KR19990009238A - Insulation resistance measuring device of insulator - Google Patents

Abstract

The present invention relates to a device for measuring insulation resistance of an insulator, in which an internal circuit is protected against disturbances (electromagnetic and electric fields) and improved to vary the selection range for the insulation resistance to be measured.

The present invention provides a measurement of the insulation resistance of an insulator in which a constant voltage is applied between a pair of symmetrical first and second nodes of a Wheatstone bridge circuit and a voltmeter is configured between another pair of symmetrical third and fourth nodes. In the apparatus, all parts except the insulator to be measured are built in the electromagnetic shielding case, and a probe terminal for connecting the insulator in parallel to the load between the second node and the fourth node is provided in the electromagnetic shielding case. It is drawn and configured for connection with the insulator to the outside.

Therefore, it is not necessary to shield the insulator and the insulation resistance value is measured by simply connecting the insulator to the device, so that workability is improved and reliable measurement results can be obtained.

Description

Insulation resistance measuring device of insulator

The present invention relates to a device for measuring the insulation resistance of an insulator, and more particularly, to protect an internal circuit against disturbances (electromagnetic and electric fields), and to improve the insulation resistance of the insulator which can be varied in a variety of selection ranges. It relates to a resistance measuring device.

As a material for electric and electronic products, those manufactured or included with insulating materials such as wire coating, insulating tape, switches, or connectors are widely used, and they are managed by mandating the performance and reliability test of insulating materials as essential measurement items. .

However, since the insulator has a very small magnitude of the electric current involved in the measurement of the insulation resistance value, a general resistance measurement method of measuring the current (or voltage) by applying a direct voltage (or current) is reliable. Measurement of the insulation resistance value was difficult.

In addition, since the insulation resistance value of the insulator is measured by using a minute current value, the insulator to be measured in order to prevent the generation of current induced by an electric field and a magnetic field acting as background noise conventionally when measuring the insulation resistance of the insulator. Tight shielding or long time measurements were required. Therefore, the measurement of the insulation resistance value of the insulator involved relatively much time and effort.

Therefore, as described above, conventionally, it is difficult to measure the insulation resistance, and thus a method for measuring the insulation resistance value is easier, simpler and more reliable.

SUMMARY OF THE INVENTION An object of the present invention is to provide an insulation resistance measuring apparatus for an insulator which can measure a wide range of insulation resistance simply and conveniently without the influence of external noise during the reliability test of the insulation material.

1 is a circuit diagram showing the principle of the insulation resistance measuring apparatus of the insulator according to the present invention.

Fig. 2 is a block diagram showing a first preferred embodiment of the insulation resistance measuring apparatus of the insulator according to the present invention.

3 is a block diagram showing a second preferred embodiment of the insulation resistance measuring apparatus of the insulator according to the present invention.

Explanation of symbols for main parts of the drawings

10 to 16, 24, 26, 34 to 44, 48 to 62, 68, 74, 76, 134 to 144, 148 to 162, 168, 174, 176: resistance

18: insulation resistance 20, 28, 30, 72, 130, 172: power

22, 80: voltmeter 26, 70, 170: variable resistor

32, 64, 132, 164: switch 46, 146: measurement range selection switch

66, 166: home balance unit 78, 178: amplifier

179: analog to digital converter 180: display unit

184: keyboard

Insulation resistance measuring device of the insulator according to the present invention for achieving the above object, a constant voltage is applied between the pair of symmetrical first and second nodes of the Wheatstone bridge circuit, the third pair of symmetrical third and In the insulation resistance measuring apparatus of the insulator in which the voltmeter is formed between the fourth node, all parts except the insulator to be measured are built in the electromagnetic shield case, and in parallel to the load between the second node and the fourth node. Probe terminal for connecting the insulator is characterized in that it is derived for the connection with the insulator to the outside of the electromagnetic shielding case.

