An online sheath insulation performance tester

Abstract

The invention discloses an online sheath insulation performance detector, comprising: a programmable controller, a display, an alarm; a detection rod, a step-down resistor, a voltage transformer, a first amplifying unit, a second amplifying unit, and an A / D conversion unit; the detection rod inputs the detected voltage value to the input end of the voltage transformer through the step-down resistor, and transmits it to the first amplifying unit through the output end of the voltage transformer, the amplified voltage value is amplified by the second amplifying unit, and then transmitted to the A / D conversion unit for analog-to-digital conversion, the converted digital signal is transmitted to the programmable controller for analysis and processing, and displayed by the display, and at the same time, it is determined whether the alarm is issued by the alarm according to the analysis data. The invention is easy to carry and use, can clearly display the voltage value of leakage, is convenient for maintenance personnel to make quantitative analysis, and will automatically alarm when the leakage voltage value exceeds the set value, thereby improving the maintenance quality and efficiency and avoiding the occurrence of safety accidents.

Description

Technical Field

[0001] The invention belongs to the technical field of power transmission and transformation, and in particular relates to an online sheath insulation performance detector. Background Art

[0002] In power transmission, substation is an indispensable and important link. Usually, substations are built on the ground floor of houses. Affected by the humid environment and the harassment of insects, short circuits often occur between the phases of the low-voltage side of the main transformer, which then cause the main transformer switch to trip. The main reason is that the insulation performance of the insulation sheath at the outlet end has deteriorated due to factors such as heat shrinkage, aging, and dirt. This degradation of insulation performance may even cause discharge between the line end and the ground in a severely humid environment, causing serious accidents. In order to check the insulation performance of the wire end at any time, ordinary testers are currently commonly used. This tester can only qualitatively detect whether the wire end or equipment is energized, and cannot quantitatively analyze the value of the leakage of the insulation sheath or equipment, and cannot make a scientific judgment on its insulation performance. The above situation is not conducive to scientific maintenance work, and it is difficult to avoid accidents. Summary of the invention

[0003] In order to solve the above-mentioned problems, the present invention proposes an online sheath insulation performance tester, which is easy to carry and use, and can clearly display the leakage voltage value, which is convenient for maintenance personnel to make quantitative analysis. When the leakage voltage value exceeds the set value, it will automatically alarm, thereby improving the maintenance quality and efficiency and avoiding the occurrence of safety accidents.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions, including:

[0005] Programmable controller, display, alarm; also includes detection rod, voltage-dropping resistor, voltage transformer, first amplification unit, second amplification unit, A / D conversion unit;

[0006] The detection rod inputs the detected voltage value to the input end of the voltage transformer through the voltage-dropping resistor, and transmits it to the first amplification unit through the output end of the voltage transformer. The amplified voltage value is amplified by the second amplification unit, and then transmitted to the A / D conversion unit for analog-to-digital conversion. The converted digital signal is transmitted to the programmable controller for analysis and processing, and displayed on the display. At the same time, it is determined whether the alarm is triggered by the alarm according to the analysis data.

[0007] Furthermore, the first amplification unit includes an instrument amplifier and an operational amplifier; the input pin 2 of the instrument amplifier is connected to a first current limiting resistor and a first bypass capacitor, the other end of the first current limiting resistor is connected to the output end of the voltage transformer and is grounded through a first bias resistor; the input pin 3 of the instrument amplifier is connected to a second current limiting resistor and a second bypass capacitor, the other end of the second current limiting resistor is connected between a first voltage dividing resistor and a second voltage dividing resistor, the other end of the first voltage dividing resistor is connected to the output end of the voltage transformer, and the other end of the second voltage dividing resistor is grounded; a gain control resistor is connected between pins 1 and 8 of the instrument amplifier; pin 6 of the instrument amplifier is connected to a first integral resistor, the other end of the first integral resistor is connected to the first integral capacitor and the second integral resistor, the other end of the second integral resistor is connected to the second integral capacitor and the third integral resistor, and the third integral resistor is grounded through the third integral capacitor; pin 5 of the instrument amplifier is connected to pins 6 and 7 of the operational amplifier.

