JP2021118589A - Electric apparatus, and overvoltage protection device - Google Patents

Abstract

To provide an electric apparatus and an overvoltage protection device capable of improving protection performance of a circuit unit of an electric apparatus from overvoltage.SOLUTION: An electric apparatus 10 is installed on a distribution board and includes: a pair of power supply connection terminals 10a and 10b; a circuit unit 30; and a protection unit 70. The pair of power supply connection terminals 10a and 10b are electrically connected to an external power supply 200. The circuit unit 30 obtains electric power from the external power supply 200 via the pair of power supply connection terminals 10a and 10b. The protection unit 70 is located between the pair of power supply connection terminals 10a and 10b and the circuit unit 30, and protects the circuit unit 30 from an overvoltage. The protection unit 70 has a plurality of overvoltage protection elements 71 connected in parallel between the pair of power supply connection terminals 10a and 10b.SELECTED DRAWING: Figure 2

Description

The present disclosure generally relates to electrical equipment and overvoltage protection devices. The present disclosure particularly relates to electrical equipment installed on a distribution board and an overvoltage protection device used in the electrical equipment.

Patent Document 1 discloses a power measuring unit (measuring device) which is a kind of electric device. The power measurement unit of Patent Document 1 has a function of measuring the power of each circuit in which a sensor unit (sensor) is installed and is installed at a predetermined position in a distribution board. The power measurement unit is connected to the sensor unit using a signal line and an electric wire, and outputs a power measurement value to an external monitoring device such as a personal computer via a communication line.

Japanese Unexamined Patent Publication No. 2014-199209

An object is to provide an electric device and an overvoltage protection device capable of improving the performance of protection from overvoltage of a circuit portion of the electric device.

The electric device of one aspect of the present disclosure is an electric device installed on a distribution board, and includes a pair of power supply connection terminals, a circuit unit, and a protection unit. An external power source is electrically connected to the pair of power supply connection terminals. The circuit unit obtains electric power from the external power source via the pair of power supply connection terminals. The protection unit is located between the pair of power supply connection terminals and the circuit unit to protect the circuit unit from overvoltage. The protection unit has a plurality of overvoltage protection elements connected in parallel between the pair of power supply connection terminals.

The overvoltage protection device of one aspect of the present disclosure is an overvoltage protection device used in an electric device installed in a distribution board, and includes a plurality of overvoltage protection elements. The plurality of overvoltage protection elements are located between a pair of power supply connection terminals to which an external power supply is electrically connected and a circuit unit that obtains power from the external power supply via the pair of power supply connection terminals. It is connected in parallel between the power connection terminals.

According to the aspect of the present disclosure, it is possible to achieve the effect that the performance of protection from overvoltage of the circuit portion of the electric device can be improved.

FIG. 1 is a schematic view of a distribution board on which a measuring device (electrical device) of one embodiment is installed. FIG. 2 is a schematic diagram of the circuit configuration of the measuring device.

(1) Embodiment (1-1) Outline This embodiment relates to a measuring device which is a kind of electric device. FIG. 1 shows a distribution board 100 to which the electric device 10 of one embodiment is applied. The distribution board 100 is used to distribute electric power from an AC power source 200 which is an external power source. That is, the distribution board 100 is electrically connected to the AC power supply 200. The AC power supply is, for example, a commercial power supply. In FIG. 1, the distribution board 100 includes a main switch (main breaker) 110 and a plurality of branch switches (branch breakers) 120. It is not essential that the distribution board 100 is provided with a plurality of branch switches 120, and it is sufficient that the distribution board 100 has one or more branch switches 120. Further, the distribution board 100 includes a main switch 110 and a cabinet 130 accommodating a plurality of branch switches 120. The cabinet 130 is attached to a building material (eg, a building wall). The construction material is not limited to the wall of the room in the building (detached house, dwelling unit of apartment house, tenant building, etc.), and may be, for example, the ceiling or floor of the room in the building.

