JPH1114689A - Leakage current sensitivity measuring device for earth leakage breaker - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To insert a ground disconnection means into a ground circuit,
By connecting a temporary high-impedance grounding means to the distribution system and a temporary simulated ground fault wire on the load side of the earth leakage breaker, the leakage current of the earth leakage breaker can be measured without disconnecting the load and cable. Provided is a sensitivity measuring device. A leakage current sensitivity measuring device for an earth leakage breaker according to the present invention is provided with a grounding means for earthing and separating which is inserted into a direct earthing path 2 of a distribution line of a direct earthing system to which the earthing leakage breaker is connected. Short-circuit bar 13a and high-impedance grounding device 15a of temporary high-impedance grounding means connected to the power distribution line
And a temporary simulated ground wire 14 for grounding the load side of the earth leakage breaker 4, and a recorder current transformer 11 and a recorder 12 of a leak current measuring means for detecting a leak current from the simulated ground fault wire 14 directly. It is characterized by becoming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measurement of leakage current sensitivity of an earth leakage breaker for measuring the leakage current sensitivity of an earth leakage breaker grounded to a distribution board or the like used for in-house power distribution in various plants and the like. Related to the device.

[0002]

2. Description of the Related Art In general, in a power distribution circuit for low-voltage electric machine equipment in various plants and the like, a distribution board and the like constituting the same are intended to protect the electric machine equipment and the circuit as a load and workers and the like. A ground fault interrupter is installed in each circuit.

As a ground fault interrupting device, a specified leakage current (ground fault current) is specified for a circuit by installing a ground fault interrupter between the low-voltage distribution line and a small-capacity electric machine which is a load. When the current flows for more than a time, the abnormal state is detected by the earth leakage breaker, and the circuit is automatically shut off in order to prevent the damage of the circuit and the load from spreading.

In general, a distribution board such as a distribution board is used for in-plant power distribution to a large number of electric machines in various plants and the like. Therefore, the earth leakage breaker is installed in the distribution board. However, in order to confirm the reliability of the above-described protection function in each of the earth leakage breakers, an interruption confirmation test, which is an operation confirmation when a leakage current flows, is required.

[0005] Generally, as a leakage breaker, a circuit breaker and a zero-phase current transformer are combined with a leakage current detection element, a trip mechanism, and a test trip button. A leakage current such as a ground fault current is detected by the zero-phase current transformer and the leakage current detecting element.

From this result, the circuit breaker is cut off by the trip mechanism, and the circuit is automatically cut off. Regarding the operation check in this earth leakage breaker, most inspectors check the interruption operation by pressing the test trip button on each earth leakage breaker in the distribution board periodically. .

However, since the earth leakage breaker is an important protection device for the safety of the circuit and the electric machine in the plant, in some plants, each earth leakage breaker is actually used as a more reliable operation check. A simulated leakage current (ground fault current) flows through the circuit, and the leakage current sensitivity measurement of the interruption test using the simulated leakage current is performed. We are implementing.

The leakage current sensitivity measurement in which the simulated leakage current flows is, for example, as shown in the circuit configuration diagram of FIG.
Distribution transformer 1 of 30kVA,% IZ = 4% at 00 / 210V
On the secondary side of the [Delta]-[Delta] connection, one phase is used as a ground phase and is directly grounded by the ground path 2 and connected to a bus 4 which is a distribution path in the distribution board 3. Distribution board 3
The internal bus 4 is branched into a large number of circuits (not shown), and an earth leakage breaker 5 and a wiring breaker 6 are connected to each other,
All are connected to a load 8 which is an electric machine via cables 7 _T , 7 _S , 7 _R to supply power.

[0009] Here, when performing leakage current sensitivity measurement by blocking confirmatory test passing a simulated leakage current is simulated ground fault for supplying a simulated leakage current to one terminal 5 _T on the load side of the earth leakage breaker 5 The line 9 is connected and grounded in series via a variable resistor 10 for simulated leakage current adjustment.

