JP5506559B2 - Power shut-off device, table tap and distribution board - Google Patents

Description

  The present invention relates to a power shut-off device corresponding to a power failure.

  In the event of a power failure of the commercial power supply, it is possible to continue supplying power to the load on the demand side by using an emergency power supply. However, since the power capacity of the emergency power supply is limited, if power supply is continued from the emergency power supply to all loads, the power supply is limited and the compensation time is shortened. In particular, in a direct current system such as a direct current distribution system used in a data center or the like, the supply voltage itself is expected to greatly decrease, and the influence on direct current equipment such as a computer is large. In addition, regardless of direct current or alternating current, if the supply of electric power is continued in a state where the voltage is lowered, it is considered that safety cannot be ensured depending on the state of the device.

  In the case of a power outage due to a disaster such as an earthquake, a secondary disaster such as a fire is assumed by the supply of power from an emergency power source such as an electric heater. For such a load, it is desirable to stop the power supply even if the power supply returns from a power failure. Therefore, in an electric power supply system using an emergency power supply, it is necessary to select a demand-side load for supplying electric power and supply electric power only to a safe and minimum necessary load. In order to select the minimum necessary load, it is conceivable to provide a separate outlet backed up by an emergency power supply in addition to a commercial power outlet. In this case, although the outlet can be selected, it is necessary to provide a distribution line different from the distribution line of the commercial power source.

Therefore, some devices for selecting a load have been proposed on the assumption that a distribution line of a commercial power source is used. Patent Document 1 relates to a DC power distribution system, and discloses a method for reducing the load of an emergency power supply. Each load is individually provided with a detector. When the remaining amount of energy of the emergency power supply decreases, the voltage of the DC bus is periodically decreased (or periodically increased), and the load is sequentially disconnected from the load with the lower priority.

  Patent Document 2 discloses a method of using a DC power supply device for a long time. Each device corresponding to the DC power distribution system is individually provided with a device disconnecting means. When the voltage of the DC power supply device decreases, each device is disconnected from the line by the device disconnecting means in the order of lower priority according to a predetermined priority.

In the AC power distribution system targeted by Patent Document 3, each slave unit is placed in a device that may lead to a disaster. When an earthquake or power outage is detected by the master unit, a signal is transmitted to the slave unit wirelessly and the power is cut off.

  In these methods, it is necessary to provide a detector and a communication means for each device, which increases costs. Also, depending on whether it is a temporary power outage or a power outage due to a disaster such as an earthquake, the equipment required at the time of the power outage differs, and power is also required during the power outage depending on the time of day, day of the week, season, etc. The equipment to change. In the above method, since the device to be stopped is determined in advance, it is difficult to change it during a power failure.

JP-A-9-191565 (FIG. 1) JP 2009-159655 A (FIG. 1) JP 2010-29004 (FIG. 1)

This invention was made in order to solve the above-mentioned problems, and selects whether the user energizes or shuts off at the time of a power failure, and enables a change in the selection even at the time of a power failure. The purpose is to realize at low cost.

The power shut-off device according to the present invention includes an output terminal to which a load that consumes power is connected, a selection switch that connects one side of the output terminal to either the always-on line or the power-off line, and the always-on line. Monitors the supply voltage, which is a voltage, and controls the open / close state of the electric circuit between the always-on line and the always-off line, and the reset circuit that operates on the low-voltage cut-off circuit and initializes the open / close state of the circuit When a drop in the supply voltage is detected, the cutoff circuit at the time of a voltage drop disconnects the OFF line at the time of a power failure from the electric circuit, and until then the reset circuit is operated, regardless of the change of the supply voltage, When the interruption is maintained and the reset circuit is operated, the OFF line at the time of power failure is connected to the electric circuit.

  If the power shut-off device according to the present application is used, the load can be supplied with power in a normal state regardless of whether the load is connected to the always-on terminal or the power-off OFF terminal. When a power failure occurs, the voltage drop circuit detects the voltage drop and the power line to the OFF line is cut off during the power failure, so only the load connected to the OFF terminal at the time of the power failure is stopped. . Since the connection between the always-on terminal and the OFF terminal during a power failure can be switched with the selection switch, the user can easily switch the load that is energized by the emergency power supply during a power failure. In addition, the devices that recover after a power failure can be easily switched, and the device can be changed according to the time of day, the day of the week, the season, etc., such as the reason for a power failure, a temporary power failure, a power failure due to a disaster such as an earthquake, or nighttime or daytime. The effect that can be switched to is obtained. Furthermore, since the interruption of the emergency OFF line is maintained until the reset circuit is operated, safety is ensured.

