CN2729735Y

CN2729735Y - 0.1 H2 electronic ultra-low frequency AC voltage test apparatus

Info

Publication number: CN2729735Y
Application number: CN 200420018640
Authority: CN
Inventors: 段天明; 魏新劳; 王永红; 隋文波; 孙显增; 刘立冰
Original assignee: Harbin Kai Xun Electronics Co Ltd
Current assignee: Harbin Kai Xun Electronics Co Ltd
Priority date: 2004-03-23
Filing date: 2004-03-23
Publication date: 2005-09-28
Anticipated expiration: 2014-03-23

Abstract

The utility model relates to a 0.1 Hz electronic ultra-low frequency AC voltage test apparatus used for voltage test of plastic cable, comprising a 0.1Hz electron low-frequency ac voltage generator and a dielectric loss tangent measurement mechanism under intrasonic alternating current voltage. The generator comprises a modulated wave generator (1), a booster transformer (2), a polarity-reversing switch (3), a controllable discharge resistor network (4), a filtering capacitance (5), a filter resistance (6), and a resistance-type potential divider (7). The dielectric loss tangent measurement mechanism comprises an intrasonic voltage generator, a resistance-type potential divider, a signal extraction capacitance, an amplifying circuit, a filter circuit, an A/D converter, a monolithic computer and a liquid crystal display. The utility model can carry out breakdown test to cable insulation, and can measure dielectric loss tangent.

Description

0.1Hz electronic type ultralow frequency alternating voltage test unit

The utility model relates to the power test device, relates in particular to a kind of 0.1Hz electronic type ultralow frequency alternating voltage test unit.

Current DC voltage test, cause damage not only can for the insulation of intact cable, and the cable insulation defective that DC voltage is tested some type is (as the cross-linked polyethylene insulated cable) that can not find, so, for using cross-linked polyethylene insulated cable more and more widely, can not test it with traditional DC voltage more.If do experiment and use power-frequency voltage instead, though the problem that DC voltage of no use test is occurred, owing to needing very big test capacity to make on-the-spot alternating voltage test become very difficult.So, very be necessary to seek a kind of new test method, make it to overcome the shortcoming of DC voltage test, can avoid the required high capacity of power-frequency voltage test again.Through great deal of experimental, 0.1Hz electronic type ultralow frequency alternating voltage test unit meets this requirement.

Research to 0.1Hz ultralow frequency ac voltage power supply was mainly carried out at large-size machine in the past, the 0.1Hz electronic type ultralow frequency alternating voltage test unit of being developed, owing to be subjected to the restriction of technical conditions, not only volume is big but also output waveform is irregular.At present, because the application need on the power cable, studying the work of novel 0.1Hz electronic type ultralow frequency alternating voltage test unit has carried out again, what this had wherein produced model machine is a kind of 0.1Hz ultralow frequency ac high voltage source of XJTU School of Electrical Engineering and the joint study of Shanghai unit, but this device is because too heavy, and reality is not applied.

The purpose of this utility model provides a kind of 0.1Hz electronic type ultralow frequency alternating voltage test unit.It not only can carry out on-the-spot withstand voltage test to cable insulation, and can carry out dielectric loss tangent and measure.

The technical scheme that ultralow frequency alternating-voltage generator of the present utility model is adopted is: the modulated wave voltage that utilizes 50 hertz of frequencies of power electronic devices generation, amplitude to change according to 0.1Hz, after the process step-up transformer boosts, utilizing inversion frequency is that 5 seconds/time polarity reversing switch carries out the positive-negative polarity conversion, after adopting filter capacitor and the detection of controlled discharge resistance again, offer test specimen, on test specimen, obtain 0.1Hz ultralow frequency alternating voltage.The generation of modulated wave voltage, polarity reversing switch and the conversion of controlled discharge resistance are by realizing for the control core circuit with the single-chip microcomputer.

The technical scheme that dielectric loss tangent measurement mechanism of the present utility model adopts is: utilize the resitstance voltage divider dividing potential drop to obtain voltage signal, obtain current signal by the big electric capacity of connecting with test specimen, re-using two amplifiers amplifies respectively two signals, then respectively by after the low-pass filter Filtering Processing, giving two carries out analog to digital conversion by monolithic processor controlled analog to digital converter and becomes digital quantity, and store in the data-carrier store, last single-chip microcomputer utilizes quasi-synchronous algorithm to calculate the dielectric loss tangent value.

