JP2003217407A - Method for confirming ground-closing of grounding device and ground-closing confirmation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for confirming ground-closing of a grounding device and a ground-closing confirmation device which allow reliable and easy confirmation of the grounding state of a system circuit both during operation and shutdown. <P>SOLUTION: A ground current flowing through a ground wire in response to a contact closing in a grounding device is detected to confirm the ground- closing state. When a contact in the grounding device is closed for its own circuit which is in a shutdown state among a multiple circuits in a power transmission and distribution system, an induction current flowing into the ground wire of its own circuit from an adjacent operating circuit or a charging current flowing through the ground wire of its own circuit is detected to confirm the ground-closing state. Additionally, a low-frequency or high-frequency monitor signal is injected into the ground wire, and the signal is detected to confirm the ground-closing state. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grounding confirmation method for confirming that a power system such as a transmission and distribution line is grounded by making contact with a grounding device, and a grounding confirmation device for implementing this method. It is about.

[0002]

2. Description of the Related Art Grounding for connecting a contact of a grounding device to ground a system line must be performed reliably in order to ensure safety of system maintenance work. Normally, a closing confirmation sensor such as a limit switch is installed in the grounding device driving unit, and the grounding state can be confirmed from this sensor information. However, if a foreign object is inserted into the contact portion of the contact of the grounding device or the contact itself is damaged, it may not be possible to confirm whether or not the contact is surely closed only by the detection by the closing confirmation sensor. Therefore, in order to further ensure safety and reliability, it has been attempted to directly check the closed state of the grounding device by visual inspection.

Here, in a closed-type grounding device such as a gas-insulated grounding device, it is unlikely that foreign matter will enter the inside, and it is usually unnecessary to visually check. However, since it is a closed type, it is difficult to visually confirm the damage or the like of the contacts. Further, even in the air grounding device, it is often difficult to visually confirm depending on the contact position. Therefore, there is a strong need to eliminate human error by electrically detecting contact closure using various sensors, and to save visual confirmation labor.
Various methods are considered.

For example, by installing a current transformer in the ground wire of the ground system and detecting the primary current of the current transformer from the current of the power supply connected to the secondary winding of the current transformer, the primary ground system Japanese Patent Laid-Open No. 60-24543 discloses a method of confirming the grounding state of
Japanese Patent Laid-Open No. 04-27 discloses an invention described in Japanese Patent Application Laid-Open No. 4 which uses a method of detecting an induction current of a transmission line by an airwave.
There is an invention described in Japanese Patent No. 2627.

Further, as a method of confirming the state of a current signal injected from the outside in a gas insulated grounding apparatus, there is an invention described in Japanese Patent Application Laid-Open No. 02-246709. Furthermore,
In addition to the main contactor of the grounding device, an auxiliary contactor for confirmation and a confirmation circuit are installed.When the contact is turned on, the auxiliary contactor is also connected and the confirmation circuit becomes a closed loop circuit, and the injected current signal flows back. There is an invention described in Japanese Patent Publication No. 56-54649 and Japanese Utility Model Publication No. 57-1376 as a method for detecting the operation state and confirming the operating state of the grounding device.

[0006]

The method of confirming the grounding by using the existing grounding device (device having only the closing confirmation sensor such as the limit switch installed) as it is without replacing it has been described above. Various proposals have been made as follows. Here, if the current flowing through the ground line is measured, it is possible to monitor the state of the ground system in addition to the closed state of the grounding device. For example, as a factor of the current induced in the ground system, an induced current from an adjacent operation line in a power transmission system in which multiple lines are parallel, or JP-A-04-27262.
Since induced current from airwaves like No. 7 is considered, in such a ground system, not only the operation of the grounding device is monitored but also the level of the induced current in these ground systems is actually detected in the transmission line. Therefore, I would like to know as the maintenance work side.

The above-described method of monitoring the closing state of the grounding device (the open / closed state of the contacts of the grounding device) by the presence or absence of the induced current can be determined only by the current detection function of the current sensor. It can be easily realized. Further, as described above, according to this method, it is possible not only to monitor the closing state of the grounding device but also to grasp and monitor the state itself of the grounding system.

However, the induced current of the ground wire is not always obtained depending on the system configuration and operating conditions, and in particular, the induced current received from the radio wave in the air is not obtained when desired. This method is not always applicable to monitoring.

