CN116908675A - Circuit breaker post-arc current measurement system and method - Google Patents
Circuit breaker post-arc current measurement system and method Download PDFInfo
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- CN116908675A CN116908675A CN202311153526.9A CN202311153526A CN116908675A CN 116908675 A CN116908675 A CN 116908675A CN 202311153526 A CN202311153526 A CN 202311153526A CN 116908675 A CN116908675 A CN 116908675A
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- G—PHYSICS
- 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
- G01R31/333—Testing of the switching capacity of high-voltage circuit-breakers ; Testing of breaking capacity or related variables, e.g. post arc current or transient recovery voltage
- G01R31/3333—Apparatus, systems or circuits therefor
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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- G—PHYSICS
- 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
- G01R31/3271—Testing of circuit interrupters, switches or circuit-breakers of high voltage or medium voltage devices
- G01R31/3272—Apparatus, systems or circuits therefor
- G01R31/3274—Details related to measuring, e.g. sensing, displaying or computing; Measuring of variables related to the contact pieces, e.g. wear, position or resistance
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Abstract
The invention provides a system and a method for measuring current after an arc of a circuit breaker, and relates to the technical field of current measurement after the arc. The system comprises a noninductive resistor, a clamping module, a current transfer module and an acquisition module; the non-inductive resistor is used for being connected with the circuit breaker to be tested in series to form a main circuit; the two ends of the clamping module are respectively connected with the two ends of the noninductive resistor, and the clamping module is used for clamping the voltage at the two ends of the noninductive resistor; the two ends of the current transfer module are respectively connected with the two ends of the non-inductive resistor, and the current transfer module is used for transferring the arc current before the zero crossing of the arc current of the main circuit; the acquisition module is used for acquiring the voltage at two ends of the non-inductive resistor, the current after the arc of the circuit breaker to be tested and the current flowing through the non-inductive resistor; wherein, noninductive resistance, clamp module and current transfer module parallel connection. The system and the method have higher detection sensitivity and anti-interference performance, the required components are easy to obtain, the cost is low, and the system and the method are very suitable for measuring the current after an arc, so that the research on the breaking characteristics of the circuit breaker is developed.
Description
Technical Field
The invention relates to the technical field of current measurement after an arc, in particular to a system and a method for measuring the current after the arc of a circuit breaker.
Background
In the technical field of high voltage, when a circuit is disconnected, an arc is generated between contact gaps of the mechanical switch, and the arc is plasma, so that the conductivity value is large, and the switch can be considered to be successfully disconnected only when the arc is extinguished. The physical process of alternating current arcs at the moment of zero crossing of the current requires special attention, and the time interval of about 100 microseconds before and after the arc zero point is called the "interaction phase" (english name: interaction period), which plays a vital role in the breaking of the alternating current arc. Therefore, by measuring the zero-zone current of the circuit breaker, research on the change characteristics of the circuit breaker near the zero point of the arc current is an important content for judging the breaking characteristics of the circuit breaker.
In the aspect of researching an arc current zero region of the circuit breaker, the duration time of the current after the arc is very small and is microsecond, and the duration time is far smaller than the power frequency; the amplitude of the current after the arc is very small, which is only a few hundred mA to a few A, and is far smaller than the break-off current. The problem of wide dynamic range in the measurement of current after an arc is faced, and how to realize accurate measurement of current after the arc is always the focus of researching the characteristics of the arc zero region of a circuit breaker.