The main switch 110 includes a primary side end terminal, a secondary side terminal, and a contact connected to an electric circuit between the primary side terminal and the secondary side terminal. When the main switch 110 detects an abnormal state in which an overcurrent such as an electric leakage current or an overload current flows through the contacts, the main switch 110 opens the contacts and cuts off the electric circuit. Since the main switch 110 may have a conventionally known configuration, detailed description thereof will be omitted.

The branch switch 120 is a circuit breaker for wiring. The branch switch 120 includes a power supply terminal portion (primary side connection portion) and a load connection portion (secondary side connection portion). Further, the branch switch 120 includes a breaking circuit. The break circuit includes a contact device inserted into an electric circuit between the power supply terminal portion and the load connection portion, and a handle for operating the contact device. The power supply terminal is used for connecting to the power supply. The power supply terminal portion is used for electrical connection with the main switch 110. The load connection is used to connect to the load. Examples of the load include wiring equipment for connecting to electrical equipment. Wiring equipment includes outlets, hook ceilings, and the like. The branch switch 120 may have a thermal tripping device. The thermal tripping device includes, for example, a thermal element such as a bimetal or a trimetal, and is configured to open the contact device of the break circuit when the thermal element operates. Further, the branch switch 120 may have an electromagnetic tripping device. The electromagnetic tripping device includes, for example, an electromagnet device, and is configured to instantly open the contact device of the break circuit when the electromagnet device is activated. The branch switch 120 does not have to have a function as a wiring breaker. The branch switch 120 may be used, for example, as a switch, relay or demultiplexer.

The cabinet 130 includes a plurality of mounting members 140. The mounting member 140 is used to secure the branch switch 120 to the cabinet 130. In this embodiment, the mounting member 140 is a DIN rail.

The electric device 10 of the present embodiment is installed on the distribution board 100. The electric device 10 is fixed to the cabinet 130 by being attached to the attachment member 140. Further, the electric device 10 is electrically connected to the branch switch 120 of the distribution board 100 and receives the electric power from the AC power supply 200. Further, the electric device 10 is electrically connected to the sensor 300 and acquires sensing information from the sensor 300.

In particular, as shown in FIG. 2, the electric device 10 of the present embodiment is an electric device 10 installed on the distribution board 100, and is a pair of power supply connection terminals 10a and 10b, a circuit unit 30, and a protection unit. 70 and. The external power supply 200 is electrically connected to the pair of power supply connection terminals 10a and 10b. The circuit unit 30 obtains electric power from the external power source 200 via the pair of power supply connection terminals 10a and 10b. The protection unit 70 is located between the pair of power supply connection terminals 10a and 10b and the circuit unit 30, and protects the circuit unit 30 from overvoltage. The protection unit 70 has a plurality of overvoltage protection elements 71 connected in parallel between the pair of power supply connection terminals 10a and 10b.

As described above, in the electric device 10 of the present embodiment, there is a protection unit 70 between the pair of power supply connection terminals 10a and 10b and the circuit unit 30. Therefore, protection from the overvoltage of the circuit unit 30 of the electric device 10 can be achieved. Further, the protection unit 70 has a plurality of overvoltage protection elements 71 connected in parallel between the pair of power supply connection terminals 10a and 10b. Therefore, if at least one of the plurality of overvoltage protection elements 71 is normal, the circuit unit 30 can be protected from the overvoltage. Therefore, according to the electric device 10, the performance of protection from the overvoltage of the circuit unit 30 of the electric device 10 can be improved.

(1-2) Details Hereinafter, the electric device 10 of the present embodiment will be described in more detail with reference to FIGS. 1 and 2. As shown in FIG. 1, the electric device 10 includes a housing 20. Further, as shown in FIG. 2, the electric device 10 includes a pair of power supply connection terminals 10a and 10b, a circuit unit 30, and a protection unit 70. The pair of power supply connection terminals 10a and 10b, the circuit unit 30, and the protection unit 70 are housed in the housing 20.

