CN113064062A - Circuit and device for monitoring secondary circuit of circuit breaker - Google Patents
Circuit and device for monitoring secondary circuit of circuit breaker Download PDFInfo
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- CN113064062A CN113064062A CN202110327387.1A CN202110327387A CN113064062A CN 113064062 A CN113064062 A CN 113064062A CN 202110327387 A CN202110327387 A CN 202110327387A CN 113064062 A CN113064062 A CN 113064062A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
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Abstract
The embodiment of the invention discloses a monitoring circuit and a device of a secondary circuit of a circuit breaker. The current acquisition circuit is used for acquiring current on the sub-loop; the voltage conversion circuit is used for converting the current signals collected by the current transformer into voltage signals. Compared with the prior art, the technical scheme provided by the embodiment of the invention does not need to destroy the original structure of the secondary circuit of the circuit breaker, and can realize that whether the secondary circuit is complete or not by monitoring the change condition of the current only by hanging the current transformer on the secondary circuit, thereby greatly reducing the number of fault nodes in the secondary circuit; and the method is simple and is beneficial to popularization.
Description
Technical Field
The embodiment of the invention relates to the technical field of power equipment, in particular to a circuit and a device for monitoring a secondary circuit of a circuit breaker.
Background
In a power system, a large number of circuit breakers exist, and whether the circuit breakers work reliably is inseparable to the safe operation of the power system, so that the monitoring of a secondary circuit of the circuit breaker is very important.
At present, the on-line monitoring method of the circuit breaker mainly comprises the step of judging whether a secondary circuit is complete or not by connecting a resistor and a Hall sensor in series in the secondary circuit. However, the method in the prior art causes the number of fault nodes in the secondary circuit to increase, and increases the possibility of the secondary circuit fault, and meanwhile, the method modifies the secondary circuit, increases the cost, and causes difficulty in popularization.
Disclosure of Invention
The embodiment of the invention provides a circuit and a device for monitoring a secondary circuit of a circuit breaker, which are used for improving the reliability of monitoring the secondary circuit on the basis of not damaging the secondary circuit.
In a first aspect, an embodiment of the present invention provides a monitoring circuit for a secondary circuit of a circuit breaker, including: the power supply module, the current transformer, the current acquisition circuit, the amplification circuit, the control circuit and the voltage conversion circuit;
the current transformers correspond to the sub-loops of the secondary loop one by one, one current transformer is hung on one sub-loop of the secondary loop, the power end of the current transformer is electrically connected with the first output end of the power module, the output end of the current transformer is electrically connected with the current acquisition circuit, and the current acquisition circuit is used for acquiring current on the sub-loops; the first end of the voltage conversion circuit is electrically connected with the output end of the current transformer, the second end of the voltage conversion circuit is grounded, and the voltage conversion circuit is used for converting the current signal acquired by the current transformer into a voltage signal;
the current acquisition circuit comprises a voltage division circuit, a first comparison output circuit and a second comparison output circuit, wherein a first power supply end of the voltage division circuit is electrically connected with a second output end of the power supply module, a second power supply end of the voltage division circuit is grounded, a first input end of the first comparison output circuit is electrically connected with a first output end of the voltage division circuit, a second input end of the first comparison output circuit is electrically connected with an output end of the current transformer, and an output end of the first comparison output circuit is electrically connected with an input end of the amplification circuit; a first input end of the second comparison output circuit is electrically connected with a second output end of the voltage division circuit, a second input end of the second comparison output circuit is electrically connected with an output end of the current transformer, and an output end of the second comparison output circuit is electrically connected with an input end of the amplifying circuit;
the output end of the amplifying circuit is electrically connected with the input end of the control circuit, and the control circuit is used for determining the state of the secondary circuit according to the current on the sub-circuit and the action logic of the secondary circuit.
Optionally, the voltage conversion circuit includes a conversion resistor, a first end of the conversion resistor is electrically connected to the output end of the current transformer, and a second end of the conversion resistor is grounded.
Optionally, the current transformer comprises an open current transformer.
Optionally, the voltage divider circuit includes a reference resistor, a zener diode, a first resistor, a second resistor, and a third resistor;
the first end of the reference resistor is electrically connected with the second output end of the power supply module, and the second end of the reference resistor is grounded through the voltage stabilizing diode;
the first end of the first resistor is electrically connected with the second end of the reference resistor, the second end of the first resistor is electrically connected with the first end of the second resistor, the second end of the second resistor is electrically connected with the first end of the third resistor, and the second end of the third resistor is grounded;
the first input end of the first comparison output circuit is electrically connected with the second end of the first resistor, and the first input end of the second comparison output circuit is electrically connected with the second end of the second resistor.