It is a circuit block diagram of the power-supply-cutoff apparatus for DC 48V concerning Embodiment 1 for implementing this invention. It is a circuit symbol and truth table of a D-flip-flop circuit of the power shutoff device according to Embodiment 1 for carrying out the present invention. It is a top view of the table tap incorporating the circuit structure of the power-supply-cutoff apparatus for DC 48V concerning Embodiment 1. FIG. It is a circuit block diagram of the power-supply-cutoff apparatus for DC 48V concerning Embodiment 2 for implementing this invention. It is a circuit block diagram of the power supply cutoff device for alternating current 100V concerning Embodiment 3 for implementing this invention. It is a top view of the distribution board incorporating the circuit structure of the power supply cutoff device for alternating current 100V concerning Embodiment 4 of this invention. It is a block diagram of the power cutoff device including the emergency power supply concerning Embodiment 5 of this invention.

Embodiment 1 FIG.
FIG. 1 is a circuit configuration diagram of a DC48V-compatible power shut-off device according to Embodiment 1 for carrying out the present invention. Power is supplied to the power shut-off device 100 from a DC 48V power source via a set of power receiving terminals 27. One distribution line connected to the power receiving terminal 27 is called a common line, and the other distribution line is always called an ON line. In this embodiment, the distribution line of 0V potential is the common line 26, and the distribution line of 48V potential is always the ON line 2. The range of the voltage drop cutoff circuit 1 is indicated by a broken line. The voltage drop cutoff circuit 1 is located between the constant ON line 2 close to the power supply side, such as a commercial power supply or emergency power supply, and the power failure OFF line 3 close to the load side, and shuts off the power failure OFF line 3 when the voltage drops. . The voltage drop cutoff circuit 1 includes a switching element 8, a D-flip flop circuit (logic circuit) 10, and a comparator 9b as main elements. The voltage drop cutoff circuit 1 is composed of a simple circuit and an inexpensive element.

The power failure selection switch 6 includes an always-on terminal 4, a power failure OFF terminal 5, and a common terminal 6b. The common terminal 6 b of the power failure selection switch 6 is connected to one side of the output terminal 7. When the always-on terminal 4 is selected, the common terminal 6 b is connected to the always-on line 2. When the power failure OFF terminal 5 is selected, the common terminal 6b is connected to the power failure OFF line 3. The load user always sets the power failure selection switch 6 to the ON terminal 4 side when using a device that must be moved even during a power failure. When using a device that can be stopped at the time of a power failure, or a device such as an electric stove that is not required to be turned on even if the system recovers in the event of a power failure due to an earthquake, etc., the power failure selection switch 6 can be turned off. Set to the OFF terminal 5 side.

In the figure, two sets of selector switch 6 and output terminal 7 at the time of power failure are shown. A common line 26 is connected to one end side of the output terminal 7, and an ON line 2 or a power failure OFF line 3 is always connected to the other end side. A power failure selection switch 6 is provided for each output terminal 7. The user connects the load (device, equipment) to be used to the output terminal 7. The right output terminal 7 is always set to the ON terminal 4 side, and the left output terminal 7 is set to the OFF terminal 5 side during a power failure. The constant ON line 2 is connected to the plus (48V) side of the DC 48V power source, and the common line 26 is connected to the minus (0V) side of the DC 48V power source. Regardless of whether the always-on terminal 4 or the power-off OFF terminal 5 is selected, the load can be supplied with power in the normal state.

The comparison circuit 9 constantly monitors the voltage of the ON line 2 and determines whether or not the supply voltage satisfies the reference voltage. The comparison circuit 9 includes an inverting circuit 9a, a comparator 9b, a comparator clamp 13, a dividing resistor, and the like. A voltage to be monitored is input to the positive terminal (+) of the comparator 9b, and a comparison voltage is input to the negative terminal (−). The comparator 9b compares the potential of the positive terminal (+) with the potential of the negative terminal (−). If the voltage of the positive terminal (+) is higher than the voltage of the negative terminal (−), the comparator 9b is positive. A signal (first signal) is output, and in the opposite case, a negative signal (second signal) is output. As the comparison voltage, a voltage which is 20 V by the comparator clamp 13 and divided by a resistor is used. The output of the comparator 9b is inverted when the monitor voltage drops to 20V or less. As described above, it can be determined whether or not the voltage supplied from the output of the comparator 9b to the output terminal 7 is lower than the reference voltage.

