JP3484040B2 - AC supply device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternating current supply device capable of supplying an alternating current to an external device and displaying a current value of the supplied alternating current. More specifically, the leakage current of a device to be measured is measured by a leakage ammeter. In this case, the present invention relates to an AC supply device suitable for supplying AC to the measurement target device.

[0002]

2. Description of the Related Art Generally, leakage current is measured in a state where commercial AC is supplied to a device to be measured. An apparatus shown in FIG. 9 is known as a test apparatus configured to supply alternating current to a device to be measured and to display the supplied current value at the time of such leakage current measurement. The test apparatus 51 detects an outlet 53 for supplying the AC 100V commercial AC input from the inlet 52 to a measurement target device (not shown), and a supply current value of the commercial AC supplied to the measurement target device via the outlet 53. Current transformer 7, a power supply unit 54 that generates direct current from commercial alternating current and supplies it to each unit, and a current that rectifies the detection voltage detected by the current transformer 7 to detect a voltage according to the supply current value. Detector 55 and current detector 55
The control unit 57 that calculates the supply current value based on the detected voltage of V and displays the calculated current value on the display unit 56.
And a switch unit 58 for selecting one of a correction operation and a normal operation described later, and a current transformer 7 for conducting a predetermined reference current when correcting the display current value displayed on the display unit 56. It is provided with a terminal portion 59 and a switch 60 for switching the alternating current path during the correction operation.

In this test apparatus 51, when measuring a leak current by a leak ammeter (not shown), the commercial AC input through the inlet 52 is output to the device under measurement through the outlet 53. At this time, the current transformer 7 detects the value of the current supplied from the outlet 53 and outputs the detected voltage to the current detector 55. Next, the current detector 55
Rectifies the detected voltage and outputs the rectified voltage to the controller 57. After that, the control unit 57 calculates the supply current value based on the rectified voltage and displays it on the display unit 56.

On the other hand, in general, the magnetic permeability of the magnetic core used in the current transformer 7 may vary depending on the manufacturing lot. Therefore, in the inspection before shipment by the manufacturer, it is necessary to correct the display current value displayed on the display unit 56 with respect to the detection voltage detected by the current transformer 7. Therefore, in the test apparatus 51, when the correction operation is selected by the switch unit 58, the display current value can be corrected. During this correction operation, by switching the switch 60, an AC current is conducted between the input terminal 59a and the input terminal 59b of the terminal portion 59, and a short-circuit path for detecting the conduction current value by the current transformer 7 is provided. It is formed. Next, an AC constant current source is connected between the input terminals 59a and 59b of the terminal portion 59 so that the AC constant current is conducted, and when a constant current of, for example, 20A is conducted from the AC constant current source, the current transformer 7 conducts the current. A detection voltage corresponding to the current is detected. Next, the display current value of the display unit 56 is corrected to 20 A by a volume control (not shown) provided in the control unit 57. Then, after disconnecting the AC constant current source from the terminal portion 59, if the switch 60 is switched to the original state and normal operation is selected by the switch portion 58, commercial AC can be supplied from the outlet 53 to the measurement target device. An accurate supply current value during AC supply can be displayed on the display unit 56.

[0005]

However, the conventional test apparatus 51 has the following problems. That is, in the test apparatus 51, in the pre-shipment inspection by the manufacturer, the display current value is corrected after the switch 60 is switched and the correction operation is selected by the switch unit 58.
It is necessary to switch the switch 60 to the original state.
Therefore, if the switch 60 is shipped in the state of the correction operation, the commercial alternating current cannot be supplied from the outlet 53 when the user uses the test apparatus 51.