An AC power supply 200, which is an external power supply, is electrically connected to the pair of power supply connection terminals 10a and 10b. More specifically, the pair of power supply connection terminals 10a and 10b are electrically connected to the power supply line from the external power supply (AC power supply 200). In the present embodiment, the pair of power supply connection terminals 10a and 10b are electrically connected to the branch switch 120 of the distribution board 100 by the power supply line. As a result, the pair of power supply connection terminals 10a and 10b are electrically connected to the AC power supply 200.

As shown in FIG. 2, the circuit unit 30 includes a measurement unit 40, a communication unit 50, and a power supply unit 60.

The measuring unit 40 is configured by mounting an electronic component on a substrate. The measurement unit 40 includes a pair of power supply connection terminals 40a and 40b and a sensor connection unit 40c. The pair of power supply connection terminals 40a and 40b are electrically connected to the power supply unit 60. The sensor 300 (current sensor) is electrically connected to the sensor connection unit 40c.

The measurement unit 40 generates measurement information regarding a predetermined physical quantity based on sensing information (for example, a measured value) from the sensor 300. In this embodiment, the sensor 300 is a current sensor. It is a current sensor. The current sensor is used for measuring the power supplied from the AC power source 200, the power supplied from power generation equipment such as a solar cell, a power storage device, and a fuel cell, and the power consumption of a load or the like. In this case, the predetermined physical quantity includes electric power (unit: W). In the case of the present embodiment, the measurement unit 40 generates measurement information (power measurement information) related to a predetermined physical quantity (power) based on the sensing information (current value) from the sensor 300.

The communication unit 50 is configured by mounting electronic components on a substrate. The communication unit 50 includes a pair of power supply connection terminals 50a and 50b. The pair of power supply connection terminals 50a and 50b are electrically connected to the power supply unit 60. Further, the communication unit 50 includes an antenna and an operation unit. The antenna is used for wireless communication in the communication unit 50. The operation unit is used for setting communication by the communication unit 50. For example, by operating the operation unit, the communication unit 50 can register the other party of wireless communication. The operation unit is a push switch.

The communication unit 50 transmits the measurement information generated by the measurement unit 40. In the present embodiment, the communication unit 50 transmits the measurement information generated by the measurement unit 40 by wireless communication. As an example, the communication unit 50 is capable of wireless communication with a communication device such as a gateway, and transmits measurement information to the communication device. The measurement information transmitted to the communication device is transmitted from the communication device to a preset information presenting device by wireless communication or wired communication. Then, the information presenting device can present the measurement information received from the communication device, which enables the user to confirm the measurement information on the information presenting device.

The power supply unit 60 is configured by mounting electronic components on a substrate. The power supply unit 60 includes a pair of input terminals 60a and 60b and a pair of output terminals 60c and 60d. The pair of input terminals 60a and 60b are electrically connected to the pair of power supply connection terminals 10a and 10b. The pair of output terminals 60c and 60d are electrically connected to the pair of power supply connection terminals 40a and 40b of the measuring unit 40. Further, the pair of output terminals 60c and 60d are electrically connected to the pair of power supply connection terminals 50a and 50b of the communication unit 50.

The power supply unit 60 supplies electric power (operating power) to the measurement unit 40 and the communication unit 50. The power supply unit 60 generates operating power based on the power obtained via the pair of power supply connection terminals 10a and 10b. In the present embodiment, the power supply unit 60 converts the input power into output power having a voltage lower than the input power and outputs the power. In this embodiment, the input power is AC power from the AC power supply 200. Therefore, the voltage of the input power is evaluated by the effective value. The output power is the operating power of the measuring unit 40 and the communication unit 50, and is DC power. In this way, the power supply unit 60 generates and outputs output power (DC power) for operation of the measurement unit 40 and the communication unit 50 based on the input power (AC power) from the AC power supply 200. In the present embodiment, the power supply unit 60 converts the power (input power) obtained from the AC power supply 200 via the pair of input terminals 60a and 60b into the output power for operating the measurement unit 40 and the power supply unit 60. Therefore, the power is output from the pair of output terminals 60c and 60d. The output power (operating power) output from the pair of output terminals 60c and 60d is supplied to the measuring unit 40 via the pair of power supply connection terminals 40a and 40b, and further via the pair of power supply connection terminals 50a and 50b. , Is supplied to the communication unit 50. In this way, power is supplied from the power supply unit 60 to the measurement unit 40 and the communication unit 50.

