JPH07212974A - Power source switch of low-voltage distribution line work - Google Patents

Abstract

PURPOSE:To prevent an instant power interruption and avoid a bad influence on a motor load by switching a power supply of a distribution line through parallel feeding from a power supply of a work bank and a temperary power supply. CONSTITUTION:Before the work, switchgears 27, 28 are turned on after a temporary cable becomes synchronous with a power supply of a work bank #1 and after the power is parallelly supplied to a distribution line 7 from the power supply of the work bank #1 and from a temporary power supply through the switchgear 28, a lead wire 9 is cut and the switchgear 27 is opened and thereby the power supply of the distribution line 7 is switched to the temporary power supply. After the work, the switchgear 27 is turned on to open both switchgears 27, 28 and the feeding condition is turned back again to the parallel feeding from the power supply of the work bank #1 and the temporary power supply and then the lead wire 9 is connected to open both switchgears 27, 28 and thereby the power supply of the distribution line 7 is switched back to the power supply of the work bank #1. By this method, an instant power interruption accompanied by the switching of the power supply does not appear and there is no bad influence on a motor load of the distribution line 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply switching device for low-voltage distribution line work, which switches the power supply of the low-voltage distribution line uninterruptibly during distribution line work such as replacement of a distribution transformer in a construction bank.

[0002]

2. Description of the Related Art Conventionally, a low voltage distribution line of each bank, which is coupled to a high voltage bus bar (6.6 KV) via a distribution transformer such as a pole transformer, supplies power to a three-phase load and a single-phase load. Often consists of three-phase, four-wire. In addition, when replacing the distribution transformer, etc., uninterrupted low voltage distribution line construction will be carried out so that the low voltage distribution line in the construction bank will not be cut off.

In this construction, the power supply of the low voltage distribution line of the construction bank is uninterrupted from the construction bank power supply to the temporary power supply,
In order to switch to the opposite, a power supply switching device for low-voltage distribution line construction using an instantaneous switching switch is conventionally used.

Next, a conventional power supply switching device of this type will be described with reference to FIGS. In FIG.
6.6KV of construction bank # 1 and sound bank # 2
Is a high-voltage busbar, and is formed by the same or different system busbars.

Reference numerals 3 and 4 are distribution transformers of banks # 1 and # 2 whose primary sides are connected to high-voltage buses 1 and 2 through transformer primary cutout switches 5 and 6, and lead wires 7 and 8 are lead wires. 9,
It is a low voltage distribution line of, for example, 200 V of banks # 1 and # 2 connected to the secondary side of distribution transformers 3 and 4 via 10. 11, 12 and 13 are loads on the distribution line 7 and load 1
Reference numerals 1 and 12 are inductive motor loads. Reference numerals 14 and 15 are loads on the distribution line 8, and the load 14 is an inductive motor load.

Reference numerals 16 and 17 denote switches for a bypass power supply line and a temporary power supply line, which are used only during construction. The switch 16 is arranged in parallel with the lead wire 9, and the switch 17 is a low-voltage distribution line 7, It is provided between eight. In addition, although shown as a single line in FIG. 4, normally, the three-phase power source of the high voltage busbars 1 and 2 is stepped down by the transformers 3 and 4, and the three-phase power source of the secondary side of the transformers 3 and 4 is three. It is supplied to the low-voltage distribution lines 7 and 8 of phase 4 wire or 3 phase 3 wire.

Further, the switches 16 and 17 are formed by so-called low voltage instantaneous switching switches, and these switches have a main circuit section and a control circuit section. As shown in the one-phase configuration of the switch 16 in FIG. 5, the main circuit section includes a normally open contact 16a and a triac 16b between the power supply side and load side terminals for each phase.
And a parallel circuit is provided.

