JPH08182181A - Three-phase four-wire system ground detector - Google Patents

Abstract

PURPOSE: To provide a three-phase four-wire system ground detector which is economically structured and can separate ground troubles from the other ones accurately and detect the troubles in the early stage and can specify faulty items and recover the faults in the early stage. CONSTITUTION: This system is provided with power units 20u-20w to correspond to three phases and four wires, loads 12-12c which are connected to the output terminals of the power units through feeders La-Ld and are fed from the power units, output current detecting means 19a-19d which detect output currents Iu-Iw, In from the three phases of the power units and a natural line, a ground current detecting means 23 which detects ground current Ig of the power units, and a ground detecting means 60 which detects a ground based on the detected values including the output currents of three phases. A ground is detected based on the result obtained from comprehensive calculation of all the current values. Therefore, cases that the cause of overcurrent of the output current is a ground trouble are accurately separated from the other cases that the cause is other troubles than the ground trouble.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase four-wire ground fault detection device in the case where a power feeding system for a load is a three-phase four-wire system. The present invention relates to a three-phase four-wire type ground fault detection device which has been improved in reliability by detecting the above.

[0002]

2. Description of the Related Art In recent power supply devices, various types of detectors are installed inside the power supply device or in the vicinity of the load, because various kinds of detection information are stored in the power supply device because high-precision and high-speed control is required for loads such as electric motors. The power supply to the load is controlled while grasping the power supply state based on the above. In such a conventional power supply control device, various abnormalities due to control abnormalities or failure of the power supply device or load are detected by various control detectors, and self-protection of the entire device is implemented. ing.

FIG. 6 shows a conventional three-phase four-wire ground fault detection device described in FIG. 1 in "Control system of PWM multiple inverter for LSM drive" at the National Conference of Industrial Application Division of the Institute of Electrical Engineers of Japan in 1990, for example. It is a circuit diagram shown. Here, a case is shown in which an inverter device widely used in recent motor control is applied, and only one of the three phases is circuitized.

In the figure, reference numerals 1 to 5 are known inverter devices composed of semiconductor elements, which convert input DC power into AC power and output it. 6 is each inverter device 1
A DC power supply for supplying a DC voltage Ed to 5, and 7 to 10 are output transformers for insulation installed at the output terminals of the respective inverter devices 1 to 4.

V1 to V5 are output voltages of the respective inverter devices 1 to 5, and output voltages V1 to V1 of the inverter devices 1 to 4 are shown.
V4 is output from the secondary side of the output transformers 7-10.
V is the total output voltage of the output voltages V1 to V5, and I is the output current for one phase supplied by the output voltage V. Inverter devices 1-5, DC power supply 6 and output transformers 7-1
Reference numeral 0 indicates a power supply device for outputting AC power, and a similar power supply device is arranged in parallel to form a three-phase power supply device.

R and L are loads consisting of a resistor and a reactance to which the output current I is supplied, and correspond to, for example, an electric motor or the like. Reference numeral 13 is an equivalent AC power supply that generates a back electromotive force eo of the electric motor, and one end thereof is connected to the ground and an intermediate point of the DC power supply 6 via a ground wire.

Reference numeral 19 is an output current detector for detecting the output current I, and 23 is a ground current detector for detecting the ground current Ig flowing through the ground line. Although not shown, the output transformer 7
Voltage detectors for detecting the output voltages V1 to V5 are installed at the secondary side of the inverters 10 to 10 and the output terminals of the inverter device 5, respectively. Various detection information including the detected current value is input.

Next, the operation of the conventional three-phase four-wire ground fault detector shown in FIG. 6 will be described. First, the control means
Power supply control to the loads R and L is performed based on the output voltages V1 to V5 detected by the voltage detectors in the inverter devices 1 to 5, the output current I detected from the output current detector 19, and the like. Further, the abnormality detection means detects an overvoltage or an overcurrent based on the output voltages V1 to V5, the output voltage I, etc., and performs self-protection of the inverter devices 1 to 5.

That is, the abnormality detecting means has the output voltage V1.
~ V5 or at least one of the detected values of the output current I
When one indicates a threshold value or more, it is detected that an accident such as a ground fault has occurred. In addition, at the time of a ground fault on the load R and L sides, the ground fault current flowing to the ground returns to the power supply device via the ground wire, and one of the phases is always an overcurrent. It can be detected similarly.

However, the cause of such a detection result is not limited to the ground fault accident. For example, in the case of an overcurrent detected by the output current detector 19, a transient due to a short-circuit accident of the loads R and L is generated. It may be due to phase imbalance. Further, the overcurrent detected by the ground current detector 23 may be caused by an accident in the power supply device, and other accidents and the ground fault cannot be clearly separated.

[0011]

As described above, the conventional three-phase, four-wire type ground fault detection device has each current detector 1 in the power supply device.
When an overcurrent of the output current I or the ground current Ig detected from 9 or 23 is detected, a ground fault accident on the load R and L sides is detected, so that it can be reliably separated from other accidents. However, there is a problem in that the reliability of ground fault detection is low.

The present invention has been made in order to solve the above-mentioned problems, and reliably isolates a ground fault accident on the load side and detects it at an early stage without inviting an increase in cost, and identifies a failure item. It is an object of the present invention to obtain a three-phase four-wire ground fault detection device that can be quickly restored.