At present, two main methods for measuring the current in the zero region of the electric arc are available for researchers at home and abroad:
the first is a shunt; the shunt measurement method is the method used for measuring the current in the zero region of the arc at the earliest time and is the most commonly used method at present. The shunt is a very well characterized resistive element placed in a measurement loop, and by measuring the voltage across it, the arc zero current is obtained from ohm's law. However, this approach has the disadvantage that the peak value of the short-circuit current limits the shunt resistance, which must be small (milliohm-level), whereas the zero-arc current is only a few a or hundreds of mA, and the measured voltage across the shunt will be very small, which is susceptible to electromagnetic interference. In order to reduce the measuring range of the current divider and improve the measuring precision, students at home and abroad make a lot of attempts, such as a way of connecting the current divider with a mechanical switch in parallel, short-circuiting the current divider by the mechanical switch in a high current stage, and transferring the current to the current divider before the current crosses zero. However, as the shunt method is a direct voltage measurement mode, the measurement system is in electrical communication with the measured loop, and electromagnetic interference is difficult to reduce to a tolerable level; in addition, since the shunt resistance is small (several milliohms), stray inductance can cause a large deviation in measurement results in the case of high di/dt.
Secondly, a Rogowski coil (also called a Rogowski coil); the Rogowski coil is similar to a current transformer, is electrically isolated from a measured loop, measures the loop current through electromagnetic coupling, has the characteristics of wide measurement range, small volume and the like, and is widely applied to measurement of large current and pulse current. But the signal measured by the Rogowski coil cannot be used directly and requires a post integrator. The Rogowski coil is divided into self-integrating and external-integrating coils. The voltage signal output by the self-integration Rogowski coil through the sampling resistor is in proportional relation with the measured current; after the external integration circuit passes through the integration circuit, the output voltage proportional to the measured current can be obtained. Currently, microsecond-level current signal measurement often adopts an external integration rogowski coil, and the frequency band of a measurement loop can be widened and the measurement sensitivity can be improved by improving an integrator. The self-integration rogowski coil has high frequency response and is an ideal means for measuring nanosecond pulse large signals. However, since circuit breakers short circuit current peaks up to tens of kiloamperes, the current after an arc is typically only a few hundred milliamperes to tens of amperes, which are orders of magnitude too different.
In summary, the current measurement mode of the current arc zero region is greatly influenced by environmental interference factors (electromagnetic interference, environmental factors such as measurement orders of magnitude, and the like), and is difficult to achieve in a large-range and high-precision manner, the problem of a wide dynamic range faced by the measurement of the current arc zero region is not solved by a common Rogowski coil, and the measurement precision of the current after the arc is difficult to guarantee.
Disclosure of Invention
The technical problems to be solved by the embodiment of the invention are as follows: the current measurement mode of the current in the zero region of the existing electric arc is greatly influenced by environmental interference factors (electromagnetic interference, measurement order of magnitude and other environmental factors), and has the problems of large range and high precision.
In order to solve the above technical problems, an embodiment of the present invention may be implemented as follows:
in a first aspect, the invention provides a system for measuring current after an arc of a circuit breaker, comprising a non-inductive resistor, a clamping module, a current transfer module and an acquisition module;
the non-inductive resistor is used for being connected with the circuit breaker to be tested in series to form a main circuit;
the two ends of the clamping module are respectively connected with the two ends of the noninductive resistor, and the clamping module is used for clamping the voltage at the two ends of the noninductive resistor;
the two ends of the current transfer module are respectively connected with the two ends of the non-inductive resistor, and the current transfer module is used for transferring the arc current before the zero crossing of the arc current of the main circuit;
the acquisition module is used for acquiring the voltage at two ends of the non-inductive resistor, the current after the arc of the circuit breaker to be tested and the current flowing through the non-inductive resistor;
wherein, noninductive resistance, clamp module and current transfer module parallel connection.
