CN113614553B - Contact abnormality monitoring device and circuit breaker using the same - Google Patents
Contact abnormality monitoring device and circuit breaker using the same Download PDFInfo
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- CN113614553B CN113614553B CN201980093734.XA CN201980093734A CN113614553B CN 113614553 B CN113614553 B CN 113614553B CN 201980093734 A CN201980093734 A CN 201980093734A CN 113614553 B CN113614553 B CN 113614553B
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
Abstract
The invention provides a contact portion abnormality monitoring device for contactlessly monitoring abnormal voltage drop of an opening/closing contact portion. The contact abnormality monitoring device includes: a current transformer (3) that detects a load current flowing through the circuit (1) when the opening/closing contact (2) that opens/closes the circuit (1) is in a closed state; a load current detection unit (4) that outputs a signal of a load current; a power supply side voltage detection resistor (5) connected to a circuit on the power supply side of the opening/closing contact; a load-side voltage detection resistor (6) connected to a circuit on the load side of the opening/closing contact; an abnormality detection current transformer (7) for detecting a differential current generated by a current flowing through the power supply side voltage detection resistor and the load side voltage detection resistor; a voltage drop detection unit (8) that outputs an output signal that is an actual measurement value of the voltage drop at the opening/closing contact point, based on the differential current; and a waveform comparison unit (10) which calculates a normal voltage drop value based on the value of the load current and the initial value of the contact resistance of the opening/closing contact, calculates a voltage drop difference value based on the normal voltage drop value and the actual voltage drop value, compares the calculated voltage drop difference value with a preset alarm level value, and determines that the contact resistance of the opening/closing contact is abnormal when the voltage drop difference value exceeds the alarm level value, and outputs an alarm signal.
Description
Technical Field
The present invention relates to a contact portion abnormality monitoring device for monitoring abnormality of an opening/closing contact portion and a circuit breaker using the same.
Background
As an abnormality monitoring of an open/close contact portion of a circuit breaker, a method of measuring a contact resistance of the open/close contact portion by a voltage drop method is adopted, that is, a resistance value of the contact portion is calculated by a voltage of the contact portion detected via an insulating amplifier connected to both ends of the monitored open/close contact portion in a circuit and a current flowing in the circuit detected via a current transformer, and whether or not abnormality is present is determined by comparing the calculated resistance value with a reference value of the resistance (for example, patent document 1).
Patent document 1: japanese laid-open patent publication No. 1-179281
Disclosure of Invention
However, in the conventional method, in an apparatus for opening and closing contacts such as a circuit breaker, in order to directly measure a voltage drop at an opening and closing contact portion, the contacts are conducted via a voltage measuring instrument connected to both ends of the contacts after the opening and closing contacts are opened, and therefore, insulation between the contacts at the time of opening the contacts is not substantially ensured.
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a contact portion abnormality monitoring device and a circuit breaker using the same, which can safely monitor an abnormality of an opening/closing contact portion by measuring a voltage drop of the opening/closing contact portion without contact.
The contact abnormality monitoring device according to the present invention includes: a current transformer that detects a load current flowing through a circuit when an opening/closing contact that opens/closes the circuit that connects the power supply and the load is in a closed state; a load current detection unit that outputs a signal of a load current; a power supply side voltage detection resistor connected to a circuit on the power supply side of the opening/closing contact; a load-side voltage detection resistor connected to a circuit on the load side of the opening/closing contact; an abnormality detection current transformer that detects a differential current generated by a current flowing through a power supply side voltage detection resistor and a load side voltage detection resistor; a voltage drop detection unit that outputs an output signal that is an actual measurement value of a voltage drop at the opening/closing contact point based on the differential current; and a waveform comparing unit for calculating a normal value of the voltage drop based on the value of the load current and an initial value of the contact resistance of the opening/closing contact, calculating a voltage drop difference value based on the normal value of the voltage drop and an actual measurement value of the voltage drop, comparing the voltage drop difference value with a preset alarm level value, and when the voltage drop difference value exceeds the alarm level value, determining that the contact resistance of the opening/closing contact is abnormal, and outputting an alarm signal.
The circuit breaker according to the present invention includes: an opening/closing contact provided in a circuit for connecting the power supply and the load, the opening/closing contact opening/closing the power supply and the load; a current transformer that detects a load current flowing through the circuit when the opening/closing contact is in a closed state; a load current detection unit that outputs a signal of a load current; a power supply side voltage detection resistor connected to a circuit on the power supply side of the opening/closing contact; a load-side voltage detection resistor connected to a circuit on the load side of the opening/closing contact; an abnormality detection current transformer that detects a differential current generated by a current flowing through a power supply side voltage detection resistor and a load side voltage detection resistor; a voltage drop detection unit that outputs an output signal that is an actual measurement value of a voltage drop at the opening/closing contact point based on the differential current; a waveform comparing unit for calculating a normal value of the voltage drop based on the value of the load current and an initial value of the contact resistance of the opening/closing contact, calculating a voltage drop difference value based on the normal value of the voltage drop and an actual measurement value of the voltage drop, comparing the voltage drop difference value with a preset alarm level value, and when the voltage drop difference value exceeds the alarm level value, determining that the contact resistance of the opening/closing contact is abnormal, and outputting an alarm signal; and a trip device capable of opening the opening and closing contact.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the contact portion abnormality monitoring device and the circuit breaker using the same of the present invention, the presence or absence of abnormality of the contact portion can be monitored by comparing an actual measurement value of the voltage drop of the open/close contact calculated from the difference of currents flowing through the voltage detection resistors connected to the power source side and the load side of the open/close contact, respectively, with a normal value of the voltage drop of the open/close contact calculated from the load current and the initial value of the contact resistance of the open/close contact. Since the voltage drop at the opening/closing contact point can be measured in a noncontact manner, the safety of the circuit breaker can be improved without affecting the insulation between the opening/closing contact points.
Drawings
Fig. 1 is a block diagram of a circuit breaker according to embodiment 1 of the present invention.
Fig. 2 is a simulation result showing an operation of the circuit breaker according to embodiment 1 of the present invention.
Fig. 3 is a block diagram of a circuit breaker according to embodiment 2 of the present invention.
Fig. 4 is a block diagram of a circuit breaker according to embodiment 3 of the present invention.
Detailed Description
Next, embodiments of the circuit breaker according to the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts.
Embodiment 1.
Fig. 1 is a block diagram of a circuit breaker according to embodiment 1, and shows a configuration for detecting an abnormality of a contact portion in a three-phase 4-wire circuit.
As shown in fig. 1, the circuit breaker according to embodiment 1 includes a contact portion abnormality monitoring device including an opening/closing contact 2, a current transformer 3, a load current detecting portion 4, a power supply side voltage detecting resistor 5, a load side voltage detecting resistor 6, an abnormality detecting current transformer 7, a voltage drop detecting portion 8, an alarm level setting portion 9, and a waveform comparing portion 10, which are provided in a circuit 1, an alarm portion 11, and a tripping device 12.