[0013]

A three-phase four-wire ground fault detector according to claim 1 of the present invention is compatible with a three-phase four-wire having four output terminals including three phases and neutral wires thereof. Connected to each output terminal of the power supply, a load connected to the power supply and supplied with power from the power supply, and a neutral wire connected to the power supply to the ground Output current detection means for detecting output currents from the ground wire, three-phase and neutral wires of the power supply device, ground current detection means for detecting ground current flowing in the ground wire, and detection including output current of at least three phases And a ground fault detecting means for detecting a ground fault based on the value.

According to a second aspect of the present invention, there is provided a three-phase four-wire ground fault detecting device according to the first aspect, wherein the ground fault detecting means detects all output values of the three-phase and neutral wires. An adding unit for adding and a first judging unit including a first comparing unit for comparing the addition result of the adding unit with a predetermined condition set in advance are provided, and based on the comparison result of the first comparing unit. To determine the occurrence of a ground fault.

A three-phase four-wire type ground fault detecting device according to a third aspect of the present invention is the same as in the first or second aspect.
The ground fault detecting means includes a second comparing means for comparing each detected value of the three-phase output currents with the detected value of the ground current.
1 based on the comparison result of the determining means and the second comparing means.
And a first ground fault identifying means for identifying a point ground fault and its ground fault phase.

According to a fourth aspect of the present invention, there is provided a three-phase four-wire ground fault detecting device according to any one of the first to third aspects, in which the ground fault detecting means has each of three phases and neutral. Comparison between third comparing means and third comparing means including third comparing means for comparing a value obtained by adding detected values of output currents of the lines and having opposite polarities and a detected value of ground current It is provided with the second ground fault specifying means for specifying the two-point ground fault and the local fault phases based on the result.

A three-phase four-wire type ground fault detecting device according to a fifth aspect of the present invention is the same as in the first or second aspect.
The power supply device is a power supply device having an output current control function in which the outputs of the three phases are balanced, and the ground fault detection means sets each detected value of the output current of the three phases and the detected value of the output current of the neutral line. Fourth determining means including fourth comparing means for comparing;
Based on the comparison result of the comparison means, the one-point ground fault and the third ground fault specifying means for specifying the ground fault phase are provided.

A three-phase four-wire ground fault detector according to a sixth aspect of the present invention is the power source device according to the first aspect, the second aspect, or the fifth aspect, in which the three-phase outputs are balanced. The ground fault detection means is a power supply device having a current control function, and the ground fault detection means compares the detected values of the three-phase output currents with opposite polarities and the output current of the neutral line in a fifth comparison. It is provided with a fifth determining means including means, and a fourth ground fault specifying means for specifying a two-point ground fault and its local fault phase based on the comparison result of the fifth comparing means.

[0019]

According to the first aspect of the present invention, the power source device is
The output current from the phase and neutral wires and the ground current flowing from the neutral wire on the power supply unit side to the ground wire connected to the ground are detected, and the detected values of each output current and ground current are calculated comprehensively. By detecting the ground fault based on the result obtained as described above, it is possible to separate whether the cause of the overcurrent of the output current is a ground fault accident or another accident.

Further, in claim 2 of the present invention, 3
The result of adding the detected values of the phase output currents is compared with a predetermined condition, and the occurrence of a ground fault is determined based on the comparison result.

Further, in claim 3 of the present invention, 3
Each of the output currents of the phases is compared with the ground current, and the one-point ground fault and its ground fault phase are specified based on the comparison result.

In the fourth aspect of the present invention, 3
A value obtained by adding the output currents of the phases and the output current of the neutral line and having the opposite polarities is compared with the ground current, and the two-point ground fault and its local fault phase are specified based on the comparison result.

According to claim 5 of the present invention, 3
Using a power supply device that controls the output currents of the phases to be balanced, the output currents of the three phases are compared with the output current of the neutral line, and the one-point ground fault and its ground fault phase are specified based on the comparison result.

Further, in claim 6 of the present invention, 3
Using a power supply that controls the output currents of the phases in equilibrium, the reverse polarity values of the output currents of the three phases are compared with the output current of the neutral line, and based on the comparison result, the two-point ground fault and its local fault phase are identified. Identify.

[0025]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a circuit diagram partially showing a first embodiment of the present invention. 12a to 12c correspond to a load L composed of reactance, and 19a to 19d are output current detectors 1.
It corresponds to 9 and 23 and Ig are the ground current detector and the ground fault current similar to the above.

Reference numerals 20u to 20w denote power supply devices corresponding to the U to W phases, respectively, having four output terminals including three phases and neutral wires thereof, and having a structure corresponding to three phase and four wires. Iu to Iw are three-phase output currents from the power supply devices 20u to 20w, and In is an output current from the neutral wire in the power supply devices 20u to 20w.

La to Ld are power transmission power cables connected to the output terminals and neutral wires of the power supply devices 20u to 20w, and the power supply devices 20u to 20w are connected to the loads 12a to 12c connected at one end. Supply power from.

Here, the electric power lines La to Ld from the power supply devices 20u to 20w to the loads 12a to 12c are modeled and divided into four parts in a simulated manner, and each one division is made into a resistor 24 to 27 and a reactance, respectively. 28 to 31, resistors 32 to 35 and reactances 36 to 39, resistors 40 to 43 and reactances 44 to 47, resistors 48 to 51 and reactances 52 to 55.