The protection unit 70 is located between the pair of power supply connection terminals 10a and 10b and the circuit unit 30, and is provided to protect the circuit unit 30 from overvoltage. In the present embodiment, the protection unit 70 is located between the power supply unit 60 and the pair of power supply connection terminals 10a and 10b. Therefore, the performance of protection from the overvoltage of the power supply unit 60 of the circuit unit 30 of the electric device 10 can be improved.

In the present embodiment, the withstand voltage of the first electronic component constituting the circuit unit 30 is lower than the withstand voltage of the second electronic component used for the distribution board 100. The first electronic component may include an electronic component that constitutes the measuring unit 40, an electronic component that constitutes the communication unit 50, and an electronic component that constitutes the power supply unit 60. The second electronic component may include an electronic component constituting the main switch 110 of the distribution board 100 and an electronic component constituting the branch switch 120. Examples of the first electronic component and the second electronic component include transistors, ICs, diodes, operational amplifiers, resistors, coils, capacitors, relays, switches, connectors and the like.

By the way, as one of the safety standards, there is a standard (IEC 60664) regarding the overvoltage category. The overvoltage categories are classified into four overvoltage categories I, II, III, and IV according to the rated impact withstand voltage of the equipment and the nominal voltage corresponding to the rated voltage, and the level of the rated impact withstand voltage with respect to the nominal voltage is It is set. Hereinafter, overvoltage categories I, II, III, and IV may be abbreviated as CATI, II, III, and IV.

A CATI is a device connected to a circuit in which measures have been taken to limit transient overvoltages to low levels. For example, an electronic circuit device protected by a power supply device or the like via an insulated transformer can be mentioned. CATII is an energy-consuming device supplied from fixed wiring equipment (outlet, etc.). Examples include information processing equipment, portable tools and household equipment. CATIII is a device in fixed wiring equipment where the reliability and effectiveness of the device are particularly required. For example, switches in fixed equipment and industrial equipment that is permanently connected to the fixed equipment. CATIV is a device used at the entrance. For example, a primary side overcurrent protection device can be mentioned.

Then, in the present embodiment, the first electronic component corresponds to the first overvoltage category in which the allowable value of the transient voltage is the first value. Further, the second electronic component corresponds to the second overvoltage category in which the allowable value of the transient voltage is a second value larger than the first value. Here, the first overvoltage category assumes CATII, and the second overvoltage category assumes CATIII. The protection unit 70 is configured to reduce the voltage applied to the circuit unit 30 to less than the first value via the pair of power supply connection terminals 10a and 10b. Therefore, the protection unit 70 makes it possible to use an electronic component having a low withstand voltage even in an environment where a higher withstand voltage is required. Therefore, the manufacturing cost of the electric device 10 can be reduced.

As shown in FIG. 2, the protection unit 70 includes a plurality of (two in the present embodiment) overvoltage protection elements 71, a detection unit 72, a plurality of detection elements 721 (two in the present embodiment), and a notification unit. 73 and a current limiting element 74.

The plurality of overvoltage protection elements 71 are connected in parallel between the pair of power supply connection terminals 10a and 10b. More specifically, the first end of the overvoltage protection element 71 is electrically connected between the power supply connection terminal 10a and the input terminal 60a of the power supply unit 60, and the second end of the overvoltage protection element 71 is the power supply connection terminal. It is electrically connected between 10b and the input terminal 60b of the power supply unit 60.