Further, the simulated ground fault wire 9 is combined with a recorder current transformer 11 for detecting a simulated leakage current I ₀ flowing through the simulated ground fault wire 9, and the recorder current transformer 11 is connected to the simulated ground fault wire 9.
Time characteristics of the simulated leakage current I ₀ was measured, to connect the recorder 12 is a leakage current measuring means for recording.

[0011] Next, as simulated leakage current I _0, for example, 15mA prescribed leakage current sensitivity value in leakage breaker 5, by passing the earth leakage breaker 5 by adjusting the variable resistor 10, the earth leakage breaker 5 internal When it is detected that the current detected by the detected zero-phase current transformer 5a is equal to or more than a set value and continues for a predetermined time, a cutoff operation is performed. Accordingly, by measuring and recording the current value of the leakage current I ₀ at this time and the characteristic of the time elapsing until the interruption operation of the earth leakage breaker 5 with the recorder 12, the leakage current I ₀ of the earth leakage circuit breaker 5 is obtained. _The sensitivity and operation characteristics by ₀ become clear, and the function can be determined.

However, at this time, the simulated leakage current I
₀ is a simulated ground fault 9 from the load side terminal 5 _T of the earth leakage breaker 5.
And the ground via the variable resistor 10 and the simulated ground fault circuit formed by the distribution transformer 1, the bus 4 and the earth leakage breaker 5 from the direct ground path 2 of the distribution transformer 1.

[0013] With estimated the resistance value Rg of the variable resistor 10 for the simulated leakage current I ₀ at this time 15 mA, Rg
= (1/15 × 10 ⁻³ ) × (210 / √3) = approximately 8 kΩ, and the phase impedance j in the distribution transformer 1
Z ^{is, jZ =% IZ × V 2} /P=0.04×210 2/30 × 10
³ = 0.0588 jΩ.

However, in the circuit configuration of FIG.
Since the load 8 is connected to the load side of the earth leakage breaker 5 via the cables 7 _T , 7 _S , 7 _R , this cable 7
_T , 7 _S , 7 _R and stray capacitance C generated at load 8
As a result, the load leakage current I _R + I _S leaks to the ground.

The load leakage current I _R + I _S flows to the ground in addition to the stray capacitance C, if there is a leakage current or an unbalanced current due to poor insulation, for example. . Note that when a leakage current or an unbalanced current due to insulation failure occurs, the leakage current or the like usually flows larger than the load leakage current due to the stray capacitance C.

The load leakage current I _R + I _S is directly supplied to the power distribution transformer 1 having a smaller impedance than the resistance value Rg of the variable resistor 10 in the simulated ground wire 9 by the direct ground path 2.
Return via. As a result, the load leakage current I _R + I _S in the direct ground path 2 is added to the simulated leakage current I ₀ measured by the recorder 12 and flows through the zero-phase current transformer 5a of the earth leakage breaker 5. The current I ₀ + the load leakage current I _R + I _S is generally larger than the simulated leakage current I ₀ captured by the recorder current transformer 11 at the simulated ground wire 9.

Therefore, when the simulated leakage current I ₀ captured by the current transformer 11 for the recorder is measured by the recorder 12 and determined as the leakage current sensitivity of the leakage breaker 5, the circuit by the leakage breaker 5 is determined. In addition, an error in the leakage current sensitivity measurement due to a protection function against a load may result in an unsafe side measurement result.

That is, even if the leakage current I ₀ = 13 mA is measured by the recorder 12 during the cut-off operation, for example, if the load leakage current I _R + I _S that cannot be captured by the recorder 12 is 7 mA, for example, 5 means that the leakage current I ₀ + the load leakage current I _R + I _S has flowed through the zero-phase current transformer 5a.

As a result, the actual current value at which the earth leakage breaker 5 actually performs the breaking operation is affected by the addition of the load leakage current I _R + I _{S, and} is larger than the leakage current I ₀ = 13 mA. The measurement result by the recorder 12 is 13 mA. As described above, the apparent leakage current sensitivity is increased (determined as operating with a small leakage current value).
The error is an unsafe side as a protection function in the earth leakage breaker 5, and the reliability from the measurement result is impaired.

[0020]

In order to prevent the measurement error from being on the unsafe side and to accurately measure the leakage current sensitivity of the breaking operation, the simulated leakage current I _All you have to do is pass ₀ .