Therefore, when the induced current cannot be obtained in this way, a method of intentionally injecting some kind of monitoring signal into the ground system and detecting the presence or absence thereof to confirm the grounding can be considered. When the grounding devices on the self-end side and the other end side of the system are both operating and the contacts are closed, if it is detected that the monitoring signal (monitoring current) flows in the closed loop circuit of the grounding system including the system line, grounding is performed. You can check the input state. At this time, if the frequency of the monitoring signal is high, its impedance increases due to the reactance component of the system,
It becomes difficult for current to flow. Therefore, in monitoring the operation of the grounding device, it is considered more effective to inject a low frequency signal below the commercial frequency.

However, injecting a low-frequency signal into the ground system in this manner has the following two problems. First, when confirming the closing state of the grounding device on the self-end side by injecting a low-frequency signal, it is premised that the grounding device on the mating end side is turned on and a closed loop including a system line is formed. If the grounding device on the mating end side is in the open state or in the state of abnormal closing, it is impossible to confirm closing by this method. next,
For example, when a low-frequency signal is injected into the system by using a current transformer, the voltage level E of the injected monitoring signal is given by the following formula 1.

[0011]

[Equation 1] E = A × f × N × S × B A: Waveform ratio (4.44 for sine wave, 4 for rectangular wave) f: Frequency of monitoring signal N: Number of turns of current transformer ( (One turn in case of through type) S: Iron core cross-sectional area of current transformer B: Magnetic flux density of current transformer

According to the above formula 1, when the frequency of the monitoring signal is lowered, the voltage level of the signal is lowered, which makes it difficult to inject the signal into the ground system and detect it.

Therefore, next, consider injection of a high frequency signal as a monitoring signal. When the frequency of the signal is increased, the impedance becomes high due to the reactance component of the system and it becomes difficult for the current to flow. However, since the system is a distributed constant circuit of R, L and C by resistance, inductance and capacitor, its distribution By injecting the monitoring signal having the same frequency as the resonance frequency of the constant circuit, the monitoring current can be effectively passed through the system.

The resonance frequency differs depending on the system line length and the operating state of the grounding device at the other end, but since the current can flow regardless of the operating state of the grounding device at the other end,
With any system configuration, it is possible to confirm the closing state of the grounding device on the self-end side of the grounding system. However, since this resonance frequency differs for each system depending on the system conditions such as the system line length and the turning-on state of the grounding device on the other end side, it is difficult to specify its exact value in advance. Even with a grounded system, if a high-frequency signal is injected, high voltage may be induced in the injection-destination system, and the device connected to the system may be affected by the high-frequency signal, so caution is required. Become.

Therefore, the present invention intends to solve the above-mentioned various problems and provide a grounding confirmation method and a grounding confirmation device for a grounding device which can surely and easily confirm the grounding state of a system line. It is a thing.

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 is to detect the grounding current flowing through the grounding wire when the contact of the grounding device is turned on to confirm the grounding state. In the method of confirming the grounding of the device,
When the contact of the grounding device is turned on for the own line that is in a stopped state in the multi-line parallel power transmission and distribution system, the induced current from the adjacent operating line that flows to the ground line of the own line or the ground line of the own line The charging current is detected to confirm the grounding state.

According to a second aspect of the present invention, when a low-frequency monitoring current is injected into the ground line on the self-end side of the system line, a closed loop circuit is formed via the ground line on the other end side and the system line. In addition, the self-end side detects that the monitoring current flows, and confirms the grounding state of the self-end side and the mating end side.

According to a third aspect of the present invention, when a monitoring current having a frequency close to the resonance frequency of the system line as a distributed constant circuit is injected into the ground line on the self-end side of the system line, the other end is grounded. The self-end side detects that the monitoring current flows in the closed loop circuit formed via the line and the system line, and confirms the grounding state of the self-end side.

According to a fourth aspect of the present invention, in the grounding confirmation method for the grounding device according to the third aspect, the self-injection and detection of the monitoring current into the ground line is performed while changing the frequency of the monitoring current within a predetermined range. Repeatedly on the side, the resonance frequency of the system line is specified by the frequency of the monitoring current when the monitoring current is detected, and the grounding state of the other end is confirmed.