The output terminals of the three-phase and neutral wires of the power supply devices 20u to 20w are connected to the connection points of the reactances 28 to 31 and the resistors 32 to 35, respectively, and the loads 12a to 1 are connected.
2c and its neutral line have reactance 44
To 47 and resistors 48 to 51 are connected.

The output current detectors 19a to 19c detect the three-phase output currents Iu to Iw of the power supply devices 20u to 20w, and the output current detector 19d outputs the neutral line for the three-phase four-wire system. The output current In is detected, and the ground current detector 23
Is configured to detect a ground current Ig flowing from a neutral wire on the power supply devices 20u to 20w side to a ground wire connected to the ground.

Reference numeral 60 denotes a ground fault detecting means included in the abnormality detecting means, and among the detected values of the output currents Iu to Iw, In and the ground current Ig, at least three-phase output current Iu to.
The occurrence of a ground fault is detected based on the detection value including Iw. The ground fault detecting means 60 adds all the detected values of the three-phase output currents Iu to Iw and the neutral wire output current In.
1 and a first judging means 62 including a first comparing means for comparing the addition result Is by the adding means 61 with a predetermined condition set in advance.
A ground fault is determined on the basis of the comparison result by the first comparing means, and a determination result D indicating the occurrence of the ground fault is output.

Next, the operation of the first embodiment of the present invention shown in FIG. 1 will be described. Now, as shown in FIG. 1, the power supply 2
In the three-phase four-wire type power supply device in which one point is grounded on the 0u to 20w side, it is assumed that a ground fault accident occurs on any of the electric wires La to Ld. At this time, the output currents Iu to Iw and In supplied from the power supply devices 20u to 20w are
a to Ld, the ground point to the ground, and the power supply devices 20u to 20w through the grounding points on the power supply devices 20u to 20w side.
Come back to 0w.

Therefore, the occurrence of the ground fault can be reliably detected by detecting the output currents Iu to Iw and In and the ground current Ig which is a return line of the ground fault current. Hereinafter, loads 12a to 12c including electric wires La to Ld
A specific calculation operation in the ground fault detection means 60 when a ground fault accident occurs on the side will be described.

First, the adding means 61 adds all the detected values of the output currents Iu to Iw and In by the output current detectors 19a to 19d and outputs the addition result Is. At this time, when the detected value of each output current is represented by Iu to Iw and In, when the ground fault has not occurred, the following equation (1) is established according to Kirchhoff's law.

Is = Iu + Iv + Iw + In = 0 (1)

When the output current In of the neutral line is not 0, it means that the three phases are unbalanced. On the other hand, when the ground fault accident occurs, the electric current of the formula (1) flows out from the ground fault point to the ground, and the electric wire device 20 passes through the ground wire.
Returning to u to 20w, the above equation (1) becomes the following equation (2).

Is = Iu + Iv + Iw + In ≠ 0 (2)

Therefore, the first judging means 62
When the formula (2) (predetermined condition) is satisfied, that is, when the addition result Is is not 0, it is determined that the ground fault accident has occurred,
The determination result D is output to the outside. As a result, for example, a well-known alarm display or the like is driven, and a worker can detect a ground fault accident at an early stage and start a quick recovery work.

In this way, each detected output current Iu
By comprehensively calculating Iw and In and determining the ground fault based on the calculation result, it is possible to reliably separate and detect the ground fault accident on the side of the loads 12a to 12c including the electric power lines La to Lc. . At this time, the output current detectors 19a-
Since 19d is installed in the power supply devices 20u to 20w for control, and is not particularly installed for ground fault detection, the cost is not increased.

Example 2. In the first embodiment, the first
Although only the detection of the ground fault by the determination unit 62 of 1 has been described, the ground fault accident may be a one-point ground fault and the ground fault phase of the one-point ground fault may be specified.

FIG. 2 is a circuit diagram showing, in a partial block diagram, a second embodiment of the present invention in which a one-point ground fault and its ground fault phase are specified. 12a to 12c, 19a to 19d, 2
0u to 20w, 23 to 55, 61 and 62 are the same as described above. Further, 60A corresponds to the ground fault detection means 60, and includes the following constituent elements 63 and 64.

Reference numeral 63 is a second judgment means which responds to the judgment result D of the ground fault by the first judgment means 62.
It includes a second comparing means for comparing each detected value of the three-phase output currents Iu to Iw with the detected value of the ground current Ig at the time of inputting. The second comparing means in the second judging means 63, when any of the detected values of the output currents Iu to Iw and the detected value of the ground current Ig are equal, the output current of the phase is equal to the ground current Ig. The comparison result C2 indicating that is output.

Reference numeral 64 is a first ground fault identifying means for identifying a one-point ground fault and its ground fault phase, and the ground fault accident is a one-point ground fault based on the comparison result C2 of the second comparing means. And the ground fault phase are specified, and the specifying result E1 indicating this is output. That is, the first ground fault identification means 64 identifies that a one-point ground fault has occurred in the phase of the output current equal to the ground current Ig, based on the comparison result C2.

Next, the operation of the second embodiment of the present invention shown in FIG. 2 will be described. Now, as shown in FIG. 2, it is assumed that a ground fault occurs at a ground fault point F on the U-phase key wire La, for example. At this time, if the ground fault resistance and the ground resistance are small, the U-phase output current Iu returns to the power supply devices 20u to 20w through the ground wire on which the ground current detector 23 is installed. It is expressed as in the equation (3).