Originally, the terminal portion 59 and the switch 6 are also provided.
0 is used only in the inspection process of the manufacturer. Therefore, it is unnatural that a switch or the like unnecessary for the user is exposed to the outside of the device, which is not preferable in terms of design. Further, there is a problem that the device cost is increased because the unnecessary terminal portion 59 has to be provided during the normal operation. In addition, even if the user operates the switch 60 by mistake, the commercial AC cannot be supplied from the outlet 53.
For this reason, there is a problem that it is necessary to take measures against a user's erroneous operation. On the other hand, it is conceivable to dispose the terminal portion 59 and the switch 60 inside the device, but as a result of the complicated structure of the device, another problem that the device cost rises occurs.

The present invention has been made in view of the above problems, and its main purpose is to provide an AC supply device capable of preventing an erroneous operation with a simple structure, and is particularly suitable as a leakage current test device. Another object is to provide a usable alternating current supply device.

[0008]

In order to achieve the above object, an alternating current supply device according to claim 1 detects an outlet for supplying an external device with an alternating current output from an alternating current source and a current value of the supplied alternating current. In the AC supply device comprising a current transformer for performing, a display unit for displaying the detected current value, and a correction unit for correcting the display current value displayed on the display unit for the detected current value, At the time of correction by the correction unit, a short circuit path is formed between one output terminal of the outlet and the other output terminal to detect a constant current with a current transformer when an AC constant current source is connected between both output terminals. And a path forming means for forming an AC supply path connecting the outlet and the AC source with each other when the AC supply is performed to the external device. And butterflies. The “AC constant current source” in the present invention includes both an AC power supply configured to output a constant current and an AC power supply combining a load resistance and an AC power supply outputting a constant voltage.

In this AC supply device, the path forming means short-circuits one output terminal of the outlet and the other output terminal when the display current value is corrected by the correction section.
In this case, if an AC constant current source is connected between both output terminals to conduct an AC constant current, the current transformer detects the AC constant current value conducting the short-circuit path. On the other hand, when the AC power is supplied to the external device, the path forming means opens the short circuit path and connects the outlet and the AC source. As described above, in this AC supply device, it is possible to correct the display current value of the display unit by supplying an AC constant current from the outlet during the correction operation using one outlet, and from the outlet during the normal operation. AC can be supplied. Therefore, the terminal portion 59 and the switch 60 used in the conventional test apparatus 51 are
As a result, unnecessary operation parts for the user are not exposed to the outside of the device, which makes it possible to provide an AC supply device that has an excellent design, is extremely easy to handle, and is free from erroneous operation. . It should be noted that, for example, it is preferable to configure the switch to the correction operation by operating a special key provided in the correction unit or simultaneously operating two keys from the viewpoint of completely eliminating an erroneous operation by the user. preferable.

According to a second aspect of the present invention, there is provided the alternating current supply device according to the first aspect.
In the AC supply device described above, the path forming means includes a first switch circuit having a movable contact connected to one end of one of the AC supply paths connected to the AC source, and an AC supply having a make contact connected to the AC source. The make contact is alternating with the second switch circuit connected to the other end of the path, the break contact being connected to the make contact of the first switch circuit, and the movable contact being connected to one output terminal of the outlet. A third switch connected to one end of the other of the alternating current supply paths connected to the source, the break contact connected to the make contact of the first switch circuit, and the movable contact connected to the other output terminal of the outlet. And a circuit.

Generally, the leakage current of the equipment differs depending on the connection conditions of the power supply line and the ground line. Therefore, it is necessary to measure under various measurement conditions and confirm that the measured value is within the allowable range. In this AC supply device, during the AC supply operation, for example, the first switch circuit and the second switch circuit are activated and the third switch circuit is operated.
If one of the output lines of the AC source is deactivated, the one of the output lines of the AC source is connected to the outlet of the outlet through the movable contact and the make contact of the first switch circuit and the break contact and the movable contact of the third switch circuit. The output line of the AC source is connected to the other output terminal and the other of the output lines of the AC source is connected to one output terminal of the outlet via the make contact and the movable contact of the first switch circuit. Also, first to
By switching the third switch circuit, it is possible to set various measurement conditions such as reverse phase connection and disconnection of one of the AC power supply lines. Further, in the correction operation, if the first to third switch circuits are deactivated, one output terminal of the outlet has a movable contact and a break contact of the second switch circuit, and a break of the third switch circuit. It is short-circuited to the other output terminal of the outlet through a short-circuit path formed by the contact and the movable contact. In this case, the current transformer can detect an alternating current that conducts in the short circuit path. Therefore, by conducting an alternating constant current in the short circuit path, the display current value of the display unit relative to the detected current of the current transformer can be easily adjusted. Can be corrected to. Thus, this AC supply device can be suitably used as a test device for AC supply when measuring a leakage current.

