JP5410837B2 - Transformer load switching device - Google Patents

Description

  The present invention relates to a load switching device for a transformer that temporarily switches a low voltage side load of one transformer to the other transformer side uninterruptibly in two transformers having the same high voltage distribution system. Is.

  In order to maintain a stable power supply, maintenance and renewal work for power distribution equipment such as transformers in high-voltage power distribution systems is indispensable. For example, in the case of A and B two-bank power reception, if a replacement work for a pole transformer in B bank occurs, the load LB in B bank is temporarily switched to A bank, and even during construction of B bank, Electric power is supplied, and after completion of the work, work is performed to switch off the load LB to the B bank. There is a strong demand for the construction of such constructions without causing power outages to consumers, and various techniques for this have been proposed.

  For example, a technique as shown in FIG. 9 is disclosed as a conventional power supply switching device. A low voltage distribution line 41a (referred to as A bank) connected to the high voltage distribution line via a transformer (not shown), and a low voltage distribution line 41b (referred to as B bank) connected via another transformer Between the low-voltage distribution lines 41a and 41b, and the power switching device 42 is connected between the low-voltage distribution lines 41a and 41b. ing. The power supply switching device 42 incorporates a switch circuit 43 in which a non-contact switch and a relay contact are connected in parallel, and a detection circuit 44 that detects no-voltage of the load-side distribution line.

  First, when the secondary low-voltage switch (not shown) of the transformer connected to the B bank is manually opened, the low voltage distribution line 41b on the B bank side becomes no voltage, and this is detected. 44, and a conduction command is automatically given from the detection circuit 44 to the non-contact switch of the switch circuit 43 immediately. Then, the non-contact switch is immediately turned on, and power is supplied from the low-voltage distribution line 41a to the B-bank side low-voltage distribution line 41b through the non-contact switch via the A-bank side transformer. Thereafter, a relay contact connected in parallel with the contactless switch is turned on to complete the switching operation (see, for example, Patent Document 1).

However, bank A and bank B are often connected to different phases of the high-voltage distribution line. In this case, if the switching timing is incorrect, a short circuit occurs between bank A and bank B, a short-circuit current flows, and the bank or device is connected. May cause damage.
For this reason, for example, the voltage vector difference between the two outer wire conductors on the left and right opposite to the different bank butt point is calculated using two induction generators of the same magnitude derived using a separately installed three-winding insulation transformer. A technique is disclosed in which switching is performed after power is canceled and both systems on the left and right of the butting point are temporarily placed in parallel operation (see, for example, Patent Document 2).

Japanese Utility Model Publication No. 3-8037 (page 2-3, FIGS. 1 and 2) JP 62-163528 A (5th page, FIG. 1)

However, in the above-mentioned Patent Document 1, since no voltage is detected and switching is performed, there is a problem that an instantaneous power failure (for example, within 10 msec) cannot be avoided. In particular, recent home appliances are often equipped with a microcomputer and a CPU, and there is a strong demand for eliminating the instantaneous power interruption time in order to prevent the loss of memory and the occurrence of problems.
In addition, the technique of Patent Document 2 can avoid momentary power failure, but it is necessary to temporarily install an isolation transformer, which is portable considering the workability of pole transformers and underground power receiving facilities in buildings and condominiums. A switching device by size and weight is required, and there is a problem that these requests cannot be met.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a load switching device for a transformer having a size and weight that can be switched completely and without interruption of power. And

The load switching device for a transformer according to the present invention includes a load on one bank connected to the high-voltage distribution line via a transformer, and the other load connected to the high-voltage distribution line via another transformer. In the load switching device of the transformer for switching to the bank side, it was detachably connected between the low voltage side distribution lines of both banks, and provided in the bank on the disconnect side and the bypass cable provided with a cable switch in the middle A first switching device having an open switch connected in parallel to the switchgear, a first contactless switch connected in parallel to the cable switch, and a second contactless switch and a current limiting element in series. has a circuit body are connected in parallel, and a second switching device having a control circuit for turning on and off the two non-contact switch and opening the switch, in configured, furthermore, each proximity switch, power supply And failure detection circuit is provided having a relay contact and a current detector, the control circuit issues an closing command to open the switch of the first switching device is turned on, switchgear detach side bank is opened After commutation to the open switch side, it has a sequence control function that forms a bypass circuit between both low voltage side distribution lines before turning off the open switch.