Each of the plurality of overvoltage protection elements 71 reduces the voltage applied to the circuit unit 30 to less than a predetermined voltage via the pair of power supply connection terminals 10a and 10b. In the present embodiment, the plurality of overvoltage protection elements 71 have predetermined voltages equal to each other. That is, the plurality of overvoltage protection elements 71 have the same performance. In this embodiment, each of the plurality of overvoltage protection elements 71 is a varistor. That is, the plurality of overvoltage protection elements 71 are composed of the same parts (varistor). In other words, the plurality of overvoltage protection elements 71 are composed of varistor having the same limiting voltage. For example, the limiting voltage (that is, a predetermined voltage) is a value that can reduce the voltage applied to the circuit unit 30 to less than the first value. The first value is 2500V corresponding to a nominal voltage of 300V in CATII. In this case, as an example, a varistor having a limiting voltage of 780V can be used as the overvoltage protection element 71. With this configuration, the protection unit 70 can reduce the voltage applied to the circuit unit 30 to less than the first value.

The detection unit 72 detects a failure related to the plurality of overvoltage protection elements 71. According to the detection unit 72, it is possible to detect a failure related to the plurality of overvoltage protection elements 71, and it is possible to take measures such as repair / replacement of the protection unit 70. In the present embodiment, the detection unit 72 uses the plurality of detection elements 721 to detect failures related to the plurality of overvoltage protection elements 71. The plurality of detection elements 721 are electrically connected to each of the plurality of overvoltage protection elements 71 in series. The detection element 721 includes a photocoupler. More specifically, in the detection element 721, the photodiode is electrically connected in series with the corresponding overvoltage protection element 71, and the output from the phototransistor is given to the detection unit 72. As a result, the detection unit 72 can determine whether or not the overvoltage protection element 71 is out of order. For example, when the detection element 721 transmits a detection signal to the detection unit 72 when the photodiode emits light, the detection unit 72 can determine the failure of the overvoltage protection element 71 depending on the presence or absence of the detection signal.

The notification unit 73 notifies the result of detection by the detection unit 72. According to the notification unit 73, it is possible to notify the failure of the plurality of overvoltage protection elements 71, and it is possible to prompt measures such as repair / replacement of the protection unit 70. In the present embodiment, the notification unit 73 includes a display unit and a sound output unit. When at least one of the plurality of overvoltage protection elements 71 fails, the notification unit 73 notifies by using the display unit and the sound output unit. The display unit visually notifies the failure of the plurality of overvoltage protection elements 71. The display unit may include a light emitting element such as a light emitting diode. The display mode by the display unit includes, for example, lighting / extinguishing, emission color or lighting pattern (blinking cycle, etc.), or a combination thereof. The sound output unit audibly notifies the failure of the plurality of overvoltage protection elements 71. The sound output unit is realized by, for example, a speaker or a buzzer. The sound output unit outputs, for example, a beep sound, and notifies a failure of a plurality of overvoltage protection elements 71 depending on the mode of the beep sound which is the output sound. Examples of beep modes include "beep", "beep" or "beep" modes. However, the sound output unit is not limited to the beep sound, and may output a voice or a melody together with the beep sound or in place of the beep sound.

The current limiting element 74 is electrically connected between the plurality of overvoltage protection elements 71 and one of the pair of power supply connection terminals 10a and 10b. In the present embodiment, the current limiting element 74 is electrically connected between the plurality of overvoltage protection elements 71 and the power supply connection terminal 10a. The current limiting element 74 is configured to limit the current supplied to the circuit unit 30 from the AC power supply 200, which is an external power supply, in the event of a short-circuit failure of at least one of the plurality of overvoltage protection elements 71. Therefore, according to the current limiting element 74, it is possible to protect the circuit unit 30 of the electric device 10 in the event of a short-circuit failure of any one of the plurality of overvoltage protection elements 71. Here, the current limitation includes setting the current to zero. In this embodiment, the current limiting element 74 includes a fuse. The current value at which the fuse blows is appropriately set in consideration of the voltage value of the AC power supply 200, the withstand voltage of the circuit unit 30, and the like.