The circuit breaker post-arc current measurement system provided by the embodiment of the invention has the beneficial effects that:
1. an auxiliary measuring loop based on a clamping module is connected in series on the circuit breaker to be tested, and the auxiliary measuring loop comprises a non-inductive resistor, a clamping module and a current transfer module which are connected in parallel; in an initial state, the current transfer module is closed and conducted, and the current flowing through the circuit breaker to be tested completely flows through a branch where the current transfer module is located; before the current of the circuit breaker to be tested crosses zero after being disconnected, the current transfer module is accurately controlled to be disconnected, and the arc current of the circuit breaker to be tested is transferred to a branch where a non-inductive resistor is located and a branch where a clamping module is located, wherein the value of the current of the branch where the non-inductive resistor is located is smaller due to the clamping effect of the clamping module; along with the reduction of the arc current of the circuit breaker to be tested, when the clamping module is disconnected, the arc current of the circuit breaker to be tested is completely transferred to a branch where the non-inductive resistor is located, and at the moment, the accurate measurement of the current after the arc can be realized by utilizing the acquisition module in the branch where the non-inductive resistor is located;
2. in the measuring process of the current after the arc, the current range of the branch where the non-inductive resistor is located is far smaller than that of the main circuit, so that the accurate measurement of the small current after the arc is very facilitated, specifically, the current range of the branch where the non-inductive resistor is located is 0-100A, the current is close to hundreds of microamps to tens of amperes of current after the arc, the measuring error is small, the precision is high, the traditional measuring system directly detects from the main circuit, the current range is 0-tens of kA, the large range and the high precision are difficult to meet simultaneously, and the precision is far inferior to that of the system provided by the embodiment of the invention;
3. the system has higher detection sensitivity and anti-interference performance, and the required components are easy to obtain and low in cost, so that the system is very suitable for measuring the current after an arc, and further the research on the breaking characteristics of the circuit breaker is carried out.
In an alternative embodiment, the resistance of the non-inductive resistor is less than or equal to 100mΩ.
In an alternative embodiment, the clamping module comprises a first diode and a second diode, wherein the anode of the first diode is connected with the cathode of the second diode and is connected to a position between the circuit breaker to be tested and the noninductive resistor on the main circuit, and the cathode of the first diode is connected with the anode of the second diode and is connected to one end of the noninductive resistor far away from the circuit breaker to be tested on the main circuit.
Because the system is used for detecting the current after the alternating current arc, two diodes connected end to end are arranged, and as long as the voltage drop of the diode in the clamping module is above the threshold voltage, the clamping module can always clamp the noninductive resistor through alternating current.
In an alternative embodiment, the current transfer module includes a vacuum switch connected in parallel across the non-inductive resistor.
Therefore, the current transfer module has the advantages of simple structure, convenient control and low cost.
In an alternative embodiment, the acquisition module includes a voltage transformer, a first current transformer, and a second current transformer;
the voltage transformer is connected in parallel with two ends of the noninductive resistor and is used for measuring the voltages of the two ends of the noninductive resistor;
the first current transformer is connected to one end of the non-inductive resistor and is used for measuring current flowing through the non-inductive resistor;
the second current transformer is connected to the position where the currents output by the non-inductive resistor, the clamping module and the current transfer module are summarized on the main circuit, and is used for measuring the current after the arc.
Therefore, the voltage at two ends of the non-inductive resistor, the current flowing through the non-inductive resistor and the current after the arc can be accurately measured in real time, and comprehensive basic data is provided for the research of the arc current zero region of the circuit breaker.
In a second aspect, the present invention provides a method for measuring a current after an arc of a circuit breaker, the method adopting the system for measuring a current after an arc of a circuit breaker according to any one of the foregoing embodiments, the method comprising:
s1: building a circuit breaker arc current measurement system on the circuit breaker to be tested, and closing and conducting the circuit breaker to be tested and the current transfer module;
s2: the circuit breaker to be tested is disconnected at the moment T=0, so that the circuit breaker to be tested generates a current arc;
s3: at t=t 0 Switching off the current transfer module at the moment, wherein t 0 The moment is within 1ms before the zero crossing point of the arc current;
s4: and acquiring waveforms of arc currents in the S2 and S3 processes, wherein the waveforms of the arc currents comprise current waveforms in a preset time range before and after zero crossing of the arc currents.
In an alternative embodiment, after S2 is performed and before S3, the arc current of the circuit breaker to be tested flows entirely through the current transfer module.
In an alternative embodiment, after S3 is performed, the current transfer module does not generate an arc and is completely opened, and an arc current of the circuit breaker to be tested flows through the non-inductive resistor and the clamping module.