Optionally, the first comparison output circuit comprises a first comparator;
the positive input end of the first comparator is electrically connected with the output end of the current transformer, the reverse input end of the first comparator is electrically connected with the first output end of the voltage division circuit, and the output end of the first comparator is electrically connected with the input end of the amplifying circuit.
Optionally, the first comparison output circuit further includes a first triode, a first light emitting diode, and a first buzzer;
the control end of the first triode is electrically connected with the output end of the first comparator, the first pole of the first triode is electrically connected with the cathode of the first light-emitting diode, the anode of the first light-emitting diode is electrically connected with the second output end of the power supply module, and the second pole of the first triode is grounded;
the first buzzer is connected with the first light-emitting diode in parallel.
Optionally, the second comparison output circuit comprises a second comparator;
the reverse input end of the second comparator is electrically connected with the output end of the current transformer, the forward input end of the second comparator is electrically connected with the second output end of the voltage division circuit, and the output end of the second comparator is electrically connected with the input end of the amplifying circuit.
Optionally, the second comparison output circuit further includes a second triode, a second light emitting diode, and a second buzzer;
the control end of the second triode is electrically connected with the output end of the second comparator, the first pole of the second triode is electrically connected with the cathode of the second light-emitting diode, the anode of the second light-emitting diode is electrically connected with the second output end of the power supply module, and the second pole of the second triode is grounded;
the second buzzer is connected with the second light-emitting diode in parallel.
Optionally, the amplifying circuit includes a fourth resistor, a capacitor, a first operational amplifier, a fifth resistor, a sixth resistor, a second operational amplifier, a seventh resistor, and an eighth resistor;
a first end of the fourth resistor is used as an input end of the amplifying circuit and is electrically connected with an output end of the first comparison output circuit and an output end of the second comparison output circuit respectively, a second end of the fourth resistor is electrically connected with a positive input end of the first operational amplifier, a negative input end of the first operational amplifier is electrically connected with an output end of the first operational amplifier, and the output end of the first operational amplifier is electrically connected with a negative input end of the second operational amplifier through the fifth resistor;
the positive input end of the second operational amplifier is grounded through the sixth resistor, the output end of the second operational amplifier is electrically connected with the input end of the control circuit through the seventh resistor, and the negative input end of the second operational amplifier is electrically connected with the output end of the second operational amplifier through the eighth resistor;
the first end of the capacitor is electrically connected with the positive input end of the first operational amplifier, and the second end of the capacitor is grounded.
In a second aspect, an embodiment of the present invention further provides a monitoring device for a secondary circuit of a circuit breaker, including the monitoring circuit for a secondary circuit of a circuit breaker provided in any embodiment of the present invention.
The monitoring circuit of the secondary circuit of the circuit breaker provided by the embodiment of the invention is characterized in that the current transformers are hung on each sub-circuit of the secondary circuit of the circuit breaker, current signals acquired by the current transformers are converted into voltage signals through the voltage conversion circuit, then the voltage signals are acquired, compared and output by the current acquisition circuit, the signals output by the current acquisition circuit are amplified by the amplification circuit and then input to the control circuit, and the control circuit determines whether the secondary circuit is complete or not according to the received signals (the current signals on the corresponding sub-circuit) and the action logic of the secondary circuit. Compared with the prior art, the technical scheme provided by the embodiment of the invention does not need to destroy the original structure of the secondary circuit of the circuit breaker, and can realize that whether the secondary circuit is complete or not by monitoring the change condition of the current only by hanging the current transformer on the secondary circuit, thereby greatly reducing the number of fault nodes in the secondary circuit; and the method is simple and is beneficial to popularization.
Drawings
Fig. 1 is a schematic structural diagram of a monitoring circuit of a secondary circuit of a circuit breaker according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another monitoring circuit for a secondary circuit of a circuit breaker according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of another monitoring circuit for a secondary circuit of a circuit breaker according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another monitoring circuit for a secondary circuit of a circuit breaker according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an amplifying circuit according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a secondary circuit of a circuit breaker according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic structural diagram of a monitoring circuit of a secondary circuit of a circuit breaker according to an embodiment of the present invention, and referring to fig. 1, the monitoring circuit of the secondary circuit of the circuit breaker according to the embodiment of the present invention includes: the power supply circuit comprises a power supply module 20, a current transformer 10, a current acquisition circuit 30, an amplifying circuit 40, a control circuit 50 and a voltage conversion circuit 60.