The protection unit 70 described above is an overvoltage protection device used for the electric device 10 installed on the distribution board 100. That is, the protection unit 70 is an overvoltage protection device 70 used for the electric device 10 installed on the distribution board 100, and includes a plurality of overvoltage protection elements 71. The plurality of overvoltage protection elements 71 include a pair of power supply connection terminals 10a and 10b to which the external power supply 200 is electrically connected, and a circuit unit 30 that obtains power from the external power supply 200 via the pair of power supply connection terminals 10a and 10b. Is between. The plurality of overvoltage protection elements 71 are connected in parallel between the pair of power supply connection terminals 10a and 10b. According to this overvoltage protection device, the performance of protection from overvoltage of the circuit unit 30 of the electric device 10 can be improved.

(2) Modified Example The embodiment of the present disclosure is not limited to the above embodiment. The above-described embodiment can be changed in various ways depending on the design and the like as long as the object of the present disclosure can be achieved. Examples of modifications of the above embodiment are listed below.

In one modification, the shape of the constituent members of the electric device 10 is not necessarily limited to the shape of the above-described embodiment, and can be appropriately changed according to the design of the electric device 10, specification requirements, and the like. For example, the housing 20 may have a circular or polygonal box shape as a whole. Further, the number of constituent members of the electric device 10 can be changed according to the use of the constituent members.

In one modification, the circuit unit 30 may have other circuit elements in addition to the measurement unit 40, the communication unit 50, and the power supply unit 60. Further, the circuit unit 30 does not necessarily have to include the measurement unit 40, the communication unit 50, and the power supply unit 60, and the circuit unit 30 can be appropriately changed according to the type of the electric device 10 and the like.

In one modification, the measuring unit 40 may be configured to correspond to a sensor other than the current sensor. That is, the sensor 300 is not limited to the current sensor. For example, the sensor 300 can be selected from various sensors such as a temperature sensor, a humidity sensor, a flow rate sensor for a fluid such as gas or liquid, an electromagnetic wave sensor, a human sensor, an image sensor, and an ultrasonic sensor. The measurement unit 40 can set the processing content according to the sensor 300.

In one modification, the communication unit 50 may transmit the measurement information generated by the measurement unit 40 by wire communication. When the communication unit 50 performs wired communication, the antenna and the operation unit are not indispensable.

In one modification, the power supply unit 60 may be configured to correspond to an external power source such as a solar cell, a storage battery, or a fuel cell, in addition to the AC power source 200.

In one modification, the protection unit 70 may include only a plurality of (two in this embodiment) overvoltage protection elements 71. That is, the detection unit 72, the plurality of detection elements 721 (two in the present embodiment), the notification unit 73, and the current limiting element 74 can be arbitrary elements. Further, the number of overvoltage protection elements 71 may be 3 or more instead of 2. Further, the parameters of the overvoltage protection element 71 (limit voltage of the varistor) and the like can be appropriately set according to the usage mode of the electric device 10. Further, the detection element 721 is not limited to the photocoupler, and may be an element capable of detecting whether or not a current is flowing through the overvoltage protection element 71. Further, the detection element 721 does not need to have a one-to-one correspondence with the overvoltage protection element 71. Further, the notification unit 73 does not necessarily have to include both the display unit and the sound output unit, and may include at least one of the display unit and the sound output unit. Further, the current limiting element 74 is not limited to the fuse, and may be a PTC thermistor or the like.

(3) Aspects As is clear from the above embodiments and modifications, the present disclosure includes the following aspects. In the following, reference numerals are given in parentheses only to clearly indicate the correspondence with the embodiments.