According to a fifth aspect of the present invention, the grounding confirmation operation described in the first, second and third aspects or the first, second and fourth aspects is sequentially executed in this order, and the self-end side and the other end This is to check the grounded state of the side.

According to a sixth aspect of the present invention, the frequency is variable in the grounding confirmation device for the grounding device, which detects the grounding current flowing in the grounding wire by closing the contacts of the grounding device to confirm the grounding state. The signal injection control means for injecting the monitoring current into the ground line of the own line, the induction current from the adjacent operation line flowing in the ground line of the own line or the charging current flowing in the ground line of the own line, or the monitoring current The measurement control means for measuring is provided.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, this embodiment is to electrically confirm that a contact of a grounding device connected to a system line has been turned on to be in a grounding state. The grounding is confirmed by detecting.

FIG. 1 shows a system configuration to which this embodiment is applied. Contacts 1A 'and 1B' are provided on the ground lines 2A and 2B at the self-end and the other end of the system line 2 such as a three-phase transmission line.
The grounding devices 1A and 1B for driving to open and close are connected.
Of these, a grounding confirmation device 3 for confirming the contact closing state is installed near the self-end grounding device 1A.

The grounding confirmation device 3 includes measurement CTs 4R, 4S, 4T for measuring the current flowing through the grounding wire 2A.
And signal injection CTs 5R, 5S, 5T for forcibly injecting the monitoring signal into the ground line 2A. It should be noted that only one signal injection CT may be connected to the ground line that collectively connects the three phases, as indicated by 5Z. Here, when injecting the monitoring signal into the ground line 2A for each phase individually,
Signal injection for each phase CT 5R, 5S, 5T is used, and a single signal injection C is used when the monitoring signals are injected in three phases at once.
T5Z is used.

The grounding confirmation device 3 includes a grounding device 1
The closing confirmation command is input from A, and the grounding confirmation device 3 issues a status display output of the grounding device 1A.
Here, the closing confirmation command is a command for causing the confirmation operation by the grounding confirmation device 3 to confirm the closing state of the contact 1A ′ by the grounding device 1A.

Since the power system line 2 such as a power transmission line is usually composed of a plurality of parallel lines, an induced current flows from the adjacent operation line to the line that is stopped. If this stop line is normally grounded, an induced current will flow in the ground line, and the induced current at this time will be detected by the measurement CTs 4R, 4S, 4T and the grounding confirmation device 3 will ground the stop line. You can confirm the input. The same applies to the case where the charging current of the own line flows through the ground line of the stop line. As mentioned above, the induced current from the adjacent operation line and the charging current of the own line (in the following,
A method for detecting the grounded state by detecting the induced current) is referred to as STEP 1.

However, an induced current is not always obtained depending on the system configuration and operating conditions, such as when one line power transmission line or all lines are stopped. At this time, the ground line 2 is connected through the signal injection CT 5R, 5S, 5T or 5Z described above.
By forcibly injecting the monitoring current into A, the presence or absence of the above monitoring current is detected by CT 4R, 4S, 4T in a closed loop circuit including the ground wire of the other end, the system line, and the ground wire of its own end, and grounded. The closing confirmation device 3 detects and judges the grounding state of the self-end. That is, if the monitoring current is detected at this time, it can be determined that the grounding devices at the self-end and the other end are in the closed state, and if the monitoring current is not detected, at least one of the grounding devices at the self-end and the other end is detected. It can be determined that one or both have not been input.

In the present invention, in the above-mentioned signal injection detection method, the low frequency signal injection detection method for injecting and detecting the monitoring signal of a relatively low frequency of about commercial frequency or lower is STEP2, and the system as a distributed constant circuit is used. The high frequency signal injection detection method of injecting and detecting the high frequency monitoring signal corresponding to the resonance frequency is referred to as STEP3.

FIG. 2 shows the internal structure of the grounding confirmation device 3. This device 3 communicates with a measurement control unit 31 that measures a current flowing through the grounding wire 2A at its own end, and a communication interface (I / F) that wirelessly communicates measurement data, a grounding determination result, a self-diagnosis result of the device, and the like. ) 32,
It is composed of a signal injection control unit 33 for injecting a monitoring signal of a predetermined frequency into the ground line 2A, and a power supply unit 34 for supplying power to each unit in the apparatus.