Ig = Iu (3)

Therefore, when the second determining means 63 determines that the expression (3) is established, the first ground fault identifying means 64 determines that the one-point ground on the U-phase is based on the comparison result C2 indicating this. It is possible to output the specific result E1 indicating the contact.

Similarly, when the following equations (4) and (5) are established, the one-point ground faults of the V phase and the W phase can be specified respectively.

Ig = Iv (4) Ig = Iw (5)

In this way, when a ground fault occurs,
Since the ground fault is a one-point ground fault and its ground fault phase is specified, more detailed accident countermeasures can be taken, and for example, the portion where the ground fault has occurred can be quickly separated.

In FIG. 2, the second judging means 6
3 shows the case of responding to the judgment result D of the first judging means 62, the judgment calculation processing may be executed in parallel with the first judging means 62. Alternatively, the calculation determination process may be independently executed.

Example 3. Further, in the second embodiment, the case where the one-point ground fault and its ground fault phase are specified has been described. However, the fact that the ground fault accident is a two-point ground fault among three phases, and the two-point ground fault You may make it specify two ground fault phases.

FIG. 3 is a circuit diagram showing a partial block diagram of a third embodiment of the present invention in which a two-point ground fault and its local fault phase are specified. 12a to 12c, 19a to 19d,
20u to 20w, 23 to 55, 61, 62 and F are the same as described above. Further, 60B is a ground fault detecting means 6
0A and includes the following components 65 and 66.

Reference numeral 65 is a third judging means which responds to the judgment result D of the ground fault by the first judging means 62.
A third comparison means for comparing the detected value of the ground current Ig with the value obtained by adding the detected values of the output currents Iu to Iw of each phase and the output current In of the neutral line at the time of input of. Contains.

The third comparing means in the third judging means 65 detects the ground current Ig when the reverse polarity value of the sum of any of the detected values of the output currents Iu to Iw and the output current In of the neutral line. When it is equal to the value, the comparison result C3 indicating that the value related to the phase is equal to the ground current Ig is output.

Reference numeral 66 is a second ground fault identifying means for identifying the two-point ground fault and the two ground fault phases. Based on the comparison result C3 of the third comparing means 65, the ground fault accident is a two-point ground fault. And the two ground fault phases of the two-point ground fault are specified, and the specifying result E2 indicating this is output.

That is, the second judging means 66 determines, based on the comparison result C3, when the opposite polarity value of the sum of any of the output currents of the respective phases and the output current In of the neutral line is equal to the ground current Ig. , Specify that a two-point ground fault has occurred in the other two phases.

Next, the operation of the third embodiment of the present invention shown in FIG. 3 will be described. Now, as shown in the figure, not only the ground fault point F on the U-phase key wire La but also the V-phase key wire Lb
It is assumed that a ground fault accident occurs at the ground fault point G above. At this time, according to the equation (1), the current of the following equation (6) flows as the ground current Ig in the ground.

Ig = Iu + Iv = -Iw-In (6)

From the expression (6), the ground current Ig is expressed by the following expression (7).

Ig =-(Iw + In) (7)

Therefore, the third comparing means 65 has the ground current Ig detected by the ground current detector 23 and the output current I detected by the output current detectors 19c and 19d.
When the opposite polarity value of the sum of w and In- (Iw + In) is equal, the comparison result C3 indicating the establishment of the equation (7) is output.

As a result, the second ground fault identifying means 66 is
Based on the comparison result C3 indicating the establishment of the equation (7) regarding the output current Iw of the W phase, two phases other than the W phase (that is,
It is specified that a two-point ground fault has occurred in the U phase and the V phase), and the specification result E2 is output.

Similarly, in the case of a two-point ground fault in the U phase and the W phase, the following equation (8) regarding the output current Iv is established in the V phase, and the two-point ground fault in the V phase and the W phase is established. In this case, the following expression (9) regarding the U-phase output current Iu is established.

Ig =-(Iv + In) (8) Ig =-(Iu + In) (9)

Therefore, the second ground fault identifying means 66 is
Based on the comparison result C3, the two-point ground fault
Two ground faults can be identified.

Incidentally, in FIG. 3, the third judging means 6
5 shows the case of responding to the judgment result D of the first judging means 62, the judgment calculation processing may be executed in parallel with the first judging means 62. Alternatively, the determination calculation process may be independently executed.

Further, in the ground fault detecting means 60B, only the second ground fault specifying means 66 for specifying the two-point ground fault and its local fault phase on the basis of the comparison result C3 is provided, but based on the comparison result C2. The first ground fault identifying means 64 (see FIG. 2) for identifying the one-point ground fault and its ground fault phase may be provided in parallel, and the one-point ground fault or the two-point ground fault may be specified. Well, in this case, more detailed accident countermeasures can be taken.

Example 4. Further, in each of the above-described embodiments, the case where the general three-phase, four-wire power supply devices 20u to 20w are targeted has been described. However, an inverter device using a semiconductor that is widely used in recent motor control (see FIG. 6) may be used.

A fourth embodiment of the present invention in the case of using a power supply device composed of an inverter device will be described below. Fourth Embodiment FIG. 4 is a circuit diagram showing a partial block diagram of a fourth embodiment of the present invention. 12a to 12c, 19a to 19d, 23.
˜55, 61, 62 and F are the same as above. Here, first, a case where a one-point ground fault and its ground fault phase are specified will be described.

