JPH0560811A - Insulation resistance measuring instrument - Google Patents

Abstract

PURPOSE:To select a sample to be measured which becomes an object to be measured out of a plurality of samples to be measured and to stably and highly reliably measure high insulation resistance values by increasing the insulation of the cases of an applied voltage switching circuit and sample select circuit for selecting samples and providing a driving guard switching means. CONSTITUTION:This insulation resistance measuring instrument is constituted of a plurality of measuring samples 12, constant voltage power source 1 for supplying voltages, a switching circuit 2 provided with a switch 7 for switching applied voltages and protective resistance 11, sample select circuit 4 provided with switches 8, 9, and 10 for selecting samples to be measured and switching driving guards, and insulation resistance meter 5 for measurement. In order to increase the insulation resistances of the circuits 2 and 4, the circuits 2 and 4 are connected to each other while the circuits 2 and 4 are separately housed in different cases. Therefore, high insulation resistances can be measured, because the leakage of a current flowing to a detected signal can be prevented and external inducting actions, noise action, etc., which give influences to the detected signal can be removed by the driving guard switching function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulation resistance measuring apparatus for measuring insulation resistance by sequentially switching a plurality of samples to be measured.

[0002]

2. Description of the Related Art This type of insulation resistance measuring device
In order to select a plurality of samples to be measured in a sample box, a constant voltage power supply for applied voltage, a switching circuit for switching the applied voltage to the insulation resistance measuring device main body, as proposed in Japanese Patent Laid-Open No. 2-264871. The sample select circuit and the insulation resistance meter for measurement are used to measure the insulation resistance value of the sample to be measured.

FIG. 3 shows a circuit configuration when an insulation resistance value between samples to be measured is measured by a conventional insulation resistance measuring device.

The conventional insulation resistance measuring apparatus comprises a constant voltage power source 1 for supplying an applied voltage to a sample to be measured, a switch 6 for disconnecting the applied voltage, a switch 7 for constantly applying a voltage and a voltage applied during measurement, and a protective resistance. It comprises a switching circuit 2 having 11, a sample selecting circuit 4 having a switch 8 for selecting a sample 12 to be measured by a plurality of samples in a sample box 3, and an insulation resistance meter 5 for measurement.

In general, the constant voltage power supply 1 is often built in the insulation resistance meter 5. Further, in the circuit configuration diagram shown in FIG. 3, the switch contacts 7 and 8 indicated by broken lines in the circuit are in an interlocking operation. Further, the switching circuit 2 and the sample selection circuit 4 are mounted and arranged in the same case 18.

In the above configuration, first, in the case of the constant applied voltage to the sample 12 to be measured, Vs from the constant voltage power source 1
The output is supplied to the switching circuit 2. When the switch 6 of the switching circuit 2 is in the closed state and the switch 7 is on the b contact side, it forms a circuit path through the protective resistor 11 and a voltage is applied to one end of the measured sample 12.

The other end of the sample 12 to be measured is connected to the sample changeover switch 8 of the sample select circuit 4 through the measurement cable 13 using a coaxial cable. The switch 8 is located on the b-contact side and is connected to the Lo terminal of the constant voltage power source 1 to apply an applied voltage to the sample 12 to be measured, so that a current flows.

Next, at the time of measurement, the switch 7 of the changeover circuit 2 and the switch 8 of the sample selection circuit 4 are connected to the contact a side, and Vs from the constant voltage power source 1 is protected by the protective resistor 11.
Is a bypassed route, and is added to one end of the measured sample 12. On the other hand, the switch 8 described above is on the a contact side, and the other end of the sample 12 to be measured is connected to the Iin terminal of the insulation resistance meter 5 through the measurement cable 13 and the measurement cable 14.

Since the Lo terminal of the insulation resistance meter 5 and the Lo terminal of the constant voltage power supply 1 are connected, an applied voltage is applied to the sample 12 to be measured through the insulation resistance meter 5 and a current flows.
This current is detected by the ammeter in the insulation resistance meter 5, and the insulation resistance value is obtained according to Ohm's law.

[0010]

In the conventional insulation resistance measuring apparatus, the changeover switch 7 of the changeover circuit 2 and the switch 8 of the sample selection circuit 4 are constituted by interlocking contacts in the same switch. The sample selection circuit 4 and the sample selection circuit 4 are mounted and arranged in the same case 18.