The current transformers 10 correspond to the sub-loops of the secondary loop one to one, one current transformer 10 is hung on one sub-loop of the secondary loop, a power supply end a1 of the current transformer 10 is electrically connected with a first output end B1 of the power supply module 20, an output end a2 of the current transformer 10 is electrically connected with the current collecting circuit 30, and the current collecting circuit 30 is used for collecting currents on the sub-loops. The first end M1 of the voltage conversion circuit 60 is electrically connected to the output end a2 of the current transformer 10, the second end M2 of the voltage conversion circuit 60 is grounded, and the voltage conversion circuit 60 is configured to convert the current signal collected by the current transformer 10 into a voltage signal.
The current collecting circuit 30 comprises a voltage dividing circuit 301, a first comparison output circuit 302 and a second comparison output circuit 303, wherein a first power supply end D1 of the voltage dividing circuit 301 is electrically connected with a second output end B2 of the power supply module 20, a second power supply end D2 of the voltage dividing circuit 301 is grounded, a first input end E1 of the first comparison output circuit 302 is electrically connected with a first output end D3 of the voltage dividing circuit 301, a second input end E2 of the first comparison output circuit 302 is electrically connected with an output end a2 of the current transformer 10, and an output end E3 of the first comparison output circuit 302 is electrically connected with an input end G35 1 of the amplifying circuit 40; the first input terminal F1 of the second comparison output circuit 303 is electrically connected to the second output terminal D4 of the voltage divider circuit 301, the second input terminal F2 of the second comparison output circuit 303 is electrically connected to the output terminal a2 of the current transformer 10, and the output terminal F3 of the second comparison output circuit 303 is electrically connected to the input terminal G1 of the amplifier circuit 40.
The output G2 of the amplifier circuit 40 is electrically connected to the input H1 of the control circuit 50, and the control circuit 50 is used to determine the state of the secondary loop according to the current on the sub-loop and the action logic of the secondary loop.
Specifically, the power module 20 provides a power voltage for a monitoring circuit of a secondary circuit of the circuit breaker, the secondary circuit of the circuit breaker includes a closing circuit and a tripping circuit, the current transformers 10 are respectively arranged in each sub-circuit (closing circuit and tripping circuit) of the secondary circuit, each current transformer 10 is connected with a current collecting circuit 30, and the current collecting circuit 30 is used for being matched with the current transformers 10 to collect currents on each sub-circuit in the secondary circuit. The amplifying circuit 40 is used for amplifying the signal collected by the current collecting circuit 30 so that the control circuit 50 can recognize the signal. In general, the current collecting circuit 30 cannot directly collect the current signal output by the current transformer 10, and the current signal output by the current transformer 10 needs to be converted into a voltage signal by the voltage converting circuit 60, so that the current collecting circuit 30 can normally collect the signal.
The current collecting circuit 30 includes a voltage dividing circuit 301, a first comparison output circuit 302 and a second comparison output circuit 303, the first comparison output circuit 302 and the second comparison output circuit 303 are configured to compare the voltage output by the voltage dividing circuit 301 with the voltage signal output by the voltage converting circuit 60 to determine the magnitude of the current signal collected by the current transformer 10, the signal output by the first comparison output circuit 302 or the second comparison output circuit 303 is amplified by the amplifying circuit 40 and then input to the control circuit 50, and the control circuit 50 determines the loop state of the secondary loop according to the magnitude of the current signal and the action logic of the secondary loop. The control circuit 50 includes an MCU, which may be STM32F302CBT 6.