The measurement control unit 31 measures the measurement CT 4R,
A switch 311 selectively connected to 4S and 4T, an A / D converter 312 on the output side thereof, a microcomputer 314 to which the digital output signal thereof is input, and a digital signal output unit to which the output signal of the microcomputer 314 is added. (DO) 3
15 and a digital signal input unit (DI) 313 to which a closing confirmation command from the grounding device 1A and a clock signal CLK from a frequency control unit 333 to be described later are input.

In addition, the signal injection control unit 33 includes a power supply unit 34.
A switch 334 for power supply connected to the frequency control unit 333, a frequency control unit 333 to which the output signal of the digital signal output unit 315 is added, and a frequency variable signal source 332 to which the clock signal CLK from the frequency control unit 333 is input. ,
The monitoring CT 335 on the output side and the frequency variable signal source 33
2 output signal (monitoring signal) signal injection CT 5R, 5
And a switch 331 for selectively applying to S, 5T or 5Z. The switch 311,
331 and 334 are controlled to be opened and closed by the microcomputer 314 via the digital signal output unit 315.

The operation of the grounding confirmation device 3 will be described below. During normal system operation in which the grounding device 1A of FIG. 1 is not operating, only the measurement control unit 31 and the communication interface 32 are operating and the microcomputer 314 constantly performs self-diagnosis of the device. At this time, since the signal injection control unit 33 does not need to operate, the internal switch 334 is turned off to stop the power supply to the variable frequency signal source 332 and suppress unnecessary power consumption except when necessary. ing.

The grounding device 1A is also used during normal system operation.
Since the contact point 1A 'of the above is in an open state, the system induced current does not flow in the ground line 2A, and even if a monitoring signal is injected into the ground line 2A, the contact point 1B' of the other end grounding device 1B,
Since a closed loop circuit including the system line 2 and the contact 1A 'of the self-grounding device 1A is not formed and no current flows through the ground line 2A, the monitoring current is not detected from the measurement CTs 4R, 4S, 4T.

Therefore, when the grounding device 1A is not operating, the signal injection control unit 33 and the signal injection CT 5 are periodically performed.
In order to check whether the signal input up to R, 5S, 5T or 5Z and the measurement input of the A / D converter 312 of the measurement control unit 31 are normal, power is supplied to the signal injection control unit 33 at regular intervals. The switch 334 is turned on. Accordingly, while applying the monitoring signal to the signal injection CT 5R, 5S, 5T or 5Z, at the same time as switching the switch 311 of the measurement control unit 31, the monitoring CT 335 of the signal injection control unit 33 causes the signal injection CT 5R, 5S, 5T or It is monitored that an exciting current of a known level by the frequency variable signal source 332 flows in 5Z, and the measurement CT 4R, 4 of the ground line 2A is measured.
Confirm that the monitoring current is not detected from S and 4T.

In the induction current detection method of STEP 1 described above, the digital signal input unit 3 issues a closing confirmation command from the grounding device 1A while the operation of the signal injection control unit 33 is stopped.
Taken in 13, triggered by this injection confirmation command,
The induced current flowing in the ground wire 2A is measured by CT 4R, 4S,
Confirm that it can be obtained from 4T by the microcomputer 314,
Check and judge the grounding state. If the induced current cannot be obtained for a certain period of time due to the suspension of all lines,
The grounding state is confirmed by the signal injection detection method of STEP2 and STEP3.

In these signal injection detection methods, the power supply switch 334 of the signal injection controller 33 is turned on, and the monitoring signals of various frequencies controlled by the frequency controller 333 and the frequency variable signal source 332 are switched to the switch 331 and the signal. Injection CT 5R, 5S, 5T or 5Z is forcibly injected into the ground line 2A. Then, the grounding state is confirmed by measuring the monitoring signal that has passed through the closed loop circuit including the ground line 2B of the other end, the system line 2, and the ground line 2A of the own end by the measurement CTs 4R, 4S, 4T.