In this case, the insulation resistance of the switch itself and the insulation resistance inside the case pose a problem. That is, when the insulation resistance between the switch and the case is lower than the insulation resistance value of the sample to be measured, a leakage current occurs due to the insulation resistance between the switch and the case. This has the disadvantage that the true value cannot be measured.

Further, although there is no problem in the case of measuring a relatively low insulation resistance, in the case of a high insulation resistance, the current flowing through the sample to be measured is affected by external inductive action, external noise, etc.
There is a drawback that large variations and errors occur in the measured values of the sample to be measured. Therefore, the reliability and stability of the measured value become a problem.

An object of the present invention is to provide an insulation resistance measuring device capable of stable and highly reliable measurement of a high insulation resistance value by selecting a measurement sample to be measured from a plurality of measurement samples. Especially.

[0014]

In order to achieve the above object, in the insulation resistance measuring apparatus according to the present invention, the insulation resistance meter and a sample to be measured to be measured are selected from a plurality of samples to be measured, and the insulation is measured. A sample select circuit connected to an ohmmeter, a constant voltage power supply for applying the measurement voltage, and a switching circuit that switches between applying the measurement voltage from the constant voltage power supply directly to the DUT or through a protective resistor. An insulation resistance measuring apparatus that has a sample-to-be-measured selection unit and sequentially selects a plurality of samples-to-be-measured to obtain an insulation resistance value of the sample-to-be-measured, wherein the switching circuit and the sample select circuit are:
Equipped with structural means that are mounted in separate insulated cases and insulated from each other, the DUT and the sample select circuit, and the sample select circuit and the insulation resistance meter are connected using double shielded coaxial lines. The sample-to-be-measured selecting means switches the detection signal line of the double shielded coaxial line and the driving guard line to the simultaneous operation when selecting the sample to be measured.

[0015]

In the insulation resistance measuring apparatus of the present invention, the switch in the switching circuit and the switch in the sample selection circuit have different switch configurations, and the switching circuit and the sample selection circuit are mounted and arranged in different cases. The circuits are insulated from each other.Double shielded coaxial cable wires are used between the DUT and the sample select circuit, and between the sample select circuit and the insulation resistance tester, and one of the double shields is driven by the insulation resistance tester. The guard signal and the other shield are used to switch the detection signal line and the driving guard line to the simultaneous operation.

According to the insulation resistance measuring apparatus of the present invention, the switching circuit for supplying voltage and the sample selecting circuit for selecting the sample are separately arranged and connected, so that the switching circuit and the sample selecting circuit are connected. The insulation resistance is increased, and the effect of preventing current leakage of the detection signal is obtained. Further, the switching function of the driving guard removes the external inductive effect and the external noise effect that affect the detection signal, and enables the measurement of high insulation resistance.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration diagram showing another embodiment of the insulation resistance measuring apparatus of the present invention.

In the figure, the present measuring apparatus comprises a constant voltage power supply 1 for supplying an applied voltage to a sample 12 to be measured in a sample box 3, a switch 6 for disconnecting an applied voltage of the sample 12 to be measured, and a constant voltage application and measurement time. A sample having a switching circuit 2 having an application switching switch 7 and a protection resistor 11 for preventing short circuit, a selection switch 8 for a sample 12 to be measured, a driving guard switch 9, and a Lo terminal connecting switch 10 for a constant voltage power supply 1. It is composed of a select circuit 4 and an insulation resistance meter 5 for measurement.

Further, between the sample to be measured 12 and the sample selection circuit 4, a sample selection circuit 4 is connected through a measurement cable 13.
The detection signal line 15 is commonly connected to one ends of the switches 8 and 10, and the driving guard line 16 is connected to one end of the switch 9.

Further, the sample selection circuit 4 and the insulation resistance meter 5
In between, the detection signal line 15 and the driving guard line 16 are connected to the insulation resistance meter 5 through the measurement cable 14 from the other ends of the switches 8 and 9, and the insulation resistance meter 5 is connected from the other end of the switch 10. Each is connected to the Lo terminal of the voltage power supply 1.