The circuit 1 connects a power source and a load, and includes circuits 1a, 1b, 1c, and 1d. The opening/closing contact 2 is provided in a circuit 1 for opening/closing between a power source and a load, and includes opening/closing contacts 2a, 2b, 2c, and 2d.
The inverter 3 includes inverters 3a, 3b, 3c, and 3d, and outputs an output signal (current signal) proportional to a load current flowing from a power supply to the load when the opening/closing contact 2 is in a closed state.
The load current detection unit 4 converts the output signal from the converter 3 into a load current signal (analog signal or digital signal) and outputs the load current signal.
The power supply side voltage detection resistor 5 is connected to the power supply side with respect to the opening/closing contact 2, and converts a power supply side voltage (a potential difference constituted by power supply side potentials V1, V2, V3, and V4) into a power supply side voltage detection current (power supply side voltage detection currents i1, i2, i3, and i 4). The power supply side voltage detection resistors 5a, 5b, and 5c are provided corresponding to the power supply side voltage detection currents i1, i2, and i3, respectively.
The load-side voltage detection resistor 6 is connected to the load side with respect to the opening/closing contact 2, and converts the load-side voltage (potential difference composed of the load-side potentials V5, V6, V7, and V8) into a load-side voltage detection current (load-side voltage detection currents i5, i6, i7, and i 8). The load side voltage detection resistors 6a, 6b, and 6c are provided corresponding to the load side voltage detection currents i5, i6, and i7, respectively.
The abnormality detection current transformer 7 outputs an output signal (voltage signal) proportional to a differential current generated by a power supply side voltage detection current flowing through the power supply side voltage detection resistor 5 and a load side voltage detection current flowing through the load side voltage detection resistor 6. The abnormality detection current transformer 7 can be, for example, a zero sequence current transformer.
The voltage drop detection unit 8 converts an output signal proportional to the differential current from the abnormality detection current transformer 7 into a differential voltage signal (analog voltage signal or digital voltage signal), and outputs an output signal that is an actual measurement value of the voltage drop.
The alarm level setting unit 9 is configured by a memory element such as a nonvolatile memory, and stores an initial value of contact resistance, which is a resistance value in a normal closed state at an opening/closing contact point set in advance at factory adjustment, and an alarm level value. Here, the alarm level value is an allowable range of a voltage difference based on a normal value of a voltage drop at the opening/closing contact point and an actual measurement value of the voltage drop when an abnormality occurs. The alarm level value can be changed as needed, and can be input to the alarm level setting unit 9.
The waveform comparing unit 10 calculates a normal value of the voltage drop in the case of the closed state based on the value of the load current signal outputted from the load current detecting unit 4 and the initial value of the contact resistance recorded in the alarm level setting unit 9, obtains an actual measurement value of the voltage drop at the open/close contact 2 based on the differential voltage signal outputted from the voltage drop detecting unit 8, calculates a voltage drop differential value based on the normal value of the voltage drop and the actual measurement value of the voltage drop, compares the voltage drop differential value with a preset alarm level value, and determines that the contact resistance of the open/close contact 2 is deviated from the initial value when the voltage drop differential value exceeds the alarm level value, and outputs an alarm signal.
The alarm unit 11 generates an alarm when receiving the alarm signal output from the waveform comparing unit 10.
The trip device 12 can open the opening/closing contact in accordance with the current flowing through the circuit 1.
Next, the operation of the circuit breaker according to embodiment 1 of the present invention configured as described above will be described with reference to fig. 1.
In a normal closed state, the load currents Ia, ib, ic, id flowing through the circuits 1a, 1b, 1c, and 1d are detected by the inverters 3a, 3b, 3c, and 3d, respectively, and a current signal proportional to the load current Ia, ib, ic, id is output as an output signal to the load current detection unit 4.
The load current detection unit 4 converts the obtained output signal proportional to the load current Ia, ib, ic, id into a load current signal, and outputs the load current signal to the waveform comparison unit 10.
The alarm level setting unit 9 records an initial value Xa, xb, xc, xd of the contact resistance of the opening/closing contacts 2a, 2b, 2c, 2d input in advance, and outputs an initial value Xa, xb, xc, xd of the contact resistance to the waveform comparing unit 10. Here, the initial value of the contact resistance is a contact resistance value measured at the time of factory adjustment of the circuit breaker. The method of calculating the voltage drop difference value in the case where an abnormality occurs based on the normal value of the voltage drop and the actual measured value of the voltage drop is described later.
The waveform comparing unit 10 derives normal values Δua, Δub, Δuc, and Δud of voltage drops of the opening/closing contacts 2a, 2b, 2c, and 2d in a normal closed state from the obtained initial value Xa, xb, xc, xd of the contact resistance and the load current Ia, ib, ic, id by the expressions (1-1), (1-2), (1-3), and (1-4), respectively.
[ 1-1]
ΔUa＝Ia×Xa (1-1)
[ 1-2]
ΔUb＝Ib×Xb (1-2)
[ 1-3]
ΔUc＝Ic×Xc (1-3)
[ 1-4]
ΔUd＝Id×Xd (1-4)
Further, power supply side voltage detection resistors 5a, 5b, 5c are connected between the power supply side lines of the circuits 1a, 1b, 1c and 1 d. The power supply side potentials of the circuits 1a, 1b, 1c, and 1d are defined as V1, V2, V3, and V4, respectively, the currents flowing through the power supply side voltage detection resistors 5a, 5b, and 5c are defined as power supply side voltage detection currents i1, i2, and i3, respectively, and the current flowing to the circuit 1d via the power supply side voltage detection resistors is defined as a power supply side voltage detection current i4.
Here, as shown in fig. 1, if wiring is connected to the wiring connected to the power supply side voltage detection resistor 5a and the power supply side voltage detection resistor 5b and the power supply side of the circuit 1d wound around the abnormality detection converter 7, and wiring connected to the power supply side of the circuit 1d and wiring connected to the power supply side voltage detection resistor 5c wound around the abnormality detection converter 7, the total current i of the power supply side voltage detection currents outputted from the abnormality detection converter 7 is represented by the formula (2).
[ 2]
i＝N×(i1+i2-i3) (2)
Here, N represents the number of turns of wiring on the power supply side of the winding of the abnormality detection current transformer 7.
If the power supply side voltage detection currents i1, i2, i3 are represented by the power supply side potentials V1, V2, V3, V4 and the resistance values R1, R2, R3 of the power supply side voltage detection resistors 5a, 5b, 5c, the power supply side voltage detection current i4 becomes the expression (3-4) as shown in the expressions (3-1), (3-2), and (3-3), respectively. The total current i of the power supply side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by formula (4).