For this purpose, the cables 7 _T , 7 _S , 7 _R are temporarily disconnected (disconnected) from the respective load-side terminals 5 _T , 5 _S , 5 _R of the earth leakage breaker 5 at the time of measuring the leakage current sensitivity. , The cables 7 _T , 7 _S , 7 _R and the load 8 are disconnected (indicated by x), and the load leakage current I _R + I due to the stray capacitance C
_It is necessary to form a simulated ground fault circuit that eliminates the effects of leakage current and unbalanced current due to _S and insulation failure.

According to the simulated ground fault circuit thus formed, the load leakage current I _R + I due to the stray capacitance C is obtained.
_S does not flow, and therefore the zero-phase current transformer 5a of the earth leakage breaker 5
Since the current flowing through is only the simulated leakage current I ₀ adjusted by the variable resistor 10, by measuring this leakage current I ₀ , it is possible to measure and evaluate the leakage current sensitivity together with the accurate cutoff operation test. .

However, a large number of earth leakage breakers 5 and wiring breakers 6 are installed inside the distribution board 3, and the cables 7 _T , 7 _S , 7 _R for each load 8 are loosened. They are firmly connected so that they do not occur.

Therefore, among these many earth leakage breakers 5, the load side terminals 5 _T , 5 _S ,
From 5 _R, cable 7 _T, 7 _S, 7 once the operation of connecting a simulated ground絡線9 and solutions line on the load side terminal 5 _T to _R, simulated locations絡線after measurement completion from the load side terminal 5 _T Remove 9
Again, connect the cables 7 _T , 7 _S , 7 _R to the load-side terminals 5 _T ,
5 _S, 5 recovery work to be connected to the _R is required.

However, as described above, on the load side of the earth leakage breaker 5 in the distribution board 3, there are many cases where there is no room for the cable wiring space, and therefore, the cable 7 _T on the load side of the earth leakage breaker 5 is not provided. , 7 _S , 7 _R and the connection of the simulated ground fault line 9, and the restoration of these, have a problem that an excessive burden is imposed on workers and other concerned parties. Further, in the recovery work, there is a problem that a large amount of work time is required because various confirmation tests are required in order to confirm that there is no mistake due to a connection error or the like, and the workability is low.

An object of the present invention is to insert a ground disconnecting means into a ground circuit, connect a temporary high impedance grounding means to a power distribution system, and connect a temporary simulated grounding wire to a load of an earth leakage breaker. Accordingly, it is an object of the present invention to provide a leakage current sensitivity measuring device for a leakage breaker that measures a leakage current without disconnecting a load and a cable.

[0027]

According to a first aspect of the present invention, there is provided a leakage current sensitivity measuring apparatus for an earth leakage breaker, wherein the earth leakage circuit breaker is connected to a direct grounding distribution line. Ground disconnecting means inserted in a direct ground path of a power distribution path, temporary high impedance grounding means connected to the power distribution path, temporary temporary simulated ground fault wire grounding the load side of the earth leakage breaker; And a leakage current measuring means for detecting a leakage current from the simulated ground wire.

A temporary high-impedance grounding means and a simulated ground fault line are directly connected to the distribution line of the direct grounding system in which the earth leakage breaker to be measured is installed, and the leakage current measuring means is connected to the simulated ground fault line. Combine and open the ground disconnection means. By flowing the simulated earth leakage current to the earth leakage breaker until the interruption operation by the high impedance grounding means, and measuring and recording the current value and the characteristics of the passage of time by the leakage current measuring means, the leakage current sensitivity can be measured by recording, Thus, the protection function of the earth leakage breaker can be determined.

According to a second aspect of the present invention, there is provided a leakage current sensitivity measuring device for an earth leakage breaker according to the first aspect, wherein the temporary high impedance grounding means connected to the distribution line comprises a high impedance comprising a capacitor and a variable resistor. It is a grounding device. A high-impedance grounding circuit combining a capacitor and a variable resistor is formed between the distribution path and the ground, and a simulated leakage current for leak current sensitivity measurement is caused to flow to the leakage breaker by adjusting the variable resistor.