According to the load switching device of the transformer of the present invention, the bypass cable is detachably connected between the low-voltage distribution lines of both banks, and is provided in parallel with the bypass switch provided with a cable switch in the middle and the switch device of the bank on the separation side. The first switching device to be connected and the first contactless switch connected in parallel to the cable switch have a circuit in which a series body of a second contactless switch and a current limiting element is connected in parallel. And a second switching device having a control circuit for controlling on / off of both the non-contact switch and the open switch, and each non-contact switch has a power source, a relay contact, and a current detector. failure detection circuit is provided, the control circuit issues an closing command to open the switch of the first switching device is turned on, after the closing device of the disconnection-side bank is commutated to the open switch side is opened Because it has a control function that forms a bypass circuit between both low-voltage distribution lines before turning off the open switch, it can be disconnected without instantaneous power failure and the load on the bank side can be switched to another bank , Transformer replacement work and load simplification work can be performed without causing a power outage to the load.
Moreover, since the failure detection circuit is provided in each contactless switch, the reliability of the switching device can be maintained, and the switching operation can be performed safely and reliably.

It is a connection diagram which shows the load switching device of the transformer by Embodiment 1 of this invention. It is an internal wiring diagram of the 1st switching apparatus of FIG. It is an internal wiring diagram of the 2nd switching apparatus of FIG. It is a connection diagram explaining operation | movement of the load switching apparatus of the transformer of FIG. It is a connection diagram at the time of the switchback operation of the load switching device of the transformer by Embodiment 1. FIG. FIG. 2 is a time chart diagram of each switch during a switching operation in the transformer load switching device of FIG. 1. It is a failure detection circuit diagram of the non-contact switch used for the switching device of FIG. It is a connection diagram which shows the load switching apparatus of the transformer by Embodiment 2 of this invention. It is a connection diagram of a conventional power switching device for bypass construction.

Embodiment 1 FIG.
Hereinafter, a load switching device for a transformer according to Embodiment 1 will be described with reference to the drawings.
As shown in FIG. 1, single-phase, three-wire transformers 3a and 3b are connected from a U-phase, V-phase, and W-phase three-phase high-voltage distribution line 1 via primary cutouts 2a and 2b. Yes. Low-voltage switches 4a and 4b are provided on the secondary side of the transformers 3a and 3b. Low-voltage switches 4a and 4b are connected to low-voltage distribution lines 5a and 5b, respectively. Is connected. The transformer 3a side will be referred to as A bank, and the transformer 3b side will be referred to as B bank.
In the distribution load circuit configured as described above, the transformer load switching device according to the present embodiment has a need for maintenance of the transformer on one bank side, load shifting, or the like on the one bank side. Is temporarily switched so as to receive power supply from the transformer on the other bank side.

  First, the configuration of the load switching device for the transformer will be described. The load switching device includes a first switching device 10, a second switching device 20, a bypass cable 6 that bypasses between the low voltage side distribution lines 5 a and 5 b of the A bank and the B bank, and an intermediate portion of the bypass cable 6. And a cable switch 7 provided.

FIG. 2 is a wiring diagram showing the internal configuration of the first switching device 10. For the sake of clarity, a single-wire circuit is used.
In the first switching device 10, a bipolar third contactless switch 13 and a fuse 14 are connected in series between terminals 11 and 12 for connection to a main circuit, and a third contactless switch 13 is connected. A drive circuit 15 for turning on / off is incorporated. The contactless switch 13 corresponds to an “open switch” recited in the claims, and a third contactless switch is used to distinguish it from a contactless switch used in a second switching device to be described later. It is called a switch.
The third contactless switch 13 is configured, for example, by combining semiconductor switch elements such as thyristors in antiparallel.
The drive circuit 15 receives a command input through the external terminal 16 from a control circuit 27 of the second switching device 20 described later, and controls the contactless switch 13 on and off.

FIG. 3 is a wiring diagram showing the internal configuration of the second switching device 20. Similar to FIG. 2, it is represented by a single line circuit.
In the second switching device 20, a bipolar first contactless switch 23 and a switch 24 are connected in series between terminals 21 and 22 for connection to the main circuit, and the first contactless switch A series body of the second non-contact switch 25 and the current limiting element 26 is connected in parallel with 23. Both the non-contact switches 23 and 25 are composed of semiconductor switch elements as in the third non-contact switch 13, and the current limiting element 26 is composed of, for example, a resistor or a reactor.