Further, the control circuit section for turning on and off the main circuit section has various detection and control functions such as the following voltage detection, phase detection, manual closing, manual opening, and standby state control (automatic closing). . <Detection> Determine whether the voltage on the power supply side or the load side of each phase is normal or abnormal based on the voltage between the specified phase on the power supply side and ground. <Phase detection> If the load side phase rotation direction is the same as the power supply side phase rotation direction, it is determined to be normal. <Manual input> If the results of voltage detection and phase detection are not abnormal, the main circuit is closed and turned on by operating the "ON" button. <Manual release> Unconditionally open the main circuit section by pressing the "OFF" button. <Stand-by state control> (Automatic turn-on) If the results of voltage detection and phase detection are not abnormal, the standby state is set by pressing the "Standby" button. Instantly turn on each phase and automatically turn on the main circuit.

When the main circuit portion is turned on (turned on), as shown in FIG. 6, the triac 16b is turned on (O
N) to turn on (ON) the contact 16a from OFF (OFF)
Absorb the time delay of the reversal to and reliably input.
Also, when the main circuit is opened (off), the triac 16b is turned on instantly as shown in FIG. 7, the contact 16a is turned off before the triac 16b turns off to prevent an arc short circuit, and then the triac 16b. Turn off.

Then, when replacing the transformer 3 of the construction bank # 1, the work is performed in the following procedure. A. Before replacement (1) The switch 16 is attached in parallel to the lead wire 9 so that the load side terminal of the main circuit part is connected to the distribution line 7, and the switch 17 is connected to the load side terminal of the main circuit part. Is provided between the distribution lines 7 and 8 so that the connection is made to the distribution line 7.

(2) After the switch 16 is manually turned on, the lead wire 9 is cut as shown by the mark X in FIG. 4, and the power feeding path to the distribution line 7 of the secondary side output of the transformer 3 is connected to the lead wire 9. From switch 1
Switch to No. 6 bypass power supply line.

(3) After the switch 17 is controlled to be in the standby state, the switch 16 is manually opened, the load side of the switch 17 is set to no voltage, and the switch 17 is instantly and automatically turned on to supply power to the distribution line 7. Is instantaneously switched from the power source of the construction bank # 1 on the secondary side of the transformer 3 to the temporary power source based on the power source of the sound bank # 2 via the distribution line 8. (4) Open the transformer primary cutout switch 5 to open the primary and secondary sides of the transformer 3.

After the transformer 3 is replaced, the next replacement work is performed. B. After replacement (5) Turn on the transformer primary cutout switch 5 to restore power to the primary side of the transformer 3. (6) After the switch 16 is controlled to the standby state, the switch 17 is manually opened, and the switch 16 is instantly and automatically closed to distribute the distribution line 7
Instantly switch the power supply from the temporary power supply back to the work bank # 1 power supply, that is, the secondary side output of the transformer 3.

(7) After disconnecting the lead wire 9 to repair the lead wire 9, the switch 16 is opened to open the transformer 3
The secondary-side output power supply path of the switch is returned from the bypass power supply path of the switch 16 to the lead wire 9. (8) The switches 16 and 17 are removed to complete the work.

Then, the switches 16 and 17 are instantly and automatically turned on from the standby state due to the voltage loss on the load side, and the power source of the distribution line 7 is temporarily installed from the power source of the construction bank # 1 before and after replacement by this automatic turning on. Since the power source and vice versa are switched instantly, work can be performed without interruption.

Further, when the switches 16 and 17 are automatically turned on from the standby state, as shown in FIG. 8, which corresponds to the case where the switch 16 is manually opened and the switch 17 is automatically turned on in the procedure (3). , Switch 16 or 17 turns off and switch 17
Or, by the time that the power line 16 is turned on, a zero period T in which the voltage and the current of the distribution line 7 are always 0 occurs, so that the voltage phases of the distribution lines 7 and 8 are different and the power source of the construction bank # 1 and the temporary power source are different. Even if the power sources of different systems are out of phase, the power source of the distribution line 7 can be switched without causing a so-called short circuit accident.

[0017]

In the case of the conventional power supply switching device, when the power supply of the distribution line 7 of the construction bank # 1 is switched,
When the switch 17 or 16 in the standby state is closed, the above-mentioned zero period T
Therefore, when there is a motor load such as the loads 11 and 12 on the distribution line 7, there is a problem in that those loads cause inconveniences due to the power supply switching regardless of the load capacity. .