In an alternative embodiment, the voltage drop at the clamping module is t=t 1 When the time is reduced to the threshold voltage, the clamping module is cut off, and the arc current of the circuit breaker to be tested flows through the non-inductive resistor.
In an alternative embodiment, the resistance of the non-inductive resistor is 100mΩ and the rated current is 200A.
Because the current range of the branch where the non-inductive resistor is located is 0-100A, the non-inductive resistor with the parameters is selected, so that the measurement requirement is met, the cost is low, and the measurement result is accurate.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of an application scenario of a current measurement system after an arc of a circuit breaker according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method for measuring current after an arc of a circuit breaker according to an embodiment of the present invention;
FIG. 3 is a waveform diagram of the arc current measured by the system;
FIG. 4 is an enlarged view of a portion of the current flow zero region of FIG. 3;
fig. 5 is a schematic diagram showing the comparison of the arc current measurement ranges of the conventional measurement mode and the measurement mode of the present embodiment.
Icon: 100-a circuit breaker post-arc current measurement system; 1-a breaker to be tested; 2-non-inductive resistor; 3-a first diode; 4-a second diode; 5-vacuum switch; 6-a voltage transformer; 7-a first current transformer; 8-a second current transformer.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that, if the terms "upper", "lower", "inner", "outer", and the like indicate an azimuth or a positional relationship based on the azimuth or the positional relationship shown in the drawings, or the azimuth or the positional relationship in which the inventive product is conventionally put in use, it is merely for convenience of describing the present invention and simplifying the description, and it is not indicated or implied that the apparatus or element referred to must have a specific azimuth, be configured and operated in a specific azimuth, and thus it should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, if any, are used merely for distinguishing between descriptions and not for indicating or implying a relative importance.
It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.
Referring to fig. 1, the present embodiment provides a system 100 (hereinafter referred to as a system) for measuring a current after an arc of a circuit breaker, which includes a non-inductive resistor 2, a clamping module, a current transfer module and an acquisition module. Wherein, noninductive resistance 2, clamp module and electric current transfer module connect in parallel.
Specifically, the non-inductive resistor 2 is used to form a main circuit in series with the circuit breaker 1 to be tested. The resistance value of the noninductive resistor 2 is less than or equal to 100mΩ. Preferably, the resistance of the noninductive resistor 2 is 100mΩ and the rated current is 200A. Because the current range of the branch where the non-inductive resistor 2 is located is 0-100A, the non-inductive resistor 2 with the parameters is selected, so that the measurement requirement is met, the cost is low, and the measurement result is accurate.
The two ends of the clamping module are respectively connected with the two ends of the noninductive resistor 2, and the clamping module is used for clamping the voltage at the two ends of the noninductive resistor 2. In this embodiment, the clamping module includes a first diode 3 and a second diode 4, where an anode of the first diode 3 is connected to a cathode of the second diode 4 and is connected to a position between the circuit breaker 1 to be tested and the non-inductive resistor 2 on the main circuit, and a cathode of the first diode 3 is connected to an anode of the second diode 4 and is connected to an end of the non-inductive resistor 2 on the main circuit away from the circuit breaker 1 to be tested. Because the system is used for detecting the current after the alternating current arc, two diodes connected end to end are arranged, and as long as the voltage drop of the diode in the clamping module is above the threshold voltage, the clamping module can always clamp the noninductive resistor 2 through alternating current.
The first diode 3 and the second diode 4 may be high-current power diodes. The parameter selection of the high-current power diode can be that the normal through current is 2.62kA, the impact current is (10 ms and 48 kA), the cut-off voltage is 1.1V, the voltage drop is 8V when the through current is 20kA, and the on-state resistance is 0.47mΩ.
The two ends of the current transfer module are respectively connected with the two ends of the non-inductive resistor 2, and the current transfer module is used for transferring the arc current before the zero crossing of the arc current of the main circuit. In this embodiment, the current transfer module includes vacuum switches 5 connected in parallel to two ends of the non-inductive resistor 2, and the vacuum switches 5 are precisely controlled to be turned off before the zero crossing of the arc current of the main circuit, so as to realize the transfer of the arc current. Therefore, the current transfer module has the advantages of simple structure, convenient control and low cost.