The output of the comparator 9b is input to the D-flip flop circuit 10 through the inverting circuit 9a. The D-flip flop circuit 10 transmits an output (third signal or fourth signal) corresponding to the input of the inverting circuit 9a and the input of the reset circuit. When the comparison circuit 9 (comparator 9b) detects a voltage drop, the D-flip flop circuit 10 switches the switching element 8 from the closed state to the open state. As the switching element 8, an IGBT (Insulated Gate Bipolar Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), or the like is used. The D-flip flop circuit 10 stores information (instantaneous low voltage) sent from the emergency power supply through the power supply line, and the signal to the switching element 8 (fourth signal) remains as it is even when the voltage is restored. To maintain.

The reset circuit 11 is connected to the D-flip flop circuit 10. Only when the reset button 12 is pressed, the D-flip flop circuit 10 is released and initialized. When released, the D-flip-flop circuit 10 sends a normal signal (third signal) to the switching element 8 to restore the OFF line 3 during a power failure. As a result, even if the power is restored, power is not supplied to the OFF line 3 during a power failure unless the reset button 12 is pressed. The 5V output clamp 14 supplies DC 5V necessary for the D-flip-flop circuit 10 and the reset circuit 11.

FIG. 2 shows a circuit symbol and a truth table (time series from left to right) of the D-flip flop circuit 10. In the figure, peripheral circuits of the D-flip-flop circuit 10 such as the inverting circuit 9a are also drawn. “0” indicates an open state, and “1” indicates a closed state. In truth table 15, “0/1” means that the input “CLK” is inverted from “0” to “1”. Similarly, “1/0” means that the input “CLK” is inverted from “1” to “0”. “D” is connected to ground and “PR” is powered. The reset circuit 11 is connected to “CLR”. If the reset button (or reset SW) 12 is OFF, “CLR” corresponds to “1”, and if it is ON, “CLR” corresponds to “0”. As an element of the D-flip flop circuit 10, a general-purpose D-FF that is a commercially available inexpensive part can be used.

The output of the comparator 9b is input to “CLK” of the D-flip flop circuit 10 through the inverting circuit 9a. The D-flip flop circuit 10 outputs to “Q”. When the comparison circuit 9 (comparator 9b) detects an instantaneous low voltage from the emergency power supply through the power supply line, “Q” is inverted from “1” to “0”. The D flip-flop circuit 10 maintains the output to “Q” even when the output of the comparator 9b returns to the original state and “CLK” returns to the original state, and only after the manual reset button 12 is turned on, “ "Q" is returned to the initial state. Thereby, even if a voltage returns, the signal to the switching element 8 is maintained as it is.

If a power failure is restored after a power failure due to an earthquake, etc., and the building is damaged, if a heat source such as an electric stove returns to power, there may be a risk of fire if there are flammable materials around or if the electric stove falls down. However, according to the power shut-off device of the first embodiment, unless the reset button 12 is pressed, it does not return and safety is maintained.

FIG. 3 is a plan view of a table tap incorporating the circuit configuration of the DC48V power shutoff device according to the first embodiment. The table tap 16 includes a power failure selection switch 6, an output terminal 7, a reset button 12, a table tap cable 17, and a display lamp 18. One output terminal 7 requires one power failure selection switch 6. Here, four sets of output terminal 7 and power failure selection switch 6 are provided. The power failure selection switch 6 and the reset button 12 are provided close to each other on the outside of the housing (main body) of the table tap 16 and can be operated manually. The indicator lamp 18 is always yellow, and red when a power failure occurs. The display lamp 18 displays the location of the table tap 16 in an easy-to-understand manner even in the dark, and can notify the user that power is being supplied from the emergency power source, even if there is a power failure.

The user can select whether to turn on or off at the time of power failure when connecting the input terminal of the device to the table tap 16 by the power failure selection switch 6 of the table tap 16. When it is determined that it is better to always turn ON the selector switch 6 at the time of a power failure and turn it off at the time of a power failure, such as an electric heater, for a load that is determined to remain ON even during a power failure , Set the power failure selection switch 6 to the OFF side during a power failure. In FIG. 3, the three left output terminals 7 are set to an OFF state at the time of a power failure, and the remaining one output terminal 7 is always set to an ON state (ON at the time of a power failure).