[0008] Furthermore, the input pin 3 of the operational amplifier is connected to the third bypass capacitor and is connected between the third integral resistor and the third integral capacitor through the third current limiting resistor to receive the output from the instrument amplifier; the output pin 1 of the operational amplifier is connected to the input of the second amplification unit and is grounded through the third and fourth voltage-dividing resistors connected in series with each other; the pin 2 of the operational amplifier is connected between the third and fourth voltage-dividing resistors, and the two ends of the third voltage-dividing resistor are connected in parallel to the first coupling capacitor; the pin 5 of the operational amplifier is connected to the pin 1 of the first high-precision voltage regulator, the pins 2 and 3 of the first high-precision voltage regulator are grounded and connected to the pin 1 of the second high-precision voltage regulator, the pins 2 and 3 of the second high-precision voltage regulator are connected to the negative power supply through the fifth voltage-dividing resistor, the pin 1 of the first high-precision voltage regulator is connected to the positive power supply through the sixth voltage-dividing resistor, and a seventh voltage-dividing resistor is also connected between the pin 1 of the first high-precision voltage regulator and the pin 2 of the second high-precision voltage regulator.

[0009] Furthermore, the second amplification unit includes a dual operational amplifier, an input pin 2 of the dual operational amplifier is connected between the eighth and ninth voltage-dividing resistors through a fourth current-limiting resistor, and the other end of the eighth voltage-dividing resistor is connected to the output pin 1 of the operational amplifier; the input pin 3 of the dual operational amplifier is grounded through a second bias resistor; the input pin 2 of the dual operational amplifier is connected to the input pin 6 of the dual operational amplifier through a fifth current-limiting resistor in one way, and is connected to the input pin 6 of the dual operational amplifier through two reversely connected diodes in series in another way; the output pin 1 of the dual operational amplifier is connected between the two diodes; the input pin 6 of the dual operational amplifier is connected between the eighth and ninth voltage-dividing resistors through the sixth and seventh current-limiting resistors connected in series with each other; the input pin 5 of the dual operational amplifier is grounded through a third bias resistor; the output pin 7 of the dual operational amplifier is connected to the input end of the A / D conversion unit and is connected to the input pin 6 of the dual operational amplifier through a feedback resistor.

[0010] Furthermore, the A / D conversion unit includes an A / D converter and a serial counter; pins 10 and 11 of the serial counter are respectively connected to the two ends of a crystal oscillator, one end of the crystal oscillator is grounded through a first correction capacitor, and the other end of the crystal oscillator is grounded through a second correction capacitor; the output pin 5 of the serial counter is connected to the input pin 22 of the A / D converter to transmit the clock signal to the A / D converter; the input pin 10 of the A / D converter is connected between the tenth and eleventh voltage-dividing resistors connected in series and grounded through a fourth bypass capacitor, and the other end of the tenth voltage-dividing resistor is connected to the output pin 7 of the dual operational amplifier to receive the output signal from the dual operational amplifier; a second coupling capacitor is connected between pins 7 and 8 of the A / D converter; pins 3 and 9 of the A / D converter are both grounded; pin 2 of the A / D converter is connected between the thirteenth and fourteenth voltage-dividing resistors connected in series. The pin 1 of the third high-precision voltage regulator is connected between the twelfth voltage-dividing resistor and the thirteenth voltage-dividing resistor, and the pin 2 and pin 3 of the third high-precision voltage regulator are both grounded and connected to one end of the fourteenth voltage-dividing resistor; the pin 8 of the voltage converter is connected to the power supply and the filter capacitor; the pin 3 of the voltage converter is grounded, and an electrolytic capacitor is connected between the pin 2 and the pin 4; the pin 5 of the voltage converter is connected to the pin 1 of the A / D converter and connected to two filter capacitors; the pin 4 of the A / D converter is connected to the fourth integrating resistor, and the other end of the fourth integrating resistor is connected to the fourth and fifth integrating capacitors connected in series, and the other end of the fifth integrating capacitor is connected to the pin 5 of the A / D converter; the pin 6 of the A / D converter is connected between the fourth and fifth integrating capacitors through the fifth integrating resistor; and the pin 11 of the A / D converter is connected to the power supply.