Reference numerals 21u to 21w are power supply devices corresponding to the above-mentioned 20u to 20w, and in this case, three-phase output current I
It has an output current control function of controlling so that u to Iw are balanced. Further, 60C is, for example, a ground fault detecting means 60A.
(See FIG. 2) and includes the following components 67 and 68.

Reference numeral 67 denotes a fourth judging means responsive to the judgment result D of the ground fault by the first judging means 62, which is a detection value of each of the three-phase output currents Iu to Iw and the output current In of the neutral line. A fourth comparison means for comparing the detected value is included.
When any of the output currents Iu to Iw of each phase is equal to the output current In of the neutral line, the fourth comparison means in the fourth determination means 67 outputs a comparison result C4 indicating this.

Reference numeral 68 is a third ground fault specifying means for specifying the one-point ground fault and its ground fault phase, and the ground fault accident is a one-point ground fault based on the comparison result C4 of the fourth comparing means. And the one-point ground fault phase are specified, and the specifying result E3 indicating this is output. That is, the third ground fault identification means 68
Specifies that a ground fault has occurred in the phase of the output current equal to the output current In of the neutral line, based on the comparison result C4.

Next, the operation of the fourth embodiment of the present invention shown in FIG. 4 will be described. First, the power supply devices 21u to 21w, which are inverter devices, are controlled by the output current control function.
For each output current Iu to Iw, the operation is performed so that the following expression (10) is established.

Iu + Iv + Iw = 0 (10)

By substituting this into the above equation (1), the following equation (11) is established.

In = 0 (11)

However, when a ground fault occurs, the ground fault current flows into the ground current detector 23 via the ground, and therefore the following equation (12) is established.

Ig = In (12)

At this time, the ground fault is U as shown in FIG.
In the case of a one-point ground fault from the ground fault point F on the phase electric wire La, the following formula (13) is established because the formula (10) is satisfied.

In = Iu (13)

That is, if the ground fault resistance at the ground fault point F is small, the U-phase output current Iu does not flow into the load 12a but flows as the ground current Ig on the power supply devices 21u to 21w side via the ground. On the other hand, power supply devices 21v and 21w
Although the output currents Iv and Iw from the electric currents flow to the loads 12b and 12c, since the current control is performed on the side of the current devices 21u to 21w as in the above equation (10), the U-phase retrace line corresponding to −Iu occurs. Will be needed. Since the return line at this time is the output current In of the neutral line, the formulas (12) and (13) are derived.

Therefore, the fourth judging means 67 outputs the comparison result C4 indicating that the output current Iu of the U phase is equal to the output current In of the neutral line, that is, the expression (13) is satisfied. The third ground fault identification means 68 is the U phase 1
It is possible to specify that a point-to-ground fault has occurred.

Similarly, the single-point ground faults in the V phase and the W phase can be specified by the following equations (14) and (15), respectively.

In = Iv (14) In = Iw (15)

In this case, the current serving as the comparison reference for identifying the phase in which the ground fault has occurred is the output current In detected from the neutral line at one place, and the current to be compared is
It is each of the output currents Iu to Iw detected from one position of each of the three phases. Therefore, the arithmetic processing by the comparison means in the fourth determination means 67 is simplified, and the ground fault detection means 6
The configuration of 0C can be simplified.

In FIG. 4, the fourth judging means 6
7 shows the case of responding to the judgment result D of the first judging means 62, the judgment calculation process may be executed in parallel with the first judging means 62. Alternatively, the determination calculation process may be independently executed.

Example 5. In the fourth embodiment, the case where the one-point ground fault and its ground fault phase are specified for the power supply devices 21u to 21w including the inverter device has been described, but the ground fault accident is the two-point ground fault. And 2
You may make it specify each local aspect of the point ground fault.

A fifth embodiment of the present invention will be described below in which the two-point ground fault and its local fault phase are specified when the inverter device is used. FIG. 5 is a circuit diagram showing a partial block diagram of the fifth embodiment of the present invention.
12a-12c, 19a-19d, 21u-21w, 2
3 to 55, 61, 62, F and G are the same as described above. Further, 60D is, for example, ground fault detection means 60B.
(See FIG. 3) and includes the following components 69 and 70.

Reference numeral 69 is a fifth judging means which responds to the judgment result D of the ground fault by the first judging means 62, and is a neutral value and a value in which the respective detected values of the three-phase output currents Iu to Iw are reversed in polarity. It includes a fifth comparing means for comparing the value of the output current In of the line. The fifth comparison means in the fifth determination means 69 indicates, when the reverse polarity value of any of the output currents Iu to Iw of each phase is equal to the output current In of the neutral line, the comparison result C5. Is output.

Reference numeral 70 is the fourth for identifying each local phase of the two-point ground fault.
Which is the ground fault identification means of the comparison result C5 of the fifth comparison means.
Based on the above, the ground fault accident is a two-point ground fault, and the local fault phase of the two-point ground fault is identified, and the identification result E4 indicating this is shown.
Is output. That is, the fourth ground fault identifying means 70 identifies that a ground fault has occurred in two phases other than the phase of the output current In of the opposite polarity equal to the output current In of the neutral line, based on the comparison result C5.

Next, the operation of the fifth embodiment of the present invention shown in FIG. 5 will be described. When the power supply devices 21u to 21w for controlling the output currents Iu to Iw are used as in the above equation (10), for example, at the ground fault points F and G on the U-phase and V-phase key wires La and Lb. When a fault accident occurs, the ground current Ig is expressed by the following equation (16).