  Assume that a power outage actually occurs. When there is a surplus in the emergency power supply and heating is necessary in the midwinter, the table tap 16 can be used to switch the power failure selection switch 6 from the OFF side during a power failure to the always ON side. In the daytime, if it is determined that the automatic lighting with the presence sensor should be set to the OFF side at the time of power failure instead of the always ON side, the table tap 16 can be used to save the power of the emergency power supply. The power failure selection switch 6 can be switched from the constantly ON side to the OFF side during a power failure.

Furthermore, according to the power shut-off device of the present invention, in order to save the power of the emergency power supply, the device that is no longer required to be turned on is switched to the OFF side at the time of a power failure, or the device that is necessary is switched to be always turned on. Can be easily done. Even if the commercial power supply is restored, energization is not restored unless the reset button 12 is pressed. Therefore, after confirming safety, the reset button 12 can be pushed to energize.

  In the first embodiment, the case where the circuit of FIG. 1 is applied to the table tap 16 has been described. However, a tap for a mechanical device or OA equipment or a wall outlet may be used, and similar effects can be obtained. Further, instead of the outlet, a commercial power source may be applied to a distribution board that branches to a plurality of small-scale earth leakage breakers via a breaker, and the same effect can be obtained. In the case of a distribution board, an earth leakage breaker is interposed between the power failure selection switch 6 and the load side output terminal 7 so that the switching element 8 of the switching element 8 due to a leakage current or excess current on the power failure selection switch 6 side can be obtained. Damage can be prevented.

Embodiment 2. FIG.
FIG. 4 is a circuit configuration diagram of a DC 48V power shut-off device according to Embodiment 2 for carrying out the present invention. In Embodiment 1, the two-terminal type power failure selection switch that switches to either the always-on terminal 4 or the power failure OFF terminal 5 is shown, but the power failure selection switch may be a three-terminal type. The power failure selection switch 6a has a constant OFF terminal 6c, and the constant OFF terminal 6c is open at the connection destination or connected to the common line 26. Since the OFF terminal 6c is always at the zero potential point with respect to the common line 26, power cannot be supplied from the output terminal 7. When the always-off terminal 6c is selected, a complete power-off state of the load is reliably realized in a state where the load is connected to the outlet, so that an effect of ensuring safety can be obtained.

It is also conceivable to attach an LED lamp to the selection switch 6a during a power failure. If the LED lamp is not lit on the always-off 6c side, lit red on the always-on terminal 4 side, and lit green on the OFF terminal 5 side in the event of a power failure, the LED lamp can be displayed in an easy-to-understand manner even in the dark. . Based on this, the user can easily switch between always-off, always-on, and power-off when necessary even during a power failure.

  The reset button 12 is not provided directly on the table tap or the distribution board, but on the emergency power supply side or the distribution board side of the commercial power supply and operates by remotely operating the reset circuit 11a by signal transmission using wired or wireless. You may make it do. 4 shows that the reset button 12 is provided outside the housing 100a of the power shut-off device 100. FIG. Since the reset button 12 is connected to the main body by the signal line 25, the reset circuit 11a can be remotely operated. In factories, office buildings, and the like, it is possible to shorten the time required for device recovery by operating a large number of reset circuits 11a by remote control.

Embodiment 3 FIG.
FIG. 5 is a circuit configuration diagram of an AC 100V power shutoff device according to Embodiment 3 for carrying out the present invention. Although the device is partly different from the DC power supply cutoff device in FIG. 1, the basic functions are the same. The comparator 9b, the output of the AC / DC converter (converter) 20 is input. The transformer 19 reduces the AC voltage to 1/10 to facilitate handling, and also insulates the AC / DC converter 20 from the commercial power supply (AC 100 V) to facilitate grounding on the DC side. The AC / DC converter 20 enables substantially the same configuration as the voltage drop interruption circuit 1 in the DC circuit of FIG.

Functionally, it is the same as in the first embodiment, which is the difference between DC distribution and AC distribution. Since alternating current is converted into direct current using the transformer 19 and the AC / DC converter 20, the circuit configuration is realized in the third embodiment with an inexpensive element having a low withstand voltage.