The acquisition module is used for acquiring the voltage at two ends of the non-inductive resistor 2, the current after the arc of the circuit breaker 1 to be tested and the current flowing through the non-inductive resistor 2. In this embodiment, the acquisition module includes a voltage transformer 6, a first current transformer 7, and a second current transformer 8; the voltage transformer 6 is connected in parallel with two ends of the non-inductive resistor 2, and the voltage transformer 6 is used for measuring voltages at two ends of the non-inductive resistor 2; the first current transformer 7 is connected to one end of the non-inductive resistor 2, and the first current transformer 7 is used for measuring the current flowing through the non-inductive resistor 2; the second current transformer 8 is connected to the main circuit at a position where the currents outputted by the non-inductive resistor 2, the clamping module and the current transfer module are summarized, and the second current transformer 8 is used for measuring the current after the arc. Therefore, the voltage at two ends of the non-inductive resistor 2, the current flowing through the non-inductive resistor 2 and the current after the arc can be accurately measured in real time, and comprehensive basic data is provided for the research of the arc current zero region of the circuit breaker.
The first current transformer 7 and the second current transformer 8 can be high-precision hall coils. Specifically, the first current transformer 7 may be a high-precision hall coil of 150A, and is configured to collect the current flowing through the non-inductive resistor 2 for accurate measurement. The second current transformer 8 may be a high precision hall coil of 40kA for measuring the post-arc current (test current).
Referring to fig. 2, the present embodiment further provides a method for measuring a current after an arc of a circuit breaker, where the method adopts the system 100 for measuring a current after an arc of a circuit breaker according to the foregoing embodiment, and the method includes:
s1: the current measuring system 100 after the arc of the circuit breaker is built on the circuit breaker 1 to be tested, and the circuit breaker 1 to be tested and the current transfer module are closed and conducted.
Specifically, the circuit breaker 1 to be tested is closed and conducted, and the vacuum switch 5 in the current transfer module is closed and conducted.
S2: referring to fig. 3, the circuit breaker 1 to be tested is opened at time t=0, so that the circuit breaker 1 to be tested generates a current arc.
The time t=0 may be considered as a time when the current measurement system 100 starts measuring after the arc of the circuit breaker, and may be considered as a start time of the arc current collection.
After S2 is performed and before S3, since the contact resistance when the vacuum switch 5 is closed and turned on is very small, it can be considered that the arc current of the circuit breaker 1 to be tested flows entirely through the vacuum switch 5 in the current transfer module.
S3: referring to fig. 3 and 4, at t=t 0 Switching off the current transfer module at the moment, wherein t 0 The moment is within 1ms before the arc current crosses zero.
Wherein t is 0 The time is not limited to a specific value, and is only required to be within 1ms before the zero point, so as to collect current waveforms in a preset time range before and after the zero point of the arc current, wherein the preset time range can be 1ms before the zero point to 5ms after the zero point.
After execution of S3, the vacuum switch 5 of the current transfer module is turned off, and the vacuum switch 5 is not arcing and is completely turned off due to the clamping action of the diode in the clamping module, at this time, the arc current of the circuit breaker 1 to be tested flows through the non-inductive resistor 2 and the clamping module, wherein the current of the non-inductive resistor 2 is determined by the voltage drop of the diode in the clamping module.
Pressure drop at clamping module is t=t 1 When the time is reduced to the threshold voltage, t 1 At time t 0 After the moment, the diode in the clamping module is turned off (no current passes), and the arc current of the circuit breaker 1 to be tested flows through the non-inductive resistor 2. Here, as long as the noninductive resistor 2 selects a proper resistance value (the resistance value is less than or equal to 100mΩ), the zero-passing and the post-arc current of the arc current can be ensured to completely pass through the noninductive resistor 2, and the accurate waveform near the zero region of the arc current can be obtained through the first current transformer 7 and the voltage transformer 6.