The current transformer 10 on the closing circuit is exemplarily described. The first comparison output circuit 302 may be a high current monitoring output circuit, the second comparison output circuit 303 may be a low current monitoring output circuit, the voltage conversion circuit 60 converts a current signal on the closing loop collected by the current transformer 10 into a voltage signal, and if an amplitude of the voltage signal is greater than a voltage value output by the first output end D3 of the voltage division circuit 10, the amplitude of the voltage signal is also inevitably greater than a voltage value of the second output end D4 of the voltage division circuit 10. Therefore, the first comparison output circuit 302 outputs a high level signal that the amplification circuit 40 can receive; the second comparison output circuit 303 outputs a low level signal, the second comparison output circuit 303 is not turned on, and the amplification circuit cannot receive the low level signal. Therefore, the amplifying circuit 40 amplifies the high level signal output by the first comparing output circuit 302 and inputs the amplified high level signal to the control circuit 50, and the control circuit 50 determines that the received signal is a large current signal on the corresponding closing circuit, and determines whether the closing circuit is complete according to the action of the circuit breaker, for example, the circuit breaker is in a closing state, and then the control circuit 50 determines that the closing circuit is in a closing state according to the current existing in the closing circuit, and the circuit is complete. If the amplitude of the voltage signal output by the voltage converting circuit 60 is smaller than the voltage value output by the second output terminal D4 of the voltage divider circuit 10, the amplitude of the voltage signal is inevitably smaller than the voltage value output by the first output terminal D3 of the voltage divider circuit 10. Therefore, the first comparison output circuit 302 outputs a low level signal, the first comparison output circuit 302 is not turned on, and the amplifying circuit 40 cannot receive the low level signal; the second comparison output circuit 303 outputs a high level signal, the second comparison output circuit 303 is turned on, and the amplification circuit can receive the low level signal. Therefore, the amplifying circuit 40 amplifies the high level signal output by the second comparing and outputting circuit 303 and inputs the amplified high level signal to the control circuit 50, the control circuit 50 determines that the received signal is a small current signal on the corresponding closing loop, and determines whether the closing loop is complete according to the action of the circuit breaker, for example, the circuit breaker is in an opening state, and then the control circuit 50 determines that the closing loop is in the opening state and the loop is complete according to the current existing in the loop.
The monitoring circuit of the secondary circuit of the circuit breaker provided by the embodiment of the invention is characterized in that the current transformers are hung on each sub-circuit of the secondary circuit of the circuit breaker, current signals acquired by the current transformers are converted into voltage signals through the voltage conversion circuit, then the voltage signals are acquired, compared and output by the current acquisition circuit, the signals output by the current acquisition circuit are amplified by the amplification circuit and then input to the control circuit, and the control circuit determines whether the secondary circuit is complete or not according to the received signals (the current signals on the corresponding sub-circuit) and the action logic of the secondary circuit. Compared with the prior art, the technical scheme provided by the embodiment of the invention does not need to destroy the original structure of the secondary circuit of the circuit breaker, and can realize that whether the secondary circuit is complete or not by monitoring the change condition of the current only by hanging the current transformer on the secondary circuit, thereby greatly reducing the number of fault nodes in the secondary circuit; and the method is simple and is beneficial to popularization.
Fig. 2 is a schematic structural diagram of another monitoring circuit for a secondary circuit of a circuit breaker according to an embodiment of the present invention, and referring to fig. 2, on the basis of the foregoing technical solution, a voltage converting circuit 60 includes a converting resistor RZ, a first end of the converting resistor RZ is electrically connected to an output terminal a2 of a current transformer 10, and a second end of the converting resistor RZ is grounded.
In this embodiment, the current transformer 10 is an open current transformer, and the structure thereof is an open-close structure, so that the installation can be performed without cutting off a cable, and the reduction of fault nodes in a secondary circuit is facilitated. The current transformer 10 is directly mounted on a cable of a secondary circuit of the circuit breaker in a hanging manner, and can measure the current on the circuit. However, since the current collecting circuit 30 cannot directly collect the current signal output by the current transformer 10, the current signal needs to be converted into a voltage signal by the voltage converting circuit 60. The voltage conversion circuit 60 may include a conversion resistor RZ for converting the current signal output from the current transformer 10 into a voltage signal, so that the current collection circuit 30 can collect the voltage signal normally.
Fig. 3 is a schematic structural diagram of another monitoring circuit for a secondary circuit of a circuit breaker according to an embodiment of the present invention, and referring to fig. 3, on the basis of the foregoing technical solution, a voltage dividing circuit 301 includes a reference resistor RC, a zener diode VD, a first resistor R1, a second resistor R2, and a third resistor R3; a first end of the reference resistor RC is electrically connected to the second output end B2 of the power module 20, and a second end of the reference resistor RC is grounded through the zener diode VD; a first end of the first resistor R1 is electrically connected with a second end of the reference resistor RC, a second end of the first resistor R1 is electrically connected with a first end of the second resistor R2, a second end of the second resistor R2 is electrically connected with a first end of the third resistor R3, and a second end of the third resistor R3 is grounded; the first input terminal E1 of the first comparison output circuit 302 is electrically connected to the second terminal of the first resistor R1, and the first input terminal F1 of the second comparison output circuit 303 is electrically connected to the second terminal of the second resistor R2.