[ 3-1]
i1＝(V1-V4)/R1 (31)
[ 3-2]
i2＝(V2-V4)/R2 (3-2)
[ 3-3]
i3＝(V3-V4)/R3 (3-3)
[ 3-4]
i4＝-i1-i2-i3
＝-(V1-V4)/R1-(V2-V4)/R2-(V3-V4)/R3
＝-1/(R1R2R3)×(R2R3V1+R1R3V2+R1R2V3(R1R2+R2R3+R3R1)V4) (3-4)
[ 4]
i＝N×1/(R1R2R3)×(R2R3V1+R1R3V2-R1R2V3+(R1R2-R2R3-R3R1)V4) (4)
On the other hand, load-side voltage detection resistors 6a, 6b, and 6c are connected between the circuits 1a, 1b, and 1c and the load-side line of the circuit 1 d. The load-side potentials of the circuits 1a, 1b, 1c, and 1d are defined as V5, V6, V7, and V8, respectively, the currents flowing through the load-side voltage detection resistors 6a, 6b, and 6c are defined as load-side voltage detection currents i5, i6, and i7, respectively, and the current flowing to the circuit 1d via the load-side voltage detection resistor is defined as load-side voltage detection current i8.
Here, as shown in fig. 1, if wiring is connected to the wiring connected to the load-side voltage detection resistor 6a and the load-side voltage detection resistor 6b and the load side of the circuit 1d wound around the abnormality detection converter 7, and wiring connected to the load side of the circuit 1d and wiring connected to the load-side voltage detection resistor 6c wound around the abnormality detection converter 7, the total current i10 of the load-side voltage detection currents outputted from the abnormality detection converter 7 is represented by the formula (5).
[ 5]
i10＝N10×(i5+i6-i7) (5)
Here, N10 represents the number of turns of the wiring on the load side of the winding of the abnormality detection current transformer 7.
If the load side voltage detection currents i5, i6, i7, i8 are represented by the resistance values R5, R6, R7 of the load side potentials V5, V6, V7, V8 and the load side voltage detection resistors 6a, 6b, 6c, the expressions (6-1), (6-2), (6-3) and (6-4) are respectively obtained. The total current i10 of the load-side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by formula (7).
[ 6-1]
i5＝(V5-V8)/R5 (6-1)
[ 6-2]
i6＝(V6-V8)/R6 (6-2)
[ 6-3]
i7＝(V7-V8)/R7 (6-3)
[ 6-4]
i8＝-i5-i6-i7
＝-(V5-V8)/R5-(V6-V8)/R6-(V7-V8)/R7
＝1/(R5R6R7)×(R6R7V5+R5R7V6+R5R6V7-(R5R6+R6R7+R7R5)V8)(6-4)
[ 7]
i10＝N10×1/(R5R6R7)×(R6R7V5+R5R7V6-R5R6V7+(R5R6--R6R7-R7R5)V8) (7)
Here, if r1=r2=r3=r5=r6=r7=rΩ, and n=n1=m [ turns ], the differential current signal Δi=i-i 10 generated by the current output from the abnormality detection current transformer 7 becomes expression (8).
[ 8]
Δi＝M×1/R×((V1-V5)+(V2-V6)-(V3-V7)-(V4-V8))
＝M×1/R×(ΔVa+ΔVb-ΔVc-ΔVd) (8)
Further, Δva, Δvb, Δvc, and Δvd represent voltage drops of the opening/closing contacts 2a, 2b, 2c, and 2d, respectively, and are expressed by expression (9-1), expression (9-2), expression (9-3), and expression (9-4).
[ 9-1]
ΔVa＝V1-V5 (9-1)
[ 9-2]
ΔVb＝V2-V6 (9-2)
[ 9-3]
ΔVc＝V3-V7 (9-3)
[ 9-4]
ΔVd＝V4-V8 (9-4)
An output signal proportional to the differential current signal Δi detected by the abnormality detection current transformer 7 is output to the voltage drop detection unit 8. The voltage drop detection unit 8 outputs an output signal proportional to the obtained differential current signal Δi to the waveform comparison unit 10.
The waveform comparing unit 10 calculates an actual measurement value Δv of the voltage drop at the opening and closing contacts 2a to 2d from the value of the obtained differential current signal Δi by the equation (10).
[ 10]
ΔV＝Δi×R/M
＝ΔVa+ΔVb-ΔVc-ΔVd (10)
Assuming that the actual measurement values of the contact resistances at the opening and closing contacts 2a, 2b, 2c, and 2d are Ra, rb, rc, rd, the expression (10) is expressed by the expression (11) using the load current Ia, ib, ic, id.
[ 11]
ΔV＝(Ia×Ra)+(Ib×Rb)-(Ic×Rc)-(Id×Rd) (11)
On the other hand, the waveform comparing unit 10 uses the normal values Δua, Δub, Δuc, and Δud of the voltage drops in the normal closed state, which are derived by the formulas (1-1), (1-2), (1-3), and (1-4), and estimates the normal value Δu of the voltage drop at the contact point at the opening/closing contact points 2a, 2b, 2c, and 2d by the formula (12).
[ 12]
ΔU＝ΔUa+ΔUb-ΔUc-ΔUd
＝(Ia×Xa)+(Ib×Xb)-(Ic×Xc)-(Id×Xd) (12)
Here, fig. 2 shows an example of simulation results of the operation of the circuit breaker according to embodiment 1. In fig. 2, the horizontal axis represents time and the vertical axis represents voltage level.
As shown in fig. 2 (a), when the opening/closing contacts 2a, 2b, 2c, and 2d are in a normal closed state, the actual measured value Ra, rb, rc, rd of the contact resistance and the initial value Xa, xb, xc, xd of the contact resistance substantially match, and thus the voltage drop differential value Δv- Δu becomes formula (13).
[ 13]
When the actual measurement value Ra, rb, rc, rd of the contact resistance increases due to an abnormality in the opening/closing contacts 2a, 2B, 2c, and 2d, the divergence between the actual measurement value Ra, rb, rc, rd of the contact resistance and the initial value Xa, xb, xc, xd of the contact resistance increases, and therefore, as shown in fig. 2 (B), the amplitude of the voltage drop differential value Δv- Δu increases with the actual measurement value of the contact resistance, and becomes greater than or equal to the positive direction alarm level value and the negative direction alarm level value.
Therefore, by monitoring the magnitude of the voltage drop differential value Δv to Δu and comparing the magnitude with the alarm level value set in the alarm level setting unit 9, it is possible to detect an abnormality of the opening/closing contact.