That is, when the motor load is relatively small and the influence of the motor load on the voltage and current of the distribution line 7 can be neglected, immediately when the switch 16 is manually opened and turned off as shown in FIG. Transition to the zero period T. Although this period T is an instant of 10 msec or less, the rotation speed of the motor load decreases due to the disappearance of the voltage and current of the distribution line 7 during this period.

Therefore, when the switch 17 in the standby state is automatically turned on and turned on after the lapse of the zero period T, and the power supply of the distribution line 7 is switched, immediately after this, the energizing current of the motor load rapidly increases and the torque is increased. There is a problem that mechanical shock is added due to the rapid increase of the current and the protection device operates due to so-called transient current.

When the motor load is large and the influence of this load cannot be ignored, for example, when the switch 17 is placed in the standby state and the switch 16 is manually opened, the motor load is generated even if the switch 16 is turned off. As a result, the voltage and current of the distribution line 7 do not instantly become zero but gradually decrease due to the regenerative power.

In this case, it takes a time T'to decrease the voltage of the distribution line 7 to the detection loss level V _L of the voltage detection, and after the time T ', the zero period T is entered to turn on the switch 16. Since the switch 17 is turned on, it takes time until the switch 17 is turned on and the temporary power is supplied to the distribution line 7. Therefore, switch 1
Immediately after the switch 7 is turned on and turned on, the voltage of the distribution line 7 based on the regenerative power of the motor load and its frequency are significantly different from those of the temporary power source, and in this case, the same problem as that when the motor load is small occurs.

It is an object of the present invention to provide a power source switching device which eliminates the momentary interruption when switching the power source of the distribution line 7 of the construction bank # 1 so as not to inconvenience the motor load.

[0023]

In order to achieve the above object, in a power source switching device for low voltage distribution line construction of the present invention, a construction transformer connected to a secondary side of a distribution transformer of a construction bank. Side terminal and the construction distribution line side terminal connected to the low voltage distribution line of the construction bank,

A sound distribution line side terminal connected to the low voltage distribution line of the sound bank, a rectifier circuit for converting the AC power supply of the terminal into DC, and an inverter for converting the output of the rectifier circuit into AC for temporary power supply. An isolation transformer whose output is fed to the primary side,

A switch for a bypass power supply path provided between the construction transformer side terminal and the construction distribution line side terminal, and between the secondary side of the insulation transformer and the construction distribution line side terminal. Switch for temporary power supply line,

The inverter is controlled so that the secondary voltage of the insulation transformer matches the power supply voltage of the construction bank on the secondary side of the distribution transformer, and the secondary voltage matches the power supply voltage of the construction bank. With a control circuit that prohibits the turning on and off of both switches,

Before installation of the distribution line, both switches are turned on to cut the lead wire, and then the switch for the bypass power supply line is opened to switch to the temporary power supply. After the distribution line work, the switch for the bypass power supply line is opened. Turn on and connect the lead wires with both switches on, then open both switches to switch back to the construction bank.

[0028]

In the case of the power source switching device for low-voltage distribution line construction of the present invention configured as described above, during the distribution line construction such as replacement of the distribution transformer of the construction bank, the control circuit causes The output of the inverter based on the power supply is controlled so as to be synchronized with the power supply of the construction bank to form a temporary power supply on the secondary side of the insulation transformer.

Before the construction, the temporary power source is synchronized with the power source of the construction bank, and then the switch for the bypass power feeding line and the switch for the temporary power feeding line are both closed and closed, and the low voltage distribution of the construction bank is performed. The power supply for the construction bank and the temporary power supply are supplied in parallel to the electric wire. Furthermore, the lead wire is cut during this parallel power supply, the switch for the bypass power supply line is opened after this disconnection, and the power supply of the low-voltage distribution line in the construction bank is switched to the temporary power supply via the switch for the temporary power supply line. Replace

After the construction, the switch for the bypass power feeding path is turned on to close both switches, and the power is supplied again to the construction bank and the temporary power supply in parallel, and then the distribution transformer for the construction bank is transformed. The lead wire between the container and the low voltage distribution line is connected.