The utility model compared with prior art has following advantage: traditional DC voltage withstand test not only can not be found the insulation defect of cable effectively, and can cause major injury to the good insulation of cable.The ultralow frequency test method is an ac test, not only can reduce the harm of DC voltage withstand test to cable itself, make cable that be arranged longer serviceable life, and can find with DC voltage withstand test the insulation defect that can not find, thereby improved the confidence level that withstand voltage test is judged the cable insulation defective, reduce the generation of the insulation fault that causes because of erroneous judgement, effectively improved the Operation of Electric Systems reliability.

The utility model can not produce residual charge in insulation, cause the electricity tree, and further develops the water tree that forms the ultimate failure that causes insulating.

The utility model is equipped with the dielectric loss instrument, and dielectric loss tg δ can be used to measure the insulation status of cable (other capacitive load), follows the tracks of the aging state of cable and provides data for laying of new cable.The variation that dielectric loss detects is indicating the aging of insulation, like this with regard to serviceable life of deducibility cable.

The utility model is described in further detail below in conjunction with accompanying drawing and example:

Fig. 1 is the utility model Ultra-low Frenquency Voltage generator main circuit partial circuit schematic diagram;

Fig. 2 is the utility model Ultra-low Frenquency Voltage generator control section circuit theory diagrams;

Fig. 3 is a dielectric loss tangent measure portion schematic diagram under the Ultra-low Frenquency Voltage.

As shown in Figure 1, Ultra-low Frenquency Voltage generator main circuit comprises a modulated wave generator (1) in the utility model, it is exported to step-up transformer (2) and boosts, pass through again by R7, K1, K2, the polarity reversing switch (3) that D1 and D2 form converts the voltage wave of positive-negative polarity to, process is by R1, R2, R3, R4, K1, K2, controlled discharge resistor network (4) and filter capacitor C1 that K3 and K4 form, C2 (5) detection, obtain the ultralow frequency sine voltage, again through filter resistance R5, behind the R6 (6), offer test specimen capacitor C x (8), on test specimen electric capacity, obtain 0.1Hz Ultra-low Frenquency Voltage waveform.The resitstance voltage divider of being made up of R8 and R9 (7) is used to measure the voltage swing on the test specimen.

As shown in Figure 2, ultralow frequency generator main circuit control section is made up of the circuit that with single-chip microcomputer (1) is core, by the control silicon-controlled device, control modulated wave generator (2) produces modulated wave voltage, control polarity reversing switch (5) changed a polarity in per 5 seconds, and control discharge switch (6) discharges by the regular hour in wave period.Input equipment (3) comprises that the working time is set and duty is determined button, and output device (4) comprises that working time and operating voltage show.

As shown in Figure 3, the dielectric loss tangent metering circuit comprises Ultra-low Frenquency Voltage generator (1) under ultralow frequency, the resitstance voltage divider of forming by R1 and R2 (2), signal extraction electric capacity is C1 (3), can obtain voltage and current signal on the test specimen capacitor C x from (2) (3) parts, after two signals amplify through amplifying circuit (4), export to filtering circuit (5) filtering, again after A/D converter (6) conversion, becoming digital quantity stores in the single-chip microcomputer (7), after single-chip microcomputer utilized quasi-synchronous algorithm to calculate, output was the result shown by LCD (8).

Claims

0.1Hz electronic type ultralow frequency alternating voltage test unit, comprise Ultra-low Frenquency Voltage generator main circuit part, Ultra-low Frenquency Voltage generator control section, the dielectric loss tangent measure portion, Ultra-low Frenquency Voltage generator main circuit comprises a modulated wave generator (1), step-up transformer (2), polarity reversing switch (3), controlled discharge resistor network (4), filter capacitor C1 (5), filter resistance R7 (6), test specimen capacitor C x (8), resitstance voltage divider (7), ultralow frequency generator main circuit control section comprises that with single-chip microcomputer (1) be the circuit of core, control modulated wave generator (2), control polarity reversing switch (5), control discharge switch (6), input equipment (3), output device (4), dielectric loss tangent measure portion circuit comprises Ultra-low Frenquency Voltage generator (1), resitstance voltage divider (2), signal extraction capacitor C 1 (3), amplifying circuit (4), filtering circuit (5), A/D converter (6), single-chip microcomputer (7), LCD (8), it is characterized in that the Ultra-low Frenquency Voltage generator comprises that also transformer output utilizes polarity reversing switch to convert the voltage wave of positive-negative polarity to, through controlled discharge resistor network (4) and filter capacitor C1 (5) detection, obtain the ultralow frequency sine voltage, the dielectric loss tangent measurement comprises adopts resitstance voltage divider (2), signal extraction capacitor C 1 (3) is extracted ultra-low frequency signal, calculates through single-chip microcomputer (1) and outputs to external unit (8).