Specifically, the first voltage VCC1 output by the first output terminal B1 of the power supply module 20 is used for providing the power supply voltage for the current transformer 10, and the second voltage VCC2 output by the second output terminal B2 of the power supply module 20 is used for providing the power supply voltage for the voltage dividing circuit 301. Considering the magnitude of the current output by the current transformer VCC1 after being converted into a voltage by the conversion resistor RZ and the magnitude of the second voltage VCC2 output by the power module 20, in order to better satisfy the normal operation of the first comparison output circuit 302 and the second comparison output circuit 303, it is necessary to set a reference voltage by the reference resistor RC and stabilize the reference voltage by the voltage stabilizing diode VD, so as to prevent the voltage from fluctuating and causing measurement errors. For example, if the second voltage VCC2 is 5V, the reference voltage may be 2.5V. The first resistor R1, the second resistor R2 and the third resistor R3 are connected in series in sequence to divide the remaining 2.5V voltage.
In the present embodiment, the first comparison output circuit 302 includes a first comparator OC 1; a positive input end of the first comparator OC1 is electrically connected with the output end a2 of the current transformer 10, a negative input end of the first comparator OC1 is electrically connected with the first output end D3 of the voltage dividing circuit 301, and an output end of the first comparator OC1 is electrically connected with the input end G1 of the amplifying circuit 40.
The second comparison output circuit 303 includes a second comparator OC 2; an inverting input terminal of the second comparator OC2 is electrically connected to the output terminal a2 of the current transformer 10, a forward input terminal of the second comparator OC2 is electrically connected to the second output terminal D4 of the voltage dividing circuit 301, and an output terminal of the second comparator OC2 is electrically connected to the input terminal G2 of the amplifying circuit 40.
In this embodiment, it is assumed that the voltage at the second end of the first resistor R1 is OV1, the voltage at the second end of the second resistor R2 is OV2, and the voltage of the current signal collected by the current transformer 10 is OVC after being converted by the voltage conversion circuit 60. When the voltage OVC is greater than the voltage OV1, it is also necessarily greater than the voltage OV2, and therefore, the first comparator OC1 outputs a high level signal and the second comparator OC2 outputs a low level signal, and the second comparator OC2 outputting the low level signal at this time is configured not to output the low level signal to the amplifying circuit 40. The amplifying circuit 40 receives a high level signal output by the first comparator OC1, the high level signal is amplified by the amplifying circuit 40 and then output to the control circuit 50, the control circuit 50 determines that the high level signal corresponds to a large current after signal analysis and processing, and determines whether a closing loop is complete according to the action of the circuit breaker, for example, the circuit breaker is in a closing state, and then the control circuit 50 determines that the closing loop is in a closing state according to the current existing in the closing loop, and the loop is complete. When the voltage OVC is less than the voltage OV2, it is also necessarily less than the voltage OV1, and therefore, the first comparator OC1 outputs a low level signal, and the second comparator OC2 outputs a high level signal, at which time the first comparator OC1 outputting a low level signal is configured not to output the low level signal to the amplifying circuit 40. The amplifying circuit 40 receives a high level signal output by the second comparator OC2, the high level signal is amplified by the amplifying circuit 40 and then output to the control circuit 50, the control circuit 50 determines that the high level signal corresponds to a small current after signal analysis and processing, and determines whether a closing loop is complete according to the action of the circuit breaker, for example, the circuit breaker is in an opening state, then the control circuit 50 determines that the closing loop is in an opening state according to the current existing in the secondary loop, and the loop is complete.
When the voltage OVC is greater than the voltage OV2 and less than the voltage OC1, the first comparator OC1 and the second comparator OC2 both output low level signals, and the control circuit 50 cannot accept the signals and cannot identify the integrity of the secondary loop, so that the value of the voltage OVC can be prevented from being between the voltage OV2 and the voltage OC1 by reasonably setting the resistance values of the reference resistor RZ, the first resistor R1, the second resistor R2 and the third resistor R3, and the effectiveness and reliability of the monitoring circuit can be improved.