[0011] Furthermore, the instrument amplifier is an AD620 amplifier; the operational amplifier is an LM2904 amplifier; the dual operational amplifier is an LM358 amplifier; the A / D converter is an ICL7135 analog-to-digital converter; the serial counter is a CD4060 counter; the first high-precision voltage regulator, the second high-precision voltage regulator, and the third high-precision voltage regulator are all TL431 high-precision voltage regulators; and the voltage converter is an ICL7660 voltage converter.

[0012] Furthermore, the programmable controller is a STC89C52 single-chip microcomputer, and pins 25, 20, 19, 18, 17, 12, 13, 14, 15, 16, and 23 of the A / D converter ICL7135 are connected one-to-one with pins P1.0, P1.1, P1.2, P1.3, P1.4, P1.5, P1.6, P1.7, P3.3, P3.2, and P3.5 of the STC89C52 single-chip microcomputer.

[0013] Furthermore, the ratio of the input voltage to the output voltage of the voltage transformer is 1:1.

[0014] Furthermore, the display is a liquid crystal display, and the alarm is an audible and visual alarm.

[0015] Furthermore, the programmable controller, display, alarm, detection rod, voltage-dropping resistor, voltage transformer, first amplifying unit, second amplifying unit, and A / D conversion unit are all installed in the instrument box.

[0016] The invention discloses an online sheath insulation performance tester, which is easy to carry and use, can clearly display the voltage value of leakage, and is convenient for maintenance personnel to make quantitative analysis. When the leakage voltage value exceeds a set value, an alarm will be automatically given, thereby improving maintenance quality and efficiency and avoiding the occurrence of safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the overall principle diagram of the present invention.

[0018] Figure 2 This is the circuit diagram of the first amplifying unit of the present invention.

[0019] Figure 3 This is the circuit diagram of the second amplifying unit of the present invention.

[0020] Figure 4 It is the circuit diagram of the A / D conversion unit of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings to facilitate a clearer understanding for those skilled in the art.

[0022] like Figure 1 As shown, the present invention includes a programmable controller, a display, and an alarm; it also includes a detection rod, a voltage-dropping resistor, a voltage transformer, a first amplifying unit, a second amplifying unit, and an A / D conversion unit;

[0023] The detection rod inputs the detected voltage value to the input end of the voltage transformer through the voltage-dropping resistor, and transmits it to the first amplification unit through the output end of the voltage transformer. The amplified voltage value is amplified by the second amplification unit, and then transmitted to the A / D conversion unit for analog-to-digital conversion. The converted digital signal is transmitted to the programmable controller for analysis and processing, and displayed on the display. At the same time, it is determined whether the alarm is triggered by the alarm according to the analysis data.

[0024] Further, such as Figure 2As shown, the first amplification unit includes an instrument amplifier 1 and an operational amplifier 2; the input pin 2 of the instrument amplifier is connected to a first current limiting resistor R3 and a first bypass capacitor C3, the other end of the first current limiting resistor is connected to the output end of the voltage transformer and is grounded through a first bias resistor R5; the input pin 3 of the instrument amplifier is connected to a second current limiting resistor R4 and a second bypass capacitor C2, the other end of the second current limiting resistor is connected between a first voltage dividing resistor R1 and a second voltage dividing resistor R2, the other end of the first voltage dividing resistor is connected to the output end of the voltage transformer to receive the output voltage from the voltage transformer, and the other end of the second voltage dividing resistor is grounded; the pin 1 of the instrument amplifier is connected to the A gain control resistor R6 is connected between pin 8; pin 6 of the instrument amplifier is connected to a first integrating resistor R7, the other end of the first integrating resistor is connected to a first integrating capacitor C8 and a second integrating resistor R8, the other end of the second integrating resistor is connected to a second integrating capacitor C9 and a third integrating resistor R9, the third integrating resistor is grounded via a third integrating capacitor C1, and the output waveform of the instrument amplifier is shaped through three-stage integration; pin 7 of the instrument amplifier is connected to a positive power supply +15V and two filter capacitors C6 and C7; pin 4 of the instrument amplifier is connected to a negative power supply -15V and two filter capacitors C4 and C5; pin 5 of the instrument amplifier is connected to pins 6 and 7 of the operational amplifier.

