JPS63139258A - High resistance measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a measuring device for measuring the insulation properties of an insulating material used in high-voltage electrical equipment, and particularly to a measuring device that is equipped with a means for automatically selecting a measurement range. This invention relates to a digital high resistance measuring device (high voltage megohmmeter).

(Problems to be solved by Juto technology and invention) In ordinary high resistance measuring devices such as high resistance measuring branches and megohmmeters, which measure the insulation properties and absorption rates of electrical devices, cables, various materials, etc. , a needle-hole indicator driven by an electromagnetic drive mechanism was used to display the measured value.

However, the accuracy of reading by these devices depends mostly on the measurer, which makes measurement errors extremely large and makes measurement operations extremely inconvenient.

In particular, it has been extremely difficult to measure the absorption rate of an object to be measured using this device. Regarding this absorption rate, the People's Republic of China stipulates as follows. In other words, 6 seconds have passed since the high voltage was applied to the object to be measured.
The instantaneous value measured after 0 seconds is R60, the instantaneous value measured after 15 seconds is RI5, and R1
The ratio of R60 to R5 (R60/R15) is defined as the absorption rate of the object to be measured. Therefore, when using the measurement branch in the needle hole, at least three people are required to perform the measurement, including a person who turns on the high voltage source, a person who reads the measured values, and a person who measures the time and records the data. Without proper operation, insulation resistance and absorption rate cannot be measured.

Furthermore, if there is carelessness or mistake on the part of the measurer, the measuring arm may be damaged due to discharge of the measuring material. Furthermore, various factors such as time measurement operation, reading by the measurer, non-linearity of the scale, etc. produce measurement errors.
There was a problem that the measurement results did not better represent the actual insulation properties of the object to be measured.

Therefore, in recent years, many digital high resistance measuring devices have been developed. However, in all of these, a single sampling branch circuit with a reference resistor connected in series with the object to be measured is considered.

An example of this type of device is given in Japanese Patent Laid-Open No. 59-5969, in which a sample voltage taken from a reference resistor is fed to an A/D converter and then a computer calculates the result. It is designed to be output. Disadvantages of this type of measuring device are the high accuracy required for the high voltage power supply, the inability to eliminate ripple effects, and the high cost.

Another example is shown in U.S. Pat. No. 4,217,453, in which two sample voltages taken from a single branch circuit are fed into a dual slope A/D converter. and then the measurement results are calculated. This patent describes two different double integration methods that can be used to construct digital resistance measurement devices and digital conductivity measurement devices.

However, even in such devices, only a single sample branch circuit is employed and the voltage to be integrated is taken directly from the object under test, thereby limiting the input level of the subsequent A/D converter and integrator. Therefore, a voltage exceeding about 20 volts cannot be applied to the object to be measured.Therefore, this type of digital resistance measuring device cannot measure the high voltage insulation resistance of the object to be measured. Further, for the same reason, the above-mentioned digital conductivity measuring device cannot measure the high voltage insulation conductivity of the object to be measured.

Furthermore, according to this digital conductivity measuring device,
Additional reciprocal calculations are required based on indirect measurements of the device.

The present invention was devised in view of the above problems, and its purpose is to provide a new high resistance measuring device that can accurately measure the insulation resistance and absorption rate of an object to be measured.

Another object of the present invention is to provide a digital display type high resistance measuring device comprising a two-branch voltage ratio sampling circuit in order to eliminate the effects of ripples and voltage fluctuations of a high voltage power supply and improve stability. There is a particular thing.

Another object of the present invention is to directly display the resistance over a wide range by using the input voltage terminal (INl (I) and the reference voltage terminal (vR) of the double integral integrated circuit interchangeably with each other. An object of the present invention is to provide a digital direct read layer high resistance measuring device that can accurately measure the resistance of the layer.