According to a third aspect of the present invention, in the leakage current sensitivity measuring device for an earth leakage breaker according to the first aspect, the temporary high impedance grounding means connected to the distribution line comprises a fixed resistor and a variable resistor. It is a high resistance grounding device. A high-resistance ground circuit combining a fixed resistor and a variable resistor is formed between the distribution line and the ground, and a simulated leakage current for measuring a leakage current sensitivity is measured for the leakage breaker by adjusting the variable resistor. Flow.

According to a fourth aspect of the present invention, there is provided a leakage current sensitivity measuring device for an earth leakage breaker according to the first aspect, wherein the temporary high impedance grounding means connected to the distribution line comprises the variable resistor. It is characterized by being.
A high-resistance grounding circuit using a variable resistor is formed between the distribution line and the ground, and a simulated leakage current for leak current sensitivity measurement flows to the leakage breaker by adjusting the variable resistor.

According to a fifth aspect of the present invention, there is provided a leakage current sensitivity measuring device for an earth leakage circuit breaker according to the first aspect, wherein the ground separating means inserted into a direct grounding path of the distribution path grounds the distribution path when measuring the leakage current. And a ground short-circuit bar or a ground switch. When measuring the leakage current sensitivity, the distribution circuit is disconnected from the ground by removing the shorting bar of the grounding shorting bar or opening the grounding switch, and the load leakage current flows through the low impedance direct simulated grounding wire.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. Note that the same components as those of the above-described related art are denoted by the same reference numerals, and detailed description thereof will be omitted. Also, the following description will be made taking a ground fault circuit breaker with a rated sensitivity current value of 15 mA as an example.

As shown in the overall circuit diagram of FIG. 1A, for example, a distribution transformer 1 of 30 kVA at 6600/210 V and% IZ = 4% has one phase on the secondary side with Δ-Δ connection. As a grounding phase, a grounding short-circuit bar 13a, which is a ground separating means, is inserted directly into the grounding path 2 and connected to a bus 4 (T, S, R phase) as a power distribution path in the distribution board 3.

As for the ground short-circuit bar 13a, the short-circuit bar is normally fixed with a screw (not shown) and the power distribution transformer 1 is directly grounded by the ground path 2. However, when measuring the leakage current sensitivity of the leakage breaker 5, The ground is separated by loosening the screw and removing the short bar.

The ground disconnecting means is provided for simplifying the measurement work for a large number of earth leakage breakers 5.
For example, as shown in the circuit configuration diagram of FIG. 1B, the grounding switch 13b may be provided with an interlock for prohibiting an open circuit in addition to the leakage current sensitivity measurement, and may be opened and closed by a remote operation to disconnect the ground. (Claim 5). Further, the bus 4 in the distribution board 3 is branched into a large number of circuits (not shown), and an earth leakage breaker 5 and a wiring breaker 6 are connected to each of them.
In each case, power is supplied by connecting to a load 8 which is an electric machine via cables 7 _T , 7 _S , and 7 _R.

[0037] Here, when performing leakage current sensitivity measurement by blocking confirmatory test passing a simulated leakage current flows and one terminal 5 _R on the load side of the earth leakage breaker 5, the simulated leakage current between the ground Connect a temporary simulated ground fault wire 14 for
Ground the load side terminal _5R directly.

Further, the direct simulated ground fault line 14 is provided with a transformer current for detecting a leakage current I (I = I ₀ + I _T + I _S ) flowing along with the simulated leakage current I ₀ in the direct simulated ground fault line 14. Combining the current transformer 11
Thus, the recorder 12 which is a leakage current measuring means for measuring and recording the leakage current I and the time characteristic is connected (claim 6).

Further, a high-impedance grounding device 15a, which is temporary high-impedance grounding means, is connected to the load side of the circuit breaker 6 connected to the bus 4 in the distribution board 3 as the power distribution path and grounded. (Claim 1).