According to a third aspect of the present invention, there is provided the alternating current supply device according to the second aspect.
In the AC supply device described above, the path forming means is further provided with a fourth switch circuit for connecting the ground wire and the ground terminal of the outlet.

In this alternating current supply device, if necessary, the fourth
By activating or deactivating the switch circuit of
The ground wire of the AC source and the ground wire of the external device can be short-circuited or opened. Thereby, for example, it becomes possible to set the measurement condition of the ground wire disconnection state at the time of measuring the leakage current, and thus it can be more preferably used as an AC supply test device at the time of measuring the leakage current.

According to a fourth aspect of the present invention, there is provided the alternating current supply device of the second aspect.
Further, in the AC supply device described in 3, the switch circuit is configured by a relay and further includes a control unit that controls the operation of the relay.

The AC path forming means may be configured to manually switch the AC supply path. On the other hand, like this AC supply device, when the control unit switches the relay as the switch circuit, for example, when used as a test device for measuring leakage current, the AC supply path is formed automatically and surely. It becomes possible.

According to a fifth aspect of the present invention, there is provided the alternating current supply device according to the first aspect.
In the AC supply device according to any one of 1 to 4, the AC supply device is a leakage current measurement test device that supplies AC to an external device that is a measurement target in order to measure the leakage current.

In this AC supply device, by controlling the first to fourth switch circuits, for example, various connection conditions for two AC power supply lines and one ground line, which are specified in the leakage current measurement, can be set. Since it can be easily set, it can be suitably configured as a leakage current measuring test device.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments in which the AC supply apparatus according to the present invention is applied to a leak current measuring test apparatus will be described below with reference to the accompanying drawings. The same components as those of the conventional test apparatus 51 are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 1, the test apparatus 1 has two power source input terminals 2a and 2b for inputting commercial alternating current.
And an inlet 2 having an input terminal 2c for connecting a ground line, a power supply unit 3 for generating a direct current _VDC for a device power supply from a commercial AC and supplying it to each unit, and disposed between the inlet 2 and the power supply unit 3. Main power switch 4 and two output terminals 5a, 5 for outputting commercial AC to the device under test
an outlet 5 having an output terminal 5c for connecting b and the ground wire, and an outlet 5 and an inlet 2
It is provided with a breaker 6 arranged between them, and a current transformer 7 configured by winding a winding around a magnetic core and detecting an alternating current value supplied to the device under test.

Further, the test apparatus 1 includes a detection section 11, a range section 12, an A / D conversion section 13, a control section 14 corresponding to a correction section and a control section in the present invention, a display section 15, a switch section 16, and four sections. The drivers 17 to 20 and four relays 21 to 24 corresponding to the path forming means and the switch circuit in the present invention are provided.