Furthermore, another object of the present invention is to provide power from an AC or DC power source such as 500V, 1.000V, 2.500V.
V, 5.000V, 10.0OOV or 15.000
A built-in DC high voltage generator that generates a series of high voltages consisting of V, and a digital high voltage sensor with automatic measurement range selection means that has a display hold function and a buzzer warning function to ease measurement operations. An object of the present invention is to provide a resistance measuring device.

(Structure of the Invention and Its Effects) According to the present invention, there is provided an input circuit, a voltage/resistance conversion means for converting a voltage value into a resistance value, a control circuit for automatically selecting a measurement range, and a display for displaying a measured value. A digital high-resistance measuring device is provided, which includes output means for generating a DC high voltage, and clock pulse generation means for supplying clock pulses to the voltage/resistance conversion means.

According to the present invention configured as described above, the DC high voltage generating means supplies the DC high voltage to the input circuit including the object to be measured, the measurement sampling voltage and the reference sampling voltage are taken out from the input circuit, and the voltage , /resistance conversion means are controlled by the clock pulse generation means to convert the measurement sampling signal and the reference sampling signal into resistance values displayed by the output means.

A feature of the present invention is that ! for voltage/resistance conversion! A product circuit (
The point is that the terminals "INIII" and "VR" for the input voltage and reference voltage of the IC are used interchangeably. This eliminates the arithmetic processing necessary to measure the resistance of the object to be measured without increasing manufacturing costs.

Another feature of the present invention is that a two-branch sampling circuit is used to extract two signals from the input circuit. This can eliminate R''13 noise caused by disturbances and ripples on the circuit.

EXAMPLES Before describing embodiments of the present invention in detail, a detailed description of the present invention is provided.The present invention is directed to an apparatus for detecting high voltage electrical insulation properties of materials.

The device according to the invention is based on the principle of voltage ratio measurement,
Large scale for two-branch sampling voltage ratio circuit and A/'D conversion along with digital display to display the resistance value being measured! A voltage/resistance converter configured with a product circuit LSI module is used. This device is powered and driven by both direct current and alternating current, providing a wide range of high voltages. According to this device, the insulation resistance and absorption rate of electrical equipment can be measured with an accuracy of ±0.1% and between 20 and 20%.
Accurate measurements can be made over a measurement range of 0,000 megohms. Also, if you make some changes to this device, 1,000
It is also possible to measure resistance values in excess of 0,000 megohms.

Hereinafter, a preferred embodiment of the digital high resistance measuring device according to the present invention will be described in detail. As shown in FIG. 1, the high resistance measuring device according to the present invention includes a DC high voltage generator and an input circuit. , a control circuit, a voltage/resistance converter (hereinafter simply referred to as a V/R converter), a clock signal generator, and an output system. The DC high-voltage generator consists of a DC high-voltage power supply 1 shown in Fig. 1, and depending on the different objects to be measured, the DC high-voltage power supply 1 supplies a series of different values of voltage, each regulated by each country. It looks like this. For example, in the People's Republic of China, the series of voltage values are 500V and 1.000V.

5.0OOV, in, 0OOV, +5. QOOV etc. The object Rx to be measured is connected between terminals E and L of the DC high voltage power supply 1.

The input circuit includes a two-branch voltage ratio sampling circuit 2 and two identical low-pass filters 3, 4.

FIG. 2 shows a detailed circuit diagram of a two-branch voltage ratio sampling circuit 2 consisting of a reference sampling technique and a measurement sampling technique connected in parallel. The reference sampling technique consists of fixed resistors R1 and R2 connected in series, and the voltage between the node P and the shield terminal G (ie, the voltage applied to the resistor R2) is extracted as the reference voltage. The measurement sampling technique is to connect the object to be measured Rx and fixed resistance Rs in series.
The voltage measured is the voltage between node X (line terminal L) and shield terminal G (ie, the voltage across resistor Rs). These two branches are connected in parallel between nodes E and G. Generally, R1>R2,Rx>
Satisfies the relationship Rs. The high voltage provided by the DC high voltage power supply 1 is applied between the terminals E and G of the two-branch voltage ratio sampling circuit 2, and the voltage between the terminals P and G is taken out as a reference voltage Vp, etc. , G is taken out as the measurement voltage Vx. These two voltages V
p and Vx are each sent to a low pass filter 3.4.