FIG. 6 is a plan view of a distribution board incorporating the circuit configuration of the AC 100V power shutoff device according to Embodiment 3 of the present invention. The distribution board 40 includes a reset button 12, a display lamp 18, a main breaker 21, and a child breaker 22. The primary side of the main breaker 21 is connected to the power supply side. A child breaker 22 branches from the main breaker 21. In this example, the main breaker 21 bundles six child breakers 22. On the secondary side of the main breaker 21, a voltage drop interruption circuit 1, a reset button 12, and a display lamp 18 are incorporated. The primary terminal of the child breaker 22 is connected to the output terminal 7 of FIG.

The power failure selection switch 6 is provided on the primary side of each of the child breakers 22 and connects one terminal of the child breaker 22 to either the ON line or the power failure OFF line. In the distribution board 40, the user determines whether to turn on or off at the time of power failure when connecting the input terminal of the device to the child breaker 22 by the power switch 6 at the time of power failure on the table tap. If it is determined that it is better to always turn on the power failure selection switch 6 and turn it off at the time of a power failure, the power failure selection switch 6 should be turned off. Set to OFF side.

  The reset button 12 may be on the emergency power supply side, not the distribution board 40, and may activate the reset circuit 11 by signal transmission using wired or wireless. By remote operation, for example, the distribution board of the entire factory or office building can be reset instantaneously, and the time can be reduced.

In the third embodiment, the case of single-phase alternating current has been described. However, three-phase alternating current generally used in factories or the like may be used. If the transformer 19 or the like is changed to three-phase alternating current, a simple circuit and low cost are possible. With such an element, the same structure as in the second embodiment can be obtained, and the same effect can be obtained.

Embodiment 4 FIG.
FIG. 7 is a configuration diagram of a power shutoff device including an emergency power supply according to the fourth embodiment for carrying out the present invention. An emergency power source 23 is provided between the power supply power source and the distribution board or outlet (AC and DC). Three types of power supply sources are illustrated: three-phase AC distribution, single-phase AC distribution, and DC distribution. DC distribution is often wired when a large number of DC devices such as data centers are used. Each of the distribution boards or outlets (including wall outlets and table taps) incorporates a power shut-off device according to the present invention, and the user can use a breaker to determine whether or not power is always supplied when a power failure occurs. Or it judges for every outlet and selects the selection switch 6 at the time of a power failure.

  When a power failure occurs, the emergency power source 23 causes a voltage drop in a time range in which each device does not stop. In the distribution board, the AC outlet, or the DC outlet, each of the cutoff circuits 1 at the time of a voltage drop is operated, and the OFF line 3 is not energized at the time of a power failure, and the load is reduced all at once. As a result, the power demand is greatly reduced, and the required power generation amount of the emergency power source 23 is reduced. Therefore, when the emergency power source 23 is, for example, diesel power generation, a short time without waiting until the output is completely increased. It is possible to start up and start power transmission. If the power outage is prolonged, the user can adjust the load with the power failure selection switch 6 based on the remaining power of the emergency power supply 23 and the remaining amount of fuel.

  When the emergency power source 23 uses a power storage device such as a battery or a capacitor, the power shut-off device according to the present invention reduces the load, so that it is possible to withstand a longer power outage or momentary power failure. Become. If it is determined that the normal state has returned from the power outage accident, the emergency power source 23 sends a low voltage return pulse signal 24 to the reset circuit 11 of the distribution board through the signal line 25 to return it. Further, the table tap is restored by the manual reset button 12.

In the grid distribution system, which is called micro-grid or smart grid, which largely incorporates unstable solar power generation or wind power generation, the system voltage may fluctuate and temporary power outages may occur frequently. The power cutoff device of the present invention can be expected to have a particularly great effect.

1 Cut-off circuit at low voltage, 2 always ON line, 3 power OFF line, 4 always ON terminal, 5 power OFF terminal, 6 power failure selection switch, 7 output terminal, 8 switching element, 9 comparison circuit, 9b comparator, 10 D-flip-flop circuit, 11 reset circuit, 12 reset button, 13 comparator clamp, 14 5V output clamp, 15 truth table, 16 table tap, 17 table tap cable, 18 indicator lamp, 19 transformer, 20 AC / DC converter, 21 main breaker, 22 child breaker, 23 emergency power supply, 24 pulse signal, 25 signal line, 26 common line, 100 power cut-off device.

