JPH05172880A - Insulation resistance tester - Google Patents

Abstract

PURPOSE:To obtain an insulation resistance tester which possesses high safety and with which the safety of an operator can be secured even if the erroneous operation outsides specification is carried out. CONSTITUTION:As for an insulation resistance meter for measuring the insulation resistance of a measurement object through a measurement probe, an insulation resistance meter 10 body is equipped with a rectifying circuit 15 for rectifying the ac voltage inputted into the connection terminal of the probe 20 for measurement, filter 16 for smoothing the output signal of the rectifying circuit 15, comparator 17 for comparing the output voltage of the filter 16 and an alarm standard voltage, and an alarm display element 18 which is lighting-driven by the output signal of the comparator 17. The measurement probe 20 is equipped with a fuse 21 which is melting-cut by the flow of excessive electric current and a voltage detector 22 which is connected in parallel with the fuse 21 and lighting-displays the melting-cut of the fuse.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulation resistance tester and, more particularly, to ensuring the safety of a user when a measurement target in a live state is erroneously connected.

[0002]

2. Description of the Related Art Insulation resistance meters often measure the insulation resistance of switchboards, transformers, etc. at various sites. Therefore,
To ensure the safety of the user (measuring person), a light-emitting diode (LED) is provided if there is an AC voltage measurement function or voltage.
It has a function that lights up to call attention.

[0003]

However, in such a conventional structure, when an overvoltage exceeding the measurement range is applied, the inside may be destroyed and the device may not function.
Above all, in the power receiving and transforming equipment, there are many cases in which the voltage is more than doubled from the rating of the equipment, which may cause damage to the inside due to defective withstand voltage, and in the worst case, the operator is in danger. there is a possibility.

The present invention has been made in view of the above problems, and an object thereof is to ensure the safety of a measurer even if an erroneous operation out of specifications is made. To provide an insulation resistance tester.

[0005]

An insulation resistance meter according to the present invention is an insulation resistance meter for measuring an insulation resistance of an object to be measured through a measurement probe, wherein the insulation resistance meter body is connected with a measurement probe. A rectifier circuit that rectifies an AC voltage input to a terminal, a filter that smoothes an output signal of the rectifier circuit, a comparator that compares an output voltage of the filter with a warning reference voltage, and a light output by the output signal of the comparator A warning display element to be driven is provided, and the measurement probe is provided with a fuse that is blown by an overcurrent, and a voltage detector that is connected in parallel with the fuse and illuminates and displays a blown fuse. It is what

[0006]

[Function] Irrespective of the setting state of the insulation resistance tester, the warning display element lights up when a voltage higher than the preset warning reference voltage is applied from the measurement target to the connection terminal of the measurement probe. Therefore, the measurer can correctly recognize the dangerous state.

When a voltage is applied to the internal circuit of the insulation resistance tester, the fuse provided in the measuring probe is blown and the blown fuse is illuminated. , The safety of the measurer can be secured.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a conceptual configuration diagram of the present invention. In the figure, 10 is a main body of the insulation resistance meter, 20 is a measurement probe connected to the main body 10, and 30 is a measurement target for p insulation resistance measurement by the measurement probe 20.

In addition to the original insulation resistance measuring function, the main body 10 is provided with a function of detecting and displaying that a voltage is applied to the measuring object 30. Measuring probe 2
0 is connected to the line terminal (Line) 11 and the earth terminal (Earth) 12 of the main body 10, and the line side probe has a fuse 21 and a voltage detector 22 which are blown when an overcurrent flows. Parallel circuit is provided.

FIG. 2 is a concrete configuration diagram of FIG. In the main body 10, the earth terminal 12 is connected to a high-voltage generation circuit 13 for performing the original insulation resistance measurement, and the line terminal 11 is provided with a measurement circuit 14 for performing the original insulation resistance measurement.
Are connected. The operating states of the high voltage generating circuit 13 and the measuring circuit 14 are appropriately changed in association with the switching of the function of the main body 10 and the switching of the range.
On the other hand, a rectifier circuit 15 composed of a resistor and a diode is also connected to the ground terminal 12, and an output signal of the rectifier circuit 15 is applied to an inverting input terminal of a comparator 17 via a low pass filter 16. A reference voltage for voltage warning is input to the non-inverting input terminal of the comparator 17.
The output terminal of the comparator 17 is connected to a warning display element 18 made of, for example, a light emitting diode.

In the measurement probe 20, the parallel portion of the fuse 21 and the voltage detector 22 which is blown when an overcurrent flows is provided at the grip portion of the probe on the line side, as described above. The voltage detector 2 in FIG.
2 is composed of a series circuit of a resistor 23 and a warning lamp 24.

In such a configuration, no matter how the function switching or range switching of the main body 10 is set, the AC voltage from the measuring object 30 is applied between the line terminal 11 and the ground terminal 12. When added, it is half-wave rectified by the rectifier circuit 15, input to the low-pass filter 16, and smoothed. The smoothed input voltage is compared with the reference voltage by the comparator 17, and if the input voltage is higher than the reference voltage, the warning display element 18 is driven to light.

As a result, regardless of the setting of the function or range switching state of the main body 10, the measurer always determines that the measurement target 30 is in danger from the lighting drive state of the warning display element 18. It is possible to accurately detect whether it is in a proper voltage level state.

However, the line terminal 11 and the ground terminal 1
When an excessive voltage that causes dielectric breakdown inside the main body 10 is input between the two, the above-described circuit does not operate, and sparks or the like occur inside the main body 10 and the measurer is endangered. There is a risk that

In this case, the fuse 21 provided in the grip portion of the measuring probe 20 on the line side can be blown to avoid the danger. And further, fuse 2
When the fuse 1 is blown, the warning lamp 24, which is connected in parallel with the fuse 21 and constitutes a voltage detector 22, is supplied with a current through a resistor 23 to drive the lamp, so that the fuse 21 is blown. Dangerous voltage is measured 30
It is possible to notify the measurer of the addition by the user and call attention.

Although the low-pass filter composed of the active element is used as the smoothing means in the above embodiment, it may be composed of the passive element.

[0017]

According to the present invention described in detail above, the following effects can be obtained. No matter what the measurement setting state of the insulation resistance tester is, if a voltage higher than the preset warning reference voltage is applied from the measurement target to the connection terminal of the measurement probe, the insulation resistance tester Since the warning display element provided at is driven to light, the measurer can correctly recognize the dangerous state and can take appropriate measures to avoid the danger.

When a voltage is applied to the internal circuit of the insulation resistance tester, the fuse provided in the measuring probe is blown and the blown fuse is illuminated. , The safety of the measurer can be secured.

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram of the present invention.

FIG. 2 is a specific configuration diagram of FIG.

[Explanation of symbols]

 10 Insulation resistance meter main body 11 Line terminal 12 Earth terminal 15 Rectifier circuit 16 Low-pass filter 17 Comparator 18 Warning display element 20 Measuring probe 21 Fuse 22 Voltage detector 23 Resistance 24 Warning lamp 30 Measurement target

Claims (1)

[Claims] 1. An insulation resistance tester for measuring an insulation resistance of a measurement target through a measurement probe, wherein the insulation resistance tester main body includes a rectifier circuit for rectifying an AC voltage input to a connection terminal of the measurement probe. A probe for smoothing the output signal of the rectifier circuit, a comparator for comparing the output voltage of the filter with a warning reference voltage, and a warning display element that is driven to light by the output signal of the comparator, The insulation resistance tester is provided with a fuse that is blown by an overcurrent and a voltage detector that is connected in parallel with the fuse and lights up and indicates that the fuse is blown.