JPH10253685A - Apparatus for inspecting measuring leakage current - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an electric shock accident by outputting a detection signal at the time for a measuring AC output current value to exceed a specified current value, and cutting off the measuring current to an output terminal based on its detection signal. SOLUTION: When a voltage of about 6mV or more is inducted across a variable resistor 30 via an output shut-off unit 8, a voltage of an amplified signal differentially amplified by a differential amplifier 31 exceeds a reference voltage of a reference voltage source 32, and a comparator 33 outputs a detection signal. The detection signal operates a thyristor 37 to short-circuit a capacitor 35. Therefore, a load of a diode bridge becomes heavy, and sufficient operating current flows to coils 4C1, 4C2 of a circuit breaker 4. Thus, the breaker 4 is reset, movable contacts 4a1, 4a2 become non-contact state with fixed contacts 4b1, 4b2 to cut off an input to the apparatus of a commercial power source. In this manner, an electric shock accident can be effectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test apparatus for measuring a leakage current or an insulation resistance of a device under test for applying a predetermined alternating current to the device under test. More particularly, the present invention relates to a leakage current measurement inspection device suitable for measuring leakage current of medical equipment.

[0002]

2. Description of the Related Art Generally, a plurality of ME (Medical Electrical) devices are used for treatment and examination. For example, as shown in FIG. 2, two electrocardiographs 41 and 42,
The electrocardiograph of the patient may be measured using one printer 43 that prints out the electrocardiogram of the electrocardiograph 41.
In this case, when a failure such as deterioration of insulation resistance occurs in the electrocardiograph 42 or the printer 43, commercial power may leak from the failed electrocardiograph 42 or the printer 43. Specifically, when the electrocardiograph 42 fails, the leakage current leaking from the electrocardiograph 42
2a, body of patient K1, mounting part 41a of electrocardiograph 41, power transformer 44 of electrocardiograph 41, and power transformer 4
Through 4 of the insulation resistance R _Z flows to the ground line. When the printer 43 breaks down, the leakage current leaked from the printer 43 passes through the input / output terminal 41b of the electrocardiograph 41, the housing of the electrocardiograph 41, the mounting portion 41c, and the body of the patient K2. Spills to the ground line. As a result, the leakage current caused by the failure of the ME device may cause a serious situation in which the patients K1 and K2 receive an electric shock. Therefore, ME
It is necessary to periodically measure the leakage current of the equipment and confirm that it is below the allowable value. When measuring such a leakage current, for example, a leakage current measurement system shown in FIG. 3 is used.

In the leakage current measuring system shown in FIG. 1, an inspection device 51 for measuring leakage current and two leakage current meters 5 are provided.
2,53 are used. Here, the inspection device 51 for measuring leakage current incorporates a step-up transformer 54 that generates a measuring AC by boosting a commercial AC of, for example, 100 V to 110 V, and converts the generated measuring AC into a failed ME device. Is output in place of the leakage current leaking from the switch. That is, the leakage current measuring inspection device 51 has a function of replacing the failed electrocardiograph 42 and the printer 43 in FIG. The leak ammeters 52 and 53 indicate that the patient K
2 and K1 function as pseudo-resistors for replacing the body resistance, respectively, and are connected in series in the leakage path of the leakage current.

Next, a method of measuring a leakage current in this measuring system will be described. Note that the measurement items and allowable values in the leakage current measurement of the ME device are variously determined by prescribed standards such as IEC601-1 and JIST1001.1992, and an example will be described here.

First, in the case where the electrocardiograph 41 is an ME device having a B-type mounting portion defined in the IEC standard, a printer 43 is used.
Connect the crocodile clip 61 of the leakage current measurement inspection device 51 to the signal input / output terminal 41b of the electrocardiograph 41 connected to
Further, the crocodile clip 62 on the input side of the leak ammeter 52 is connected to the mounting portion 41c of the electrocardiograph 41, and the crocodile clip 63 connected to the ground wire is connected to the output portion of the leak ammeter 52. Next, the hand switch 55 of the leakage current measuring inspection device 51 is turned on. As a result, the measurement AC current I ₁ is supplied to the hand switch 55, the crocodile clip 61, the signal input / output terminal 41b, the mounting portion 41c,
2, and flows out to the ground line via the internal resistance 71 of the leakage ammeter 52. As a result, the internal resistance 7
Since a voltage is generated at both ends of 1, the leakage current can be measured by the internal voltmeter 72. Since the allowable value of the leakage current in this measurement item is specified to be 5 mA or less, the leakage current measuring inspection device 51 outputs the current without interposing the current limiting resistor 57.