FIG. 3 shows a typical circuit of the low-pass filter 3 and the low-pass filter 4. This is a normal secondary active type R
It is a C low pass filter. Circuit elements R3, R4, CI
, C3 and operational amplifier AI eliminate the effects of fluctuations and ripples in the electric circuit,
They are used to reduce the cost of the voltage generator and improve the operational stability of the device, respectively. Two identical filters are required for bifurcated sampling. For operational amplifier AI, 5G7650 or integrated circuit ICT65 manufactured by Shanghai Parts Factory No. 5
1] may be used. The reference voltage Vp from the two-branch voltage ratio sampling circuit 2 is filtered by the low-pass filter 4 and supplied to the input voltage terminal (bin) "I N HI" of the V/R converter. The measured voltage VX is filtered by a low-pass filter 3 and supplied to the control circuit.

The control circuit consists of an automatic measurement range selection circuit 5, a shift logic circuit 6, and a star I/control circuit 7.

FIG. 4 shows a detailed circuit of the automatic measurement range selection circuit 5, in which the automatic measurement range selection circuit 5 is shown in detail.
G765Q may be selected as the voltage follower 3-^5 and CD4066 (or C544) may be selected as the logic switch GO-Gl. Also, 5G14574 or MC manufactured by the same manufacturer as mentioned above.
Preferably, I4574 is selected as voltage comparator A6-^7.

1403 high precision energy throttle power supply as a high precision constant voltage source, the voltage output from the power supply is the comparator A6-AV
is selected as the reference voltage. The measured voltage Vx is filtered by a low-pass filter 3. Output vy of filter 3
is sent to the input terminal Y of the automatic measurement range selection circuit 5.

If vy is lower than the reference voltage of the comparator ^7, a logical value "O" appears at both the output terminal DPI of the comparator ^6 and the output terminal DPO of the comparator shoulder, and the switches GO and GI are opened, and the measurement is started. Voltage is not reduced.

If vy is higher than the reference voltage of comparator A7 and comparator A
If it is lower than the reference voltage of Comparison Masato 6, the logic output [I
Pl becomes "0" and switch G1 is opened, while the logic output DPO of comparator A7 becomes "1'°" and switch G1 is opened.
O interjects. As a result, the automatic measurement range selection circuit 5 as a whole can reduce the pressure of the measurement signal vy by a certain amount of decibel value (for example, 20 dB) by selecting the resistors R9 and 910. If vy is higher than the reference voltage of comparator ^6, then comparator ^6. The logic outputs DPI and DPO of ^7 both become "1" and the logic switches GO and Gl are closed. As a result, the measurement range automatic selection circuit 5 as a whole receives the measurement signal v.
y can be reduced by a larger amount of decibel values (eg, 40 dB). The output Vz of voltage follower A5 is sent via node 2 to the reference voltage input terminal (bin) VR of V/R converter 8, and is also sent to the start control port via node F! ! Sent to 87. Comparator A6. The logic outputs DPI, DI'0 of AV are sent to the shift logic circuit 6.

FIG. 5 shows a detailed circuit of the shift logic circuit 6.

The shift logic circuit 6 can be constructed by a 4-invert gate 1-5G4807 and a 6-invert gate 5GJQ69 manufactured by Shanghai Parts Factory No. 5. The logical relationship between the logic outputs DPL, DPM, DPR of the shift logic circuit 6 and the logic outputs DPO, I)PI is as follows.

DPL=DPI-DPO DPR=DPI・ROPO DPM=DPI・OPo+[)PI・ROPO Further, the truth table of the circuit 6 is as follows.