The first aspect is an electric device (10) installed on a distribution board (100), which includes a pair of power supply connection terminals (10a, 10b), a circuit unit (30), and a protection unit (70). To be equipped. An external power supply (200) is electrically connected to the pair of power supply connection terminals (10a, 10b). The circuit unit (30) obtains electric power from the external power supply (200) via the pair of power supply connection terminals (10a, 10b). The protection unit (70) is located between the pair of power supply connection terminals (10a, 10b) and the circuit unit (30) to protect the circuit unit (30) from overvoltage. The protection unit (70) has a plurality of overvoltage protection elements (71) connected in parallel between the pair of power supply connection terminals (10a, 10b). According to this aspect, the performance of protection from overvoltage of the circuit unit (30) of the electric device (10) can be improved.

The second aspect is the electrical device (10) based on the first aspect. In the second aspect, the plurality of overvoltage protection elements (71) have the same performance. According to this aspect, the performance of protection from overvoltage of the circuit unit (30) of the electric device (10) can be improved.

The third aspect is the electrical device (10) based on the first or second aspect. In the third aspect, each of the plurality of overvoltage protection elements (71) reduces the voltage applied to the circuit unit (30) to less than a predetermined voltage via the pair of power supply connection terminals (10a, 10b). The plurality of overvoltage protection elements (71) have the predetermined voltages equal to each other. According to this aspect, the performance of protection from overvoltage of the circuit unit (30) of the electric device (10) can be improved.

A fourth aspect is an electrical device (10) based on any one of the first to third aspects. In the fourth aspect, each of the plurality of overvoltage protection elements (71) is a varistor. According to this aspect, the performance of protection from overvoltage of the circuit unit (30) of the electric device (10) can be improved.

A fifth aspect is an electrical device (10) based on any one of the first to fourth aspects. In the fifth aspect, the withstand voltage of the first electronic component constituting the circuit unit (30) is lower than the withstand voltage of the second electronic component used for the distribution board (100). According to this aspect, the manufacturing cost of the electric device (10) can be reduced.

The sixth aspect is the electrical device (10) based on the fifth aspect. In the sixth aspect, the first electronic component corresponds to a first overvoltage category in which the allowable value of the transient voltage is the first value. The second electronic component corresponds to a second overvoltage category in which the allowable value of the transient voltage is a second value larger than the first value. The protection unit (70) reduces the voltage applied to the circuit unit (30) to less than the first value via the pair of power supply connection terminals (10a, 10b). According to this aspect, the manufacturing cost of the electric device (10) can be reduced.

A seventh aspect is an electrical device (10) based on any one of the first to sixth aspects. In a seventh aspect, the protection unit (70) includes a detection unit (72) that detects a failure of the plurality of overvoltage protection elements (71). According to this aspect, it is possible to detect a failure related to a plurality of overvoltage protection elements (71), and it is possible to take measures such as repair / replacement of the protection unit (70).

The eighth aspect is the electrical device (10) based on the seventh aspect. In the eighth aspect, the protection unit (70) includes a notification unit (73) that notifies the result of detection by the detection unit (72). According to this aspect, it is possible to notify a failure of a plurality of overvoltage protection elements (71), and it is possible to prompt measures such as repair / replacement of the protection unit (70).

A ninth aspect is an electrical device (10) based on any one of the first to eighth aspects. In the ninth aspect, the protection unit (70) is a current limiting element electrically connected between the plurality of overvoltage protection elements (71) and one of the pair of power supply connection terminals (10a, 10b). (74). According to this aspect, it is possible to protect the circuit unit (30) of the electric device (10) in the event of a short-circuit failure of any of the plurality of overvoltage protection elements (71).

A tenth aspect is an electrical device (10) based on any one of the first to ninth aspects. In a tenth aspect, the circuit unit (30) includes a power supply unit (60) that generates operating power based on the electric power obtained through the pair of power supply connection terminals (10a, 10b). The protection unit (70) is located between the power supply unit (60) and the pair of power supply connection terminals (10a, 10b). According to this aspect, the performance of protection from overvoltage of the power supply unit (60) of the circuit unit (30) of the electric device (10) can be improved.