Insulation resistance measuring apparatus of the insulator according to the present invention, the power supply unit for applying a constant voltage, the measurement range selection switch to form a first and second loads connected in parallel to the power supply unit and connected in parallel thereto to amplify the current to a voltage Two terminals connected in parallel to the first load and the Wheatstone bridge circuit including a display means for displaying and a zero point balance portion connected in series with the display means and adjusting a zero point of the display means by adjusting a current flowing through the display means. It is a further feature of the invention that it comprises switching means for electrically turning on and off the resulting path.

The power supply unit may include a power supply, a switch, and a plurality of resistors to select a supply voltage, and a node between two other loads connected in parallel to the measurement range selection switch may be configured to be connected to the power supply unit. Do.

The measurement range selection switch is configured of a parallel resistor in which the first load and the second load have different values, respectively, and selects any one of the resistors as a resistor representing the first load and the second load, respectively. It may be configured to.

The display means preferably includes an amplifier and an analog voltmeter to which the output of the amplifier is applied.

The home balance unit may be configured as a lin deck type high resistance variable divider.

In addition, each of the two parts is preferably embedded in the electromagnetic shield case and configured to be connected to the external insulator, the two terminals connected to the switching means.

The insulation resistance measuring apparatus of the insulator according to the present invention includes a power supply unit for supplying a variable voltage and a first and a second load connected in parallel to the power supply unit through a first node. Measurement means for varying the resistance value and the display means connected in parallel to the display means for amplifying the current to digitally display the voltage and the display means connected in series with the display means by adjusting the current flowing to the display means A Wheatstone bridge circuit including an origin balance unit for adjusting the zero point of the switch, switching means for electrically turning on and off a path in which two terminals are drawn in parallel to the first load, and a contact connection state between the power supply unit and the measurement range selection switch. Control and switch And a control means for controlling the switching state of the measuring means and controlling the display means to calculate the insulation resistance value measured by the signal interface with the display means and to display it on the display means.

In addition, the display means is preferably composed of a digital display device.

The control means incorporates first to fourth registers to store digital data output values of the supply voltage value and the detected voltage shift value selected for measurement in the first register and the second register, respectively, The resistance value of the insulation resistance selection switch may be determined and stored in the third register, and the voltage shift value displayed at the end of the measurement may be stored in the fourth resistor to obtain an insulation resistance value.

In addition, each of the two parts may be configured to be connected to an external insulator, and two terminals embedded in the electromagnetic shielding case and connected to the switching means.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, the present invention uses a Wheatstone bridge circuit for measuring insulation resistance.

The insulating resistor 18 is connected to the resistor 16 among the resistors 10 to 16 constituting the well-known Wheatstone bridge circuit, and the power source 20 is connected between the nodes n1 and n2, and the node n3, The voltmeter 22 is connected between n4), and is a Lindeck type high resistance variable voltage divider in series with the voltmeter 22, and the resistor 24 and the variable resistor 26 and a small power supply connected in parallel thereto. (28) is comprised.

The parallel condition of the Wheatstone bridge circuit configured as described above is sensitively changed in accordance with the change in the resistance value between each node.

When both ends of the arbitrary resistor 16 in the balanced state of the Wheatstone bridge circuit are used as the input terminals for the insulating resistor 18 and the arbitrary insulating resistor 18 is connected thereto, the resistance 16 and the insulating resistor 18 The synthetic resistance value is approximately reduced by the ratio of the resistance 16 value and the insulation resistance 18 value of the original Wheatstone bridge circuit, and a current flow due to the shift occurs between the node n3 and the node n4, Accordingly, a voltage proportional to the amount of deviation is applied to the voltmeter 22. Since this shift amount is inversely proportional to the value of the insulation resistance 18, the insulation resistance value is obtained from the shift amount.