Ig = Iu + Iv = −Iw = In (16)

The equation (16) is derived by returning the neutral line to the return line in the case of a ground fault accident, as in the case of the above equation (13). From equation (16), 2 on the U phase and V phase
In the case of a point-to-ground fault, it can be seen that the output current In of the neutral line is equal to the value obtained by reversing the output current Iw of the W phase.
Therefore, the fifth determination unit 69 outputs the comparison result C5 indicating that In = −Iw, and thus the fourth determination unit 69 outputs the fourth comparison result C5.
The ground fault specifying means 70 specifies that a two-point ground fault has occurred in two phases other than the W phase, that is, in the U phase and the V phase, and outputs a specification result E4 indicating this.

Similarly, when the V-phase and the W-phase or the U-phase and the W-phase are grounded at two points, the following (1)
It can be specified by the establishment of the expression (7) or the expression (18).

In = -Iu (17) In = -Iv (18)

Incidentally, in FIG. 5, the fifth judging means 6
7 shows the case of responding to the judgment result D of the first judging means 62, the judgment calculation process may be executed in parallel with the first judging means 62. Alternatively, the determination calculation process may be independently executed.

In the ground fault detecting means 60D, only the fourth ground fault identifying means 70 for identifying the two-point ground fault and its local fault phase based on the comparison result C5 is provided, but based on the comparison result C4. A third ground fault identifying means 68 (see FIG. 4) for identifying the one-point ground fault and its ground fault phase may be provided in parallel, and the one-point ground fault or the two-point ground fault may be specified. Well, in this case, more detailed measures can be taken when a ground fault occurs.

[0098]

As described above, according to the first aspect of the present invention, the power supply device corresponding to the three-phase four-wire having the four output terminals including the three-phase and the neutral wires, and each of the power supply devices. Three-phase power supply unit, a power supply device connected to the output terminal, a load connected to the power supply line to which power is supplied from the power supply device, a ground wire connected from the neutral wire on the power supply device side to the ground, and a power supply device And an output current detecting means for detecting an output current from the neutral wire, a ground current detecting means for detecting a ground current flowing through the ground wire, and a ground fault based on a detection value including output currents of at least three phases. A ground fault detection means is provided, and a ground fault is detected based on the result obtained by comprehensively calculating the detection values of each output current and ground current, and the cause of the overcurrent of the output current is a ground fault accident. Since it can be separated whether or not it will not increase the cost. Detected early and reliably separated ground fault on the load side, the effect of specific and recovery early out 3-phase 4-wire ground fault capable of performing a device failure item is obtained.

According to a second aspect of the present invention, in the first aspect, the ground fault detecting means includes an adding means for adding all the detected values of the output currents of the three-phase and neutral wires, and an adding means. A first determination means including a first comparison means for comparing the addition result with a predetermined condition set in advance is provided, and the occurrence of a ground fault is determined based on the comparison result by the first comparison means. Therefore, based on the comprehensive calculation result of the output current, there is an effect that the three-phase four-wire ground fault detection device capable of reliably separating the load side ground fault accident and detecting it early can be obtained. .

According to a third aspect of the present invention, in the first or second aspect, the ground fault detecting means compares each detected value of the three-phase output current with the detected value of the ground current. Since the second judging means including the second comparing means of No. 1 and the first ground fault specifying means for specifying the one-point ground fault and its ground fault phase based on the comparison result of the second comparing means are provided. , The load side ground fault accident is reliably separated and detected early,
There is an effect that a three-phase four-wire type ground fault detection device capable of specifying that a ground fault accident is a one-point ground fault and the ground fault phase thereof and performing detailed measures can be obtained.

Further, according to claim 4 of the present invention, in any one of claims 1 to 3, the ground fault detecting means detects the detection value of each output current of each of the three phases and the neutral line. A third judging means including a third comparing means for comparing the value obtained by adding and having the opposite polarity and the detected value of the ground current;
Since the two-point ground fault and the second ground fault specifying unit that specifies each local fault are provided based on the comparison result of the comparison unit of
A three-phase four-wire system that can reliably isolate the ground fault on the load side and detect it at an early stage, identify the fact that the ground fault is a two-point ground fault, and identify each local fault phase and take more detailed countermeasures. There is an effect that the type ground fault detection device can be obtained.

According to Claim 5 of the present invention, in Claim 1 or Claim 2, the power supply device is a power supply device having an output current control function for balancing outputs of three phases, and ground fault detection. The means includes fourth determining means including fourth comparing means for comparing the respective detected values of the output currents of the three phases and the detected value of the output current of the neutral line, and the comparison result of the fourth comparing means. Based on the third point to identify the one-point ground fault and its ground fault phase
Since the ground fault specifying means of No. 1 is provided, the ground fault on the load side can be reliably separated and detected at an early stage, and the ground fault is a one-point ground fault by the simplified comparison calculation process. There is an effect that a 3-phase 4-wire type ground fault detection device capable of identifying the ground fault phase can be obtained.

