JP2005218155A - Electric leak detection power supply device and distribution board equipped with electric leak detection power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric leak detection power supply device that can detect an electric leak that occurs at either or both the high-potential side and the low-potential side of a primary-side power supply line of an apparatus being a load. <P>SOLUTION: The electric leak detection power supply device comprises a transformer 11 with a center tap at its secondary side, and an electric leak blocker 12. A center terminal 11e of the transformer 11 is connected to the ground, an AC power supply is connected to primary-side terminals 11a, 11b of the transformer 11, and power is fed to the load from secondary-side terminals 11c, 11d via the electric leak blocker 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power supply device that supplies power to a load, and more particularly to a leakage detection power supply device that can detect a leakage even if a leakage occurs on either the HOT side or the COLD side of a load device.

  2. Description of the Related Art Conventionally, a power supply device that supplies power supplied from an electric power company or the like to a load is provided with a leakage breaker for ensuring safety at the time of leakage.

  The principle of operation of a general earth leakage breaker is to detect the presence or absence of earth leakage by detecting the difference between the forward path and the return path of the current and to interrupt the circuit at the time of earth leakage. In other words, when there is no leakage, there is no current difference between the current forward path and the return path, but when there is a current leakage, a current difference according to the leakage current occurs between the current forward path and the return path. By detecting with a current transformer (zero current transformer), the presence or absence of electric leakage is detected, and when there is electric leakage, the circuit is interrupted.

  Prior art relating to an earth leakage breaker is disclosed in Patent Literature 1, and prior art relating to a power supply device including the earth leakage breaker is disclosed in Patent Literature 2.

JP 7-21901 A JP 2003-87960 A

  As described above, when a predetermined current difference occurs between the current forward path and the return path, the earth leakage breaker determines that there is a leakage due to the current corresponding to this current difference occurring in the zero-phase current transformer. It is. The commercial power supply has one pole grounded. Therefore, for example, when an electric device as a load is connected to a commercial power supply via a leakage breaker, a failure that causes a leakage in the high-potential power line on the primary side of the electric device (that is, If there is a ground connection via a resistor), the potential difference between the power line on the high potential side and the ground is large, and a leakage current proportional to this potential difference flows. A current difference corresponding to the current is generated between the forward path and the return path of the current in the leakage breaker, and the leakage breaker can be correctly determined as “leakage”.

  However, in the same way as described above, the electrical equipment that is the load is connected to the commercial power supply via the earth leakage breaker, and the earth leakage is connected to the power line on the low potential (ground) side on the primary side of the electrical equipment. If there is a fault that causes a fault (that is, a state in which it is grounded via a resistor), there is almost no potential difference between the power line on the low potential (ground) side and the ground, so the leakage current Therefore, since there is no current difference between the forward path and the return path of the current in the earth leakage breaker, the earth leakage breaker determines that “no earth leakage”. In other words, if there is no predetermined current difference between the current forward path and the return path, it is determined that there is no current leakage, regardless of whether or not there is an actual current leakage (a failure that may cause electrical leakage in electrical equipment). Become.

  Therefore, when the commercial power source is non-polar, the power plug of an electrical device or the like can be inserted into a power outlet in any direction (for example, a commercial power source in Japan). Depending on the insertion direction of the power plug, there was a situation where the earth leakage circuit breaker made different judgments and operations. This is because, in an electrical device that has a fault that causes a leakage in one of the primary poles, the leakage side pole is also at a low potential (ground) due to the insertion of the power plug of the electrical device. Because it will also be on the side. As described above, it is not preferable that the earth leakage circuit breaker, which is a device for ensuring safety, make different judgments / operations for devices having the same failure.

  In view of the above-described problems, the present invention detects leakage even if a leakage occurs at either the high potential side or the low potential side of the power supply line on the primary side of the device serving as a load in order to enhance safety. An object of the present invention is to provide a leakage detection power supply device that enables the above.

  The leakage detection power supply device according to claim 1 is a power supply device that supplies power to a load, and includes a transformer with a center tap on the secondary side and a leakage breaker, and a center tap on the secondary side. An AC power source is connected to the primary side of the connected transformer, and power is supplied from the secondary side to the load via the leakage breaker.

  According to the leakage detection power supply apparatus having the above configuration, the transformer 2 with respect to the potential of the center terminal of the transformer with a center tap (for example, the voltage of the constant voltage source when the center terminal is connected to the constant voltage source). One terminal on the next side has a high potential and the other terminal has a low potential.

  According to a second aspect of the present invention, there is provided an electric leakage detection power supply apparatus according to the first aspect, wherein a center terminal of a transformer having a center tap on the secondary side is grounded.

  According to the leakage detection power supply apparatus having the above configuration, at the secondary terminal of the transformer with the center tap, one terminal has a higher potential than the ground with respect to the potential (ground) of the center terminal, and the other terminal is grounded. Lower potential. Since the secondary terminal of the transformer with the center tap is connected to the load via the earth leakage circuit breaker, one terminal on the primary side of the load is at a higher potential than the ground, and the other terminal is lower than the ground. It becomes a potential.