That is, if the resistance value of the resistor 16 is 'r' and the resistance value of the insulation resistor 18 is 'R', the synthesized resistance value is approximately r (1-r / R). If the input resistance of 22) is very large compared to 'r' and the voltage across the resistor 14 is 'U', the deviation amount of the voltmeter 22 according to the insulation resistance 18 is U (r / R).

The value of the insulation resistance 18 is determined by the amount of deviation calculated as described above, and the circuit component and cable of FIG. 1 are installed in a case (not shown) that shields electromagnetic, and the insulation to be measured. The resistor 18 is configured to be exposed to the outside.

Since the insulation resistance 18 exposed to the outside does not directly affect the configuration of the Wheatstone bridge circuit, induction of electric current by electric or electromagnetic fields does not occur, and thus noise of background magnetic field, which is the biggest problem in high resistance measurement, is caused. The influence of magnetic field interference due to fluctuations is reduced.

In addition, it is unnecessary to shield the insulation resistance 18, that is, the target insulator, to be measured against electromagnetic waves. Therefore, it is possible to measure the insulation resistance of large insulators.

In addition, even when measuring an insulation resistance having a high resistance value of several ㏁ to several GΩ, when the resistor 16 is fixed to a resistance of several 저항, the input resistance viewed by the voltmeter 22 may be maintained at several ㏀. Can be. Therefore, stability is ensured in the measurement.

By applying the principle of FIG. 1 described above, the present invention can be implemented as an insulation resistance measuring apparatus of an analog insulator as the first embodiment, as shown in FIG. 2, and as shown in FIG. It may be implemented as an insulation resistance measuring device.

First embodiment

Referring to FIG. 2, the first embodiment measures an insulation resistance value of an insulator in an analog manner, in which the power supply 30, the switch 32, and the plurality of resistors 34, 36, 38, and 40 are closed loops. The nodes n21 to n24 corresponding to the nodes n1 to n4 in FIG. 1 are formed.

In addition, a resistor 42 is connected between the node n21 and the node n23, a resistor 44 is connected between the node n21 and the node n24, and a measurement including the node n22 between the node n23 and the node n24. The range selection switch 46 is comprised.

In addition, the resistances 48 to 54 corresponding to the resistors 14 of FIG. 1 and the resistors 56 to 62 corresponding to the resistors 16 are parallel to the node n22 in the measurement range selection switch 46. The node n22 is formed between the resistors 48-54 and the resistors 56-62. In addition, the connection between the node n23 and the resistors 48 to 54 is configured to be a variable contact, and the connection between the node n24 and the resistors 56 to 62 is also configured to be a variable contact.

The switch 64 is connected between the node n22 and the node n24 so as to form a switch 64 between the terminals T21 and T22 for connecting to the insulation resistor to be measured.

The node n23 includes an origin balance unit 66 for adjusting an origin set as a reference for the deviation measurement, and the origin balance unit 66 includes a resistor 68 and a variable resistor 70 connected in parallel thereto. And a Lindeck type high resistance variable voltage divider configured by connecting a power supply 72 connected in series to the variable resistor 70.

The home balance unit 66 is connected to the first input side of the amplifier 78 whose amplification degree is determined according to the ratio of the values of the resistor 74 and the resistor 76, and the node n24 is connected to the first input side of the amplifier 78. 2 It is connected to the input side. And the voltmeter 80 is comprised so that the output of the amplifier 78 may be applied.

The node n21 is connected to the variable contact so as to variably contact between the resistors 34 to 40 configured in series for selectively determining the level of the constant voltage and supplying it to the Wystone bridge circuit.

In the above-described configuration, the power supply 30 configured to supply the voltage may be configured to include a constant voltage circuit that outputs after stabilizing and outputting an external general power supply such as AC 110V or 220V using a battery. The resistors 34 to 40 are connected to the node n21 to be selectively connected to each other so that the voltage of the power supply 30 is divided and supplied to the Wheatstone bridge circuit.