When the measurement is started, the measurement voltage to be applied to the sample to be measured is set in the constant voltage power source 1. The voltage output from the Vs-Lo terminal of the constant voltage power supply 1 is always continuously applied to the sample to be measured via the protective resistance 11 and is directly applied only during measurement without using the protective resistance 11.

First, in the normal state, the switch 6 of the switching circuit 2 is in the closed state, the switch 7 is on the b contact side, and a voltage is applied to one end of the sample 12 to be measured through the protective resistor 11. On the other end side of the measured sample 12, the sample selection circuit 4
Switch 8 and switch 9 are open, switch 10
Is closed, and the switch 10 is used to
The other end of 2 is connected to the Lo terminal of the constant voltage power supply 1, a voltage is applied to the measured sample 12, and a current flows. In this case, the circuit is protected by the protective resistor 11 even when a short-circuit state occurs due to the migration phenomenon of the measured sample 12.

Next, at the time of measurement, an applied voltage is applied to one end of the sample 12 to be measured through a path bypassing the protective resistance 11 with the switch 7 of the switching circuit 2 set to the a contact side. On the other end side of the sample to be measured 12, the switch 8 and the switch 9 are closed, and the switch 10 is connected to the Iin terminal of the insulation resistance meter 5 through the measurement cable 14 in the open state.

As a result, the Lo terminals of the insulation resistance meter 5 and the constant voltage power source 1 are connected to each other, and the sample to be measured 1 is measured.
The applied voltage is applied to 2, and the current flows through the insulation resistance tester 5.
It flows into the measured sample 12. The current is detected and the insulation resistance value is obtained by the insulation resistance meter 5.

As a method for detecting the short-circuited state, a voltage is applied to the sample to be measured 12 and the flowing current is measured by the insulation resistance tester 5 by the same operation as in the above measurement.
The voltage applied to the sample 12 to be measured is stopped by closing the switch 6 of the switching circuit 2 when the measured value exceeds a predetermined value.

FIG. 2 is a block diagram showing another embodiment of the present invention. The switching circuit 2 and each switch in the sample selection circuit 4 are configured by switches that can be controlled from the outside, such as a relay, respectively.
7 is provided to control the output voltage of these switches and the constant voltage power supply 1, and the measured value of the insulation resistance meter 5 is read, so that the high insulation resistance of the plurality of DUTs 12 to be measured is automatically stabilized. Can be measured. 1 and 2
In the above, the constant voltage power supply 1 may be built in the insulation resistance meter 5.

[0027]

As described above, according to the present invention, the switching circuit for supplying the applied voltage, the high insulation of the sample selection circuit of the sample to be measured, and the switching of the detection signal line and the driving guard line are performed simultaneously. The drawbacks of reliability and stability of the measuring device are improved, and high insulation resistance can be measured. Further, there is an effect that automatic measurement of high insulation resistance becomes possible.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an insulation resistance measuring device according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a circuit configuration diagram of an insulation resistance measuring device according to a conventional method.

[Explanation of symbols]

 1 constant voltage power supply 2 switching circuit 4 sample selection circuit 5 insulation resistance tester 12 measured sample 17 controller system

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor's place New Year 5-7 Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Inventor Chiharu Ishiue 5-7 Shiba, Minato-ku, Tokyo No. 1 Inside NEC Corporation (72) Inventor Yuji Ikuta 5-7-1 Shiba, Minato-ku, Tokyo Inside NEC Corporation

Claims (1)

[Claims] 1. An insulation resistance meter, a sample selection circuit for selecting a sample to be measured from a plurality of samples to be measured and connecting the sample to the insulation resistance meter, a constant voltage power source for applying a measurement voltage, and a constant voltage source. It has a switching circuit for switching whether to apply the measurement voltage from the voltage source directly to the sample to be measured or to apply it via a protective resistor, and the sample to be measured selecting means, and selects a plurality of samples to be measured in sequence. An insulation resistance measuring device for obtaining an insulation resistance value of the sample to be measured, wherein the switching circuit and the sample selection circuit are mounted and arranged in separate insulated cases, and are provided with structural means insulated from each other, The sample to be measured and the sample select circuit, and the sample select circuit and the insulation resistance meter are connected using a double shielded coaxial line, and the sample to be measured means is connected to the double shielded coaxial line when selecting the sample to be measured. detection An insulation resistance measuring device characterized in that the signal line and the driving guard line are simultaneously switched.