[0025] Further, such as Figure 2 As shown, the input pin 3 of the operational amplifier 2 is connected to the third bypass capacitor C11 and is connected between the third integral resistor and the third integral capacitor through the third current limiting resistor R12 to receive the output voltage from the instrument amplifier; the output pin 1 of the operational amplifier is connected to the input of the second amplification unit and is grounded through the third and fourth voltage-dividing resistors R10 and R11 connected in series with each other; the pin 2 of the operational amplifier is connected between the third and fourth voltage-dividing resistors, and the two ends of the third voltage-dividing resistor are connected in parallel to the first coupling capacitor C10; the pin 5 of the operational amplifier is connected to the pin 1 of the first high-precision regulator U1 to obtain a high-precision reference voltage Pins 2 and 3 of the first high-precision voltage regulator are grounded and connected to pin 1 of the second high-precision voltage regulator U2, pins 2 and 3 of the second high-precision voltage regulator are connected to the negative power supply -15V through the fifth voltage-dividing resistor R15, pin 1 of the first high-precision voltage regulator is connected to the positive power supply +15V through the sixth voltage-dividing resistor R13, and a seventh voltage-dividing resistor R14 is also connected between pin 1 of the first high-precision voltage regulator and pin 2 of the second high-precision voltage regulator; pin 8 of the operational amplifier is connected to the positive power supply +15V and two filter capacitors C14 and C15; pin 4 of the operational amplifier is connected to the negative power supply -15V and two filter capacitors C12 and C13.

[0026] Further, such as Figure 3As shown, the second amplification unit includes a dual operational amplifier 3, the input pin 2 of the dual operational amplifier is connected between the eighth and ninth voltage-dividing resistors R16 and R16' through a fourth current-limiting resistor R17, and the other end of the eighth voltage-dividing resistor is connected to the output pin 1 of the operational amplifier, so as to obtain the output of the operational amplifier; the input pin 3 of the dual operational amplifier is grounded through a second bias resistor R18; the input pin 2 of the dual operational amplifier is connected to the input pin 6 of the dual operational amplifier through a fifth current-limiting resistor R20 in one way, and is connected to the input pin 6 of the dual operational amplifier in the other way through two reversely connected diodes D1 and D2; the dual operational amplifier The output pin 1 of the dual operational amplifier is connected between the two diodes; the input pin 6 of the dual operational amplifier is connected between the eighth and ninth voltage-dividing resistors through the sixth and seventh current-limiting resistors R21 and R19 connected in series with each other; the input pin 5 of the dual operational amplifier is grounded through the third bias resistor R22; the output pin 7 of the dual operational amplifier is connected to the input end of the A / D conversion unit and is connected to the input pin 6 of the dual operational amplifier through the feedback resistor R23; the pin 8 of the dual operational amplifier is connected to the positive power supply +15V and two filter capacitors C16 and C17; the pin 4 of the dual operational amplifier is connected to the negative power supply -15V and two filter capacitors C18 and C19.

[0027] Further, such as Figure 4As shown, the A / D conversion unit includes an A / D converter 4 and a serial counter 5; pins 10 and 11 of the serial counter are respectively connected to the two ends of the crystal oscillator Y1, one end of the crystal oscillator is grounded through a first correction capacitor C32, and the other end of the crystal oscillator is grounded through a second correction capacitor 33; pin 16 of the serial counter is connected to a power supply +5V and two filter capacitors C31 and C34; the output pin 5 of the serial counter is connected to the input pin 22 of the A / D converter to transmit the clock signal to the A / D converter; the input pin 10 of the A / D converter is connected between the tenth and eleventh voltage-dividing resistors R24 and R25 connected in series and grounded through a fourth bypass capacitor C24, and the other end of the tenth voltage-dividing resistor is connected to the output pin 7 of the dual operational amplifier to receive the analog signal output from the dual operational amplifier; a second coupling capacitor C30 is connected between pins 7 and 8 of the A / D converter; pins 3 and 9 of the A / D converter are both grounded; pin 2 of the A / D converter is connected to the thirteenth and fourteenth voltage-dividing resistors R26 and R30 connected in series. to obtain a high-precision reference voltage, the other end of the thirteenth voltage-dividing resistor is connected to the power supply +5V through the twelfth voltage-dividing resistor R27, the pin 1 of the third high-precision voltage regulator U3 is connected between the twelfth voltage-dividing resistor and the thirteenth voltage-dividing resistor, the pins 2 and 3 of the third high-precision voltage regulator are both grounded and connected to one end of the fourteenth voltage-dividing resistor; the pin 8 of the voltage converter 6 is connected to the power supply +5V and the filter capacitor C25; the pin 3 of the voltage converter is grounded, and the electrolytic capacitor C35 is connected between the pins 2 and 4; the pin 5 of the voltage converter is connected to the pin 1 of the A / D converter and is connected to two filter capacitors C28 and C29 to transmit the negative voltage to the A / D converter; the pin 4 of the A / D converter is connected to the fourth integral resistor R29, the other end of the fourth integral resistor is connected to the fourth and fifth integral capacitors C26 and C27 connected in series with each other, and the other end of the fifth integral capacitor is connected to the pin 5 of the A / D converter; the pin 6 of the A / D converter is connected between the fourth and fifth integral capacitors through the fifth integral resistor; the pin 11 of the A / D converter is connected to the power supply +5V.

[0028] Furthermore, the instrument amplifier 1 is an AD620 amplifier; the operational amplifier 2 is an LM2904 amplifier; the dual operational amplifier 3 is an LM358 amplifier; the A / D converter 4 is an ICL7135 analog-to-digital converter; the serial counter 5 is a CD4060 counter; the first high-precision voltage regulator U1, the second high-precision voltage regulator U2, and the third high-precision voltage regulator U3 are all TL431 high-precision voltage regulators; and the voltage converter 6 is an ICL7660 voltage converter.

[0029] Furthermore, the programmable controller is a STC89C52 single-chip microcomputer, and pins 25, 20, 19, 18, 17, 12, 13, 14, 15, 16, and 23 of the A / D converter ICL7135 are connected one-to-one with pins P1.0, P1.1, P1.2, P1.3, P1.4, P1.5, P1.6, P1.7, P3.3, P3.2, and P3.5 of the STC89C52 single-chip microcomputer.

[0030] Furthermore, the ratio of the input voltage to the output voltage of the voltage transformer is 1:1.

[0031] Furthermore, the display is a liquid crystal display, and the alarm is an audible and visual alarm.

[0032] Furthermore, the programmable controller, display, alarm, detection rod, voltage-dropping resistor, voltage transformer, first amplifying unit, second amplifying unit, and A / D conversion unit are all installed in the instrument box.

[0033] The present invention is not limited to testing the in-line sheath, but can be widely applied to testing the insulation performance of other electrical equipment.

[0034] The invention discloses an online sheath insulation performance tester, which is easy to carry and use, can clearly display the voltage value of leakage, and is convenient for maintenance personnel to make quantitative analysis. When the leakage voltage value exceeds a set value, an alarm will be automatically given, thereby improving maintenance quality and efficiency and avoiding the occurrence of safety accidents.

[0035] The present invention is not limited to the above-mentioned specific implementation modes, and various improvements made by those skilled in the art to the technical solutions according to the concept of the present invention shall all fall within the scope of protection claimed by the present invention.