On the other hand, when the electrocardiograph 41 is a ME device having a CF type mounting part defined by the IEC standard, a crocodile clip 64 is connected to the input part of the leak ammeter 53 and the output of the leak ammeter 53 is output. The side alligator clip 65 is connected to the mounting portion 41a of the electrocardiograph 41. Next, the hand switch 56 is turned on. As a result, the current I ₂ of the measurement AC is supplied to the current limiting resistor 57, the hand switch 56, the crocodile clip 64, the internal resistance 73 of the leakage ammeter 53, the output crocodile clip 65, 41a, and flows to the ground line via an insulation resistance R _Z of the power transformer 44. As a result, a voltage is generated at both ends of the internal resistor 73 due to the leakage current, so that the internal voltmeter 74 can measure the leakage current. Since the allowable value of the leakage current in this measurement item is specified to be 50 μA or less, the inspection device for leakage current measurement 51 outputs an alternating current for measurement via the current limiting resistor 57.

[0007]

However, the conventional leakage current measuring inspection apparatus 51 has the following problems. In other words, the allowable value of the alternating current that conducts through the human body varies depending on gender, etc.
A or less. Therefore, the measuring AC output from the leakage current measuring inspection device 51 is applied to the current limiting resistor 57.
In this case, there is no danger because the current is limited. On the other hand, when the leakage current is measured by the leakage ammeter 52, the measuring AC is output without the current limiting resistor 57 interposed. Therefore, if the measurer accidentally touches the crocodile clip 61 with his or her hand during the measurement of the leakage current, the measurement AC that is higher than the current value that is permissible for the human body is conducted, which may cause an electric shock accident. There is a problem.

In this case, in order to prevent an electric shock accident, a current limiting resistor for protection may be connected in series between the output winding of the step-up transformer 54 and the hand switch 55. However, by setting the current limiting resistor to about 10KΩ,
In the case where the measurement AC current flowing through the human body is limited to about 5 mA, if the measurement AC flows 5 mA in the leakage current measurement, the voltage drop due to the current limiting resistor is 50 V (10 kΩ).
× 5 mA). For this reason, only about 60 V can be applied to the device to be measured such as the electrocardiograph 41, so that accurate measurement of the leakage current becomes impossible.

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 inspection device for measuring a leakage current capable of preventing an electric shock accident. Another object of the present invention is to provide an inspection device for measuring leakage current.

[0010]

According to a first aspect of the present invention, there is provided an inspection apparatus for measuring a leakage current which applies an alternating current for measurement to an apparatus to be measured via an output terminal. Output current detection means for outputting a detection signal when the output current value of the measurement AC exceeds a predetermined current value, and output cutoff means for cutting off the output of the measurement AC to the output terminal based on the detection signal. It is characterized by having. Note that the “leakage current measurement” in the present invention includes measurement of only the leak current and indirect measurement of the leak current when measuring the insulation resistance. Further, the “output terminal” includes all connection means for supplying alternating current for measurement, such as a clip for connection and a connector, to the device under test.

For example, if the measurer accidentally touches the output terminal when measuring the leakage current of the device under test, the alternating current for measurement conducts through the body of the measurer via the output terminal. In such a case, in the leakage current measuring inspection device, when the output current of the measuring AC exceeds a predetermined current value, the output current detecting means outputs a detection signal. As a result, the output cutoff unit cuts off the output of the measurement AC to the output terminal. As a result, it is possible to prevent an electric shock accident.

According to a second aspect of the present invention, there is provided the inspection apparatus for measuring a leakage current according to the first aspect.
A voltage conversion transformer that generates a measurement AC by boosting or stepping down a commercial AC input into the device to a predetermined voltage, and a polarity for switching the polarity of the measurement AC output from an output winding of the voltage conversion transformer. And a changeover switch.

The leakage current may be measured in a state where a measuring AC of 110% of the rated voltage is applied to the device under test, or by switching the polarity of the measuring AC. In such a case, for example, an alternating current for measurement may be generated by an alternating current generator or the like, but generally, the price of the inspection device for leakage current measurement rises. In this leakage current measuring inspection device, the voltage conversion transformer generates a measuring AC by stepping up or down the commercial power supply, and the polarity of the measuring AC is switched by switching a polarity switch. As a result, it is possible to easily configure the leakage current measuring inspection device.

According to a third aspect of the present invention, there is provided an inspection apparatus for measuring a leakage current according to the first or second aspect, wherein the output cut-off means is provided for interrupting the input of the commercial AC into the apparatus. It is characterized by comprising a breaker, and a switch circuit that is activated when a detection signal is output and controls the breaker to be in a cutoff state by applying a commercial alternating current to a control coil of the breaker.

Various configurations can be considered as the output cutoff means. For example, connect a relay before the output terminal,
When the detection signal is output, the relay may be operated to cut off the output of the measurement AC. On the other hand, in this leakage current measuring inspection device, when the detection signal is output, the breaker is controlled to be in the cutoff state by the switch circuit. Therefore, since the input of the commercial alternating current into the apparatus is cut off, it is possible to configure an extremely safe inspection apparatus. In addition, by using the breaker as the main power switch, the output cutoff means can be configured without increasing the price of the device.

According to a fourth aspect of the present invention, there is provided the inspection apparatus for measuring a leakage current according to any one of the first to third aspects, wherein the output current detecting means includes one end of an output winding of the voltage conversion transformer. A current detection transformer having a primary winding connected in series between the output terminal and a primary winding, and a secondary winding that induces an induced voltage by causing a measurement AC to flow through the primary winding; and It is characterized by comprising an amplifier circuit for amplifying an induced voltage, and a comparator circuit for outputting a detection signal when an output signal of the amplifier circuit exceeds a predetermined reference voltage.

As the output current detecting means, a low-resistance resistor or the like for detecting the output current is connected in series in the output path of the AC for measurement, and a detection signal is output based on the voltage generated at both ends of the resistor. It is also possible. However, even in this case, the voltage value of the AC for measurement may be lower than the rated voltage specified by the standard or the like due to the voltage drop of the resistor. In this leakage current measuring inspection device, since a so-called current transformer functions as an output current detecting means, accurate measurement of the leakage current can be performed as a result of not lowering the voltage value of the measuring AC.

According to a fifth aspect of the present invention, there is provided the inspection apparatus for measuring a leakage current according to the fourth aspect.
A variable resistance means is connected in parallel to the secondary winding of the current detecting transformer and adjusts the value of the induced voltage with respect to the value of the measuring AC current flowing through the primary winding.

The permissible value of the alternating current that conducts through the human body is considered to be about 6 mA or less in women, while the permissible value of the leakage current is specified to be 5 mA or less depending on the measurement item. Therefore, the difference is as small as about 1 mA. Therefore, it is conceivable that the output cut-off means may be activated at the time of measuring the leakage current depending on aging and the like. In this inspection device for measuring leakage current,
By varying the resistance value of the variable resistance means, the voltage value of the induced voltage induced in the secondary winding of the current detection transformer can be adjusted. It is possible to reliably prevent electric shock accidents while preventing accidents.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, an inspection apparatus for measuring leakage current according to the present invention will be described below.
An embodiment will be described in which the present invention is applied to an AC output device for applying a measuring AC to the device under test when measuring the leakage current of the device under test according to the provisions of JIST1001.1992 and the like.

FIG. 1 shows a circuit diagram of the AC output device 1. As shown in FIG.
AC plug 3 connectable to outlet 2 for supplying a commercial AC of 00 V, breaker 4 for turning on and off the commercial AC output from AC plug 3, and boosting the commercial AC input through breaker 4 to 110 V A voltage converting transformer 5, an output control unit 6 for controlling the output of the measuring AC output from the output winding 5b of the transformer 5, and a current transformer for detecting the output current value of the measuring AC. 7 and an output cutoff unit 8 that controls the breaker 4 to a cutoff state when the output current detected by the current transformer 7 exceeds a predetermined current value. Also,
The AC output device 1 includes a crocodile clip 9 connected to a predetermined portion of the device to be measured when the measuring AC output from the output control section 6 is applied to the device to be measured, and a crocodile clip connected to a ground line. A clip 10 and a hand switch 11 for turning on / off the output of the measurement AC are provided. From the viewpoint of safety, the hand switch 11 is designed to output the measurement AC only while the push button is being pressed.
It consists of a momentary (automatic return) switch.

The breaker 4 is of a bipolar cut type, and functions also as a main power switch of the AC output device 1. As a specific function, when a lever (not shown) is turned on, the movable contacts 4a1 and 4a2
When a commercial AC is supplied into the apparatus by contacting the movable contacts 4a and 4b2, and the lever is returned, the movable contact 4a
1, 4a2 and fixed contacts 4b1, 4b2 are brought out of contact with each other, so that the supply of commercial AC into the apparatus is stopped. When the current value of the AC for measurement supplied to the device to be measured via the alligator clip 9 exceeds a predetermined value, the breaker 4 excites the coils 4c1 and 4c2 so that the movable contacts 4a1 and 4a2 are closed. The on state is automatically released and the supply of commercial AC is stopped.

The transformer 5 has an input winding 5a and an output winding 5
b is set to 10 to 11, and 100 V
Has a simple configuration suitable for boosting the commercial AC to 110 V which is 110% of the normal input voltage of the device under test. Note that the voltage conversion transformer in the present invention is not limited to this, and is configured to be able to boost up to 110% of the rated voltage or the maximum rated voltage of the device under test, or to reduce 200 V commercial AC to 110V. It may be configured to be able to do so. Further, when the rated voltage of the device under test is AC 200 V, a transformer that boosts the commercial AC of AC 200 V to AC 220 V can be used. Further, the transformer 5 is provided with a plurality of taps for voltage adjustment on the input winding 5a and the output winding 5b, respectively, so that the input voltage is in the range of AC100V to AC25.
You may be comprised so that it can tolerate to 0V and can output the alternating current for a measurement of arbitrary voltage values.

The output control unit 6 includes an output winding 5 of the transformer 5.
b, a polarity changeover switch 21 for switching the polarity of the measurement AC, a diode bridge 22 for rectifying the measurement AC to generate DC, a two-winding type latching relay 23, and a current limiting resistor. 24, a switch 25 for controlling whether the primary winding 7a of the current transformer 7 and the crocodile clip 9 are connected via the resistor 24 or short-circuited, a capacitor 26 for smoothing,
A capacitor 27 for charge storage and a resistor 2 for current limiting
8, 29.

The current transformer 7 has a resistance value of, for example, 2
The variable resistor 30 for detecting a current of kΩ is connected in parallel to the secondary winding 7b. In this current transformer 7, the primary winding 7
a, the induced voltage of the secondary winding 7b with respect to the value of the alternating current for measurement flowing through the output signal a can be varied. In this case, the deviation can be corrected. The current transformer 7 is
When the variable resistor 30 has an intermediate resistance value of 1 kΩ and an alternating current of 6 mArms flows through the primary winding 7 a, a voltage of 6 mVrms is induced across the current detecting variable resistor 30.

The output cutoff section 8 includes a differential amplifier circuit 31 for differentially amplifying an induced voltage induced in the secondary winding 7b of the current transformer 7, and an amplified signal output from the differential amplifier circuit 31 and a reference voltage. A comparison circuit 33 that compares the reference voltage of the source 32 and outputs a detection signal SP when the voltage value of the amplified signal exceeds the reference voltage; and coils 4c1 and 4c2 of the breaker 4.
, A diode bridge 34 for full-wave rectification of a commercial alternating current input through the power supply circuit, a capacitor 35 for smoothing, and a power supply circuit 36 for generating a direct current and outputting the direct current to the comparison circuit 33, the differential amplifier circuit 31, and the reference voltage source 32 And a thyristor 37 for short-circuiting the capacitor 35, which corresponds to a switch circuit in the present invention. Note that the current transformer 7, the differential amplifier circuit 31, the reference voltage source 32, and the comparison circuit 33 correspond to an output current detection unit in the present invention.

In the output cutoff unit 8, when a voltage of about 6 mVrms or more is induced across the variable resistor 30, the voltage value of the amplified signal differentially amplified by the differential amplifier circuit 31 is applied to the reference voltage source 32. The voltage exceeds the voltage value, whereby the comparison circuit 33 outputs the detection signal SP. When the detection signal SP is output, the thyristor 37 operates to short-circuit both ends of the capacitor 35. For this reason,
As a result of the heavy load of the diode bridge 34, a sufficient operating current is conducted to the coils 4C1 and 4C2 of the breaker 4. Thereby, the breaker 4 is reset, and the movable contacts 4a1, 4a2 and the fixed contacts 4b1, 4b2 are brought into a non-contact state, respectively. That is, when a voltage of about 6 mVrms or more is induced across the variable resistor 30, the output cutoff unit 8 resets the breaker 4 by dramatically increasing the current consumption in the circuit by the thyristor 37. Cut off the input of the commercial power supply into the device. After the input of the commercial power is cut off, the thyristor 37
Is turned off, so that when the breaker 4 is turned on again, the measurement AC is output as usual unless a voltage of about 6 mVrms or more is induced again across the variable resistor 30.

Next, the overall operation of the AC output device 1 will be described.

First, when the breaker 4 is turned on,
The commercial power supply conducts the input winding 5 a of the transformer 5, so that a measuring AC having a predetermined voltage is output to the output winding 5 b of the transformer 5. In this case, the polarity of the measuring AC output from the output winding 5b can be easily switched by switching the polarity switch 21. The AC for measurement is rectified by the diode bridge 22 and then smoothed by the capacitor 26. Next, the smoothed DC is supplied to the reset coil 2 of the latching relay 23.
3a, resistor 28, break contact 11 of hand switch 11
a, and the capacitor 28 is charged by flowing into the capacitor 27 via the movable contact 11c. Therefore, during the period when the capacitor 27 is charged,
As a result of the excitation of the reset coil 23a, the latching relay 23 is reset. FIG. 3 shows a state where the latching relay 23 is reset.

Next, when the hand switch 11 is turned on, the make contact 11b and the movable contact 11c come into contact with each other, so that the electric charge accumulated in the capacitor 27 is transferred to the movable contact 11c, the make contact 11b, It is discharged via the resistor 29 and the set coil 23b of the latching relay 23. As a result, the set coil 23b is excited, and the latching relay 23 is set. As a result, the relay contacts 23c and 23d maintain the contact state, and as a result, the alternating current for measurement is continuously output to the crocodile clip 9 via the primary winding 7a of the transformer 7. In this case, assuming that a single-stable type relay is used, when the relay is in an ON state, an AC voltage drops due to a winding resistance of the output winding 5b of the transformer 5 due to a current flowing through the coil. On the other hand, in the AC output device 1 according to the present embodiment, while the measurement AC is being output, a voltage drop does not occur on the output winding 5b side of the transformer 5, so that the measurement AC having a constant voltage is output. It can output stably. Further, since the measurement AC is not conducted to the hand switch 11, the operation can be performed extremely safely.

In the case of measuring a measurement item having an allowable leakage current of 50 μA or less, the changeover switch 25 is operated to bring the movable contact 25c into contact with the fixed contact 25a. Is output via the resistor 24 of FIG. In this case, the resistance value of the resistor 24 is 10 k
By setting the resistance to about Ω, the voltage drop due to the resistor 24 is limited to 0.5 V even if the measurement AC of 50 μA which is the upper limit of the allowable value of the leakage current flows. Can be output. On the other hand, when measuring a measurement item having an allowable leakage current of 5 mA or less, the changeover switch 25 is operated to bring the movable contact 25c into contact with the fixed contact 25b. Is output.

On the other hand, if the measurer accidentally touches the crocodile clip 9 with his hand or the like, the measuring AC conducts through the human body. In this case, about 6m that may pose a danger to the human body
When a current of more than A flows, 6 mV
The above induced voltage is generated. Accordingly, since the amplified signal amplified by the differential amplifier circuit 31 exceeds the reference voltage of the reference voltage source 32, the comparison circuit 33 outputs a detection signal. As a result, the thyristor 27 conducts, and the commercial alternating current conducts the coils 4c1 and 4c2 of the breaker 4, whereby the breaker 4 is cut off. In this case, the output cutoff unit 8 cuts off the breaker 4 with a response time of 23 mS or less from the time when the measuring AC of about 6 mA or more flows. For this reason, even when the human body resistance is set to about 500Ω, a dangerous state of ventricular fibrillation does not occur, and extremely high safety is secured.

The present embodiment is not limited to the configuration shown in the above embodiment. For example, the inspection device for measuring leakage current according to the present invention is applicable not only to an inspection device for measuring leakage current but also to a power supply device and an inspection device for outputting high-voltage AC or DC. In the present embodiment, the current transformer 7 detects the current value of the AC for measurement. However, the current transformer 7 is connected to the input winding 5a side of the transformer 5 so that the current value of the commercial AC exceeds a predetermined value. May be configured to shut off the breaker 4 when the power is turned off. Further, a fixed resistor may be connected in parallel to the secondary winding 7b of the current transformer 7. However, when a change in the circuit components in the device due to aging is considered, it is preferable to use the variable resistor 30 as described in the present embodiment.

As the output cutoff means in the present invention, a relay separate from the breaker 4 is connected to a relay contact between a commercial AC or measurement AC output line, and the output cutoff unit 8 turns on / off the relay coil. You may comprise so that off control may be carried out.

Further, the switch circuit according to the present invention comprises:
The present invention is not limited to the thyristor 37 shown in the present embodiment, and may be constituted by semiconductor elements such as transistors and FETs and switch means such as relays.

[0036]

As described above, according to the leakage current measuring inspection apparatus according to the first aspect, for example, when the measurer touches the output terminal by mistake, the output current of the measuring AC is measured. Exceeds a predetermined current value, based on the detection signal output by the output current detection means, the output cutoff means cuts off the output of the measurement AC to the output terminal, so that an electric shock accident can be reliably prevented. .

According to the second aspect of the present invention, the voltage conversion transformer generates an alternating current for measurement by stepping up or stepping down the commercial power supply, and switches the polarity changeover switch. Since the polarity of the AC for measurement can be switched, the inspection device for measuring leakage current can be configured simply and inexpensively.

According to the third aspect of the present invention, there is provided a leakage current measuring inspection device, wherein a breaker for interrupting the input of a commercial AC power into the device and a breaker which is activated when a detection signal is output. The output cutoff means is composed of a switch circuit that controls the breaker to a cut-off state by supplying commercial AC to the control coil, so that if the measurer accidentally touches the output terminal, As a result of interrupting the input of the commercial AC into the inside, an extremely safe inspection device can be configured. In addition, by using the breaker as the main power switch, the output cutoff means can be configured without increasing the price of the device.

According to the leakage current measuring inspection device of the present invention, the output current detecting means is constituted by the current transformer, so that the voltage value of the AC for measurement does not decrease, and as a result, accurate It is possible to perform a leak current measurement.

According to the leakage current measuring inspection apparatus of the present invention, the resistance value of the variable resistance means connected in parallel to the secondary winding of the current detecting transformer is varied.
The voltage value of the induced voltage induced in the secondary winding of the current detection transformer can be adjusted, thereby preventing the measurement alternating current from being interrupted by the output interrupting means when measuring the leakage current, and preventing an electric shock accident. Can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an AC output device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a therapeutic inspection system for explaining a path through which leakage current leaks when an ME device fails.

FIG. 3 is a schematic configuration diagram of a leakage current measurement system using a conventional leakage current measurement inspection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC output device 4 Breaker 5 Transformer 5b Output winding 7 Current transformer 7a Primary winding 7b Secondary winding 8 Output cutoff part 9 Alligator clip 21 Polarity changeover switch 30 Variable resistance 31 Differential amplifier circuit 32 Reference voltage source 33 Comparison circuit 37 Thyristor

Claims (5)

[Claims] 1. A leakage current measuring inspection device for applying a measuring AC to a device under test via an output terminal, wherein a detection signal is output when an output current value of the measuring AC exceeds a predetermined current value. An inspection apparatus for measuring a leakage current, comprising: an output current detecting means; and an output cutoff means for cutting off the output of the measuring AC to the output terminal based on the detection signal. 2. A voltage conversion transformer for generating the measurement AC by boosting or stepping down a commercial AC input into the apparatus to a predetermined voltage, and the measurement AC output from an output winding of the voltage conversion transformer. 2. The leakage current measuring inspection device according to claim 1, further comprising a polarity switch for switching the polarity of the alternating current. 3. The output cutoff means includes a breaker for cutting off input of the commercial AC into the device, and an output cutoff means that is activated when the detection signal is output, and outputs the commercial AC to a control coil of the breaker. 3. The leakage current measuring inspection apparatus according to claim 1, further comprising: a switch circuit that controls the breaker to a cutoff state by applying an alternating current. 4. The output current detecting means includes a primary winding connected in series between one end of an output winding of the voltage conversion transformer and the output terminal, and the AC for measurement flowing through the primary winding. A current detecting transformer having a secondary winding that induces an induced voltage, an amplifier circuit that amplifies the induced voltage of the secondary winding, and an output signal of the amplifier circuit that exceeds a predetermined reference voltage. 4. The leakage current measuring inspection apparatus according to claim 1, further comprising: a comparison circuit that outputs the detection signal. 5. A variable resistance means, which is connected in parallel to a secondary winding of the current detecting transformer and adjusts a voltage value of the induced voltage with respect to a current value of a measuring AC flowing through the primary winding. The inspection device for measuring a leakage current according to claim 4, wherein