When the magnitude of the voltage drop differential value Δv to Δu exceeds the alarm level value, the waveform comparing unit 10 outputs an alarm signal to the alarm unit 11. When receiving the alarm signal output from the waveform comparing unit 10, the alarm unit 11 outputs an alarm to an external device, thereby notifying the abnormality of the opening/closing contacts 2a, 2b, 2c, 2 d.
In embodiment 1, when there is fluctuation in the resistance values of the power supply side voltage detection resistors 5a, 5b, 5c and the load side voltage detection resistors 6a, 6b, 6c, a measurement error occurs in the actual measurement value Δv of the voltage drop of the opening/closing contacts 2a, 2b, 2c, 2d due to the fluctuation in the resistance values, and therefore, the waveform comparison unit 10 has a function of correcting the fluctuation in the resistance values of the power supply side voltage detection resistors 5a, 5b, 5c and the load side voltage detection resistors 6a, 6b, 6c, so that the measurement accuracy can be further improved.
The fluctuation in resistance value is caused by temperature, humidity environment and time degradation, but by unifying constants of the power supply side voltage detection resistors 5a, 5b, 5c and the load side voltage detection resistors 6a, 6b, 6c, a circuit is constituted by the same specification of resistance components, and thus uniform resistance value change is obtained for all components against temperature, humidity environment and time degradation, and thus the reliability of measurement can be further improved.
Further, by disposing the power supply side voltage detection resistors 5a, 5b, 5c and the load side voltage detection resistors 6a, 6b, 6c on the same substrate, it is possible to prevent the influence of the temperature and humidity environment due to the position, and to further improve the reliability of measurement.
According to the contact portion abnormality monitoring device and the circuit breaker using the same in accordance with embodiment 1, the presence or absence of abnormality of the contact portion can be monitored by comparing an actual measurement value of the voltage drop of the open/close contact calculated from the difference of currents flowing through the voltage detection resistors connected to the power source side and the load side of the open/close contact, respectively, with a normal value of the voltage drop of the open/close contact calculated from the load current and the initial value of the contact resistance of the open/close contact. Since the voltage drop at the opening/closing contact point can be measured in a noncontact manner, the safety of the circuit breaker can be improved without affecting the insulation between the opening/closing contact points.
Embodiment 2.
Fig. 3 is a block diagram of the circuit breaker according to embodiment 2, and shows a configuration for detecting an abnormality of a contact portion in a single-phase 3-wire circuit and a three-phase 3-wire circuit.
As shown in fig. 3, the circuit breaker according to embodiment 2 is configured by a contact portion abnormality monitoring device including an opening/closing contact 2, a current transformer 3, a load current detection unit 4, a power supply side voltage detection resistor 5, a load side voltage detection resistor 6, an abnormality detection current transformer 7, a voltage drop detection unit 8, an alarm level setting unit 9, and a waveform comparison unit 10, an alarm unit 11, and a tripping device 12 provided in the circuit 1, as in embodiment 1.
The circuit 1 connects a power source and a load, and includes circuits 1a, 1b, and 1c. The opening/closing contact 2 is provided in a circuit 1 for opening/closing between a power source and a load, and includes opening/closing contacts 2a, 2b, and 2c.
The inverter 3 includes inverters 3a, 3b, and 3c, and outputs an output signal (current signal) proportional to a load current flowing from a power supply to the load when the opening/closing contact 2 is in a closed state.
The load current detection unit 4 converts the output signal from the converter 3 into a load current signal (analog signal or digital signal) and outputs the load current signal.
The power supply side voltage detection resistor 5 is connected to the power supply side with respect to the opening/closing contact 2, and converts a power supply side voltage (a potential difference constituted by power supply side potentials V1, V2, and V3) into a power supply side voltage detection current (power supply side voltage detection currents i1, i2, and i 3). The power supply side voltage detection resistors 5a, 5b, and 5c are provided corresponding to the power supply side voltage detection currents i1, i2, and i3, respectively.
The load-side voltage detection resistor 6 is connected to the load side with respect to the opening/closing contact 2, and converts the load-side voltage (potential difference composed of the load-side potentials V4, V5, and V6) into a load-side voltage detection current (load-side voltage detection currents i4, i5, and i 6). The load side voltage detection resistors 6a, 6b, and 6c are provided corresponding to the load side voltage detection currents i4, i5, and i6, respectively.
The abnormality detection current transformer 7 outputs an output signal (voltage signal) proportional to a differential current generated by a power supply side voltage detection current flowing through the power supply side voltage detection resistor 5 and a load side voltage detection current flowing through the load side voltage detection resistor 6. The abnormality detection current transformer 7 can be, for example, a zero sequence current transformer.
The voltage drop detection unit 8 converts an output signal proportional to the differential current from the abnormality detection current transformer 7 into a differential voltage signal (analog voltage signal or digital voltage signal), and outputs an output signal that is an actual measurement value of the voltage drop.
The alarm level setting unit 9 is configured by a memory element such as a nonvolatile memory, and stores an initial value of contact resistance, which is a resistance value in a normal closed state at an opening/closing contact point set in advance at factory adjustment, and an alarm level value. Here, the alarm level value is an allowable range of a voltage difference based on a normal value of a voltage drop at the opening/closing contact point and an actual measurement value of the voltage drop when an abnormality occurs. The alarm level value can be changed as needed, and can be input to the alarm level setting unit 9.
The waveform comparing unit 10 calculates a normal value of the voltage drop in the closed state based on the value of the load current signal outputted from the load current detecting unit 4 and the initial value of the contact resistance recorded in the alarm level setting unit 9, obtains an actual measurement value of the voltage drop at the open/close contact 2 based on the differential voltage signal outputted from the voltage drop detecting unit 8, calculates a voltage drop differential value based on the normal value of the voltage drop and the actual measurement value of the voltage drop, compares the voltage drop differential value with a preset alarm level value, and determines that the contact resistance of the open/close contact 2 is deviated from the initial value when the voltage drop differential value exceeds the alarm level value, and outputs an alarm signal.
The alarm unit 11 generates an alarm when receiving the alarm signal output from the waveform comparing unit 10.
The trip device 12 can open the opening/closing contact in accordance with the current flowing through the circuit 1.
Next, the operation of the circuit breaker according to embodiment 2 of the present invention configured as described above will be described with reference to fig. 3.
In a normal closed state, load currents Ia, ib, ic flowing through the circuits 1a, 1b, 1c are detected by the inverters 3a, 3b, 3c, respectively, and current signals proportional to the load currents Ia, ib, ic are output as output signals to the load current detection unit 4.
The load current detection unit 4 converts the obtained output signals proportional to the load currents Ia, ib, ic into load current signals, and outputs the load current signals to the waveform comparison unit 10.