Claims

1. An online sheath insulation performance tester, comprising a programmable controller, a display, and an alarm; characterized in that: It also includes a detection rod, a voltage-dropping resistor, a voltage transformer, a first amplifying unit, a second amplifying unit, and an A / D conversion unit; The detection rod inputs the detected voltage value to the input end of the voltage transformer through the voltage-dropping resistor, and transmits it to the first amplification unit through the output end of the voltage transformer. The amplified voltage value is amplified by the second amplification unit, and then transmitted to the A / D conversion unit for analog-to-digital conversion. The converted digital signal is transmitted to the programmable controller for analysis and processing, and displayed on the display. At the same time, it is determined whether the alarm is triggered by the alarm according to the analysis data. The first amplification unit comprises an instrument amplifier (1) and an operational amplifier (2); an input pin 2 of the instrument amplifier is connected to a first current limiting resistor (R3) and a first bypass capacitor (C3); the other end of the first current limiting resistor is connected to the output end of a voltage transformer and is grounded via a first bias resistor (R5); an input pin 3 of the instrument amplifier is connected to a second current limiting resistor (R4) and a second bypass capacitor (C2); the other end of the second current limiting resistor is connected between a first voltage dividing resistor (R1) and a second voltage dividing resistor (R2); the other end of the first voltage dividing resistor is connected to the output end of the voltage transformer, and the other end of the second voltage dividing resistor is grounded; pin 1 of the instrument amplifier is connected to pin 8 is connected to a gain control resistor (R6); pin 6 of the instrument amplifier is connected to a first integral resistor (R7), the other end of the first integral resistor is connected to a first integral capacitor (C8) and a second integral resistor (R8), the other end of the second integral resistor is connected to a second integral capacitor (C9) and a third integral resistor (R9), and the third integral resistor is grounded through a third integral capacitor (C1); pin 7 of the instrument amplifier is connected to a positive power supply (+15V) and two filter capacitors (C6, C7); pin 4 of the instrument amplifier is connected to a negative power supply (-15V) and two filter capacitors (C4, C5); and pin 5 of the instrument amplifier is connected to pins 6 and 7 of the operational amplifier.

2. The online sheath insulation performance tester according to claim 1, characterized in that: The input pin 3 of the operational amplifier (2) is connected to the third bypass capacitor (C11) and is connected between the third integral resistor and the third integral capacitor through a third current limiting resistor (R12) to receive the output from the instrument amplifier; the output pin 1 of the operational amplifier is connected to the input of the second amplification unit and is grounded through third and fourth voltage-dividing resistors (R10, R11) connected in series with each other; the pin 2 of the operational amplifier is connected between the third and fourth voltage-dividing resistors, and the two ends of the third voltage-dividing resistor are connected in parallel to the first coupling capacitor (C10); the pin 5 of the operational amplifier is connected to the pin 1 of the first high-precision voltage regulator (U1), and the pin 2 of the first high-precision voltage regulator is connected to the first high-precision voltage regulator (U1). , 3 are grounded and connected to pin 1 of the second high-precision voltage regulator (U2), pins 2 and 3 of the second high-precision voltage regulator are connected to a negative power supply (-15V) through a fifth voltage-dividing resistor (R15), pin 1 of the first high-precision voltage regulator is connected to a positive power supply (+15V) through a sixth voltage-dividing resistor (R13), and a seventh voltage-dividing resistor (R14) is also connected between pin 1 of the first high-precision voltage regulator and pin 2 of the second high-precision voltage regulator; pin 8 of the operational amplifier is connected to a positive power supply (+15V) and two filter capacitors (C14, C15); pin 4 of the operational amplifier is connected to a negative power supply (-15V) and two filter capacitors (C12, C13).

3. The online sheath insulation performance tester according to claim 2 is characterized in that: The second amplifying unit comprises a dual operational amplifier (3), wherein an input pin 2 of the dual operational amplifier is connected between an eighth and a ninth voltage-dividing resistor (R16, R16') via a fourth current-limiting resistor (R17), and the other end of the eighth voltage-dividing resistor is connected to an output pin 1 of the operational amplifier; an input pin 3 of the dual operational amplifier is grounded via a second biasing resistor (R18); one path of the input pin 2 of the dual operational amplifier is connected to an input pin 6 of the dual operational amplifier via a fifth current-limiting resistor (R20), and the other path is connected to the input pin 6 of the dual operational amplifier via two reversely connected diodes (D1, D2); the output pin 1 of the dual operational amplifier is connected to the two The invention relates to a dual operational amplifier, wherein the input pin 6 of the dual operational amplifier is connected between the eighth and ninth voltage-dividing resistors through the sixth and seventh current-limiting resistors (R21, R19) connected in series with each other; the input pin 5 of the dual operational amplifier is grounded through the third bias resistor (R22); the output pin 7 of the dual operational amplifier is connected to the input end of the A / D conversion unit and is connected to the input pin 6 of the dual operational amplifier through the feedback resistor (R23); the pin 8 of the dual operational amplifier is connected to the positive power supply (+15V) and two filter capacitors (C16, C17); the pin 4 of the dual operational amplifier is connected to the negative power supply (-15V) and two filter capacitors (C18, C19).