In the configuration of FIG. 2, signal injection CT
When the three-phase is set to 5Z, the switch 331 of the signal injection control unit 33 becomes unnecessary, and the variable frequency signal source 332 is used.
The signal injection CT 5Z is directly connected to the signal injection CT 5Z. Further, the clock signal CL which is the output of the frequency control unit 333
By taking K into the measurement control unit 31 via the digital signal input unit 313, it is possible to grasp the frequency of the monitoring signal and monitor the frequency control unit 333 at the same time.

FIG. 3 is a flow chart showing the processing of each of the STEPs (induction current detection method and signal injection detection method), which is mainly processing executed by the grounding confirmation device 3 in FIG. When the closing confirmation command is input from the grounding device 1A (S1), as the induced current detection method of STEP1, first, the detection flag r of each phase is set to r = s = t = 0, and then it flows to the grounding wire 2A of each phase. Measure the induced current CT 4
The R, 4S, and 4T are sequentially measured from the R phase (S2), and the presence or absence of the induced current is determined (S3). The detection flag is set to 1 each time the induced current of each phase is detected, and the process jumps to S23 by the determination process (S4) that the induced currents of all phases are detected (detection flag r = s = t = 1). Then, a display indicating that the grounding state is normal is output. This display output is executed via the communication interface 32 and the digital signal output unit 315 in FIG. If there is a phase in which the induced current is not detected for a certain period of time, S4
After the No branch of No., the process moves to the next STEP2.

In the low frequency signal injection detection method of STEP2, a monitoring signal of a low frequency equivalent to or lower than the commercial frequency is injected into the ground line 2A, but this signal injection could not be confirmed in STEP1. Only the phase (phase in which no induced current is detected) is performed. Before injecting the low frequency signal, it is always confirmed that no induced current is present in the ground line 2A (S5, S6), and then the low frequency signal is injected in S7. By inserting the above confirmation processing (S5, S6), it is possible to avoid the occurrence of a failure due to the reverse input from the signal injection CT 5R, 5S, 5T or 5Z to the signal injection control unit 33 in the presence of the induced current. . The control circuit provided in the signal injection control unit 33 for preventing the failure due to the reverse input will be described later with reference to FIG. It should be noted that the low frequency signal is injected by the variable frequency signal source 332, the switch 331 and the signal injection CT 5R, 5S, 5T or 5 in the signal injection control unit 33.
Through Z.

Next, the low frequency signal injected in the above S7 is measured by the measurement CT and the presence or absence thereof is determined (S8, S
9) When the ground currents of all the phases are detected together with the result of STEP1, the detection flag s = r = t = 1 for each phase, and the injection stop of the monitoring signal (S10) and the determination process (S1).
Through step 1), the fact that the grounded state is normal is displayed and output (S23).

When a low-frequency monitoring signal is injected into the ground line 2A, the monitoring current flows in the closed loop including the system line 2 because the other end is also grounded as shown in FIG. 4 (a). Since the monitoring current does not flow when is not in the grounded state, it is impossible to determine whether or not the grounding device 1A at its own end is in the closed state. In FIG. 4A, R + jX
Is the impedance of the system, R is the resistance component, and X is the reactance component. For low frequency signals,
The capacitance component existing between the system line 2 and the ground can be ignored. As described above, in the low frequency signal injection detection method according to STEP2, it may not be possible to confirm the grounding on the self-end side, and in that case, the process shifts to the high frequency signal injection detection method in STEP3.

When considering the injection of the high frequency monitoring signal into the system, the system line 2 can be considered as a distributed constant circuit of R, L and C as shown in FIG. 4 (b). If a high frequency signal corresponding to the resonance frequency of the distributed constant circuit is injected into the ground line 2A, a current effectively flows through the capacitance component C. At this time, the system resonance frequency greatly changes depending on the open / closed state of the grounding device 1B (contact 1B ') at the other end, but since the resonance frequency exists in any state, the monitoring current flows regardless of the grounding state at the other end. It is possible to check the grounding state of the grounding device 1A at its own end by detecting this monitoring current.

Referring again to FIG. 3, the determination processing by the high frequency signal injection detection method in STEP3 is the same as that in STEP1,
It is executed only for the phase whose grounding cannot be confirmed in STEP2. Here, before injecting the high frequency signal, it is surely confirmed that there is no induced current in the ground line 2A as in STEP 2 (S12, S13). Further, as described above, by applying a high frequency signal to the system, depending on the system configuration and operating conditions, a high voltage may induce a high voltage in the system, or a high frequency signal may be applied to equipment connected to the system. There is a possible problem. Therefore, the user of the grounding confirmation device according to the present embodiment has a function of locking the process of STEP 3 as needed (S14).