The alarm level setting unit 9 records initial values Xa, xb, xc of the contact resistances of the opening/closing contacts 2a, 2b, 2c input in advance, and outputs the initial values Xa, xb, xc of the contact resistances to the waveform comparing unit 10. Here, the initial value of the contact resistance is a contact resistance value measured at the time of factory adjustment of the circuit breaker. The method of calculating the voltage drop difference value in the case where an abnormality occurs based on the normal value of the voltage drop and the actual measured value of the voltage drop is described later.
The waveform comparing unit 10 derives normal values Δua, Δub, and Δuc of voltage drops of the opening/closing contacts 2a, 2b, and 2c in a normal closed state from the obtained initial values Xa, xb, and Xc of the contact resistances and the load currents Ia, ib, and Ic, respectively, by the formulas (14-1), (14-2), and (14-3).
[ 14-1]
ΔUa＝Ia×Xa (14-1)
[ 14-2]
ΔUb＝Ib×Xb (14-2)
[ 14-3]
ΔUc＝Ic×Xc (14-3)
Further, power supply side voltage detection resistors 5a, 5b, 5c are connected between the power supply side lines of the circuits 1a, 1b, 1 c. The power supply side potentials of the circuits 1a, 1b, and 1c are defined as V1, V2, and V3, respectively, and the currents flowing through the power supply side voltage detection resistors 5a, 5b, and 5c are defined as power supply side voltage detection currents i1, i2, and i3, respectively.
Here, as shown in fig. 3, if wiring connected to the power supply side voltage detection resistor 5a and the power supply side voltage detection resistor 5b is wound around the abnormality detection current transformer 7 and wiring connected to the power supply side voltage detection resistor 5c of the circuit 1c wound around the abnormality detection current transformer 7 is connected, the total current i of the power supply side voltage detection currents outputted from the abnormality detection current transformer 7 is expressed by the expression (15).
[ 15]
i＝N×i3 (15)
Here, N represents the number of turns of wiring on the power supply side of the winding of the abnormality detection current transformer 7.
If the power supply side voltage detection currents i1, i2, i3 are represented by the power supply side potentials V1, V2, V3 and the resistance values R1, R2, R3 of the power supply side voltage detection resistors 5a, 5b, 5c, the expressions (16-1), (16-2), and (16-3) are respectively obtained. The total current i of the power supply side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by formula (17).
[ 16-1]
i1＝1/(R1R2+R2R3+R3R1)×((R2+R3)V1-R3V2-R2V3) (16-1)
[ 16-2]
i2＝1/(R1R2+R2R3+R3R1)×(-R3V1+(R1+R3)V2-R1V3) (16-2)
[ 16-3]
i3＝1/(R1R2+R2R3+R3R1)×(-R2V1-R1V2+(R1+R2)V3) (16-3)
[ 17]
i＝N×1/(R1R2+R2R3+R3R1)×(-R2V1-R1V2+(R1+R2)V3) (17)
On the other hand, load-side voltage detection resistors 6a, 6b, and 6c are connected between the load-side lines of the circuits 1a, 1b, and 1 c. The load-side potentials of the circuits 1a, 1b, and 1c are defined as V4, V5, and V6, respectively, and the currents flowing through the load-side voltage detection resistors 6a, 6b, and 6c are defined as load-side voltage detection currents i4, i5, and i6, respectively.
Here, as shown in fig. 3, if wiring connected to the load-side voltage detection resistor 6a and the load-side voltage detection resistor 6b is wound around the abnormality detection current transformer 7 and wiring connected to the load-side voltage detection resistor 6c connected to the load side of the circuit 1c wound around the abnormality detection current transformer 7, the total current i10 of the load-side voltage detection currents outputted from the abnormality detection current transformer 7 is expressed by the expression (18).
[ 18]
i10＝N10×i6 (18)
Here, N10 represents the number of turns of the wiring on the load side of the winding of the abnormality detection current transformer 7.
If the load-side voltage detection currents i4, i5, i6 are represented by the load-side potentials V4, V5, V6 and the resistance values R4, R5, R6 of the load-side voltage detection resistors 6a, 6b, 6c, the expressions (19-1), (19-2) and (19-3) are respectively obtained. The total current i10 of the load-side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by formula (20).
[ 19-1]
i4＝1/(RAR5+R5R6+R6R4)×((R5+R6)V4-R6V5-R5V6) 19-1)
[ 19-2]
i5＝1/(R4R5+R5R6+R6R4)×(-R6V4+(R4+R6)V5-R4V6) 19-2)
[ 19-3]
i6＝1/(R4R5+R5R6+R6R4)×(-R5V4-R4V5+(R4+R5)V6) (19-3)
[ 20]
i10＝N10×1/(R4R5+R5R6+R6R4)×(-R5V4-R4V5+(R4+R5)V6) (20)
Here, if r1=r2=r3=r4=r5=r6=rΩ, n=n10=m [ turns ], the differential current signal Δi=i-i 10 generated by the current output from the abnormality detection current transformer 7 becomes the expression (21).
[ 21]
Δi＝M×1/3R×(-ΔVa-ΔVb+2ΔVc) (21)
Further, ΔVa, Δvb, and ΔVc represent voltage drops of the opening/closing contacts 2a, 2b, and 2c, respectively, and are expressed by formulas (22-1), (22-2), and (22-3).
[ 22-1]
ΔVa＝V1-V4 (22--1)
[ 22-2]
ΔVb＝V2-V5 (22-2)
[ 22-3]
ΔVc＝V3-V6 (22-3)
An output signal proportional to the differential current signal Δi detected by the abnormality detection current transformer 7 is output to the voltage drop detection unit 8. The voltage drop detection unit 8 outputs an output signal proportional to the obtained differential current signal Δi to the waveform comparison unit 10.
The waveform comparing unit 10 calculates an actual measurement value Δv of the contact portion voltage drop at the opening and closing contacts 2a to 2c from the value of the obtained differential current signal Δi by the equation (23).
[ 23]
ΔV＝Δi×3R/M
＝-ΔVa-ΔVb+2ΔVe (23)
Assuming that the actual measurement values of the contact resistances at the opening and closing contacts 2a, 2b, and 2c are Ra, rb, and Rc, the expression (23) is expressed by the expression (24) using the load currents Ia, ib, and Ic described above.
[ 24]
ΔV＝-(Ia×Ra)-(Ib×Rb)+2(Ic×Rc) (24)
On the other hand, the waveform comparing unit 10 uses the normal values Δua, Δub, and Δuc of the voltage drops in the normal closed state derived by the formulas (14-1), (14-2), and (14-3), and estimates the normal value Δu of the contact point voltage drop at the opening/closing contacts 2a to 2c by the formula (25).