Fig. 4 is a schematic structural diagram of another monitoring circuit for a secondary circuit of a circuit breaker according to an embodiment of the present invention, and referring to fig. 4, based on the above technical solutions, the first comparison output circuit 302 further includes a first transistor Q1, a first light emitting diode LED1, and a first buzzer FM 1; a control end of the first triode Q1 is electrically connected with an output end of the first comparator OC1, a first pole of the first triode Q1 is electrically connected with a cathode of the first light-emitting diode LED1, an anode of the first light-emitting diode LED1 is electrically connected with the second output end B2 of the power module 20, and a second pole of the first triode Q1 is grounded; the first buzzer FM1 is connected in parallel with the first light emitting diode LED 1.
The second comparison output circuit 303 further includes a second triode Q2, a second light emitting diode LED2 and a second buzzer FM 2; a control terminal of the second triode Q2 is electrically connected to an output terminal of the second comparator OC2, a first pole of the second triode Q2 is electrically connected to a cathode of the second light emitting diode LED2, an anode of the second light emitting diode LED2 is electrically connected to the second output terminal B2 of the power module 20, and a second pole of the second triode Q2 is grounded; the second buzzer FM2 is connected in parallel with the second light emitting diode LED 2.
In this embodiment, a triode may be used to control the conducting state of the first comparing output circuit 302 and the second comparing output circuit 303, wherein a buzzer and a light emitting diode are used to play a warning role. When the voltage OVC is greater than the voltage OV1, it is also necessarily greater than the voltage OV2, so that the first comparator OC1 outputs a high level signal, the second comparator OC2 outputs a low level signal, the first transistor Q1 is turned on, the second transistor Q2 is turned off, so that the first light emitting diode LED1 emits light, the first buzzer FM1 emits sound, the amplifying circuit 40 receives the high level signal output by the first comparator OC1, the high level signal is amplified by the amplifying circuit 40 and then output to the control circuit 50, the control circuit 50 determines that the high level signal corresponds to a large current after signal analysis processing, determines whether the closing circuit is complete according to the action of the circuit breaker, for example, the circuit breaker is in the closing state, and the control circuit 50 determines that the closing circuit is in the closing state and the circuit is complete according to the current existing in the closing circuit. When the voltage OVC is less than the voltage OV2, it is also necessarily less than the voltage OV1, therefore, the first comparator OC1 outputs a low level signal, the second comparator OC2 outputs a high level signal, the first triode Q1 is turned off, the second triode Q2 is turned on, so the second light emitting diode LED2 emits light, the second buzzer FM2 emits sound, the amplifying circuit 40 receives the high level signal output by the second comparator OC2, the high level signal is amplified by the amplifying circuit 40 and then output to the control circuit 50, the control circuit 50 determines that the high level signal corresponds to a small current after signal analysis processing, determines whether the closing circuit is complete according to the action of the circuit breaker, for example, the circuit breaker is in the opening state, then the control circuit 50 determines that the circuit is in the opening state according to the current existing in the closing circuit, and the circuit is complete.
Fig. 5 is a schematic structural diagram of an amplifying circuit according to an embodiment of the present invention, and referring to fig. 4 and fig. 5, based on the above technical solutions, the amplifying circuit 40 includes a fourth resistor R4, a capacitor C, a first operational amplifier OP1, a fifth resistor R5, a sixth resistor R6, a second operational amplifier OP2, a seventh resistor R7, and an eighth resistor R8.
A first end of the fourth resistor R4 is electrically connected to the output terminal E3 of the first comparison output circuit 302 and the output terminal F3 of the second comparison output circuit 303 as the input terminal G1 of the amplifying circuit 40, respectively, a second end of the fourth resistor R4 is electrically connected to the positive input terminal of the first operational amplifier OP1, the negative input terminal of the first operational amplifier OP1 is electrically connected to the output terminal of the first operational amplifier OP1, and the output terminal of the first operational amplifier OP1 is electrically connected to the negative input terminal of the second operational amplifier OP2 through the fifth resistor R5.
The positive input end of the second operational amplifier OP2 is grounded through a sixth resistor R6, the output end of the second operational amplifier OP2 is electrically connected with the input end H1 of the control circuit 50 through a seventh resistor R7, and the negative input end of the second operational amplifier OP2 is electrically connected with the output end of the second operational amplifier OP2 through an eighth resistor R8; a first end of the capacitor C is electrically connected to the positive input end of the first operational amplifier OP1, and a second end of the capacitor C is grounded.