STE including S12 to S14 described above
If the usage condition of P3 is satisfied, a high frequency signal of frequency f will be injected as a monitoring signal (S15). Here, when the frequency f of the monitoring signal is a signal corresponding to the resonance frequency of the system, a peak point appears in the magnitude of the current flowing through the ground line 2A. Since it depends on the system configuration and operating conditions such as the grounding state at the end, it is difficult to identify and inject the resonance frequency in advance.

Therefore, in S15 to S19, the frequency f of the high-frequency signal to be injected is changed (sweep) while adding (changing) from the F _min value to the F _max value in steps of Δf.
The presence or absence of the injection current is detected in S16 and S17, and the detection flag is set to 1 for the detected phase to stop the injection of the monitoring signal (S20). When the monitoring current is detected for all the phases by combining the detection result of S17 and the determination results of the previous STEP1 and STEP2, the detection flag r = of each phase
Since s = t = 1, the judgment processing (S21) is performed and the fact that the grounding state is normal is displayed and output (S23). Here, the frequency sweep of the high-frequency signal to be injected will be described with reference to FIG. 6 described later.

When the ground current (induction current or monitoring current) cannot be detected in STEP1, STEP2, and STEP3, it is determined that the contact of the grounding device 1A is abnormal or a foreign object is inserted in the contact portion, and the grounding device closing error is displayed. Output (S22).

Next, FIG. 5 shows an output control circuit of the signal injection control unit 33. In FIG. 5, 331Rx, 33
1Sx and 331Tx are AND gates to which monitoring signals of respective phases are input, 331Ra, 331Sa and 331Ta are a-contacts that operate by the output of the AND gate, 331R
b, 331Sb, 331Tb are b contacts operated by the output of the AND gate, and 331y is a signal injection C of each phase.
The protective elements are respectively connected to both ends of T 5R, 5S, 5T. In addition, a-contacts 331Ra, 331Sa, 3
31Ta and b contact 331Rb, 331Sb, 331T
b corresponds to the switch 331 in FIG.

Normally, when the monitoring signal is not injected, the b contacts 331Rb, 331Sb, 331Tb are closed,
Conversely, the a contacts 331Ra, 331Sa, 331Ta are open. As a result, signal injection CT 5R, 5S, 5T
Alternatively, even if a reverse input signal such as a system induced current is input from 5Z, these signals are not input to the variable frequency signal source 332. Therefore, after surely confirming that there is no induced current, as in S6 of FIG. 3 described above,
The monitoring signal is injected by switching the a contact and the b contact according to the output of the AND gate.

Next, FIG. 6 shows the above STEP2 and STEP3.
3 shows an example of the waveform of the supervisory signal injected into the ground line. Although a sine wave signal or a rectangular wave signal can be considered as this type of monitoring signal, in the present embodiment, the monitoring signal is a rectangular wave in order to simplify and easily realize the configuration of the frequency variable signal source 332.

As shown in FIG. 6 (a), the low frequency signal in STEP 2 corresponds to a commercial frequency of 50 Hz,
As shown in FIG. 6B, the high frequency signal in STEP 3 changes the frequency f from F _min to F _{max in} steps of Δf while repeating signal injection and stop at a cycle of 10 ms. As a result, the rectangular wave having the same cycle can be obtained a plurality of times at a certain interval, so that the measurement control unit 31 can perform the detection determination operation of the monitoring current a plurality of times, and the transient noise signal and the monitoring are detected. It is possible to measure and determine the signal separately.