The eleventh aspect is an electric device (10) based on the tenth aspect. In the eleventh aspect, the circuit unit (30) includes a measurement unit (40) that generates measurement information regarding a predetermined physical quantity based on sensing information from the sensor (300). According to this aspect, the electric device can be used as a measuring device.

A twelfth aspect is an overvoltage protection device (70) used in an electric device (10) installed on a distribution board (100), which includes a plurality of overvoltage protection elements (71). The plurality of overvoltage protection elements (71) are provided via a pair of power supply connection terminals (10a, 10b) to which an external power supply (200) is electrically connected and the pair of power supply connection terminals (10a, 10b). It is between the circuit unit (30) that obtains power from the external power source (200). The plurality of overvoltage protection elements (71) are connected in parallel between the pair of power supply connection terminals (10a, 10b). According to this aspect, the performance of protection from overvoltage of the circuit unit (30) of the electric device (10) can be improved.

10 Electrical equipment 10a, 10b Power connection terminal 30 Circuit unit 40 Measuring unit 60 Power supply unit 70 Protection unit 71 Overvoltage protection element 72 Detection unit 73 Notification unit 74 Current limiting element 100 Distribution board 200 AC power supply (external power supply)

Claims (12)

Electrical equipment installed on the distribution board
A pair of power connection terminals to which an external power supply is electrically connected,
A circuit unit that obtains power from the external power supply via the pair of power supply connection terminals, and
A protective unit between the pair of power supply connection terminals and the circuit unit that protects the circuit unit from overvoltage.
With
The protection unit has a plurality of overvoltage protection elements connected in parallel between the pair of power supply connection terminals.
Electrical equipment. The plurality of overvoltage protection elements have the same performance.
The electrical device of claim 1. Each of the plurality of overvoltage protection elements reduces the voltage applied to the circuit unit via the pair of power supply connection terminals to less than a predetermined voltage.
The plurality of overvoltage protection elements have said predetermined voltages equal to each other.
The electrical equipment of claim 1 or 2. Each of the plurality of overvoltage protection elements is a varistor.
An electrical device according to any one of claims 1 to 3. The withstand voltage of the first electronic component constituting the circuit unit is lower than the withstand voltage of the second electronic component used in the distribution board.
An electrical device according to any one of claims 1 to 4. The first electronic component corresponds to the first overvoltage category in which the allowable value of the transient voltage is the first value.
The second electronic component corresponds to a second overvoltage category in which the allowable value of the transient voltage is a second value larger than the first value.
The protection unit reduces the voltage applied to the circuit unit via the pair of power supply connection terminals to less than the first value.
The electrical device of claim 5. The protection unit includes a detection unit that detects a failure related to the plurality of overvoltage protection elements.
An electrical device according to any one of claims 1 to 6. The protection unit includes a notification unit that notifies the result of detection by the detection unit.
The electrical device of claim 7. The protection unit has a fuse that is electrically connected between the plurality of overvoltage protection elements and one of the pair of power connection terminals.
An electrical device according to any one of claims 1 to 8. The circuit unit includes a power supply unit that generates operating power based on the electric power obtained through the pair of power supply connection terminals.
The protection unit is located between the power supply unit and the pair of power supply connection terminals.
An electrical device according to any one of claims 1 to 9. The circuit unit includes a measurement unit that generates measurement information regarding a predetermined physical quantity based on sensing information from the sensor.
The electrical device of claim 10. An overvoltage protection device used in electrical equipment installed on distribution boards.
Between a pair of power supply connection terminals to which an external power supply is electrically connected and a circuit unit that obtains power from the external power supply via the pair of power supply connection terminals, in parallel between the pair of power supply connection terminals. With multiple overvoltage protection elements connected,
Overvoltage protection device.

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