Here, the high impedance grounding device 15a connected to the distribution line is basically composed of three capacitors connected to each terminal of the circuit breaker 6 which is each phase of the distribution line and having an impedance Z ₀ of about 24 kΩ. One variable resistor 17 is connected in series between 16a to 16c (corresponding to 0.13 μF at 50 Hz). The variable resistor 17 changes the resistance value Rg from infinity ∞ to 0Ω, so that the simulated leakage current I ₀
Can be changed (I ₀ = 15 mA at 0Ω) (claim 2).

As the high impedance grounding means, the same operation as that of the high impedance grounding device 15a can be obtained, and as shown in the circuit configuration diagram of FIG. Three fixed resistors 18 to connect
a to 18c and a high-resistance grounding device 15b configured by connecting one variable resistor 19 in series. The variable resistor 19 can change the simulated leakage current I ₀ by changing the resistance value Rg from infinity ∞ to 0Ω (I ₀ = 15 mA at 0Ω). ).

Further, as shown in the circuit diagram of FIG. 1D, another high-impedance grounding means 15 is provided with a variable resistor 20 connected to each phase of the distribution line.
There is c. The high-resistance grounding device 15c can change the phase resistance Z ₀ in the range from infinity ∞ to 24 kΩ (I ₀ = 15 mA at 24 kΩ).

Next, the operation of the above configuration will be described. For the leakage current sensitivity measurement for the leakage breaker 5 connected to the bus 4 which is a distribution path in the distribution board 3, all the leakage breakers 5 including the measurement target leakage breaker 5 and the wiring breaker 6 are opened. I do. Thereafter, on the primary side of the distribution transformer 1, a power supply circuit breaker (not shown) is opened to put the bus 4 and the like after the distribution transformer 1 into a power outage state.

[0044] Next, connect directly simulated ground絡線14 between the ground and the load side terminal 5 _R of the measurement target earth leakage breaker 5, after grounding the load side terminal 5 _R fault interrupter 5 Then, the ground short-circuit bar 13a is opened to disconnect the ground path 2 directly from the ground.
The high-impedance grounding device 15a is connected between each load-side terminal and the ground by the wiring circuit breaker 6 that is reserved in the distribution board 3, and then closed to close the high-impedance grounding device 15a. A circuit breaker 6, a bus 4 and the earth leakage circuit breaker 5 to be measured, and a simulated ground fault circuit formed by the simulated ground fault wire 14 and the ground are formed.

In each of the direct simulated ground fault wire 14 and the high impedance grounding device 15a, since the simulated earth leakage current I ₀ is around the rated sensitivity current value of about 15 mA,
The wiring may be thin and flexible and easy to handle.

Further, the earth leakage breaker 5 of the
For connection to the earth leakage breaker 5, a screw for tightening each load side terminal of the earth leakage breaker 5 may be used. Provision of the dummy ground wire 14 facilitates direct attachment / detachment without touching the tightening screw of the load-side terminal, thereby improving safety and reliability.

If there is no spare circuit breaker 6 for connecting the high impedance grounding device 15a in the distribution board 3, the spare earth leakage breaker 5 may be used. However, the rated sensitivity current value of the earth leakage breaker 5 is selected to be higher than that of the earth leakage breaker 5 to be measured, and the earth leakage breaker 5 connected to the high impedance grounding device 14a at the time of the earth leakage current sensitivity measurement becomes unnecessary. It is necessary to consider so as not to perform the breaking operation.

[0048] Furthermore, if there is a ground-fault interrupter 5 of the leakage current sensitivity measured in another in the same distribution board 3, should be connected separately directly simulated locations絡線14 to their load terminal 5 _R .
Thereafter, a circuit breaker is turned on at the primary side of the distribution transformer 1 and power is restored. Then, the simulated ground fault wire 14 is combined with the recorder current transformer 11 which is a leakage current measuring means, and this recorder is used. When the recorder 12 is connected to the current transformer 11, the measurement preparation is completed.

Next, the measuring operation of the leakage current sensitivity is carried out. After closing the earth leakage breaker 5 to be measured, the variable resistor 17 in the high impedance grounding device 15a is adjusted.
The simulated leakage current I ₀ is set in advance to the rated sensitivity current value of 15 mA. After this, once the earth leakage breaker 5 to be measured is opened, the recorder 12 is started again, and then the earth leakage breaker 5 to be measured is closed.