[0051]

As described above in detail, according to the present invention, since the grounding state is electrically confirmed, the electrical grounding failure due to the damage of the contacts of the grounding device or the insertion of foreign matter into the contacts is surely ensured. It is possible to detect. Further, the state of the ground system can be monitored by measuring the induced current from the adjacent operation line, and the state of the adjacent operation line can be estimated from the induced current level. In addition, even in systems where an induced current cannot be obtained, by injecting a low-frequency signal or high-frequency sweep signal as a monitoring signal and detecting them, it is possible to reliably confirm the grounding state for all types of systems. You can

Further, for example, in the system line as shown in FIG. 4B, the resonance frequency of the system line greatly changes depending on the grounding state of the other end, but the theoretical value of this resonance frequency can be easily obtained if the system constant is known. It can be calculated. Therefore, since the resonance frequency of the system can be grasped by the high-frequency signal injection detection method of STEP3 described above, if the system constant and the system condition can be grasped, the signal of this resonance frequency is injected and detected, thereby grounding the other end. It is possible to determine the state from the self end.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration to which an embodiment of the present invention is applied.

FIG. 2 is a configuration diagram of the grounding confirmation device in FIG.

FIG. 3 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a monitoring current path in the signal injection detection method.

FIG. 5 is a configuration diagram of an output control circuit of the signal injection control unit according to the embodiment of the present invention.

FIG. 6 is a diagram showing an example of waveforms of a supervisory signal in the embodiment of the present invention.

[Explanation of symbols]

1A Self-grounding device 1B Opposite end grounding device 1A ', 1B' contacts 2 lines 2A, 2B ground wire 3 Grounding confirmation device 4R, 4S, 4T Measurement CT 5R, 5S, 5T, 5Z Signal injection CT 31 Measurement control unit 32 communication interface 33 Signal injection controller 34 Power Supply 311, 331, 334 switch 312 A / D converter 313 Digital signal input section (DI) 314 Microcomputer 315 Digital signal output section (DO) 331Ra, 331Sa, 331Ta a contact 331Rb, 331Sb, 331Tb b contact 331Rx, 331Sx, 331Tx AND gate 331y protection element 332 Frequency variable signal source 333 Frequency control unit 335 Surveillance CT

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideki Ota             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Masanori Toi             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Koji Yutani             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd.

Claims (6)

[Claims] 1. A grounding confirmation method for a grounding device, which detects a grounding current flowing through a grounding wire when a contact of the grounding device is turned on to check the grounding state. When the contact of the grounding device is turned on for the own line in, the grounding state is confirmed by detecting the induced current from the adjacent operating line flowing in the ground line of the own line or the charging current flowing in the ground line of the own line. A method for confirming that the grounding device is grounded. 2. A method for confirming the grounding of a grounding device, which detects a grounding current flowing in a grounding wire when a contact of the grounding device is turned on to check the grounding state, wherein a low grounding wire is added to the grounding wire on the self-end side of the system line. When the monitoring current of the frequency is injected, the self-end side detects that the monitoring current flows in the closed loop circuit formed via the grounding wire and the system line on the other end side, and the self-end side and the other end side A method for confirming the grounding of a grounding device, characterized by confirming the grounding state of. 3. A method for confirming the grounding of a grounding device, which detects a grounding current flowing in a grounding wire when a contact of the grounding device is turned on to check the grounding state, wherein the grounding wire on the self-end side of the system line is: When a monitoring current having a frequency close to the resonance frequency of the system line as a distributed constant circuit is injected, it is possible to prevent the monitoring current from flowing in the closed loop circuit formed via the ground line on the other end side and the system line. A method for confirming the grounding of a grounding device, characterized by detecting the grounding state of the self-side by detecting at the end side. 4. The grounding confirmation method for the grounding device according to claim 3, wherein the monitoring current is repeatedly injected and detected at the self-end side while changing the frequency of the monitoring current within a predetermined range, and monitoring is performed. A method for confirming grounding of a grounding device, characterized in that a resonance frequency of a system line is specified by a frequency of a monitoring current when a current is detected to confirm a grounding state of a mating end. 5. Claims 1, 2, 3 or claim 1,
A method for confirming grounding of a grounding device, characterized in that the grounding confirmation operation described in 2 and 4 is sequentially executed in this order to confirm the grounding state of the self-end side and the other end side. 6. A grounding-on confirmation device for a grounding device, which detects a grounding current flowing through a grounding wire when a contact of the grounding device is turned on to confirm a grounding-on state. Signal injection control means for injecting into the ground line, and an induced current from an adjacent operation line flowing through the ground line of the own line or a charging current flowing through the ground line of the own line, or measurement control for measuring the monitoring current A grounding confirmation device for a grounding device, comprising: