JPH10253689A - Ac supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an AC supply apparatus whose configuration is simple and which can prevent a wrong operation. SOLUTION: An AC supply apparatus is provided with an outlet 5 by which an alternating current to be output from an AC source is supplied to an external apparatus, with a current transformer 7 which is used to detect the current value of a supplied alternating current, with a display part 15 which displays the detected current value and with a correction part 14 by which a displayed current value displayed on the display part 15 is corrected with reference to the detected current value. The AC supply apparatus is provided with route formation means 21 to 24 in such a way that, when the displayed current value is corrected by the correction part 14, a short-circuit route which is formed across an output terminal 5a on one side and an output terminal 5b on the other side at the outlet and which is used to detect a constant current by the current transformer 7 when an AC constant current source is connected across both output terminals 5a, 5b is formed, that, when the alternating current is supplied to the external apparatus, the short-circuit route is opened and that an AC supply route which connected the outlet 5 to the AC source is formed.

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 which supplies an alternating current to an external device and which can display a current value of the supplied alternating current. The present invention relates to an AC supply device suitable for supplying an AC to the device to be measured.

[0002]

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

[0003] In this test apparatus 51, when a leakage current is measured by a leakage ammeter (not shown), a commercial AC input through an inlet 52 is output to a device to be measured through an outlet 53. At this time, the current transformer 7 detects the value of the supply current from the outlet 53 and outputs the detected voltage to the current detection unit 55. Next, the current detection unit 55
Rectifies the detected voltage and outputs the rectified voltage to the control unit 57. Thereafter, the control unit 57 calculates the supply current value based on the rectified voltage and causes the display unit 56 to display it.

On the other hand, in general, the magnetic permeability of a magnetic core used in the current transformer 7 may vary depending on a 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. For this reason, in the test apparatus 51, when the correction operation is selected by the switch unit 58, the test apparatus 51 enters an operation state in which the display current value can be corrected. At the time of 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 allowing the current transformer 7 to detect the conducted current value 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 an AC constant current is conducted. When a constant current of, for example, 20 A is conducted from the AC constant current source, the current is conducted by the current transformer 7. A detection voltage corresponding to the current is detected. Next, correction is performed by a volume or the like (not shown) provided in the control unit 57 so that the display current value of the display unit 56 becomes 20 A. Next, after disconnecting the AC constant current source from the terminal unit 59, if the switch 60 is switched to the original state and the normal operation is selected by the switch unit 58, the commercial AC can be supplied from the outlet 53 to the device to be measured, and An accurate supply current value at the time of 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 of 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 with the switch 60 in the state at the time of the correction operation, there is a problem that when the user uses the test apparatus 51, commercial AC cannot be supplied from the outlet 53.

Also, the terminal portion 59 and the switch 6
0 is used only in the inspection process of the manufacturer. Therefore, the fact that switches and the like unnecessary for the user are exposed to the outside of the apparatus itself is unnatural, which is not preferable in terms of design. In addition, there is a problem that the cost of the apparatus is increased because an unnecessary terminal portion 59 must be provided during normal operation. In addition, even if the user operates the switch 60 by mistake, 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. However, as the structure of the device becomes complicated, there is another problem that the device cost increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its main object to provide an AC supply device that can prevent erroneous operation with a simple configuration, and is particularly suitable as a leakage current test device. It is another object to provide a usable AC supply device.

[0008]

According to a first aspect of the present invention, there is provided an AC supply apparatus for supplying an AC output from an AC source to an external device and detecting a current value of the supplied AC. A current transformer, a display unit for displaying the detected current value, and a correction unit for correcting the display current value displayed on the display unit with respect to the detected current value. During correction by the correction unit, a short-circuit path formed between one output terminal of the outlet and the other output terminal and for detecting a constant current by 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 for connecting the outlet and the AC source while opening the short-circuit path at the time of AC supply to an 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 that combines an AC power supply that outputs a constant voltage and a load resistor.

In this AC supply device, when correcting the display current value by the correction unit, the path forming means short-circuits one output terminal of the outlet and the other output terminal.
In this case, if an AC constant current source is connected between both output terminals and an AC constant current is conducted, the current transformer detects a constant current value of the AC conducting through the short-circuit path. On the other hand, when the AC is supplied to the external device, the path forming means opens the short-circuit path and connects the outlet to the AC source. As described above, in this AC supply device, the display current value of the display unit can be corrected by supplying 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 unit 59 and the switch 60 used in the conventional test apparatus 51 are used.
As a result, unnecessary operation parts for the user are not exposed to the outside of the apparatus, whereby it is possible to provide an AC supply apparatus having an excellent design, extremely easy handling, and no erroneous operation. . It should be noted that, for example, a configuration in which the operation can be switched to the correction operation by performing an operation of a special key provided in the correction unit or a simultaneous operation of two keys from the viewpoint of completely eliminating an erroneous operation by the user is more preferable. preferable.

[0010] The second aspect of the present invention provides an AC supply device.
In the alternating current supply device described above, the path forming means includes a first switch circuit connected to one end of one of the alternating current supply paths having a movable contact connected to the alternating current source, and an alternating current supply having a make contact connected to the alternating current source. A second switch circuit connected to one end of the other path and having a break contact connected to a make contact of the first switch circuit and a movable contact connected to one output terminal of the outlet; A third switch connected to one end of the other side of the AC supply path connected to the source, the break contact being connected to the make contact of the first switch circuit, and the movable contact being connected to the other output terminal of the outlet. And a circuit.

Generally, the leakage current of a device differs depending on the connection conditions of a power supply line and a ground line. For this reason, it is necessary to measure under various measurement conditions and confirm that the measured value is within an allowable range. In the 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 activated.
If one of the switch circuits is inactivated, one of the output lines of the AC source is connected to the outlet via the movable contact and make contact of the first switch circuit and the break contact and movable contact of the third switch circuit. The other output terminal and the other output line of the AC source are connected to one output terminal of the outlet via the make contact and the movable contact of the first switch circuit. Also, the first to first
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, at the time of the correction operation, if the first to third switch circuits are deactivated, one output terminal of the outlet is connected to the movable contact and the break contact of the second switch circuit and the break contact 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, since the current transformer can detect an alternating current conducted in the short-circuit path, by conducting the constant AC current in the short-circuit path, the display current value of the display unit with respect to the detected current of the current transformer can be easily set. Can be corrected. Thus, this AC supply device can be suitably used as an AC supply test device when measuring leakage current.

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

In this AC supply device, a 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. This makes it possible to set, for example, the measurement conditions of the ground wire disconnection state at the time of leakage current measurement, so that it can be more suitably used as an AC supply test device at the time of measuring leakage current.

According to a fourth aspect of the present invention, there is provided an AC supply device.
3. The AC supply device according to item 3, wherein the switch circuit includes a relay, and further includes a control unit that controls an operation of the relay.

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

According to a fifth aspect of the present invention, there is provided an AC supply device.
5. The AC supply device according to any one of items 1 to 4, wherein the AC supply device is a leakage current measurement test device that supplies an alternating current to an external device to be measured in order to measure a leakage current.

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

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an AC supply device according to the present invention is applied to a test device for measuring leakage current will be described below with reference to the accompanying drawings. Note that the same components as those of the conventional test apparatus 51 are denoted by the same reference numerals, and redundant description will be omitted.

As shown in FIG. 1, the test apparatus 1 has two power supply input terminals 2a and 2b for inputting commercial AC.
And an input terminal 2c for connecting a ground line, a power supply unit 3 that generates a DC _VDC for a device power supply from a commercial AC and supplies the DC _VDC to each unit, and is disposed between the inlet 2 and the power supply unit 3. Main power switch 4 and two output terminals 5a and 5 for outputting commercial AC to the device under test.
b, and an outlet 5 having an output terminal 5c for connecting the ground line, and an outlet 5 and an inlet 2
The device includes a breaker 6 disposed therebetween, 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.

The test apparatus 1 includes a detection unit 11, a range unit 12, an A / D conversion unit 13, a control unit 14 corresponding to a correction unit and a control unit in the present invention, a display unit 15, a switch unit 16, and four 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 of the AC voltage detected by the current transformer 7 during the normal operation in which the AC is output from the outlet 5 and the correction operation described later, and converts the rectified voltage to the range unit. 12 is output. Range section 12 generates a detection voltage within a predetermined voltage range by amplifying or attenuating the rectified voltage at a predetermined ratio. The A / D converter 13 converts the detected voltage from analog to digital, and outputs the converted digital data, the detected voltage, to the controller 14. The control unit 14, for example,
U, a built-in ROM and a built-in RAM, and calculates an AC current value that is conducted through a current path inserted in the current transformer 7 based on the input detection voltage and the ratio of the range circuit 12. 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 sets a display current value to be displayed on the display unit 15 when the correction operation is selected. A correction operation for correction is performed. The display unit 15 includes, for example, a liquid crystal panel, and displays the AC current value detected by the current transformer 7 on the control unit 14.
Display under control of. The switch unit 16 is used to select one of a normal operation and a correction operation. The drivers 17 to 20 are each configured by, for example, a transistor, and are controlled by the relay 2 under the control of the control unit 14.
Controls the operation and 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 unit 16, the control unit 14 first controls the relays 21 to 24 to a non-operating state. In this state, the output terminal 5a of the outlet 5 is connected to the movable contact 22c and the break contact 22a of the relay 22, and the break contact 23 of the relay 23.
a and the movable contact 23c is short-circuited to the output terminal 5b of the outlet 5 by a short-circuit path formed by the movable contact 23c. In this case, the current transformer 7 can detect an alternating current value that is 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. Next, the control unit 14 controls the display unit 15
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 detected current value is multiplied by a coefficient (20/18), and the multiplied value is displayed on the display unit 15. Value. Thereby, even when the magnetic permeability of the magnetic core of the current transformer 7 differs for each device, the accurate value of the AC current output from the outlet 5 can be displayed on the display unit 1.
5 can be displayed.

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

In this operation, the control unit 14 controls the input terminals 2a, 2b and 2c of the inlet 2 and the device under test 41
Is automatically set according to a program stored in the internal ROM. In this case, the control unit 14 sequentially sets a plurality of measurement conditions by controlling the relays 21 to 24. This is because the leakage current of the device under test 41 is different depending on the connection conditions of the power supply line and the ground line, and therefore, it is confirmed that the maximum leakage current value is within the allowable value under the assumed measurement conditions. That's why.

Next, specific examples of the measurement conditions will be described. First, it is assumed 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 condition is represented by an equivalent circuit shown in FIGS. FIG. 2 shows that 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.
FIG. 3 shows measurement conditions (hereinafter, referred to as “measurement conditions 1”) normally connected to the input terminal for connecting the ground line G in the inlet of FIG. 1, and FIG. And the measurement conditions under which the ground wire 33 is disconnected (hereinafter, referred to as
FIG. 4 shows the power supply line 31,
FIG. 5 shows a measurement condition (hereinafter referred to as “measurement condition 3”) in which the power lines 32 and 32 are connected in opposite phases and the ground line 33 is normally connected. FIG. 6 shows a measurement condition in which the ground line 33 is disconnected (hereinafter referred to as “measurement condition 4”). FIG. 6 shows that the power line 31 is connected in the positive phase, the power line 32 is disconnected, and the ground line is disconnected. FIG. 7 shows a measurement condition (hereinafter, referred to as “measurement condition 5”) in which the power supply line 31 is connected in the opposite phase, the power supply line 32 is disconnected, and the ground line is normally connected. Measurement conditions (hereinafter referred to as “measurement conditions 6”).

Next, the control unit 14 during the normal operation
Will be described with reference to FIG.

First, for example, when setting the measurement condition 1, the control unit 14 outputs a drive signal to the drivers 17 and 18 so that, as shown in FIG.
1 and 22 are controlled to an operating state, and the relays 23 and 24 are controlled to a non-operating state. Thereby, the input terminal 2a of the inlet 2 is connected to the outlet 5 via the breaker 6, the make contact 22b and the movable contact 22c of the relay 22.
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.
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. Furthermore, 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 connected to the input terminal for connecting the ground line 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 to an operation state or a non-operation state, so that the measurement conditions 2 to 6
Are sequentially set. This makes it possible to automatically set the measurement conditions for measuring the leakage current.