In addition, the measurement range selection switch 46 included in the Wheatstone bridge circuit is configured so that the internal resistance value can be determined by interlocking the insulation resistance value of the insulator according to the measurement range.

That is, since the measurement range selector switch 46 is expressed as U (r / R), the value of the probe resistance r to increase the sensitivity of the insulation resistance measurement in order to measure the insulation resistance value R is very large. Has the function to adjust the selection. For this purpose, the measurement range selection switch 46 preferably uses a two-pole multi-contact switch, and a high voltage switch may be used as the measurement range selection switch 46 if necessary depending on the magnitude of the output voltage used for the measurement.

In addition, the amplifier 78 and the voltmeter 80 are devices that display the small voltage deviation as a resistance value, and the voltmeter 80 is scaled to display a resistance value corresponding to the input insulation resistance value and the selected measurement range. desirable. However, the scale of the voltmeter 80 is formed in the number corresponding to the selected measurement range, and accordingly, an analog low noise amplifier whose input resistance is infinitely large can also be used in the first embodiment according to the present invention.

In addition, the home balance unit 66 may be configured such that a small battery having a stable electromotive force characteristic is used as the power source 72, and at this time, the supply of voltage is supplied in association with the switching state of the power source 30. The home balance unit 66 is a lindeck type high resistance variable voltage divider that adjusts a small current flowing from the power supply 72 to the variable resistor 42 to adjust the voltage drop applied to the resistor 68 placed in the detection line. Accordingly, a function of finely controlling the origin of the voltmeter 80 is performed. The polarity of the power supply 72 is determined according to the resistance value of the measurement circuit.

In addition, the cable to the probe terminals T21 and T22 including the switch 64 is for connecting the insulator, and the cable is preferably composed of a coaxial cable using a high insulation material such as Teflon, and the high level side and the low side, respectively. It is used as the level side input and the shielding material of the cable may be the same material as for shielding the case.

In addition, the switch 64 is composed of a two-pole double-contact switch for connecting the core of the cable, and performs the function of electrically separating the insulator to be measured from the Wheatstone bridge circuit and connecting the insulator, which may be involved in the measurement. The purpose is to enhance the safety of the user by exposing the external voltage only while reading the insulation resistance value. In addition, the insulation resistance of cables and switches should be greater than the maximum insulation resistance of the insulator to be measured.

In addition, the case should be made of a metal material having a high effect of shielding low-frequency electric and magnetic fields.

In the first embodiment configured as described above, the measurement is performed in the following order.

In the state where the switch 64 is turned off, the switch 32 connected to the power supply 30 is turned on to preheat each part. Then, the insulator to be measured is connected between the terminals T21 and T22, the variable contact position of the node n21 is determined, and the resistance connection state inside the measurement range selector switch 46 is selected to select the measurement voltage and the measurement range. Then, the variable resistor 70 of the home balance unit 66 is adjusted to set the home position of the voltmeter 80. When the operation as described above is finished, the switch 64 is turned on and the insulation resistance is read.

Second embodiment

Referring to FIG. 3, the second embodiment measures the insulation resistance of the insulator digitally, wherein the power supply 130, the switch 132, and the plurality of resistors 134, 136, 138, and 140 form a closed loop. The nodes n31 to n34 corresponding to the nodes n1 to n4 in Fig. 1 are formed.

In addition, the resistor 142 is connected between the node n31 and the node n33, the resistor 144 is connected between the node n31 and the node n34, and the measurement including the node n32 between the node n33 and the node n34. The range selection switch 146 is configured.

Inside the measurement range selection switch 146, the resistors 148 to 154 corresponding to the resistor 14 of FIG. 1 and the resistors 156 to 162 corresponding to the resistor 16 are parallel to the node n32. The node n32 is formed between the resistors 148-154 and the resistors 156-162. The connection between the node n33 and the resistors 148 to 154 is configured to be a variable contact, and the connection between the node n34 and the resistors 156 to 162 is also configured to be a variable contact.