The function of the shift logic circuit 6 is to use the logic input signal D P 1. to automatically select the measurement range. , D P O
The different logic states cause one of the three decimal points (M1, R) to illuminate or appear on the digital display screen.

FIG. 7 shows an example of the star I control circuit 7.

The start control circuit 7 is an astable oscillator initialized by the measurement sample signal VF. The measurement voltage Vx appears only when the object to be measured is connected to the input circuit and a high DC voltage is applied. After passing through the low-pass filter 3 and the automatic measurement range selection circuit 5, the voltage causes the start signal VF to reach the input terminal of the comparator A8 in FIG. 7, and turns on the logic switch G2 as described above. Activate the transmitter. This circuit is based on the integrated circuit IC5G7556 (or ICM75) for dual time base circuits that outputs control signals such as:
56).

(1,) V, sample hold signal supplied to the R/I-1 terminal of the /R converter 8; This signal is an outgoing signal with variable hold and sample times. For example, the sampling time is 1 second and the hold time is 14
seconds, so the operator has sufficient time to dictate the data shown by the digital display 14.

(2) A time counting start signal for starting the operation of the time display 12 and time display.

(3) A sound signal used by the buzzer 13 to generate a sound every 15 seconds as a caution signal.

The time counting circuit 12 is ZhaBzhou.
Integrated circuit ICICL102 manufactured at a semiconductor equipment factory
It can be composed of

FIG. 6 shows a typical configuration of a V/R converter. 2
The measurement voltage extracted from the measurement sampling technique of the branch voltage ratio sampling circuit 2 passes through the low-pass filter 3 and the measurement range automatic selection circuit 5, and then passes through the reference voltage input terminal (bin) "VR" of the V/R converter 8. sent to. On the other hand, 2
The reference voltage extracted from the reference sampling technique of the branch voltage ratio sampling circuit 2 is sent to the input voltage terminal (bin) "INIII" of the V/R converter 8.

In other words, the method of providing these two signals in this embodiment is such that the measurement signal is connected to the input voltage terminal (bin) "INI (
This is contrary to the method of applying a signal in a conventional device, where the reference voltage is sent to the reference voltage input terminal (bin) ``VR''. is as follows.

That is, since the sampling voltage Vx is inversely proportional to the resistance Rx of the object to be measured, it is necessary to perform a division operation on the sampling voltage in order to facilitate direct reading. In this division operation, the terminal (bin) "IN old" and the terminal (bin) "VR" are used simply by exchanging each other.
This can be easily accomplished by a V/R converter 8. Implementing a high-precision analog divider with electronic technology is very expensive. In order to reduce the manufacturing cost in this manner, the inventor selected the double integral AD converter 5G7175 (or 5GI4433, ICL7106, 1cL7+26) to construct a 52 double integral divider.

FIG. 6 also shows a clock pulse generator 9 and an output system including a bit driver 10, a decoder 11 and a digital display 14.

Since these circuits are well known, a detailed explanation of each circuit will be omitted here.

Terminal (bin) vFL” of V,/R converter 8 and terminal (
Based on the measured sampling voltage and the reference sampling voltage supplied to the bin>“INHI”, the converter 8 performs a voltage/resistance conversion by means of a clock signal from a clock pulse generator 9. The result is the output terminal (bin) Bi,
82. B3. B4 and DI, D2. [13, D4. D5
After being outputted via the bit driver 10 and decoded by the decoder 11, it is output to the digital display 1 along with the doro-tube DPL, DPM, and DI'R.
4 will be displayed on top. As a result, the final resulting display shows the resistance of the object being measured.

The following table shows data measured by the high resistance measuring device according to the present invention under conditions of 21 degrees Celsius and 70% humidity.