According to claim 6 of the present invention, in claim 1 or claim 2 or claim 5, the power supply device is a power supply device having an output current control function for balancing outputs of three phases. The ground fault detection means includes fifth determination means including fifth comparison means for comparing the values of the output currents of the three phases having opposite polarities and the output current value of the neutral line. ,
Since the fourth ground fault identification means for identifying the two-point ground fault and its local fault phase on the basis of the comparison result of the fifth comparison means is provided, the ground fault on the load side can be reliably separated and early. There is an effect that a three-phase four-wire type ground fault detection device capable of detecting that the ground fault accident is a two-point ground fault and the ground fault phase thereof can be obtained by the detection processing and the simplified comparison calculation processing. .

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a partial block diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram partially showing a second embodiment of the present invention in a block diagram.

FIG. 3 is a circuit diagram showing a partial block diagram of a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a partial block diagram of a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram showing a partial block diagram of a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram showing one phase of a conventional three-phase four-wire ground fault detection device.

[Explanation of symbols]

12a to 12c load, 19a to 19d output current detector, 20u to 22w, 21u to 21w power supply device, 23
Ground current detector, 60, 60A to 60D Ground fault detection means, 61 Addition means, 62 First determination means, 63 Second determination means, 64 First ground fault identification means, 65 Third
Determination means, 66 second ground fault identification means, 67 fourth determination means, 68 third ground fault identification means, 69 fifth determination means, 70 fourth ground fault identification means, C2-C5 comparison results , D determination result, E1 to E4 identification result, F, G ground fault, Ig ground current, In neutral wire output current, Is
Addition result, Iu to Iw three-phase output current, La to Ld
Electric wire.

[Procedure amendment]

[Submission date] April 10, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 4

[Correction method] Change

[Correction content]

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

Next, the operation of the conventional three-phase four-wire ground fault detector shown in FIG. 6 will be described. First, the control means
Power supply control to the loads R and L is performed based on the output voltages V1 to V5 detected by the voltage detectors in the inverter devices 1 to 5, the output current I detected from the output current detector 19, and the like. Further, the abnormality detecting means detects an overvoltage or an overcurrent based on the output voltages V1 to V5, the output current I, and the like, and self-protects the inverter devices 1 to 5.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

According to a fourth aspect of the present invention, there is provided a three-phase four-wire type ground fault detecting device according to any one of the first to third aspects, in which the ground fault detecting means has two phases out of three phases. Based on the comparison result of the third comparing means and the third comparing means for comparing the detected value of the ground current with the value obtained by adding the detected value of the output current of And a second ground fault identifying means for identifying the ground fault and its respective local phase.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

In the fourth aspect of the present invention, 3
The value obtained by adding the output currents of the two phases among the phases is compared with the ground current, and the two-point ground fault and its local fault phase are specified based on the comparison result.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

According to claim 5 of the present invention, 3
Using a power supply device that controls the output currents of the phases to be balanced, each of the output currents of the three phases is compared with the output current of the neutral line, and the one-point ground fault and its ground fault phase are specified based on the comparison result. .

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

[0025]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a circuit diagram partially showing a first embodiment of the present invention. 12a to 12c correspond to a load L composed of reactance, and 19a to 19d are output current detectors 1.
It corresponds to 9, and 23 and Ig are the ground current detector and the ground current similar to those described above.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction content]

Reference numeral 65 is a third judging means which responds to the judgment result D of the ground fault by the first judging means 62.
Of the output currents Iu to Iw of each phase at the time of input of
It includes a third comparing means for comparing a value obtained by adding the detected value of the force current and the detected value of the ground current Ig.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0054

[Correction method] Change

[Correction content]

The third comparing means in the third judging means 65 outputs two phases of the detected values of the output currents Iu to Iw.
When the sum of the currents is equal to the detected value of the ground current Ig, the comparison result C3 indicating that the value related to the phase is equal to the ground current Ig is output.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

That is, the second judging means 66 outputs the output of two phases of the output current of each phase based on the comparison result C3.
When the sum of currents is equal to the ground current Ig, it is specified that a two-point ground fault has occurred in the other two phases.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Name of item to be corrected] 0058

[Correction method] Change

[Correction content]

Ig = Iu + Iv (6)

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0059

[Correction method] Delete

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0060

[Correction method] Delete

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0061

[Correction method] Change

[Correction content]

[0061] Thus, the third comparison means 65 of the ground current Ig detected from ground current detector 23, the output current detector 19a and 19b is detected from the output current I
When the sum of u and Iv is equal, the comparison result C3 indicating the establishment of the equation (6) is output.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction content]

As a result, the second ground fault identifying means 66 is
About the output current Iu and Iv of the U-phase and V-phase
Based on the comparison result C3 indicating the establishment of the equation (6) , it is specified that a two-point ground fault has occurred in the U phase and the V phase, and the specification result E2 is output.

[Procedure Amendment 16]

[Document name to be amended] Statement

[Correction target item name] 0063

[Correction method] Change

[Correction content]

Similarly, in the case of a two-point ground fault in the U phase and the W phase, the following equation (7) for the U phase and the W phase is established, and in the case of the two point ground fault in the V phase and the W phase. Is V phase and
The following expression (8) regarding the output current of the W phase is established.