As a result, the earth leakage breaker 5 to be measured has:
Since the flow of 15mA of simulated ground fault current I ₀ corresponding to the rated sensitivity current value, automatically interrupting operation after lapse of a certain time is performed, time and leakage current I ₀ at this time, the recorder 12
And recorded in detail.

Accordingly, by checking the recording of the leakage current sensitivity measurement by the recorder 12, etc., it is possible to easily determine the leakage current sensitivity and the leakage interruption function in the leakage circuit breaker 5 to be measured. Also, for the other earth leakage breaker 5 described above,
The direct current ground fault wire 14 is sequentially combined with the current transformer 11 for the recorder, and the leakage current sensitivity is measured by the recorder 12.

After the work of measuring the leakage current sensitivity of all the earth leakage breakers 5 is completed, after the power distribution transformer 1 is again stopped, the ground short-circuit bar 13a is surely short-circuited, and then the simulated ground fault line 14 Then, the current transformer 11 for the recorder is removed. Thereafter, the spare circuit breaker 6 is opened, the high-impedance grounding device 15a is removed, the circuit is returned to the normal circuit state, and then the power distribution transformer 1 is restored, and is used in the distribution board 3. The current leakage breaker 5 and the wiring breaker 6 are sequentially closed to complete the leakage current sensitivity measurement operation.

As described above, in the present embodiment, FIG.
When the leakage current sensitivity measurement shown in the load from the cable 7 _T, 7 _S, 7 load through the _R 8 is connected to the measurement object leakage breaker 5, and the cable 7 _T, 7 _S, 7 _R 8
The load leakage currents I _S and I _T leak to the ground via the stray capacitance C and the like generated in step (1).

However, the load leakage currents I _S , I
_T indicates that in the formed simulated ground fault circuit, the impedance of the simulated ground fault line 14 is lower than that of the high impedance grounding device 15a. To the distribution transformer 1 via the zero-phase current transformer 5a. Therefore, in the earth leakage breaker 5, S
Phases and the load leakage current I _S and I _T flows through the T-phase, will be canceled by the load leakage current I _S + I _T flowing in the R phase.

That is, when the leakage current sensitivity is measured, even if the cables 7 _T , 7 _S , 7 _R and the load 8 are connected to the earth leakage breaker 5 to be measured, these cables 7 _T , 7 _S , 7 _R.
And the load leakage current I _S + I _T in the load 8 is not only the stray capacitance C, but also, for example, due to poor insulation or imbalance, when measuring the leakage current sensitivity of the leakage breaker 5. It does not contribute to the breaking operation.

Thus, each time the leakage current sensitivity is measured as in the prior art, the load side terminals 5 _T , 5 _S , 5
_The cables 7 _T , 7 _S , and 7 _R are unwound from the _R , and the workability and reliability are improved because there is no need for restoration and confirmation work. The simulated leakage current I ₀ that flows to the zero-phase current transformer 5a in the earth leakage breaker 5 and performs the breaking operation is supplied to the recorder 12.
Leakage current I = I ₀ flowing through the simulated ground fault line 14 measured at
Less than + I _T + I _S.

Accordingly, it is apparent that the determination of the leakage current sensitivity to the earth leakage breaker 5 is performed by the leakage current I directly captured by the recorder current transformer 11 at the simulated ground fault line 14 and measured and recorded by the recorder 12. Current sensitivity becomes low (determined as operating with a large leakage current value)
Therefore, the error is measured as a safe side in the protection function of the earth leakage breaker 5.

From this, the stray capacitance C is included in the determination result.
Even if an error occurs due to the influence of load leakage current such as insulation failure and imbalance, the application of the earth leakage breaker 5 does not pose a security problem. That is, a leakage current value of an actual interruption operation flowing through the zero-phase current transformer 5a in the leakage leakage breaker 5 to be measured,
Comparing the leakage current value flowing through the current transformer 11 for the recorder directly on the simulated ground fault wire 14, an error of I _T + I _S appears.