It should be understood that those with ordinary knowledge in the art to which this invention pertains can make various modifications and variations without departing from the technical scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic block diagram showing an example of a digital high resistance measuring device according to the present invention, FIG. 2 is a circuit diagram of the two-branch voltage ratio sampling circuit shown in FIG. 1, and FIG. 3 is a circuit diagram of the two-branch voltage ratio sampling circuit shown in FIG. A circuit diagram showing a typical example of a low-pass filter; FIG. 4 is a circuit diagram showing an example of the measurement range automatic selection circuit shown in FIG. 1;
FIG. 5 is a circuit diagram showing a typical shift logic circuit, FIG. 6 is a block diagram showing a typical configuration of the voltage/resistance converter shown in FIG. 1, and FIG. FIG. 3 is a circuit diagram showing a start control circuit. Explanation of symbols 1: DC high voltage power supply, E: Ground terminal for external connection, G: Shield terminal for external connection, L: Line terminal for external connection, 2: 2-branch voltage ratio sampling circuit,
3.4...Low-pass fill signal 6...Shift logic circuit, 7...Start control circuit, 8...Voltage/resistance converter (V/R converter), 9...Clock pulse generation device, 10... bit driver, 11... decoder, 1
2...Time display, 13...Buzzer, 14...Digital display. Applicant: People's Republic of China University of Science and Technology (1 other person) Agent: Patent attorney Teru Hase - (1 other person) Figure 41 Figure 5 Figure 6

Claims (6)

[Claims] (1) A DC high voltage generation means, an input circuit connected to the DC high voltage generation means and from which a measurement voltage and a reference voltage are taken out, and a control means connected to the input circuit for automatically selecting a measurement range; a converting means connected to the control circuit and converting the measured voltage and the reference voltage into a resistance value; an output means connected to the converting means displaying the resistance value; and an output means connected to the converting means converting the clock signal to the converting means. A high resistance measuring device characterized by comprising: a clock signal generating means for supplying a clock signal to a clock signal. (2) The input circuit has a two-branch sampling circuit in which a measurement branch consisting of a resistor to be measured and a fixed resistance connected in series, and a reference branch consisting of two fixed resistances connected in series are connected in parallel, and 2. A high resistance measuring device according to claim 1, wherein the measuring voltage is taken out from a fixed resistance end in the measuring branch. (3) The conversion means is constituted by a double integral type analog-to-digital conversion integrated circuit, and a reference voltage filtered by a filter is supplied to the input voltage terminal "INHI" of the integrated circuit, and the reference voltage of the integrated circuit is 2. The high resistance measuring device according to claim 1, wherein the measurement voltage filtered by a filter is supplied to the terminal "V_R". (4) DC high voltage generation means, an input circuit connected to the DC high voltage generation means and consisting of a measurement branch and a reference branch connected in parallel, from which the measurement voltage and the reference voltage are taken out, respectively; and the input circuit. A high resistance measuring device comprising: a control means connected to the control means; an automatic measurement range selection circuit that automatically selects a measurement range; a start control circuit that supplies the time display and an audible signal to the audible alarm; a shift logic control circuit that is connected to the automatic measurement range selection circuit and shifts the decimal point on the display screen; and the automatic measurement range selection circuit. a conversion circuit connected to and converting the measurement voltage and reference voltage into resistance values; output means connected to the conversion circuit and displaying the resistance value; and output means connected to the conversion circuit and supplying a clock signal to the conversion circuit. 1. A high resistance measuring device characterized by comprising clock signal generating means. (5) The input circuit has a two-branch sampling circuit in which a measurement branch consisting of a resistor to be measured and a fixed resistance connected in series and a reference branch consisting of two fixed resistances connected in series are connected in parallel, and 5. The high resistance measuring device according to claim 4, wherein the measuring voltage is taken out from a fixed resistance end in the measuring branch. (6) The conversion circuit is constituted by a double integral type analog-to-digital conversion integrated circuit, and a reference voltage filtered by a filter is supplied to the input voltage terminal "INHI" of the integrated circuit, and the reference voltage of the integrated circuit is 5. The high resistance measuring device according to claim 4, wherein the measuring voltage filtered by a filter is supplied to the terminal "V_R".