  Furthermore, a control circuit 27 for sequentially turning on and off the two contactless switches 23 and 25 is built in. The control circuit 27 is connected to the first switching device described above via the external terminal 28. It is connected to 10 drive circuits 15 so that commands can be issued and controlled. Further, a READY button, a START button, operation indicators for both contactless switches 23 and 25, and the like are arranged on the case panel of the second switching device 20, but the illustration is omitted.

  Next, using the transformer load switching device configured as described above, the load LA on the A bank side in FIG. 1 is temporarily switched to receive power supply from the transformer 3b on the B bank side. Will be described. As shown in FIG. 1, first, the first switching device 10 in the off state is connected in parallel with the low-voltage switch 4a in the on state (corresponding to the “switching device” in the claims), The secondary low-voltage distribution lines 5a and 5b of the transformers 2a and 2b are connected by a bypass cable 6 and a cable switch 7 in an open state. And the 2nd switching apparatus 20 is connected in parallel with the cable switch 7, and the switch 24 is in an OFF state. Further, the external terminal 28 of the second switching device 20 and the external terminal 16 of the first switching device 10 are connected by a signal line. This state is shown in FIG.

Next, the operation will be described. FIG. 4 is an explanatory connection diagram in which the switching devices 10 and 20 connected as shown in FIG. 1 are shown as a single line for easy understanding. FIG. 6 is a time chart of each contactless switch. This will be described with reference to both the drawings.
First, the 3rd non-contact switch 13 (open switch) in the 1st switching apparatus 10 will be in a conduction | electrical_connection state by operating the RADY button installed in the 2nd switching apparatus 20. FIG. Next, by manually opening the low pressure switch 4a, the low pressure switch 4a can be commutated from the low pressure switch 4a side to the third contactless switch 13 side.

Next, after the switch 24 in the second switching device 20 is turned on (manually), the following switching operation is automatically started by operating the START button. That is, the second contactless switch 25 is turned on, and power is supplied from the low voltage side distribution line 5b of the B bank to the low voltage side distribution line 5a of the A bank. However, since 5a and 5b are different systems, a cross current flows simultaneously. However, since the current limiting element 26 is inserted in series in the second contactless switch 25, the magnitude of the cross current is limited to be equal to or lower than the rated current level (in this way, the constant of the current limiting element 26 is set to be constant). Set).
Next, the third contactless switch 13 (open switch) of the first switching device 10 is turned off, the cross current circuit is cut off, and the power supply from the transformer 3a is stopped. Subsequently, after the first contactless switch 23 is turned on, the second contactless switch 25 is turned off, so that the current limiting element 26 is removed and the load LA and the load are loaded from the transformer 3b side of the B bank. Electric power is supplied to the LB.

These series of operations are set to operate at a specified time difference by a timer (or sequencer) built in the control circuit 27. As shown in FIG. 6, since the second contactless switch 25 of the second switching device 20 is on and the third contactless switch 13 (open switch) of the first switching device 10 is turned off, Since a lap time occurs, power supply to the load LA on the A bank side is not interrupted, and no instantaneous power failure occurs.
After the operation of each non-contact switch is completed by the above operation, the bypass circuit of both banks A and B is completed and connected without passing through the first non-contact switch 23 by manually turning on the cable switch 7. Is completed, and the switching devices 10 and 20 can be disconnected from the main circuit.

  Next, an operation procedure for switching the load LA back to the A bank from the above state will be described. When switching back, the connection of both switching devices 10 and 20 is changed. FIG. 5 is a connection diagram of both the switching devices 10 and 20 at the time of switching back. As shown in the figure, the first switching device 10 is connected in parallel with the cable switch 7 connected to the bypass cable 6, and the second switching device 20 is connected in parallel with the low-voltage switch 4a on the A bank side. . Compared to FIG. 1, the first switching device 10 and the second switching device 20 are interchanged, and the rest is exactly the same. Therefore, the switch back operation can be switched by the same operation method as described above.

  Briefly, after the third contactless switch 13 of the first switching device 10 is turned on and the cable switch 7 is manually turned off by operating the RADY button of the second switching device 20, When the switch 24 of the second switching device 20 is turned on and the START button is pressed, the second contactless switch 25 of the second switching device 20 is turned on, and the third contactless switch of the first switching device 10 is turned on. 13 is turned off, the first contactless switch 23 of the second switching device 20 is turned on, and the second contactless switch 25 is turned off (see FIG. 6). Thereafter, the low pressure switch 4a is turned on.