[ 25]
ΔU＝-ΔUa-ΔUb+2ΔUc
＝(Ia×Xa)-(Ib×Xb)+2(Ic×Xc) (25)
When the opening/closing contacts 2a, 2b, 2c are in the normal closed state, the actual measurement values Ra, rb, rc of the contact resistance substantially match the initial values Xa, xb, xc of the contact resistance, and therefore the voltage drop differential value Δv- Δu becomes the formula (26).
[ 26]
When the actual measurement values Ra, rb, rc of the contact resistances increase due to abnormality of the opening/closing contacts 2a, 2b, 2c, the divergence between the actual measurement values Ra, rb, rc of the contact resistances and the initial values Xa, xb, xc of the contact resistances increases, and therefore the amplitude of the voltage drop differential value Δv- Δu increases with the actual measurement values of the contact resistances, and becomes greater than or equal to the positive direction alarm level value and the negative direction alarm level value.
Therefore, by monitoring the magnitude of the voltage drop differential value Δv to Δu and comparing the magnitude with the alarm level value set in the alarm level setting unit 9, it is possible to detect an abnormality of the opening/closing contact.
When the magnitude of the voltage drop differential value Δv to Δu exceeds the alarm level value, the waveform comparing unit 10 outputs an alarm signal to the alarm unit 11. When receiving the alarm signal output from the waveform comparing unit 10, the alarm unit 11 outputs an alarm to an external device, thereby notifying the abnormality of the opening/closing contacts 2a, 2b, 2 c.
In embodiment 2, when there is fluctuation in the resistance values of the power supply side voltage detection resistors 5a, 5b, 5c and the load side voltage detection resistors 6a, 6b, 6c, as in embodiment 1, a measurement error occurs in the measured value Δv of the voltage drop at the opening/closing contacts 2a, 2b, 2c due to the fluctuation in the resistance values, and therefore, the waveform comparing unit 10 has a function of correcting the fluctuation in the resistance values of the power supply side voltage detection resistors 5a, 5b, 5c and the load side voltage detection resistors 6a, 6b, 6c, whereby the measurement accuracy can be further improved.
As for the power supply side voltage detection resistors 5a, 5b, 5c and the load side voltage detection resistors 6a, 6b, 6c, it is preferable to use the same-specification resistor members as in embodiment 1. Further, by being disposed on the same substrate, the sensor is less susceptible to the temperature and humidity environments caused by the position, and the reliability of measurement can be further improved.
According to the contact portion abnormality monitoring device and the circuit breaker using the same in accordance with embodiment 2, the presence or absence of abnormality of the contact portion can be monitored by comparing the actual measurement value of the voltage drop of the open/close contact calculated from the difference of the currents flowing through the voltage detection resistors connected to the power source side and the load side of the open/close contact, respectively, with the normal value of the voltage drop of the open/close contact calculated from the load current and the initial value of the contact resistance of the open/close contact. Since the voltage drop at the opening/closing contact point can be measured in a noncontact manner, the safety of the circuit breaker can be improved without affecting the insulation between the opening/closing contact points.
Embodiment 3.
Fig. 4 is a block diagram of the circuit breaker according to embodiment 3, and shows a configuration for detecting an abnormality of a contact portion in a single-phase 2-wire circuit.
As shown in fig. 4, the circuit breaker according to embodiment 3 is configured by a contact portion abnormality monitoring device including an opening/closing contact 2, a current transformer 3, a load current detection unit 4, a power supply side voltage detection resistor 5, a load side voltage detection resistor 6, an abnormality detection current transformer 7, a voltage drop detection unit 8, an alarm level setting unit 9, and a waveform comparison unit 10, and alarm units 11 and trip devices 12 provided in a circuit 1, as in embodiments 1 and 2.
The circuit 1 connects a power supply and a load, and includes circuits 1a and 1b. The opening/closing contact 2 is provided in a circuit 1 for opening/closing between a power source and a load, and has opening/closing contacts 2a and 2b.
The inverter 3 includes inverters 3a and 3b, and outputs an output signal (current signal) proportional to a load current flowing from a power supply to the load when the opening/closing contact 2 is in a closed state.
The load current detection unit 4 converts the output signal from the converter 3 into a load current signal (analog signal or digital signal) and outputs the load current signal.
The power supply side voltage detection resistor 5 is connected to the power supply side with respect to the opening/closing contact 2, and converts a power supply side voltage (a potential difference between the power supply side potentials V1 and V2) into a power supply side voltage detection current (power supply side voltage detection currents i1 and i 2). The power supply side voltage detection resistors 5a and 5b are provided corresponding to the power supply side voltage detection currents i1 and i2, respectively.
The load-side voltage detection resistor 6 is connected to the load side with respect to the opening/closing contact 2, and converts the load-side voltage (potential difference between the load-side potentials V3 and V4) into a load-side voltage detection current (load-side voltage detection currents i3 and i 4). The load-side voltage detection resistors 6a and 6b are provided corresponding to the load-side voltage detection currents i3 and i4, respectively.
The abnormality detection current transformer 7 outputs an output signal (current signal or voltage signal) proportional to a differential current generated by a power supply side voltage detection current flowing through the power supply side voltage detection resistor 5 and a load side voltage detection current flowing through the load side voltage detection resistor 6. The abnormality detection current transformer 7 can be, for example, a zero sequence current transformer.
The voltage drop detection unit 8 converts an output signal proportional to the differential current from the abnormality detection current transformer 7 into a differential voltage signal (analog voltage signal or digital voltage signal), and outputs an output signal that is an actual measurement value of the voltage drop.
The alarm level setting unit 9 is configured by a memory element such as a nonvolatile memory, and stores an initial value of contact resistance, which is a resistance value in a normal closed state at an opening/closing contact point set in advance at factory adjustment, and an alarm level value. Here, the alarm level value is an allowable range of a voltage difference based on a normal value of a voltage drop at the opening/closing contact point and an actual measurement value of the voltage drop when an abnormality occurs. The alarm level value can be changed as needed, and can be input to the alarm level setting unit 9.
The waveform comparing unit 10 calculates a normal value of the voltage drop in the case of the closed state based on the value of the load current signal outputted from the load current detecting unit 4 and the initial value of the contact resistance recorded in the alarm level setting unit 9, obtains an actual measurement value of the voltage drop at the open/close contact 2 based on the differential voltage signal outputted from the voltage drop detecting unit 8, calculates a voltage drop differential value based on the normal value of the voltage drop and the actual measurement value of the voltage drop, compares the voltage drop differential value with a preset alarm level value, and determines that the contact resistance of the open/close contact 2 is deviated from the initial value when the voltage drop differential value exceeds the alarm level value, and outputs an alarm signal.
The alarm unit 11 generates an alarm when receiving the alarm signal output from the waveform comparing unit 10.
The trip device 12 can open the opening/closing contact in accordance with the current flowing through the circuit 1.
Next, an operation of the circuit breaker according to embodiment 3 of the present invention configured as described above will be described with reference to fig. 4.