S4: and acquiring waveforms of arc currents in the S2 and S3 processes, wherein the waveforms of the arc currents comprise current waveforms in a preset time range before and after zero crossing of the arc currents.
It should be noted that the execution of S4 is not started after S3 is completed, but is started in synchronization with S2, so that waveforms of arc currents of the S2 and S3 processes can be acquired, as shown in fig. 3 and 4.
Referring to fig. 5, in the conventional measurement mode, the arc current completely flows through the measuring resistor, and the measuring range is: 0-I 1 Wherein I 1 Can reach tens of kiloamperes;
only a small part of arc current measured by the system and the method provided by the embodiment of the invention flows through a measuring resistor (non-inductive resistor 2), and the measuring range is as follows: 0-I 2 Wherein I 2 Not more than 100A).
It can be seen that I 2 Far less than I 1 The smaller the measurement range, the higher the measurement accuracy thereof.
The system 100 and the method for measuring the current after the arc of the circuit breaker provided by the embodiment have the following beneficial effects:
1. an auxiliary measuring loop based on a clamping module is connected in series on the circuit breaker 1 to be measured, and the auxiliary measuring loop comprises a non-inductive resistor 2, the clamping module and a current transfer module which are connected in parallel; in an initial state, the current transfer module is closed and conducted, and the current flowing through the circuit breaker 1 to be tested completely flows through a branch where the current transfer module is located; before the current crosses zero after the circuit breaker 1 to be tested is disconnected, the current transfer module is accurately controlled to be disconnected, and the arc current of the circuit breaker 1 to be tested is transferred to a branch where the non-inductive resistor 2 is located and a branch where the clamping module is located, wherein the value of the current of the branch where the non-inductive resistor 2 is located is smaller due to the clamping effect of the clamping module; along with the reduction of the arc current of the circuit breaker 1 to be tested, when the clamping module is disconnected, the arc current of the circuit breaker 1 to be tested is completely transferred to the branch circuit where the noninductive resistor 2 is located, and at the moment, the accurate measurement of the current after the arc can be realized by utilizing the acquisition module in the branch circuit where the noninductive resistor 2 is located;
2. in the measuring process of the current after the arc, the current range of the branch where the non-inductive resistor 2 is positioned is far smaller than that of the main circuit, which is very favorable for accurately measuring the small current after the arc, specifically, the current range of the branch where the non-inductive resistor 2 is positioned is 0-100A, which is close to hundreds of microamps to several amperes of current after the arc, the measuring error is small, the precision is high, the traditional measuring system and method directly detect from the main circuit, the current range is 0-dozens of kA, the large measuring range and the high precision are difficult to meet simultaneously, and the precision is far lower than that of the system and the method provided by the embodiment of the invention;
3. the system and the method have higher detection sensitivity and anti-interference performance, and the required components are easy to obtain and low in cost, so that the system and the method are very suitable for measuring the current after an arc, and further the research on the breaking characteristics of the circuit breaker is carried out.
The present invention is not limited to the above embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (10)
1. A circuit breaker post-arc current measurement system, characterized in that the system comprises a non-inductive resistor (2), a clamping module, a current transfer module and an acquisition module;
the non-inductive resistor (2) is used for being connected with the circuit breaker (1) to be tested in series to form a main circuit;
the two ends of the clamping module are respectively connected with the two ends of the non-inductive resistor (2), and the clamping module is used for clamping the voltage at the two ends of the non-inductive resistor (2);
the two ends of the current transfer module are respectively connected with the two ends of the noninductive resistor (2), and the current transfer module is used for transferring the arc current before the zero crossing of the arc current of the main circuit;
the acquisition module is used for acquiring the voltage at two ends of the non-inductive resistor (2), the current after the arc of the circuit breaker (1) to be tested and the current flowing through the non-inductive resistor (2);
wherein the non-inductive resistor (2), the clamping module and the current transfer module are connected in parallel.
2. The system according to claim 1, characterized in that the non-inductive resistor (2) has a resistance value of 100mΩ or less.