After the lead wires are connected, both switches are opened, and the power source of the low voltage distribution line of the construction bank is switched back to the power source of the bank via the lead wires. Therefore,
Before and after the construction, the power supply of the low voltage distribution line of the construction bank is switched through the parallel power supply state of the construction bank power supply and the temporary power supply synchronized with this power supply, and there is no interruption of power as in the past. .

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIGS. In FIG. 1, the same reference numerals as those in FIG. 4 indicate the same elements, and the difference from the figure is that a power switching device 18 of a one-dot chain line is provided in place of the switches 16 and 17 of FIG. 4 during construction. Is.

In this device 18, 19 is a construction transformer side terminal connected to the secondary side of the transformer 3, and 20 is a distribution line 7.
Is a construction distribution line side terminal, 21 is a sound distribution line side terminal connected to the distribution line 8, and 22 is a DC power receiving terminal connected to an external DC power source 23.

Reference numeral 24 denotes a rectifier circuit having a diode rectifier structure for converting the AC power source of the distribution line 8 via the terminal 21 into DC.
Reference numeral 25 is an inverter to which the DC power of the terminal 22 and the rectifier circuit 24 is supplied, and 26 is an insulating transformer to which the output of the inverter 25 is supplied to the primary side.

Reference numeral 27 is a switch for the bypass feeding path provided between the terminals 19 and 20, and corresponds to the switch 16 of FIG. Reference numeral 28 denotes a switch for the temporary power supply path provided between the secondary side of the transformer 26 and the terminal 20, and the switch 1 of FIG.
Corresponds to 7.

29 is an inverter 25 and switches 27, 2
8 is a control circuit for controlling the inverter 8 and the inverter 25 so that the output voltage of the transformer 26 matches the power supply voltage of the construction bank # 1 based on the comparison between the voltage of the terminal 19 and the voltage of the secondary side of the transformer 26. Is controlled, and the switches 27 and 28 are prohibited from being turned on until both voltages match.

The distribution lines 7 and 8 are 3-phase 4-wire and 3-phase 3-wire.
The terminals 19 to 21 are each composed of a three-phase, four-wire terminal, and the switches 27 and 28 each have a four-pole contactor so that it can be applied to either a wire or a single-phase two-wire or three-wire. It is formed by an electromagnetic switch.

Further, the inverter 25 generates a three-phase three-wire AC output, and the transformer 26 supplied with this output has a primary side 26a formed as a three-phase three-wire input as shown in FIG. At the same time, the secondary side 26b is formed as a three-phase four-wire output.

When the distribution lines 7 and 8 are 3-phase 4-wire or 3-phase 3-wire, the terminals U, V and W of the 3-phase 4-wire on the secondary side 26b are used.
And O or terminals U, V, W to extract three-phase output, and in the case of single-phase two-wire or single-phase three-wire, terminals U, O or terminal U,
A single-phase output is taken out from O and V.

Further, in order to prevent a short circuit due to a mismatch of the ground phases, the secondary side 26b of the transformer 26 is ungrounded. Further, the power source switching device 18 is formed by accommodating the terminals 19 to 22, the rectifier circuit 24, the inverter 25, the transformer 26, the switches 27 and 28, the control circuit 29, and the like in the same housing for easy transportation. ing.

Next, replacement of the transformer 3 of the construction bank # 1 will be described. First, the device 18
Is transported to the construction site.

Then, the work is performed in the following procedure. A. Before replacement (before construction) (1) Connect the terminal 19 to the secondary side of the transformer 3 and
Connect 0 and 21 to the distribution lines 7 and 8. By this connection, the switch 27 is provided in parallel with the lead wire 9, and the distribution lines 7, 8
A switch 28, a transformer 26 forming a temporary power source, an inverter 25, and a series circuit of a rectifier circuit 24 are provided between them.