In a normal closed state, load currents Ia and Ib flowing through the circuits 1a and 1b are detected by the inverters 3a and 3b, respectively, and current signals proportional to the load currents Ia and Ib are output as output signals to the load current detection unit 4.
The load current detection unit 4 converts the obtained output signals proportional to the load currents Ia and Ib into load current signals, and outputs the load current signals to the waveform comparison unit 10.
The alarm level setting unit 9 records initial values Xa and Xb of the contact resistances of the opening and closing contacts 2a and 2b, which are input in advance, and outputs the initial values Xa and Xb of the contact resistances to the waveform comparing unit 10. Here, the initial value of the contact resistance is a contact resistance value measured at the time of factory adjustment of the circuit breaker. The method of calculating the voltage drop difference value in the case where an abnormality occurs based on the normal value of the voltage drop and the actual measured value of the voltage drop is described later.
The waveform comparing unit 10 derives normal values Δua and Δub of voltage drops of the opening/closing contacts 2a and 2b in a normal closed state from the obtained initial values Xa and Xb of the contact resistances and the load currents Ia and Ib, respectively, by the formulas (27-1) and (27-2).
[ 27-1]
ΔUa＝Ia×Xa (27--1)
[ 27-2]
ΔUb＝Tb×Xb (27-2)
Further, power supply side voltage detection resistors 5a and 5b are connected between the power supply side lines of the circuits 1a and 1 b. The power supply side potentials of the circuits 1a and 1b are defined as V1 and V2, respectively, and the currents flowing through the power supply side voltage detection resistors 5a and 5b are defined as power supply side voltage detection currents i1 and i2, respectively.
As shown in fig. 4, the wires connected to the power supply side voltage detection resistor 5a and the power supply side voltage detection resistor 5b are wound around the abnormality detection current transformer 7, and the total current i of the power supply side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by the formula (28).
[ 28]
i＝N×i1 (28)
Here, N represents the number of turns of wiring on the power supply side of the winding of the abnormality detection current transformer 7.
If the power supply side voltage detection currents i1 and i2 are represented by the power supply side potentials V1 and V2 and the resistance values R1 and R2 of the power supply side voltage detection resistors 5a and 5b, the expressions (29-1) and (29-2) are respectively obtained. The total current i of the power supply side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by formula (30).
[ 29-1]
i1＝(V1-V2)/(R1+R2) (29--1)
[ 29-2]
i2＝-(V1-V2)/(R1+R2) (29-2)
[ 30]
i＝N×V1-V2)/(R1+R2) (30)
On the other hand, load-side voltage detection resistors 6a and 6b are connected between the load-side lines of the circuits 1a and 1 b. The load-side potentials of the circuits 1a and 1b are defined as V3 and V4, respectively, and the currents flowing through the load-side voltage detection resistors 6a and 6b are defined as load-side voltage detection currents i3 and i4, respectively.
As shown in fig. 4, the wiring connected to the load-side voltage detection resistor 6a and the load-side voltage detection resistor 6b is wound around the abnormality detection current transformer 7, and the total current i10 of the load-side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by formula (31).
[ 31]
i10＝N10×i3 (31)
Here, N10 represents the number of turns of the wiring on the load side of the winding of the abnormality detection current transformer 7.
If the load-side voltage detection currents i3 and i4 are represented by the load-side potentials V3 and V4 and the resistance values R3 and R4 of the load-side voltage detection resistors 6a and 6b, the equations (32-1) and (32-2) are obtained. The total current i10 of the load-side voltage detection currents outputted from the abnormality detection current transformer 7 is represented by formula (33).
[ 32-1]
i3＝(V3-V4)/(R3+R4) (32-1)
[ 32-2]
i4＝-(V3-V4)/(R3+R4) (32-2)
[ 33]
i10＝N10×(V3-V4)/(R3+R4) (33)
Here, if r1=r2=r3=r4=rΩ, n=n10=m [ turns ], the differential current signal Δi=i-i 10 generated by the current output from the abnormality detection current transformer 7 becomes the formula (34).
[ 34]
Δi＝M×1/2R×(ΔVa-ΔVb) (34)
Further, Δva and Δvb represent voltage drops of the opening/closing contacts 2a and 2b, and are expressed by formulas (35-1) and (35-2).
[ 35-1]
ΔVa＝V1-V3 (35-1)
[ 35-2]
ΔVb＝V2-V4 (35--2)
An output signal proportional to the differential current signal Δi detected by the abnormality detection current transformer 7 is output to the voltage drop detection unit 8. The voltage drop detection unit 8 outputs an output signal proportional to the obtained differential current signal Δi to the waveform comparison unit 10.
The waveform comparing unit 10 calculates an actual measurement value Δv of the voltage drop at the opening and closing contacts 2a to 2b from the value of the obtained differential current signal Δi by the equation (36).
[ 36]
ΔV＝Δi×2R/M
＝ΔVa-ΔVb (36)
Assuming that the actual measurement values of the contact resistances at the opening and closing contacts 2a, 2b are Ra, rb, the expression (36) is expressed by the expression (37) using the load currents Ia, ib described above.
[ 37]
ΔV＝(Ia×Ra)-(Ib×Rb) 37)
On the other hand, the waveform comparing unit 10 uses the normal values Δua and Δub of the voltage drop in the normal closed state derived by the formulas (27-1) and (27-2), and estimates the normal value Δu of the contact point voltage drop at the opening/closing contacts 2a and 2b by the formula (38).
[ 38]
ΔU＝ΔUa-ΔUb
＝(Ia×Xa)-(1b×Xb) (38)
When the opening/closing contacts 2a, 2b are in the normal closed state, the actual measurement values Ra, rb of the contact resistances and the initial values Xa, xb of the contact resistances substantially match, and therefore the voltage drop differential value Δv- Δu becomes the formula (39).
[ 39]
When the actual measurement values Ra and Rb of the contact resistances increase due to abnormality of the opening and closing contacts 2a and 2b, the divergence between the actual measurement values Ra and Rb of the contact resistances and the initial values Xa and Xb of the contact resistances increases, and therefore the amplitude of the voltage drop differential value Δv to Δu increases with the actual measurement values of the contact resistances, and becomes greater than or equal to the positive direction alarm level value and the negative direction alarm level value.
Therefore, by monitoring the magnitude of the voltage drop differential value Δv to Δu and comparing the magnitude with the alarm level value set in the alarm level setting unit 9, it is possible to detect an abnormality of the opening/closing contact.
When the magnitude of the voltage drop differential value Δv to Δu exceeds the alarm level value, the waveform comparing unit 10 outputs an alarm signal to the alarm unit 11. When receiving the alarm signal output from the waveform comparing unit 10, the alarm unit 11 outputs an alarm to an external device, thereby notifying the abnormality of the opening/closing contacts 2a, 2 b.