Here, the detection unit 11 performs full-wave rectification on the AC voltage detected by the current transformer 7 during the normal operation in which AC is output from the outlet 5 and the correction operation described later, and the rectified voltage is ranged. Output to 12. The range unit 12 generates a detection voltage within a predetermined voltage range by amplifying or attenuating the rectified voltage at a predetermined ratio. The A / D conversion unit 13 performs analog-to-digital conversion on the detected voltage and outputs the converted detected voltage, which is digital data, to the control unit 14. The control unit 14 uses, for example, the CP
U, a built-in ROM and a built-in RAM are provided, and an AC current value for conducting a current path inserted through the current transformer 7 is calculated based on the input detection voltage and the ratio of the range circuit 12. In addition, the control unit 14
Performs a normal operation of outputting commercial AC from the outlet 5 when the normal operation is selected by the switch unit 16, and displays a display current value displayed on the display unit 15 when the correction operation is selected. Perform the correction operation to correct. The display unit 15 is composed of, for example, a liquid crystal panel, and displays the AC current value detected by the current transformer 7 in the control unit 14.
Display under the control of. The switch unit 16 is used to select either the normal operation or the correction operation. The drivers 17 to 20 are each configured by, for example, a transistor, and under the control of the control unit 14, the relay 2
Controls the operation / non-operation of 1 to 24.

Next, the operation of the test apparatus 1 will be described.

When the correction operation is selected by the switch section 16, the control section 14 first controls the relays 21 to 24 in the inoperative state. In this state, the output terminal 5a of the outlet 5 has the movable contact 22c and the break contact 22a of the relay 22 and the break contact 23 of the relay 23.
The output terminal 5b of the outlet 5 is short-circuited by a short-circuit path formed by a and the movable contact 23c. In this case, the current transformer 7 can detect the alternating current value conducted in the short circuit path. Therefore, both output terminals 5
By connecting an AC constant current source between a and 5b and conducting a constant current of, for example, 20 A as a reference current in the short circuit path, the current value can be detected by the current transformer 7. Then, the control unit 14 causes the display unit 15 to
The coefficient in the internal calculation is corrected so that the display current value to be displayed at 20 A becomes 20 A. That is, for example, when it is determined that the detected current value detected by the current transformer 7 is 18 A, the coefficient (20/18) is multiplied by the detected current value, and the multiplied value is displayed on the display unit 15. The value. As a result, even if the magnetic permeability of the magnetic core of the current transformer 7 is different for each device, the accurate value of the alternating current value output from the outlet 5 can be displayed.
5 can be displayed.

Next, the case where the normal operation is selected by the switch section 16 will be described with reference to FIGS.

In this operation, the controller 14 controls the input terminals 2a, 2b and 2c of the inlet 2 and the device under test 41.
The connection with the input terminal of the inlet is automatically set according to the program stored in the internal ROM. In this case, the control unit 14 controls the relays 21 to 24 to sequentially set a plurality of measurement conditions. This is because the leak current of the device under test 41 differs depending on the difference in the connection conditions of the power supply line and the ground line, and therefore it is confirmed that the maximum leak current value is within the allowable value under the assumed measurement conditions. This is because.

Next, specific examples of measurement conditions will be described. First, assuming that the power supply line 31 of the AC voltage Ea is connected to the input terminal 2a of the inlet 2, the power supply line 32 of the AC voltage Eb is connected to the input terminal 2b, and the ground line G is connected to the input terminal 2c. For example, the connection conditions are represented by the equivalent circuits shown in FIGS. In FIG. 2, the power supply lines 31 and 32 are connected in positive phase to the input terminals of the AC voltages Ea and Eb at the inlet of the device under test 41, and the ground line 33 is connected to the device under test 4
The measurement condition (hereinafter referred to as “measurement condition 1”) normally connected to the input terminal for connecting the ground wire G in the inlet of 1 is shown, and FIG. 3 shows that the power supply lines 31 and 32 are connected in a positive phase. And the measurement condition that the ground wire 33 is disconnected (hereinafter,
"Measurement condition 2") is shown in FIG.
32 shows a measurement condition (hereinafter, referred to as “measurement condition 3”) in which 32 is connected in a reverse phase and the ground wire 33 is normally connected. In FIG. 5, the power supply lines 31 and 32 are connected in a reverse phase, 6 shows a measurement condition in which the ground wire 33 is disconnected (hereinafter, referred to as "measurement condition 4"). In FIG. 6, the power supply wire 31 is connected in a positive phase, the power supply wire 32 is disconnected, and the ground wire is FIG. 7 shows the measurement conditions that are normally connected (hereinafter referred to as “measurement condition 5”). In FIG. 7, the power supply line 31 is connected in reverse phase, the power supply line 32 is disconnected, and the ground line is normally connected. The measured measurement conditions (hereinafter, referred to as “measurement condition 6”) are shown.

