS grounded through sampling resistors Ri5 and Ri5B, a current value signal IS input to a signal input end of an operational amplifier A2 through Ri6, and the amplified current value signal IS input to a pin 3 of the MCU singlechip through an operational amplifier A2 and R91;
the phase C current IS obtained by a mutual inductor IS3, IS subjected to full-wave rectification by BR3, a negative electrode signal IS grounded by sampling resistors Ri9 and Ri9b, a current value signal IS input to a signal input end of an operational amplifier A3 through Ri10, and IS input to a pin 5 of the MCU singlechip through an operational amplifier A3 and R92 after being amplified;
the N-phase current IS obtained by a mutual inductor IS4, IS subjected to full-wave rectification by BR4, a negative electrode signal IS grounded by sampling resistors Rin and Rinb, a current value signal IS input to a signal input end of an operational amplifier A4 through Rn1, and IS amplified and then input to a pin 7 of the MCU singlechip through an operational amplifier A4 and R95;
the starting current trigger loop is formed by connecting the anodes of A/B/C/N, 4 groups of current signal rectifying loops in parallel to a trigger loop mainly composed of Q4.
2. The circuit for solving the problem of residual current protection device malfunction caused by large motor starting according to claim 1 is characterized in that: the residual current phase detection signal IS input into the MCU singlechip 9 pin through the IS4 secondary winding via the R98, and the phase of the residual current signal IS captured.
3. The circuit for solving the problem of residual current protection device malfunction caused by large motor starting according to claim 1 is characterized in that: the phase-A current value signal is used for measuring the magnitude of the phase-A current and judging the phase of the phase-A current, and the phase-B current value signal is used for measuring the magnitude of the phase-B current and judging the phase of the phase-B current.
4. The circuit for solving the problem of residual current protection device malfunction caused by large motor starting according to claim 1 is characterized in that: the C-phase current value signal is used for measuring the magnitude of the C current and judging the phase of the C-phase current, and the N-phase current value signal is used for measuring the magnitude of the N current and is also used as a calculation basis for the phase deviation of the central point of the A/B/C three phases.
5. The circuit for solving the problem of residual current protection device malfunction caused by large motor starting according to claim 1 is characterized in that: the specific principle of the starting current trigger loop is as follows: when the load current of a certain phase or multi-phase main loop reaches a certain threshold value, the R61/ZD1/R62 series loop is triggered to break down, at the moment, a voltage value proportional to the load current is formed on the R62, for the triode Q4, a base input signal is amplified through the Q4, a Q4 emitter resistor R60 generates a voltage signal synchronous with the load current, the signal is input into a pin 2 of the MCU singlechip through the R65, and the MCU singlechip starts an internal phase and amplitude comparison function according to a preset threshold value.
6. The circuit for solving the problem of residual current protection device malfunction caused by large motor starting according to claim 1 is characterized in that: the reference time base generation circuit is to give consideration to three-phase three-wire and three-phase four-wire systems, the A phase is connected in series with R1/R2/R3, the B phase is connected in series with R4/R5/R6, the C phase is connected in series with R7/R8/R9 and then is connected with the system ground, the A/B/C three phases of the main circuit are completed, a virtual central point separated from a zero line is formed, the signal end of the A phase R3 is input to the + input end of an A0 operational amplifier, a zero-crossing pulse square wave completely synchronous with the A phase is formed at the output end of an A0 operational amplifier, the square wave is used as the phase reference of the whole system and is sent to a4 pin of an MCU singlechip by the R22, A/B/C three-phase voltage values are respectively obtained to a 6/8/10 pin sent to the MCU singlechip by the R3/R6/R9, and simultaneously, the phases, and the MCU singlechip completes detection calculation through internal functions.
7. The circuit for solving the problem of residual current protection device malfunction caused by large motor starting according to claim 1 is characterized in that: the residual current, the real-time phase of the three-phase load current and the real-time phase of the three-phase incoming line voltage are compared respectively, the judgment is carried out through the calculation of related functions inside the MCU single chip microcomputer, the MCU single chip microcomputer executes alarm reminding and fault tripping according to the gear set by a user, an alarm signal is output by a pin 24 of the MCU single chip microcomputer, the alarm signal is driven by a pin R81 to execute Q9, and a fault tripping signal is output by a pin 27 of the MCU single chip microcomputer and is driven by a pin R42 to execute Q1.
8. A circuit for solving the problem of residual current protection device malfunction caused by large motor starting according to any one of claims 1 to 7, wherein: the residual current protection circuit is implanted into a residual current protection device comprising a zero sequence current CT, an A/B/C three-phase load current CT, a residual current detection circuit, a load current detection circuit, a reference time base generation circuit, a phase detection circuit, a starting current trigger circuit and an MCU singlechip basic circuit integrating sampling, calculating, storing and driving output for application.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010314978.0A CN111478274A (en) | 2020-04-20 | 2020-04-20 | Circuit for solving residual current protection device misoperation caused by large motor starting |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112162217A (en) * | 2020-10-29 | 2021-01-01 | 安徽广识电气有限公司 | System for detecting leakage current of outgoing line of high-voltage switch cabinet |
| CN113300344A (en) * | 2021-06-30 | 2021-08-24 | 广东电网有限责任公司 | Residual current protection method and device for low-voltage power distribution network |
| CN113659891A (en) * | 2021-08-12 | 2021-11-16 | 河北建投沙河发电有限责任公司 | Control method for preventing protection misoperation during starting of generator set |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2245290Y (en) * | 1995-06-06 | 1997-01-15 | 郑明� | Selective comprehensive protector for electrical leakage, phase-sensitive short circuit |
| CN108808709A (en) * | 2018-05-24 | 2018-11-13 | 南通三本电子有限公司 | A kind of three-phase residual current automatic-balancing system |
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2020
- 2020-04-20 CN CN202010314978.0A patent/CN111478274A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2245290Y (en) * | 1995-06-06 | 1997-01-15 | 郑明� | Selective comprehensive protector for electrical leakage, phase-sensitive short circuit |
| CN108808709A (en) * | 2018-05-24 | 2018-11-13 | 南通三本电子有限公司 | A kind of three-phase residual current automatic-balancing system |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112162217A (en) * | 2020-10-29 | 2021-01-01 | 安徽广识电气有限公司 | System for detecting leakage current of outgoing line of high-voltage switch cabinet |
| CN113300344A (en) * | 2021-06-30 | 2021-08-24 | 广东电网有限责任公司 | Residual current protection method and device for low-voltage power distribution network |
| CN113659891A (en) * | 2021-08-12 | 2021-11-16 | 河北建投沙河发电有限责任公司 | Control method for preventing protection misoperation during starting of generator set |
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