  In the description so far, the case where the non-contact switch 13 is used as the open switch used in the first switching device 10 has been described. However, in addition to using the non-contact switch, an electromagnetic contactor or a circuit breaker is used. The main circuit may be turned on / off. Since the first switching device 10 may have lower switching accuracy than the second switching device 20, any switch that can be opened / closed by a mechanical contact can be used as long as it can be remotely operated, and is less expensive. Can be configured.

Further, the second switching device 20 includes those components, that is, the first contactless switch 23, the switch 24, the second contactless switch 25, the current limiting element 26, and the control circuit 27 in one container. If it is housed and integrated, the switching device 20 can be easily carried, and can be brought into various power receiving facilities to perform switching work.
In addition, since the 1st switching device 10 and the 2nd switching device 20 can be made to approach if the transformer is arrange | positioned nearby like facilities, such as a basement of a building, both switching devices 10 are further provided. , 20 can be accommodated in the same container so as to be integrated, so that the connection work between the two becomes unnecessary and the handling becomes easier.

  Conversely, if the transformer is a pole transformer and the pole transformers to be switched are, for example, about 100 m apart, the first switching device 10 and the second switching device are used. It is difficult to connect 20 with a wire. In this case, the first switching device 10 and the second switching device 20 may be provided with a wireless transmission / reception unit so as to transmit / receive signals by wireless communication. In the case of the load switching device of the present application, there is a margin in the time difference between the time when the second contactless switch 25 is turned on and the time when the third contactless switch 13 (open switch) is turned off. Even if it exists, it is possible to switch stably with no power failure.

In the switching operation, if the contactless switch in the switching device breaks down, the switching operation will fail, and in some cases it may lead to an accident, so the contactless switch operates normally. It is desirable to add a function to determine whether or not.
FIG. 7 is a failure detection circuit diagram for pre-checking the function of the contactless switch. What is necessary is just to add a circuit like a figure to each non-contact switch 13,23,25. Normally open relay contacts 31 and 32 are connected to both ends of each contactless switch, a low-voltage power supply 33 and a current detector 34 are connected therebetween, and a relay control circuit 35 is provided.

This failure detection circuit confirms the operation of each contactless switch before using the switching device. The confirmation method is to turn on or off a non-contact switch that checks with the relay contacts 31 and 32 turned on. If it can be detected by the current detector 34 in synchronization with the ON / OFF command of the contactless switch, the relay control circuit 35 determines that the operation is normal, and returns an error if it cannot be detected in synchronization.
By adding such a function to each of the switching devices 10 and 20, the reliability of the switching devices 10 and 20 can be maintained, and the bank can always be switched safely and reliably.

As described above, according to the load switching device for a transformer of the first embodiment, a bypass cable that is detachably connected between the low-voltage distribution lines of both banks, and a cable switch is provided in the middle, The first switching device connected in parallel to the bank switching device and the second switching device connected in parallel to the cable switch, the control circuit of the second switching device is the first switching device After turning on the release switch of the device and turning it on, the switching device of the bank on the disconnecting side is opened and commutated to the opening switch side, and before turning off the opening switch, a bypass circuit is connected between the low-voltage side distribution lines. Since it has a control function to form, the load on the bank side can be switched to a different bank without instantaneous power failure, so transformer replacement work and load simplification can be done without powering off the load. Construction Ukoto can.
In addition, this load switching device is mainly composed of a low-voltage switch, a contactless switch, a control circuit board, etc., so that it can be reduced in weight and size that can be carried by hand and can be easily handled. Can be provided.

Further, since the opening switch of the first switching device is any one of a non-contact switch, an electromagnetic contactor, or a circuit breaker, the opening switch can be configured at low cost.
In addition, since the second switching device is housed in a single container and formed integrally, it is easy to carry, so it can be easily brought into various power receiving facilities for switching work.
In addition, each contactless switch is equipped with a failure detection circuit that has a power supply, a relay contact, and a current detector, so that the reliability of the switching device can be maintained and the switching operation can be performed safely and reliably. Is possible.
In addition, since the command from the control circuit of the second switching device to the open switch of the first switching device is configured to communicate wirelessly, even if the bank to be switched is far away, switching can be performed without power failure. Is easily possible.