The switch 164 is connected between the node n32 and the node n34 so as to form a switch 164 between the terminals T31 and T32 for connection with the insulation resistor to be measured.

The node n33 includes an origin balance unit 166 for adjusting an origin set as a reference for the deviation measurement, and the origin balance unit 166 includes a resistor 168 and a variable resistor 170 connected in parallel thereto. And a Lindeck type high resistance variable voltage divider configured by connecting a power source 172 connected in series to the variable resistor 170.

And, the home balance unit 166 is connected to the first input side of the amplifier 178 whose amplification degree is determined according to the ratio of the value of the resistor 174 and the resistor 176, the node n34 is the first input of the amplifier 178 2 It is connected to the input side. And, the output of the amplifier 178 is configured to be input to the analog-to-digital converter 179, the analog-to-digital converter 179 is configured to convert the input into a digital signal and input to the microprocessor 182, The microprocessor 182 is configured to calculate the amount of deviation from the inputted information and input it to the display unit 180.

The node n31 is connected by a variable contact so as to variably contact between the resistors 134 to 140 configured in series for selectively determining the level of the constant voltage and supplying it to the Wystone bridge circuit.

In the above-described configuration, the configuration of the power supply 130 and the zero balance unit 166 is the same as that of the first embodiment, and the connection between the resistors 134 to 140 of the node n31 and the measurement resistance selection switch 146 and the switch ( The switching control of the 164 is configured to be performed by the microprocessor 182.

The microprocessor 182 is programmed to control the automatic measurement and to calculate the insulation resistance by receiving a signal for the detected amount of deviation from the analog-to-digital converter 179 and includes a resistor (not shown). The insulation resistance value calculated by the microprocessor 182 is digitally displayed on the display unit 180.

In addition, each part constituting the above-described second embodiment is also incorporated in a case having a shielding effect against magnetic and electric fields.

The method of measuring the insulation resistance value using the second embodiment configured as described above will be described.

The measurer connects the insulator to be measured between the terminals T31 and T32 and maintains the state in which the microprocessor 182 turns on the switch 164 configured in the probe cable when the operation is started. The microprocessor 182 then stores the digital data output values of the supply voltage value and the detected voltage shift value selected by the user through the keyboard 184 input into the first register (not shown) and the second register (not shown), respectively. Save it.

The microprocessor 182 automatically determines the appropriate measurement range by determining whether the voltage deviation stored in the second register is a suitable range for insulation resistance measurement and converting the resistance value for selecting the insulation resistance measurement range to another. At this time, the unique number of the selected resistor is stored in the third register (not shown) as a multiple of the resistance value of the resistor 144.

The voltage shift detected in the selected appropriate insulation resistance measurement range overwrites the measured value in the second resistor.

Then, the switch 164 is turned off and the voltage shift value shown at this time is stored in a fourth register (not shown).

The insulation resistance value is calculated from the data stored in the above-described registers, and this value is displayed on the display unit 180.

The calculation method of insulation resistance value is as follows.

That is, the values recorded in the first to fourth registers are referred to as 'V', 'U1', 'A', and 'U2', respectively, and the fixed resistance value of the Wheatstone bridge circuit is referred to as 'R'. Assuming that the value of the insulation resistance is called 'X', and the value of 'X' is very large compared to the 'R' value, the relationship between the values is established as in Equation 1 below.

Then, the insulation resistance value is determined as in Equation 2 below.

That is, Equation 2 described above is programmed in the microprocessor 182 and the insulation resistance value is calculated as a signal input from the analog / digital converter 179 and output to the display unit 180 for display.

By measuring the insulation resistance of the insulator by using the first embodiment and the second embodiment described above, a reliable result can be obtained without the influence of disturbance during the measurement.

And since the insulator itself does not form a Wheatstone bridge circuit, measurement can be made by simple terminal connection without shielding the insulator.

Therefore, it is not necessary to shield the insulator and the insulation resistance value is measured by simply connecting the insulator to the device, so that workability is improved and reliable measurement results can be obtained.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (11)

An apparatus for measuring insulation resistance of an insulator in which a constant voltage is applied between a pair of symmetrical first and second nodes of a Wheatstone bridge circuit, and a voltmeter is configured between another pair of symmetrical third and fourth nodes. All parts except the insulator to be measured are built in the electromagnetic shielding case, and a probe terminal for connecting the insulator in parallel to the load between the second node and the fourth node is provided outside of the electromagnetic shielding case. Insulation resistance measuring device of the insulator, characterized in that the configuration is derived for connection with. In the insulation resistance measuring apparatus of the insulator, A power supply unit for variably applying a constant voltage; A measurement range selection switch constituting the first and second loads connected in parallel to the power supply, display means connected in parallel to amplify a current to display a voltage, and connected in series to the display means to flow into the display means. A Wheatstone bridge circuit including an origin balance section for adjusting the zero point of the display means by adjusting current; And Switching means for electrically turning on and off a path in which two terminals are drawn in parallel to the first load; Insulation resistance measuring apparatus of the insulator, characterized in that it comprises a. The method of claim 2, The power supply unit is configured such that a power supply, a switch, and a plurality of resistors form a closed loop, and a node between two other loads connected in parallel to the measurement range selector switch is connected to a variable contact between the resistors. Insulation resistance measuring apparatus of the said insulator. The method of claim 2, The measurement range selection switch is configured such that the first load and the second load are each configured in parallel resistors having different values, and wherein any one of the resistors is selected as a resistor representing the first load and the second load, respectively. Insulation resistance measuring apparatus of the insulator, characterized in that. The method of claim 2, And said display means comprises an amplifier and a voltmeter receiving the output of said amplifier. The method of claim 2, The home balance unit is an insulator insulation resistance measuring device, characterized in that composed of a lin deck type high resistance variable divider. The method according to any one of claims 2 to 6, Each of the portions is embedded in the electromagnetic shield case and configured to connect the two terminals connected to the switching means to the insulator of the insulator, characterized in that the insulator. In the insulation resistance measuring apparatus of the insulator, A power supply for supplying a variable voltage; A measurement range selection switch for variably setting resistance values of the first and second loads, including first and second loads connected in parallel to the power supply through a first node, and amplifying current connected in parallel thereto A Wheatstone bridge circuit comprising display means for digitally displaying the voltage and an origin balance portion connected in series with the display means to adjust a zero point of the display means by adjusting a current flowing through the display means; Switching means for electrically turning on and off a path in which two terminals are drawn in parallel to the first load; And Control the contact connection state of the power supply and the measurement range selection switch, control the switching state of the switching means, calculate the insulation resistance value measured by the signal interface with the display means to control the display means Control means; Insulation resistance measuring apparatus of the insulator, characterized in that it comprises a. The method of claim 8, Insulation resistance measuring apparatus of the insulator, characterized in that the display means comprises a digital display device. The method of claim 8, The control means is built in the first to fourth registers, The digital data output values of the supply voltage value and the detected voltage shift value selected for measurement are stored in the first register and the second register, respectively, and the resistance value of the insulation resistance selection switch is determined by referring to the voltage shift value. 3. The insulation resistance measuring apparatus for the insulator according to claim 1, wherein the voltage resistance value stored at the third register is stored in the fourth register and the insulation resistance value is obtained by the following equation. (V, U1, A and U2 are the values recorded in the first to fourth registers, R is the fixed resistance value of the Wheatstone bridge circuit, X is the value of the insulation resistance to be measured, and the value of X is higher than the R value). Very big) The method according to any one of claims 8 to 10, Each of the portions is embedded in the electromagnetic shield case and configured to connect the two terminals connected to the switching means to the insulator of the insulator, characterized in that the insulator.