Fig. 6 is a schematic structural diagram of a secondary circuit of a circuit breaker according to an embodiment of the present invention, and the secondary circuit shown in fig. 6 is taken as an example to specifically describe an operating principle of a monitoring circuit according to an embodiment of the present invention. Referring to fig. 1 to 6, the secondary circuit of the circuit breaker includes a closing circuit, a trip circuit, and a closing coil circuit, and a current transformer 10 is hung on a cable of each circuit. For the closing loop, when the circuit breaker is in the open position state, the normally closed auxiliary contact QF1 of the circuit breaker is closed, the positive power supply WC +, the contacts 11-10, the green light HG, the first additional resistor RC1, the normally closed auxiliary contact QF1 of the circuit breaker, the closing coil YC and the negative power supply WC-form a loop, a small current flows through the loop, and the second comparison output circuit 303 outputs a high-level signal. When the circuit breaker is in an on-position state, a positive power supply WC +, a first alternating current contactor KM1, a first contact relay switch KL1, a closing loop contact relay coil KLI and a negative power supply WC-form a loop, and a large current flows through the loop, the first comparison output circuit 302 outputs a high level, and the control circuit 50 determines that the closing loop is intact.
For the trip loop, when the circuit breaker is in a closed state, the normally open auxiliary contact QF2 of the circuit breaker is closed, the positive power supply WC +, the contacts 14-15, the red light HR, the second additional resistor RC2, the trip loop contact relay coil KLII, the normally open auxiliary contact QF2 of the circuit breaker, the trip coil YT and the negative power supply WC form a loop, small current flows, and the second comparison output circuit 303 outputs a high-level signal. When the circuit breaker is in the open position state, the closing circuit is conducted, the first comparing output circuit 302 outputs a high level, and the control circuit 50 determines that the opening circuit is intact.
The embodiment of the invention also provides a monitoring device of the secondary circuit of the circuit breaker, which comprises the monitoring circuit of the secondary circuit of the circuit breaker provided by any embodiment of the invention, and in addition, the monitoring device also comprises a display screen, and the display screen is connected with the control circuit and is used for displaying the state of the secondary circuit. Therefore, the monitoring device for the secondary circuit of the circuit breaker provided by the embodiment of the invention also has the beneficial effects described in any embodiment of the invention.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A monitoring circuit of a secondary circuit of a circuit breaker, comprising: the power supply module, the current transformer, the current acquisition circuit, the amplification circuit, the control circuit and the voltage conversion circuit;
the current transformers correspond to the sub-loops of the secondary loop one by one, one current transformer is hung on one sub-loop of the secondary loop, the power end of the current transformer is electrically connected with the first output end of the power module, the output end of the current transformer is electrically connected with the current acquisition circuit, and the current acquisition circuit is used for acquiring current on the sub-loops; the first end of the voltage conversion circuit is electrically connected with the output end of the current transformer, the second end of the voltage conversion circuit is grounded, and the voltage conversion circuit is used for converting the current signal acquired by the current transformer into a voltage signal;
the current acquisition circuit comprises a voltage division circuit, a first comparison output circuit and a second comparison output circuit, wherein a first power supply end of the voltage division circuit is electrically connected with a second output end of the power supply module, a second power supply end of the voltage division circuit is grounded, a first input end of the first comparison output circuit is electrically connected with a first output end of the voltage division circuit, a second input end of the first comparison output circuit is electrically connected with an output end of the current transformer, and an output end of the first comparison output circuit is electrically connected with an input end of the amplification circuit; a first input end of the second comparison output circuit is electrically connected with a second output end of the voltage division circuit, a second input end of the second comparison output circuit is electrically connected with an output end of the current transformer, and an output end of the second comparison output circuit is electrically connected with an input end of the amplifying circuit;
the output end of the amplifying circuit is electrically connected with the input end of the control circuit, and the control circuit is used for determining the state of the secondary circuit according to the current on the sub-circuit and the action logic of the secondary circuit.
2. The circuit breaker secondary circuit monitoring circuit of claim 1, wherein said voltage converting circuit comprises a converting resistor, a first end of said converting resistor is electrically connected to an output terminal of said current transformer, and a second end of said converting resistor is grounded.