In the high impedance grounding device 15a, the simulated leakage current I ₀ and the load leakage current I _T + I _S are both in phase, so that the load leakage current I _T +
If I _S is j1 mA and the simulated leakage current I ₀ is j 15 mA, I = I ₀ + I _T + I _S is j 16 mA, and the absolute value of the leakage current I is about 7% of the error of the simulated leakage current I ₀ .

In the high-resistance grounding devices 15b and 15c, which are other high-impedance grounding means, the load leakage current I _T + I _S is j1 mA, and the simulated leakage current I ₀ is 15 mA.
Then, the absolute value of I = I ₀ + I _T + I _S obtained by vector synthesis is 15.03 mA, and the error from the simulated leakage current I ₀ is small (about 0.2%).

As a result, the high-resistance grounding devices 15b and 15c have the effect of reducing the measurement error, and the error of the leakage current sensitivity measurement is about 0.2%. Sensitivity measurement can be obtained with high precision, and the problem of erroneously rejecting a non-defective product in determination can be almost avoided.

[0062]

As described above, according to the present invention, a direct simulated ground fault wire having a current carrying capacity of about a specified leakage current value is temporarily provided at the load side terminal of the earth leakage circuit breaker to be measured, and the temporary high grounding wire is provided on the wiring path. By simply connecting the impedance grounding means and disconnecting the distribution transformer from the ground, the leakage current sensitivity can be measured without disconnecting the load-side cable of the leakage breaker. In addition, there is little error in the leakage current sensitivity measurement, and even if there is an error, it is on the safe side from the viewpoint of the protection function of the earth leakage breaker, so the measurement work efficiency and reliability are improved and the burden on the workers is increased. Also reduce.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a leakage current sensitivity measuring device according to an embodiment of the present invention, where (a) is the whole, (b) is a grounding switch, and (c) and (d) are high-resistance grounding devices. Is shown.

FIG. 2 is a circuit configuration diagram of a conventional leakage current sensitivity measuring device.

[Explanation of symbols]

1 ... distribution transformer, 2 ... direct grounding path, 3 ... distribution board, 4 ...
Bus, 5… earth leakage breaker, 5a… zero-phase current transformer, 5 _T ,
_5S , _5R : Load side terminal, 6: Circuit breaker, _7T , 7
_S , 7 _R ... cable, 8 ... load, 9 ... simulated ground fault wire, 10,
17, 19, 20… Variable resistor, 11… Current transformer for recorder, 12…
Recorder, 13a: ground short-circuit bar, 13b: ground switch, 14
… Direct simulated ground fault wire, 15a… High impedance grounding device,
15b, 15c: high resistance grounding device, 16a-16c: capacitor, 18a-18c: fixed resistor.

Claims (6)

[Claims] In a direct grounding distribution circuit to which an earth leakage circuit breaker is connected, ground disconnecting means inserted into the direct grounding path of the distribution path, temporary high impedance grounding means connected to the distribution path, A temporary direct simulated ground fault wire for grounding the load side of the ground fault interrupter; and a leakage current measuring means for detecting a leak current from the temporary direct simulated ground fault wire. Current sensitivity measurement device. 2. The leakage current sensitivity of an earth leakage breaker according to claim 1, wherein the temporary high impedance grounding means connected to the distribution line is a high impedance grounding device including a capacitor and a variable resistor. measuring device. 3. The leakage of the earth leakage breaker according to claim 1, wherein the temporary high impedance grounding means connected to the power distribution line is a high resistance grounding device including a fixed resistor and a variable resistor. Current sensitivity measurement device. 4. The leak current sensitivity measuring device for an earth leakage breaker according to claim 1, wherein the temporary high impedance grounding means connected to the power distribution line is a high resistance grounding device comprising a variable resistor. 5. The ground disconnecting means inserted into a direct ground path of the power distribution path is a ground short-circuit bar or a ground switch that separates the power distribution path from the ground when measuring a leakage current. Leakage current sensitivity measuring device for earth leakage breaker. 6. The leak current measuring means for detecting a leak current from a temporary simulated ground fault line is a recorder for measuring a time lapse of the leak current and a current transformer for the recorder. Leakage current sensitivity measurement device for earth leakage breaker.