Next, the control unit 14 during this normal operation
A specific control operation of will be described with reference to FIG.

First, for example, when the measurement condition 1 is set, the control unit 14 outputs a drive signal to the drivers 17 and 18 to cause the relay 2 to operate as shown in FIG.
1 and 22 are controlled to an operating state, and relays 23 and 24 are controlled to a non-operating state. As a result, the input terminal 2a of the inlet 2 is connected to the outlet 5 via the breaker 6 and the make contact 22b and the movable contact 22c of the relay 22.
2, and the output terminal 5a is connected to the input terminal for inputting the AC voltage Ea of the inlet of the device under test 41, as shown in FIG. The input terminal 2b is connected to the outlet 5 via the breaker 6, the movable contact 21c and the make contact 21b of the relay 21, and the break contact 23a and the movable contact 23c of the relay 23.
Output terminal 5b, and the output terminal 5b is connected to the input terminal for inputting the AC voltage Eb of the inlet of the device under test 41. Further, the input terminal 2 of the inlet 2
c is connected to the output terminal 5c of the outlet 5 via the movable contact 24c and the break contact 24a of the relay 24, and the output terminal 5c is an input terminal for connecting the ground wire G of the inlet of the device under test 41. Connected. Similarly, the control unit 14 outputs a drive signal to the drivers 17 to 20 to control the relays 21 to 24 in the operating state or the non-operating state, so that the measurement conditions 2 to 6 are obtained.
Are set sequentially. Thereby, the measurement condition at the time of leak current measurement can be automatically set.

As described above, according to this test apparatus 1,
At the time of the correction operation, the control unit 14 controls the relays 21 to 24 in the non-operating state, so that the output terminal 5a and the output terminal 5b of the outlet 5 are short-circuited, whereby
The value of the alternating current conducted through the short-circuit path can be detected by the current transformer 7. As a result, outlet 5
By connecting an AC constant current source between the output terminals 5a and 5b of, the display current value of the display unit 15 can be easily corrected. Further, as a result that the terminal portion 59 and the switch 60 which are used in the conventional test apparatus 51 and are necessary only during the correction operation can be eliminated, the operation parts unnecessary for the user are not exposed to the outside of the apparatus, and thus the simple configuration is achieved. Thus, it is possible to provide the test apparatus 1 which has an excellent design, is extremely easy to handle, and is free from erroneous operation.

In this embodiment, the test apparatus 1 for supplying the commercial AC to the device 41 to be measured at the time of measuring the leakage current has been described as an example. However, the present invention is not limited to the above, and can be applied to all devices capable of supplying an alternating current to an external device and displaying a supply current value at that time. Further, the AC source in the present invention is not limited to being installed outside the device, and may be installed inside the AC supply device.

Further, in the present embodiment, an example in which the switch circuit of the present invention is configured by the relays 21 to 24 has been described, but the switch circuit is not limited to this.
It can also be configured by a manual switch. Furthermore, the configurations of the relays 21 to 24 for forming the short circuit path and the AC supply path in the present invention can be appropriately changed. For example, in FIG. 1, all relays 21-2
4 describes the connection state when not operating, but it is also possible to employ a configuration in which the connection state shown in the same figure is obtained when all or part of the operation is performed. Further, the display unit 15 can also be composed of a CRT, a plasma display, or the like. Further, the display current value on the display unit 15 is manually corrected by changing the ratio of the range unit 12 by a volume or the like, or by connecting a volume in parallel to the current transformer 7 in advance and adjusting the volume. Is also possible.