In embodiment 3, when there is fluctuation in the resistance values of the power supply side voltage detection resistors 5a and 5b and the load side voltage detection resistors 6a and 6b, as in embodiment 1, a measurement error occurs in the actual measurement value Δv of the voltage drop of the opening/closing contacts 2a and 2b due to the fluctuation in the resistance values, and therefore, the waveform comparison unit 10 has a function of correcting the fluctuation in the resistance values of the power supply side voltage detection resistors 5a and 5b and the load side voltage detection resistors 6a and 6b, so that the measurement accuracy can be further improved.
As for the power supply side voltage detection resistors 5a and 5b and the load side voltage detection resistors 6a and 6b, it is preferable to use the same-specification resistor members as in embodiment 1. Further, by being disposed on the same substrate, the sensor is less susceptible to the temperature and humidity environments caused by the position, and the reliability of measurement can be further improved.
According to the contact portion abnormality monitoring device and the circuit breaker using the same in accordance with embodiment 3, the presence or absence of abnormality of the contact portion can be monitored by comparing the actual measurement value of the voltage drop of the open/close contact calculated from the difference of the currents flowing through the voltage detection resistors connected to the power source side and the load side of the open/close contact, respectively, with the normal value of the voltage drop of the open/close contact calculated from the load current and the initial value of the contact resistance of the open/close contact. Since the voltage drop at the opening/closing contact point can be measured in a noncontact manner, the safety of the circuit breaker can be improved without affecting the insulation between the opening/closing contact points.
Description of the reference numerals
1 circuit, 2 switching contacts, 3 current transformer, 4 load current detecting unit, 5 power source side voltage detecting resistor, 6 load side voltage detecting resistor, 7 abnormality detecting current transformer, 8 voltage drop detecting unit, 9 alarm level setting unit, 10 waveform comparing unit, 11 alarm unit, 12 tripping device
Claims (10)
1. A contact abnormality monitoring device is provided with:
a current transformer that detects a load current flowing through a circuit that connects a power supply and a load when an opening/closing contact that opens/closes the circuit is in a closed state;
a load current detection unit that outputs a signal of the load current;
a power supply side voltage detection resistor connected to a circuit on the power supply side of the opening/closing contact;
a load-side voltage detection resistor connected to a circuit on the load side of the opening/closing contact;
an abnormality detection current transformer that detects a differential current generated by a current flowing through the power supply side voltage detection resistor and the load side voltage detection resistor;
a voltage drop detection unit that outputs an output signal that is an actual measurement value of the voltage drop at the opening/closing contact point, based on the differential current; and
and a waveform comparing unit that calculates a normal voltage drop value based on the value of the load current and an initial value of the contact resistance of the opening/closing contact, calculates a voltage drop difference value based on the normal voltage drop value and an actual measured voltage drop value, compares the voltage drop difference value with a preset alarm level value, determines that an abnormality exists in the contact resistance of the opening/closing contact when the voltage drop difference value exceeds the alarm level value, and outputs an alarm signal.
2. The contact portion abnormality monitoring device according to claim 1, wherein,
the alarm device is provided with an alarm part which gives an alarm when the alarm signal is output.
3. The contact point abnormality monitoring device according to claim 1 or 2, wherein,
the initial value of the contact resistance is a resistance value of a normal closed state at the opening and closing contact point set in advance,
the alarm level value is an allowable range of a voltage difference based on a normal value of the voltage drop at the opening/closing contact point and an actual measurement value of the voltage drop in the case where an abnormality occurs,
the electric power meter is provided with an alarm level setting unit which stores an initial value of the contact resistance and sets the alarm level value.
4. The contact point abnormality monitoring device according to claim 1 or 2, characterized in that,
the power supply side voltage detection resistor and the load side voltage detection resistor use resistor components of the same specification and are arranged on the same substrate.
5. The contact abnormality monitoring device according to claim 3, characterized in that,
the power supply side voltage detection resistor and the load side voltage detection resistor use resistor components of the same specification and are arranged on the same substrate.
6. A circuit breaker, comprising:
an opening/closing contact provided in a circuit for connecting a power supply and a load, the opening/closing contact opening/closing between the power supply and the load;
a current transformer that detects a load current flowing through the circuit when the opening/closing contact is in a closed state;
a load current detection unit that outputs a signal of the load current;
a power supply side voltage detection resistor connected to a circuit on the power supply side of the opening/closing contact;
a load-side voltage detection resistor connected to a circuit on the load side of the opening/closing contact;
an abnormality detection current transformer that detects a differential current generated by a current flowing through the power supply side voltage detection resistor and the load side voltage detection resistor;
a voltage drop detection unit that outputs an output signal that is an actual measurement value of a voltage drop at the opening/closing contact point, based on the differential current;
a waveform comparing unit that calculates a normal voltage drop value based on the value of the load current and an initial value of the contact resistance of the opening/closing contact, calculates a voltage drop difference value based on the normal voltage drop value and an actual measured voltage drop value, compares the voltage drop difference value with a preset alarm level value, and determines that an abnormality exists in the contact resistance of the opening/closing contact when the voltage drop difference value exceeds the alarm level value, and outputs an alarm signal; and
And a trip device capable of opening the opening/closing contact.
7. The circuit breaker of claim 6, wherein,
the alarm device is provided with an alarm part which gives an alarm when the alarm signal is output.
8. The circuit breaker according to claim 6 or 7, wherein,
the initial value of the contact resistance is a resistance value of a normal closed state at the opening and closing contact point set in advance,
the alarm level value is an allowable range of a voltage difference based on a normal value of the voltage drop at the opening/closing contact point and an actual measurement value of the voltage drop in the case where an abnormality occurs,
the electric power meter is provided with an alarm level setting unit which stores an initial value of the contact resistance and sets the alarm level value.
9. The circuit breaker according to claim 6 or 7, wherein,
the power supply side voltage detection resistor and the load side voltage detection resistor use resistor components of the same specification and are arranged on the same substrate.
10. The circuit breaker of claim 8, wherein,
the power supply side voltage detection resistor and the load side voltage detection resistor use resistor components of the same specification and are arranged on the same substrate.
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| PCT/JP2019/010208 WO2020183634A1 (en) | 2019-03-13 | 2019-03-13 | Contact part abnormality monitoring device and circuit breaker using contact part abnormality monitoring device |
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| TW202033971A (en) | 2020-09-16 |
| JPWO2020183634A1 (en) | 2021-10-21 |
| JP7034374B2 (en) | 2022-03-11 |
| TWI724811B (en) | 2021-04-11 |
| WO2020183634A1 (en) | 2020-09-17 |
| CN113614553A (en) | 2021-11-05 |
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