[Procedure Amendment 17]

[Document name to be amended] Statement

[Correction target item name] 0064

[Correction method] Change

[Correction content]

Ig = Iu + Iw (7) Ig = Iv + Iw (8)

[Procedure 18]

[Document name to be amended] Statement

[Correction target item name] 0081

[Correction method] Change

[Correction content]

That is, if the ground fault resistance at the ground fault point F is small, the U-phase output current Iu does not flow into the load 12a but flows as the ground current Ig on the power supply devices 21u to 21w side via the ground. On the other hand, power supply devices 21v and 21w
The output currents Iv and Iw from the electric currents flow to the loads 12b and 12c, but since the current control is performed on the power supply devices 21u to 21w side as in the above equation (10), the U-phase return line corresponding to −Iu is generated. Will be needed. Since the return line at this time is the output current In of the neutral line, the formulas (12) and (13) are derived.

[Procedure Amendment 19]

[Document name to be amended] Statement

[Correction target item name] 0096

[Correction method] Change

[Correction content]

Incidentally, in FIG. 5, the fifth judging means 6
9 shows the case of responding to the judgment result D of the first judging means 62, the judgment calculation processing may be executed in parallel with the first judging means 62. Alternatively, the determination calculation process may be independently executed.

[Procedure amendment 20]

[Document name to be amended] Statement

[Correction target item name] 0101

[Correction method] Change

[Correction content]

According to a fourth aspect of the present invention, in any one of the first to third aspects, the ground fault detection means adds the detection values of the output currents of the two phases out of the three phases . A third judging means including a third comparing means for comparing the value and the detected value of the ground current, and a two-point ground fault and its local faults based on the comparison result of the third comparing means. Second to identify the phase
Since the ground fault identification means of No. 2 is provided, the ground fault on the load side can be reliably separated and detected at an early stage, and the fact that the ground fault is a two-point ground fault and its local fault phases are further specified. There is an effect that a three-phase four-wire type ground fault detection device capable of taking detailed measures can be obtained.

[Procedure correction 21]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[EXPLANATION OF SYMBOLS] 12a~12c load, 19 a to 19 d output current detector, 20u~ 20 w, 21u~21w power supply, 23
Ground current detector, 60, 60A to 60D Ground fault detection means, 61 Addition means, 62 First determination means, 63 Second determination means, 64 First ground fault identification means, 65 Third
Determination means, 66 second ground fault identification means, 67 fourth determination means, 68 third ground fault identification means, 69 fifth determination means, 70 fourth ground fault identification means, C2-C5 comparison results , D determination result, E1 to E4 identification result, F, G ground fault, Ig ground current, In neutral wire output current, Is
Addition result, Iu to Iw three-phase output current, La to Ld
Electric wire.

[Procedure correction 22]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (6)

[Claims] 1. A power supply device (20u) corresponding to a three-phase four-wire having four output terminals including three-phase and neutral wires thereof.
22w), a power supply line connected to each output terminal of the power supply device, loads (12a to 12c) connected to the power supply line and supplied with power from the power supply device, and A ground wire connected from the neutral wire to the ground, and output currents (Iu) from the three-phase and neutral wires of the power supply device.
~ Iw, In) output current detection means (19a ~)
19d), a ground current detecting means (23) for detecting a ground current (Ig) flowing in the ground wire, and a ground fault detecting means (23) for detecting a ground fault based on a detection value including at least the output currents of the three phases. 60) and 3 phase 4 with
Wire type ground fault detector. 2. The ground fault detecting means is preset with an adding means (61) for adding all detected values of output currents of the three-phase and neutral wires, and an addition result (Is) by the adding means. A first judging means (62) including a first comparing means for comparing the predetermined condition with the predetermined condition, and judging the occurrence of the ground fault based on the comparison result by the first comparing means. The three-phase four according to claim 1.
Wire type ground fault detector. 3. The ground fault detecting means includes second judging means (63) including second comparing means for comparing each detected value of the output currents of the three phases with the detected value of the ground current. And a ground fault detecting means (60A) including a one-point ground fault and a first ground fault specifying means (64) for specifying the ground fault and its ground fault phase based on the comparison result (C2) of the second comparing means. The three-phase four-wire type ground fault detection device according to claim 1 or 2, wherein 4. The ground-fault detecting means is for adding a detection value of each output current of each of the three phases and a neutral wire to have a reverse polarity and comparing a detection value of the ground current. Third judging means including third comparing means (6
5), and a ground fault detecting means (66) that includes a two-point ground fault and a second ground fault identifying means (66) that identifies a two-point ground fault and its local fault phase based on the comparison result (C3) of the third comparing means. 60B) is a 3-phase 4-wire type ground fault detection device according to any one of claims 1 to 3. 5. The power supply device (21u-2) having an output current control function for balancing outputs of the three phases.
1 w), and the ground fault detection means includes a fourth comparison means for comparing each detection value of the output currents of the three phases with a detection value of the output current of the neutral wire.
Based on the comparison result (C4) of the fourth comparison means and the determination means (67)
The ground fault detection means (60C) comprising a point ground fault and a third ground fault identification means (68) for identifying the ground fault phase, and the ground fault detection means (60C) according to claim 1 or claim 2. Phase 4 wire type ground fault detector. 6. The power supply device (21u-2) having an output current control function for balancing the outputs of the three phases.
1 w), and the ground fault detection means includes a fifth comparison means for comparing a value obtained by reversing the detected values of the output currents of the three phases with a value of the output current of the neutral line. A fifth determination means (69) including the fourth determination means (70) and a fourth ground fault identification means (70) for identifying the two-point ground fault and its local fault phase based on the comparison result (C5) of the fifth comparison means. The three-phase four-wire type ground fault detection device according to claim 1, 2, or 5, wherein the ground fault detection means (60D) is provided.