4. The on-line sheath insulation performance tester according to claim 3 is characterized in that: The A / D conversion unit comprises an A / D converter (4) and a serial counter (5); pins 10 and 11 of the serial counter are respectively connected to two ends of a crystal oscillator (Y1), one end of the crystal oscillator is grounded through a first correction capacitor (C32), and the other end of the crystal oscillator is grounded through a second correction capacitor (33); pin 16 of the serial counter is connected to a power supply (+5V) and two filter capacitors (C31, C34); output pin 5 of the serial counter is connected to input pin 22 of the A / D converter to transmit a clock signal to the A / D converter; input pin 10 of the A / D converter is connected between tenth and eleventh voltage-dividing resistors (R24, R25) connected in series and grounded through a fourth bypass capacitor (C24), and the other end of the tenth voltage-dividing resistor is connected to output pin 7 of the dual operational amplifier to receive the output signal from the dual operational amplifier; a second coupling capacitor (C30) is connected between pins 7 and 8 of the A / D converter; pins 3 and 9 of the A / D converter are both grounded; pin 2 of the A / D converter is connected between tenth and fourteenth voltage-dividing resistors connected in series. The pin 1 of the third high-precision voltage regulator (U3) is connected between the twelfth voltage-dividing resistor (R26, R30), the other end of the thirteenth voltage-dividing resistor is connected to the power supply (+5V) through the twelfth voltage-dividing resistor (R27), the pin 1 of the third high-precision voltage regulator (U3) is connected between the twelfth voltage-dividing resistor and the thirteenth voltage-dividing resistor, the pins 2 and 3 of the third high-precision voltage regulator are both grounded and connected to one end of the fourteenth voltage-dividing resistor; the pin 8 of the voltage converter (6) is connected to the power supply (+5V) and the filter capacitor (C25); the pin 3 of the voltage converter is grounded, and the electrolytic capacitor (C3) is connected between the pins 2 and 4. 5); Pin 5 of the voltage converter is connected to Pin 1 of the A / D converter and is connected to two filter capacitors (C28, C29); Pin 4 of the A / D converter is connected to the fourth integrating resistor (R29), the other end of the fourth integrating resistor is connected to the fourth and fifth integrating capacitors (C26, C27) connected in series, and the other end of the fifth integrating capacitor is connected to Pin 5 of the A / D converter; Pin 6 of the A / D converter is connected between the fourth and fifth integrating capacitors through the fifth integrating resistor; Pin 11 of the A / D converter is connected to the power supply (+5V).

5. The on-line sheath insulation performance tester according to claim 4, characterized in that: The instrument amplifier (1) is an AD620 amplifier; the operational amplifier (2) is an LM2904 amplifier; the dual operational amplifier (3) is an LM358 amplifier; the A / D converter (4) is an ICL7135 analog-to-digital converter; the serial counter (5) is a CD4060 counter; the first high-precision voltage regulator (U1), the second high-precision voltage regulator (U2), and the third high-precision voltage regulator (U3) are all TL431 high-precision voltage regulators; and the voltage converter (6) is an ICL7660 voltage converter.

6. The on-line sheath insulation performance tester according to claim 5, characterized in that: The programmable controller is a STC89C52 single-chip microcomputer, and the pins 25, 20, 19, 18, 17, 12, 13, 14, 15, 16, and 23 of the A / D converter ICL7135 are connected one-to-one with the pins P1.0, P1.1, P1.2, P1.3, P1.4, P1.5, P1.6, P1.7, P3.3, P3.2, and P3.5 of the STC89C52 single-chip microcomputer.

7. The on-line sheath insulation performance tester according to claim 1, characterized in that: The ratio between the input voltage and the output voltage of the voltage transformer is 1:

1.

8. The on-line sheath insulation performance tester according to claim 1, characterized in that: The display is a liquid crystal display, and the alarm is an audible and visual alarm.

9. The on-line sheath insulation performance tester according to claim 1, characterized in that: The programmable controller, display, alarm, detection rod, voltage-dropping resistor, voltage transformer, first amplifying unit, second amplifying unit and A / D conversion unit are all installed in the instrument box.

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