(2) When the preparation work of (1) is completed, the start button of the device 18 is pressed to operate the inverter 25 and the control circuit 29. At this time, the sound bank of the distribution line #
The second AC power source is converted into direct current by the rectifier circuit 24, this direct current is converted into alternating current by the inverter 25, and this alternating current is supplied to the primary side 26a of the transformer 26 and is supplied to the secondary side 26b of this transformer 26. , As a temporary power supply, bank # 1,
For example, a three-phase four-wire AC power supply similar to the AC power supply of No. 2 is generated.

The voltage V1 ^* of the AC power source of the construction bank # 1 on the secondary side of the transformer 3 applied to the terminal 19 (Maximum value V1, phase ψ1, frequency f1) and voltage V2 ^* of the temporary power supply on the secondary side 26b of the transformer 26 ^. (Maximum value V2, phase ψ
2, frequency f2) are taken into the control circuit 29.

The control circuit 29 is formed by software of a microcomputer, hardware of a logic circuit, or a combination thereof, and the detection unit 29a and the match / mismatch determination units 29b and 29c and the match notification unit 29d of FIG.
And so on.

Then, the detection unit 29a detects the voltage V1.^* , V2
^* Maximum value V1, V2, phase ψ1, ψ2, frequency f1,
f2 is detected, and the determination units 29b and 29c detect the detection unit 29a.
Based on the detection result, the voltage V1^* , V2^* Compare both
Pressure V1^* , V2^* Matches or disagrees with.

Further, based on the result of this judgment, the judgment unit 29c determines the voltage V1 ^*. Both voltage V1 ^* , V2 ^*
Error (deviation), and a drive control signal for canceling the deviation is supplied to an inverter control unit (not shown) of the control circuit 29, and the drive of the inverter 25 is feedback-controlled via this control unit.

By this control, the voltage V2 ^* Is the voltage V1 ^* When the temporary power supply is synchronized with the power supply of the construction bank # 1 of the distribution line 7, the determination unit 29b generates a match signal, lights the lamp of the notification unit 29d, and displays "parallel possible" to notify. At the same time, a coincidence signal is supplied to a switch controller (not shown) of the control circuit 29.

When the start button of the device 18 is pressed, this control unit is locked to prohibit the closing of the switches 27 and 28 until the coincidence signal of the judging unit 29b is given, and when the coincidence signal of the judging unit 29b is given, Turn off 2
It is ready to accept the input operation of 7, 28.

(3) The switches 27 and 28 provided in the device 18 are confirmed by confirming the lighting of the "parallel" lamp of the control circuit 29.
Press the input button of. At this time, the closing of the switches 27 and 28 is notified to the switch control unit of the control circuit 29, and the switches 27 and 28 are closed and closed by this control unit.

By closing the switch 27, a bypass power feeding path parallel to the lead wire 9 is formed, and by closing the switch 28, the AC power source of the construction bank # 1 and the temporary power source are fed in parallel to the distribution line 7. To be done. At this time, since both power supplies are synchronized, a cross current or the like does not occur in the loads 11 to 13 of the distribution line 7 and no inconvenience occurs.

(4) After cutting the lead wire 9, the device 18
Press the open button of the switch 27. At this time, the opening / closing of the switch 27 is notified to the control circuit 29, and the switch 27 is opened by the opening / closing control unit based on this notification.

Then, by opening the switch 27, the power source of the distribution line 7 is switched from the AC power source of the construction bank # 1 to the temporary power source same as this power source without instantaneous interruption. Further, in order to prevent the fluctuation of the temporary power supply, the detection unit 29a of the control circuit 29 stops the detection based on the notification of the opening of only the switch 27, and the determination unit 29b stops the output to prohibit the switch 27 from being closed. Then, the determination unit 29c is locked in the output state immediately before the notification.