[0032]

As described above, according to the alternating current supply device of the first aspect, the current display of the display section is corrected by using one outlet and conducting the alternating constant current from the outlet during the correction operation. It is possible to supply alternating current from an outlet to an external device during normal operation. As a result, a terminal portion that is unnecessary for the user is not exposed to the outside of the device, so that it is possible to provide an AC supply device that has a simple configuration, an excellent design, is extremely easy to handle, and is free from erroneous operation. .

According to another aspect of the present invention, the alternating current source and the outlet are connected using three switch circuits during the alternating current supply operation, and the two output terminals of the outlet are connected during the correction operation. By forming a short-circuit path for short-circuiting, it can be suitably used as a test device for alternating current supply when measuring a leakage current.

Further, according to the third aspect of the present invention, by activating or deactivating the fourth switch circuit as necessary, the ground line of the AC source and the ground line of the external device are short-circuited. Alternatively, it can be opened, so that it can be more preferably used as a test device for alternating current supply when measuring a leakage current.

Further, according to the alternating current supply device of the fourth aspect, the switch circuit is composed of a relay, and the control unit controls the operation of the relay, so that, for example, when it is used as a test device for measuring leakage current. Can automatically and surely form the AC supply path.

According to the alternating current supply device of the fifth aspect, by controlling the first to fourth switch circuits,
It is possible to easily set the connection conditions for the two AC power supply lines and the one ground line, which are specified in the leakage current measurement, and thus it can be suitably used as a leakage current measurement test device.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a test apparatus according to an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram showing a connection state of measurement condition 1 during normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram showing a connection state of measurement condition 2 during normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram showing a connection state of measurement condition 3 during normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram showing a connection state of measurement condition 4 during normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 6 is an equivalent circuit diagram showing a connection state of measurement condition 5 during normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram showing a connection state of measurement condition 6 during normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 8 is a correspondence diagram showing operating states of the relays 21 to 24 with respect to measurement conditions 1 to 6 during normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 9 is a circuit diagram of a conventional test apparatus.

[Explanation of symbols]

1 test equipment 5 outlets 5a output terminal 5b output terminal 5c output terminal 7 Current transformer 14 Control unit 15 Display 21-24 relay

Claims (5)

(57) [Claims] 1. An outlet for supplying alternating current output from an alternating current source to an external device, a current transformer for detecting a current value of the supplied alternating current, a display section for displaying the detected current value, and In an AC supply device comprising a correction unit for correcting a display current value displayed on the display unit with respect to a detected current value, at the time of the correction by the correction unit, one output terminal of the outlet and the other A short circuit path is formed between the output terminal and the AC constant current source when the AC constant current source is connected between the output terminals, and when the AC current is supplied to the external device. , A path forming means for opening the short-circuit path and forming an AC supply path connecting the outlet and the AC source. Supply device. 2. The path forming means includes a first switch circuit having a movable contact connected to one end of one of the alternating current supply paths connected to the alternating current source, and a make contact connected to the alternating current source. A second switch circuit connected to one end of the other of the AC supply path, a break contact connected to the make contact of the first switch circuit, and a movable contact connected to one output terminal of the outlet; A make contact is connected to one end of the other AC supply path connected to the AC source, a break contact is connected to the make contact of the first switch circuit, and a movable contact is the other output terminal of the outlet. The AC supply device according to claim 1, further comprising a third switch circuit connected to the. 3. The alternating current supply device according to claim 2, wherein the path forming means further includes a fourth switch circuit for connecting a ground wire and a ground terminal of the outlet. 4. The switch circuit comprises a relay,
The alternating current supply device according to claim 2, further comprising a control unit that controls the operation of the relay. 5. The leakage current measuring test device for supplying an alternating current to the external device as a measuring object for measuring the leakage current, as claimed in any one of claims 1 to 4. The AC supply device according to claim 1.