Claims (9)

Monitor the output terminal to which the load that consumes the power is connected, the selection switch that connects one side of the output terminal to either the always-on line or the power-off line, and the supply voltage that is always the on-line voltage , a voltage drop during shut-off circuit for controlling the opening and closing state of the electrical path between the always-oN line and OFF-line, have a reset circuit for initializing the open or closed state of the path to act on the voltage drop during shut-off circuit,
When interrupting circuit voltage drop, holds the shut-off of the the detecting the drop of the supply voltage power failure OFF line is disconnected from the path, then power failure regardless until operating the reset circuit to changes in the supply voltage OFF line and, power cutoff device, characterized in that connecting to the path of the power failure OFF line and operating the reset circuit. The output terminal to which the load that consumes power is connected, the selection switch that connects one side of the output terminal to either the always-on line or the power-off line, and the always-on line voltage are monitored, and it is higher than the reference voltage. A comparison circuit that outputs a first signal when the voltage of the constant ON line is high, a second signal when the voltage of the constant ON line is lower than the reference voltage, and a reset circuit that outputs a reset signal; A logic circuit that outputs the third signal or the fourth signal based on the first signal, the second signal, and the reset signal, and is provided between the OFF line at the time of a power failure and the always ON line. A switching element that is closed when the signal 3 is output and is open when the fourth signal is output,
When the output of the comparison circuit changes from the first signal to the second signal, the logic circuit inverts the output from the third signal to the fourth signal, and then changes to the output of the comparison circuit until a reset signal is input. Regardless of whether the fourth signal is held and the reset signal is inputted, the held fourth signal is inverted to the third signal. The power shut-off device according to claim 1, wherein a reset circuit and a selection switch are provided in a housing of the device. The power shut-off device according to claim 1 or 2, wherein the reset circuit can be operated from outside the device. The power cut-off device according to claim 1 or 2, wherein the selection switch is a three-point switching type, and one side of the output terminal is always connected to the ON line, the OFF line at the time of power failure, or a zero potential point. 3. The power shut-off device according to claim 2, wherein the logic circuit is a D-flip flop circuit. A transformer step-down are connected to always ON line, the output of the transformer comprise a converter that converts the direct current to claim 2 in which the output of the converter is characterized in that it is input to the comparison circuit The power cutoff device described. A plurality of output terminals to which a load that consumes power is connected, a selection switch that is provided corresponding to each of the output terminals, and that connects one side of the output terminal to either the ON line at all times or the OFF line at power failure, The voltage of the ON line is always monitored, and the first signal is output when the voltage of the ON line is always higher than the reference voltage, and the second signal is output when the voltage of the ON line is always lower than the reference voltage. A comparison circuit; a reset circuit that outputs a reset signal; a logic circuit that outputs a third signal or a fourth signal based on the first signal, the second signal, and the reset signal; A switching element that is always provided between the ON lines and is in a closed state when the third signal is output from the logic circuit and is in an open state when the fourth signal is output;
When the output of the comparison circuit changes from the first signal to the second signal, the logic circuit inverts the output from the third signal to the fourth signal, and then changes to the output of the comparison circuit until a reset signal is input. Regardless of this, the table tap is characterized in that it holds the fourth signal and inverts the held fourth signal to the third signal when a reset signal is inputted. It is provided for each of the main breaker connected to the power supply side, multiple child breakers branched from the main breaker, and the child breaker, and one side of the child breaker is always on either the ON line or the OFF line at power failure The selection switch to be connected and the always-on line voltage are monitored, and the first signal is displayed when the always-on line voltage is higher than the reference voltage, and the first signal is displayed when the always-on line voltage is lower than the reference voltage. A comparison circuit that outputs a second signal, a reset circuit that outputs a reset signal, a logic circuit that outputs a third signal or a fourth signal based on the first signal, the second signal, and the reset signal; A switching element that is provided between the OFF line at the time of a power failure and the always ON line, and is closed when the third signal is output from the logic circuit and opened when the fourth signal is output. And
When the output of the comparison circuit changes from the first signal to the second signal, the logic circuit inverts the output from the third signal to the fourth signal, and then changes to the output of the comparison circuit until a reset signal is input. Regardless of this, the distribution board holds the fourth signal and inverts the held fourth signal to the third signal when a reset signal is input.

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