  A distribution board provided with the leakage detection power supply device according to claim 3 is provided with the leakage detection power supply device according to claim 1 or 2.

  A power supply device for supplying power to a load according to claim 1 of the present invention, comprising a transformer with a center tap on the secondary side and an earth leakage breaker, and having a center tap on the secondary side According to the earth leakage detection power supply apparatus, wherein an AC power source is connected to the primary side of the transformer and power is supplied from the secondary side to the load via the earth leakage breaker, the transformer with a center tap By appropriately selecting the winding ratio and the potential of the center terminal, it is possible to cause a potential difference with respect to the ground potential on either the primary high potential side or the low potential side of the electrical equipment that is the load. Therefore, if there is a failure that causes a leakage on the primary side of an electrical device or the like as a load, a leakage current proportional to the potential difference flows regardless of which pole the failure is in, and the leakage By circuit breaker Since the leakage detection becomes possible, raise the accuracy of leakage detection, as a result, it is possible to improve safety.

  According to Claim 2 of the present invention, there is provided a leakage detection power supply apparatus according to Claim 1, wherein a center terminal of a transformer having a center tap on the secondary side is grounded. For example, a potential difference occurs with respect to the ground potential on either the primary high potential side or the low potential side of an electrical device as a load. Even if there is a fault that causes electric leakage at the pole, electric leakage detection is possible, and the accuracy of electric leakage detection is improved. As a result, safety can be improved.

  According to the distribution board provided with the leakage detection power supply device according to claim 3 of the present invention, comprising the leakage detection power supply device according to claim 1 or claim 2, the primary side of the equipment as a load It is possible to detect the leakage and interrupt the circuit regardless of whether the leakage occurs on the high potential side or the low potential side.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following embodiment is one form when the present invention is embodied, and is not intended to limit the present invention within the scope thereof.

  FIG. 1 is a circuit diagram showing an outline of a leakage detection power supply apparatus according to the present embodiment, and FIGS. 2 and 3 show the use of the leakage detection power supply apparatus and a television receiver as an example of an electric device as a load. It is a block diagram which shows the outline of a state. 5 and 6 are block diagrams showing an outline of a usage state of an example of a power supply device having a conventional earth leakage breaker and a television receiver as an example of an electric device as a load.

  As shown in FIG. 1, the leakage detection power supply apparatus 10 of the present embodiment includes a 1: 1 transformer 11 with a center tap on the secondary side and a leakage breaker 12, and the center terminal 11 e of the transformer 11 is grounded. It is connected. In the leakage detection power supply device 10, an AC power source is connected to the primary-side terminals 11 a and 11 b of the transformer 11, and power is supplied to the load from the secondary-side terminals 11 c and 11 d via the leakage breaker 12. By adopting such a configuration, both the terminal 11c and the terminal 11d have a potential difference with respect to the ground potential.

  Next, an example of a usage state of the leakage detection power supply device 10 of the present embodiment will be described with reference to FIG. An AC power supply 22 is connected to the primary side of the transformer 11 of the leakage detection power supply apparatus 10 of the present embodiment. The terminal 11b side of the AC power source 22 is grounded. A power plug 23 a of the television receiver 23 as a load is connected to the secondary side of the transformer 11 via the earth leakage breaker 12. The television receiver is grounded on the secondary side by connecting the grounded RF antenna 24 to the secondary side. The leakage circuit 25 is an equivalent circuit in the case where leakage occurs, and does not exist when the television receiver 23 is in a normal state.

  FIG. 5 and FIG. 6 show an outline of a usage state of a power supply device 54 as an example of a conventional power supply device having an earth leakage breaker and a television receiver 51 as an example of an electric device as a load. . The television receiver 51 has the same configuration as the television receiver 23 in FIG. In the conventional example shown in FIG. 5 and FIG. 6, when the leakage circuit 52 exists as shown in FIG. 5 (that is, the failure portion where the leakage occurs is on the high potential side on the primary side of the television receiver 51. If the resistance value of the earth leakage resistance 52a is R52 (Ω) and the voltage of the AC power supply 22 is V22 (V), a current of almost V22 / R52 (I) flows to the earth leakage circuit 52. The circuit breaker 53 can detect this leakage current, and can perform circuit breaking operation. On the other hand, as shown in FIG. 6, when the power plug 51a of the same television receiver 51 as in FIG. 5 is inserted in the opposite direction, the potential difference between the potential at A and the ground potential is small. Almost no current flows through the leakage circuit 52, and as a result, the leakage breaker 53 cannot detect the leakage.

  On the other hand, according to the present embodiment, when the leakage circuit 25 exists as shown in FIG. 2 (that is, when leakage occurs in A on the primary side of the television receiver 23), the resistance of the leakage resistance 25a. Assuming that the value is R25 (Ω) and the potential difference between the terminal 11c and the terminal 11e in the transformer 11 is Vce (V), a current of approximately Vce / R25 (I) flows to the leakage circuit 25. 12 can be detected and the circuit can be interrupted. Further, as shown in FIG. 3, even when the power plug 23a of the television receiver 23 is inserted in the opposite direction to that of FIG. 2, the resistance value of the leakage resistance 25a is R25 (Ω), and the terminal 11d of the transformer 11 Assuming that the potential difference of the terminal 11e is Ved (V), the current of Ved / R25 (I) flows to the leakage circuit 25. Therefore, the leakage breaker 12 can detect this leakage current and break the circuit. It is.