Due to the lock of the output state, the inverter 25 generates the same temporary power supply as before the opening of the switch 27 even after the switch 27 is opened. (5) Open the transformer primary cutout switch 5 to open the primary side and the secondary side of the transformer 3. And transformer 3
After the replacement, the operation after the next replacement is performed.

B. After replacement (after construction) (6) Turn on the transformer primary cutout switch 5 to restore the primary side of the transformer 3. (7) Press the closing button of the switch 27 provided in the device 18.

At this time, the control circuit 29 notifies the switch controller of the closing of the switch 27 based on the closing command of the switch 27 while only the switch 28 is closed, and at the same time, the detecting unit 29.
a, the determination unit 29b is activated and the output lock of the determination unit 29c is released.

Then, the voltage V2 ^{* is} generated by the operation of the detector 29a and the determiner 29c ^. Is the voltage V1 ^* When synchronized again, the determination unit 29b outputs a coincidence signal, and the signal turns on the "parallel enabled" lamp of the notification unit 29d and removes the prohibition of closing the switch 27 of the switch control unit. Is thrown in.

As a result, after the switch 27 is opened and the power source of the distribution line 7 is switched to the temporary power source, the power source of the construction bank # 1 on the secondary side of the transformer 3 is turned on by the fluctuation of the power source of the high voltage bus bar 1. Even if it fluctuates, when the switch 27 is closed again and the power supply of the distribution line 7 is turned off, the temporary power supply is synchronized with the power supply of the construction bank # 1.

(8) Construction bank with switch 27 closed
After shifting to the parallel power supply of the first power source and the temporary power source, the cut portion of the lead wire 9 is connected to repair the lead wire 9. (9) Press the release button of the switches 27, 28 provided on the device 18.

At this time, based on the closing command of both switches 27, 28 during simultaneous closing of the switches 27, 28, the control circuit 2
The switch controller of 9 opens the switches 27 and 28, and the power source of the distribution line 7 is immediately connected to the construction bank # 1 through the lead wire 9 without interruption.
Is switched back to the AC power supply.

(10) After pressing the stop button of the device 18 to stop the inverter 25 and the control circuit 29, the terminal 19
The connection of ~ 21 is opened, the device 18 is disconnected from the banks # 1 and # 2, and the work is completed.

Therefore, when the power source of the distribution line 7 is switched from the power source of the construction bank # 1 to the temporary power source and vice versa, the temporary power source and the construction bank # 1 must be always synchronized with the power source of the construction bank # 1. The switching is performed through parallel power feeding with the power source, and at this time, unlike the conventional case, the period in which the current of the distribution line 7 is zero is not provided, and the power source is switched without interruption or the like.

As a result, the transformer 3 can be replaced without adversely affecting the motor load of the distribution line 7 regardless of its load capacity. The switch 27,
It is not necessary to use an expensive instantaneous switching switch for 28, which is advantageous in terms of price and the like.

By the way, depending on the situation of the construction bank,
For example, there is a case where a sound bank is extremely far away and a temporary power supply cannot be formed using the power supply of the sound bank. Therefore,
In this embodiment, the device 18 is provided with terminals 22,
When the terminal 21 cannot be connected to the distribution line of the sound bank, the DC power supply 23 such as a battery carried with the device 18 is connected to the terminal 22 and the output of the DC power supply 23 is supplied to the inverter 25 to form a temporary power supply. However, the construction bank is able to carry out the construction under any circumstances.

Therefore, the workability is remarkably improved without the limitation of the construction bank as in the prior art. Of course, the output of the generator can be used instead of the AC power source of the sound bank.

Further, as described above, the terminals 19 to 21 and the like are formed as terminals of three-phase four-wire, so that the distribution line 7 is three-phase three-wire.
The construction can be performed by the device 18 regardless of whether the wire is a wire, a 4-wire, or a single-phase 3-wire, and a 2-wire, and a highly versatile device can be provided.

[0067]

Since the present invention is configured as described above, it has the following effects. During distribution line construction such as replacement of distribution transformer 3 in construction bank # 1,
The healthy bank # 2 is controlled by the inverter of the control circuit 29.
The output of the inverter 25 based on the power supply of the construction bank # 1
2 of isolation transformer 26 controlled to be synchronized with the power supply of
A temporary power supply for the secondary side 26b is formed.