Embodiment 2. FIG.
FIG. 8 is a connection diagram showing a load switching device for a transformer according to the second embodiment. Parts equivalent to those in FIG. 1 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
Depending on the transformer connected to the high-voltage distribution line 1, there may be no low-voltage switch (reference numerals 4a and 4b in FIG. 1) on the secondary side. The present embodiment is a load switching device applicable in such a case.

When the transformer is a columnar transformer, there may be no low voltage switch, but primary cutouts 2a and 2b exist on the primary side. Therefore, this primary cutout is used as “opening / closing device provided in the bank on the separation side”.
As shown in FIG. 8, the first switching device 10 is connected in parallel with the primary cutout 2a, and the second switching device 20 is connected between the low-voltage side distribution lines 5a and 5b as in the first embodiment. The cable switch 7 provided in the bypass cable 6 is connected in parallel.

The switching operation method is the same as that of the embodiment except that the switching operation of the low-voltage switch 4a of the first embodiment is replaced with the primary cutout 2a, and the description thereof is omitted.
In this way, even in a configuration in which the low voltage switches 4a and 4b do not exist, the transformer secondary load can be switched to another bank without a power failure, and can be realized with a portable size and weight. In particular, the transformer replacement work on the utility pole can be easily performed.
In the case of pole transformers, the pole transformers to be switched are often arranged apart from each other, so the first switching device 10 and the second switching device 20 described in the first embodiment. It is effective to adopt a configuration that transmits and receives these for wireless communication.

  As described above, according to the load switching device for a transformer of the second embodiment, the switching device for the bank on the disconnection side to which the first switching device is connected is the primary cutout on the transformer primary side. For example, the present invention can be applied to a pole transformer that does not include a low voltage switch, and the load can be switched without a power failure regardless of the presence or absence of the low voltage switch.

DESCRIPTION OF SYMBOLS 1 High voltage side distribution line 2a, 2b Primary cutout 3a, 3b Transformer 4a, 4b Low voltage switch (switching device)
5a, 5b Low-voltage side distribution line 6 Bypass cable 7 Cable switch 10 First switching device 11, 12 Terminal 13 Third contactless switch (open switch)
DESCRIPTION OF SYMBOLS 14 Fuse 15 Drive circuit 16 External terminal 20 2nd switching device 21 and 22 terminal 23 1st non-contact switch 24 Switch 25 2nd non-contact switch 26 Current limiting element 27 Control circuit 28 External terminal 31, 32 Relay contact 33 Power supply 34 Current detector 35 Relay control circuit LA, LB Load.

Claims (5)

Transformer load switching for switching the load on one bank connected to the high-voltage distribution line via a transformer to the other bank connected to the high-voltage distribution line via another transformer In the device
A bypass cable removably connected between the low-voltage side distribution lines of both banks, and a cable switch provided in the middle;
A first switching device comprising an open switch connected in parallel to a switchgear provided in the bank on the separation side;
A first contactless switch connected in parallel to the cable switch; and a circuit in which a series body of a second contactless switch and a current limiting element is connected in parallel; And a second switching device having a control circuit for controlling on / off of the opening switch,
Further, each of the contactless switches is provided with a failure detection circuit having a power source, a relay contact, and a current detector,
The control circuit issues a turn-on command to the opening switch of the first switching device to turn it on, and after the opening / closing device of the bank on the separation side is opened and commutated to the opening switch side, the opening switch A load switching device for a transformer having a sequence control function of forming a bypass circuit between the low-voltage distribution lines before turning off the power.   The switchgear to which the first switching device is connected is a primary primary cutout of a disconnecting transformer or a secondary low voltage switch of the disconnecting transformer. The transformer load switching device according to claim 1.   The load of the transformer according to claim 1 or 2, wherein the open switch of the first switching device is configured by any one of a non-contact switch, an electromagnetic contactor, or a circuit breaker. Switching device.   The load switching device for a transformer according to any one of claims 1 to 3, wherein the second switching device is housed in a single container and is integrally formed. Wherein the command to open the switch of the second of said first switching device from the control circuit of the switching device, of claims 1 to 4, characterized in that it is configured to communicate by radio The load switching apparatus of the transformer of any one of Claims 1.

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