As described above, according to the test apparatus 1,
At the time of the correction operation, the control unit 14 controls the relays 21 to 24 to a non-operating state, so that the output terminal 5a and the output terminal 5b of the outlet 5 are short-circuited.
The value of the AC current flowing 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, the display current value of the display unit 15 can be easily corrected. In addition, since the terminal unit 59 and the switch 60 which are used in the conventional test apparatus 51 and are required only at the time of the correction operation can be eliminated, unnecessary operation parts for the user are not exposed to the outside of the apparatus. It is possible to provide the test apparatus 1 which is excellent in design, is extremely easy to handle, and has no erroneous operation.

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

Also, in the present embodiment, an example in which the switch circuit of the present invention is constituted 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. Further, the configuration 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, FIG. 1 shows all the relays 21 to 2
4 shows the connection state when not operating, but it is also possible to adopt a configuration in which the connection state shown in FIG. Further, the display unit 15 can also be configured by 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 using a volume or the like, or by connecting a volume in advance to the current transformer 7 and adjusting the volume. Is also possible.

[0032]

As described above, according to the AC supply device of the first aspect, the current display of the display unit is corrected by using one outlet and conducting an AC constant current from the outlet during the correction operation. During normal operation, an AC can be supplied to the external device from the outlet. As a result, an unnecessary terminal portion or the like for the user is not exposed to the outside of the apparatus, so that it is possible to provide an AC supply apparatus having a simple configuration, an excellent design, extremely easy handling, and no erroneous operation. .

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

According to the third aspect of the present invention, the fourth switch circuit is activated or deactivated as required, thereby shorting the ground line of the AC source and the ground line of the external device. Alternatively, it can be opened, so that it can be more suitably used as a test device for AC supply when measuring leakage current.

Further, according to the AC supply device of the present invention, the switch circuit is constituted by a relay, and the control unit controls the operation of the relay. Can automatically and reliably form an AC supply path.

According to the AC supply device of the fifth aspect, by controlling the first to fourth switch circuits,
The connection conditions of two AC power supply lines and one ground line specified in the leakage current measurement can be easily set, and thereby, the device can be suitably used as a leakage current measurement test device.

[Brief description of the 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 under measurement condition 1 during a 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 under a measurement condition 2 during a 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 under 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 under 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 under 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 under a measurement condition 6 during a normal operation of the test apparatus according to the embodiment of the present invention.

FIG. 8 is a correspondence diagram showing operation states of 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 Outlet 5a Output Terminal 5b Output Terminal 5c Output Terminal 7 Current Transformer 14 Control Unit 15 Display Unit 21-24 Relay

Claims (5)

[Claims] An outlet for supplying an 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 unit for displaying the detected current value; A correction unit for correcting a display current value displayed on the display unit with respect to the detected current value, wherein at the time of the correction by the correction unit, one output terminal of the outlet and the other A short-circuit path for detecting the constant current by the current transformer when an AC constant current source is connected between the two output terminals, and when the AC is supplied to the external device. And 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 circuit according to claim 1, wherein the path forming unit includes a first switch circuit connected to one end of the AC supply path having a movable contact connected to the AC source, and a make contact connected to the AC source. A second switch circuit connected to one end of the other side of the AC supply path, a break contact connected to a 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 the other end of the 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 connected to the other output terminal of the outlet. The AC supply device according to claim 1, further comprising: a third switch circuit connected to the AC power supply. 3. The AC supply device according to claim 2, wherein said path forming means further includes a fourth switch circuit for connecting a ground wire to a ground terminal of said outlet. 4. The switch circuit comprises a relay,
The AC supply device according to claim 2, further comprising a control unit configured to control an operation of the relay. 5. The leakage current measuring test device according to claim 1, wherein the alternating current supply device supplies an alternating current to the external device to be measured in order to measure the leakage current. An AC supply device according to any one of the above.