3. Monitoring circuit of a circuit breaker secondary circuit according to claim 1, characterized in that said current transformer comprises an open current transformer.
4. The circuit breaker secondary circuit monitoring circuit according to claim 1, wherein the voltage divider circuit comprises a reference resistor, a zener diode, a first resistor, a second resistor, and a third resistor;
the first end of the reference resistor is electrically connected with the second output end of the power supply module, and the second end of the reference resistor is grounded through the voltage stabilizing diode;
the first end of the first resistor is electrically connected with the second end of the reference resistor, the second end of the first resistor is electrically connected with the first end of the second resistor, the second end of the second resistor is electrically connected with the first end of the third resistor, and the second end of the third resistor is grounded;
the first input end of the first comparison output circuit is electrically connected with the second end of the first resistor, and the first input end of the second comparison output circuit is electrically connected with the second end of the second resistor.
5. The circuit breaker secondary circuit monitoring circuit of claim 1, wherein said first comparison output circuit comprises a first comparator;
the positive input end of the first comparator is electrically connected with the output end of the current transformer, the reverse input end of the first comparator is electrically connected with the first output end of the voltage division circuit, and the output end of the first comparator is electrically connected with the input end of the amplifying circuit.
6. The circuit breaker secondary circuit monitoring circuit of claim 5, wherein said first comparison output circuit further comprises a first triode, a first light emitting diode and a first buzzer;
the control end of the first triode is electrically connected with the output end of the first comparator, the first pole of the first triode is electrically connected with the cathode of the first light-emitting diode, the anode of the first light-emitting diode is electrically connected with the second output end of the power supply module, and the second pole of the first triode is grounded;
the first buzzer is connected with the first light-emitting diode in parallel.
7. The circuit breaker secondary circuit monitoring circuit of claim 1, wherein said second comparison output circuit comprises a second comparator;
the reverse input end of the second comparator is electrically connected with the output end of the current transformer, the forward input end of the second comparator is electrically connected with the second output end of the voltage division circuit, and the output end of the second comparator is electrically connected with the input end of the amplifying circuit.
8. The circuit breaker secondary circuit monitoring circuit of claim 7, wherein said second comparison output circuit further comprises a second triode, a second light emitting diode and a second buzzer;
the control end of the second triode is electrically connected with the output end of the second comparator, the first pole of the second triode is electrically connected with the cathode of the second light-emitting diode, the anode of the second light-emitting diode is electrically connected with the second output end of the power supply module, and the second pole of the second triode is grounded;
the second buzzer is connected with the second light-emitting diode in parallel.
9. The circuit breaker secondary circuit monitoring circuit of claim 1, wherein the amplifying circuit comprises a fourth resistor, a capacitor, a first operational amplifier, a fifth resistor, a sixth resistor, a second operational amplifier, a seventh resistor, and an eighth resistor;
a first end of the fourth resistor is used as an input end of the amplifying circuit and is electrically connected with an output end of the first comparison output circuit and an output end of the second comparison output circuit respectively, a second end of the fourth resistor is electrically connected with a positive input end of the first operational amplifier, a negative input end of the first operational amplifier is electrically connected with an output end of the first operational amplifier, and the output end of the first operational amplifier is electrically connected with a negative input end of the second operational amplifier through the fifth resistor;
the positive input end of the second operational amplifier is grounded through the sixth resistor, the output end of the second operational amplifier is electrically connected with the input end of the control circuit through the seventh resistor, and the negative input end of the second operational amplifier is electrically connected with the output end of the second operational amplifier through the eighth resistor;
the first end of the capacitor is electrically connected with the positive input end of the first operational amplifier, and the second end of the capacitor is grounded.
10. A circuit breaker secondary circuit monitoring device comprising a circuit breaker secondary circuit monitoring circuit according to any one of claims 1 to 9.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110327387.1A CN113064062A (en) | 2021-03-26 | 2021-03-26 | Circuit and device for monitoring secondary circuit of circuit breaker |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110327387.1A CN113064062A (en) | 2021-03-26 | 2021-03-26 | Circuit and device for monitoring secondary circuit of circuit breaker |
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| CN113064062A true CN113064062A (en) | 2021-07-02 |
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| WO2009144266A1 (en) * | 2008-05-29 | 2009-12-03 | Areva T&D Sas | High power rectifier circuit particularly for aluminium electrolysis |
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