Before the construction work, the temporary power source is synchronized with the power source of the construction bank # 1 of the distribution line 7, and then the switches 27 and 28 are both turned on.
After the parallel power is supplied to the temporary power supply via 8, the lead wire 9
Then, the switch 27 is opened and the power source of the distribution line 7 is switched to the temporary power source. After the construction, switch 27 is closed to close both switches 27 and 28, and the power is returned to the construction bank and the temporary power supply again in parallel, and lead wire 9 is connected to open and close both. Units 27 and 28 are opened, and the distribution line 7
Power is turned back on to construction bank # 1.

Therefore, the switching of the power source of the distribution line 7
It is always carried out via the parallel power supply state of the construction bank power supply and the temporary power supply synchronized with this power supply.
It is not necessary to switch the current of No. 1 once and then switch, the instantaneous interruption due to switching does not occur, and the distribution line construction can be performed without interruption without affecting the motor load of the distribution line 7.

[Brief description of drawings]

FIG. 1 is a block wiring diagram of an embodiment of a power source switching device for low voltage distribution line construction according to the present invention.

FIG. 2 is a detailed explanatory diagram of the insulation transformer of FIG.

FIG. 3 is a detailed block diagram of the control circuit of FIG.

FIG. 4 is a block connection diagram of a conventional device.

FIG. 5 is an explanatory diagram of a main circuit portion of an instantaneous switching switch used in a conventional example device.

6 is a timing chart for explaining an operation when the switch of FIG. 5 is turned on.

7 is a timing chart for explaining an operation when the switch of FIG. 5 is turned off.

FIG. 8 is a timing chart for explaining the operation of one example when the power supply of the conventional device is switched.

FIG. 9 is a timing chart for explaining the operation of another example when switching the power supply of the conventional device.

[Explanation of symbols]

 # 1 Construction bank # 2 Sound bank 3,4 Distribution transformer 7,8 Low voltage distribution line 9,10 Lead wire 11-15 Load 19 Construction transformer side terminal 20 Construction distribution line side terminal 21 Sound distribution line side terminal 24 Rectification Circuit 25 Inverter 26 Insulation transformer 27 Switch for bypass power supply line 28 Switch for temporary power supply line 29 Control circuit

Claims (1)

[Claims] 1. A low voltage distribution line for a construction bank, in which the secondary output of the distribution transformer is fed via a lead wire before and after distribution line construction such as replacement of a distribution transformer in the construction bank. In the power source switching device for low voltage distribution line construction, which switches the power source of the power source of the construction bank formed by the secondary side output from the power source of the construction bank to the temporary power source and vice versa without interruption, it is connected to the secondary side of the distribution transformer. The construction transformer side terminal, the construction distribution line side terminal connected to the construction bank low voltage distribution line, the sound distribution line side terminal connected to the sound bank low voltage distribution line, and the AC power supply of the terminal to DC A rectifying circuit for converting, an inverter for converting the output of the rectifying circuit into an AC for temporary power supply, an insulation transformer in which the output of the inverter is fed to the primary side, the construction transformer side terminal and the construction distribution The bypass provided between the wire side terminal The switch for the power supply line, the switch for the temporary power supply line provided between the secondary side of the insulation transformer and the terminal on the work distribution line side, and the secondary side voltage of the insulation transformer The inverter is controlled so as to match the power supply voltage of the construction bank on the secondary side of the distribution transformer, and the both switches are prohibited from being turned on until the secondary voltage matches the power supply voltage of the construction bank. Before the construction, the switches for the bypass power feeding path are opened by switching on both switches and cutting the lead wires before the construction, and after the construction, for the bypass power feeding path. Power switch device for low-voltage distribution line construction, in which the switch is closed and the lead wires are connected while both switches are closed, and then both switches are opened to switch back to the power supply for the construction bank.