3. The system according to claim 1, characterized in that the clamping module comprises a first diode (3) and a second diode (4), the anode of the first diode (3) is connected to the cathode of the second diode (4) and is connected to the main circuit at a position between the circuit breaker (1) to be tested and the non-inductive resistor (2), and the cathode of the first diode (3) is connected to the anode of the second diode (4) and is connected to the main circuit at an end of the non-inductive resistor (2) away from the circuit breaker (1) to be tested.
4. The system according to claim 1, characterized in that the current transfer module comprises a vacuum switch (5) connected in parallel across the non-inductive resistor (2).
5. The system for measuring the current after an arc of a circuit breaker according to claim 1, wherein the acquisition module comprises a voltage transformer (6), a first current transformer (7) and a second current transformer (8);
the voltage transformer (6) is connected in parallel with two ends of the non-inductive resistor (2), and the voltage transformer (6) is used for measuring voltages at two ends of the non-inductive resistor (2);
the first current transformer (7) is connected to one end of the non-inductive resistor (2), and the first current transformer (7) is used for measuring the current flowing through the non-inductive resistor (2);
the second current transformer (8) is connected to the main circuit at a position where currents output by the non-inductive resistor (2), the clamping module and the current transfer module are summarized, and the second current transformer (8) is used for measuring currents after arcs.
6. A method for measuring a current after an arc of a circuit breaker, wherein the method adopts the system for measuring a current after an arc of a circuit breaker according to any one of claims 1 to 5, and the method comprises:
s1: building the current measuring system after the arc of the circuit breaker on the circuit breaker (1) to be tested, and closing and conducting the circuit breaker (1) to be tested and the current transfer module;
s2: opening the circuit breaker (1) to be tested at the time t=0, so that the circuit breaker (1) to be tested generates a current arc;
s3: at t=t 0 Switching off the current transfer module at any time, wherein t is 0 The moment is within 1ms before the zero crossing point of the arc current;
s4: and acquiring waveforms of arc currents in the S2 and S3 processes, wherein the waveforms of the arc currents comprise current waveforms in a preset time range before and after zero crossing of the arc currents.
7. The method according to claim 6, characterized in that after S2 is performed and before S3 the arc current of the circuit breaker (1) to be tested flows entirely through the current transfer module.
8. The method according to claim 6, characterized in that after executing S3, the current transfer module does not generate an arc and is completely opened, and the arc current of the circuit breaker (1) to be tested flows through the non-inductive resistor (2) and the clamping module.
9. The method of claim 8, wherein the voltage drop across the clamp module is at T = T 1 When the moment is reduced to the threshold voltage, the clamping module is cut off, and the arc current of the circuit breaker (1) to be tested flows through the non-inductive resistor (2).
10. The method according to claim 9, characterized in that the resistance of the non-inductive resistor (2) is 100mΩ and the rated current is 200A.
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| FR2673762A1 (en) * | 1991-03-05 | 1992-09-11 | Merlin Gerin | Device for measuring the post-arc current of an electrical power switch |
| CN106597271A (en) * | 2016-12-16 | 2017-04-26 | 大连理工大学 | Post arc current measurement method based on current transfer characteristics and magnetic blowout |
| CN111244909A (en) * | 2020-01-17 | 2020-06-05 | 西安交通大学 | Modularized mechanical direct current circuit breaker and switching-on and switching-off method thereof |
| CN114609517A (en) * | 2022-03-21 | 2022-06-10 | 广东电网有限责任公司 | Post-arc current measuring system and control method thereof |
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2023
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| FR2673762A1 (en) * | 1991-03-05 | 1992-09-11 | Merlin Gerin | Device for measuring the post-arc current of an electrical power switch |
| CN106597271A (en) * | 2016-12-16 | 2017-04-26 | 大连理工大学 | Post arc current measurement method based on current transfer characteristics and magnetic blowout |
| CN111244909A (en) * | 2020-01-17 | 2020-06-05 | 西安交通大学 | Modularized mechanical direct current circuit breaker and switching-on and switching-off method thereof |
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