  As described above, according to the leakage detection power supply device 10 of the present embodiment, a potential difference is generated with respect to the ground potential on either the high potential side or the low potential side of the primary side such as an electric device as a load. If there is a failure that causes a leakage on the primary side of a load such as an electrical device, the leakage breaker 12 can detect the leakage even if a leakage occurs at any pole, increasing the accuracy of the leakage detection. As a result, safety can be improved. Therefore, for example, if the leakage detection power supply device 10 of the present embodiment is used in a power supply device for performing a product operation test in a factory or the like, it is possible to accurately detect the presence or absence of leakage of the product.

  In this embodiment, a 1: 1 transformer is used as the transformer 11 with a center tap on the secondary side. However, the present invention is not limited to this, and for example, the AC power supply 22 is 200 V and is a load. If the electrical equipment is rated at 100V, a 2: 1 transformer can be used so that it can have a transforming function at the same time. The center terminal 11e of the transformer 11 is preferably at the ground potential, but it is not always necessary to be at the ground potential, and the center terminal 11e may be connected to a constant voltage source. In the present embodiment, the leakage detection power supply 10 is used on the power supply side for the device. However, the present invention is not limited to this. For example, the leakage detection power supply 10 is used as a power supply inside the load device. May be built in the device.

  FIG. 4 is a block diagram showing an outline of a distribution board provided with the leakage detection power supply device of this embodiment.

  A distribution board 40 including the leakage detection power supply device of the present embodiment includes a leakage detection power supply device 41, an overcurrent circuit breaker 42, and distribution circuit breakers 43a to 43d. The overcurrent circuit breaker 42 is provided between the primary side of the transformer 41a provided in the leakage detection power supply device 41 and the AC power supply, and the secondary side of the transformer 41a is disconnected for distribution via the leakage breaker 41b. Devices 43a-43d are connected in parallel.

  Hereinafter, the case where the distribution board 40 provided with the leakage detection power supply device of the present embodiment is used in a general household will be described as an example. The overcurrent circuit breaker 42 cuts off the circuit when the current corresponding to the total electric power used in the home including the electric leakage exceeds a predetermined current (for example, 30 A). The distribution circuit breakers 43a to 43d supply power separately to each section, and when the current corresponding to the power used in each section including electric leakage exceeds a predetermined current (for example, 15A). Further, the circuit of the section is cut off. The operation concept of the leakage detection power supply apparatus 41 of the present embodiment is the same as that of the leakage detection power supply apparatus 10 of the first embodiment, and thus description thereof is omitted here.

  According to the distribution board 40 provided with the leakage detection power supply device of the present embodiment, the ground potential can be maintained on either the primary side high potential side or the low potential side of the electrical equipment supplied with power through the power distribution breaker. On the other hand, since a potential difference is generated, if there is a fault that causes a leakage on the primary side of an electric device or the like that is a load, the leakage detection can be performed regardless of which leakage occurs.

  In the present embodiment, since all of the power distribution breakers 43a to 43d are connected to the leakage detection power supply device 41, even if leakage occurs only in one electrical device in any section, The power supply will be cut off. For example, between a load breaker and a distribution circuit breaker that supplies power to a section (such as around water) or a device (such as a washing machine or refrigerator) where leakage of electricity is likely to occur. By configuring the power supply line to include the leakage detection power supply device 41, when a leakage occurs in the section, it is possible to cut off the power supply only in the section and not affect other sections. is there.

1 is a circuit diagram illustrating an outline of a leakage detection power supply device according to a first embodiment. FIG. 3 is a block diagram illustrating an outline of a usage state of the electric leakage detection power supply device and the television receiver according to the first embodiment. FIG. 3 is a block diagram showing an outline of another usage state of the leakage detection power supply apparatus and the television receiver according to the first embodiment. The block diagram which shows the outline of a distribution board provided with the electrical leakage detection power supply device of Example 2. FIG. The block diagram which shows the outline of the use condition with the power supply device and television receiver which have the conventional earth-leakage circuit breaker The block diagram which shows the outline of another use condition with the power supply device and television receiver which have the conventional earth-leakage circuit breaker

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Earth leakage detection power supply device 11 Transformer 12 Earth leakage breaker 23 Television receiver 25 Earth leakage circuit 25a Earth leakage resistance 40 Distribution board provided with earth leakage detection power supply device 41 Earth leakage detection power supply device

Claims (3)

  A power supply device for supplying power to a load, comprising a transformer with a center tap on the secondary side and a leakage breaker, and an AC power source on the primary side of the transformer with a center tap on the secondary side Is connected to the load from the secondary side via the leakage breaker, and the leakage detecting power supply device is characterized in that   2. The leakage detection power supply apparatus according to claim 1, wherein a center terminal of a transformer having a center tap on the secondary side is grounded.   A distribution board equipped with a leakage detection power supply device comprising the leakage detection power supply device according to claim 1.

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