CN2181008Y - High-voltage megohmmeter for precision measuring capacitive performance - Google Patents

Abstract

The utility model provides a high-voltage megger for precision measuring capacitive performance, and the input end of the test loop of the high voltage megger is added with a compensation capacitor. Owing to need not to be in series connection with a large resistor, the utility model can make full used of the power supply capacity of the high voltage megger, the measurement accuracy of absorptance and polarized coefficient can be enhanced. The utility model can cause a short circuit protective device with the high voltage megger to normally operate capacitive sample measuring, and the utility model can reduce the counterbalance of a pointer from an instant starting up current. The utility model has simple circuit structure, convenient manufacture and strong practicability.

Description

High-voltage megohmmeter for precision measuring capacitive performance

The utility model relates to high tension megger.

High tension megger is the indispensable instrument of electric system testing apparatus insulating property, can be used to test the absorptance and the polarization coefficient of capicitive sample.Absorptance and polarization coefficient then are to judge some equipment, as power transformer, and the important indicator of the performance of power capacitor etc.

The resistance value of absorptance require to be measured the start back the 15th second and the 60th second.Absorptance η=R60s/R15s.Polarization coefficient require to be measured the resistance value of the 1st minute and the 10th minute.Polarization coefficient λ=R10m/R1m.For absorptance and polarization coefficient are measured accurately, must judge the time of sampling insulating resistance value exactly.

High tension megger has pointer-type and digital.Pointer table is used manual manual time-keeping always, double operation, and error is bigger.Digital table itself has time set, and has timing to keep function, will make things convenient for relatively with accurate.On the other hand, the Insulation test instrument must have enough power supply capacitys, and powering up moment can provide enough big measuring current, could guarantee normal polarization process.

At present, the high tension megger of domestic use typically has: Japanese KYORITSU company produce 3121,3122 type tables, the HV type table that U.S. HIROTRONNICS company produces, the 210400 type tables that U.S. BIDDLE company produces, the GZ-5A type table that Chinese University of Science and Technology produces etc.The HV type table of the U.S. and 210400 type tables adopt the slowly method of pressurization, are not suitable for measuring absorptance and polarization coefficient.3121,3122 type tables of Japan, power supply capacity is less, and the short-circuit test electric current of tens μ A can only be provided, and can not guarantee normal polarization process.The GZ-5A type table that Chinese University of Science and Technology produces, measurement range is 20M Ω-200000M Ω.When the equipment resistance was lower than 20M Ω, high voltage protective interrupted.Capicitive sample is equivalent to short circuit starting moment.Therefore, when the test capicitive sample, the 20M Ω resistance of must in test circuit, connecting, this has just limited the accurate measurement of absorptance and polarization coefficient.

The purpose of this utility model is to overcome the shortcoming of above-mentioned megohmmeter, makes full use of the power supply capacity of high tension megger, improves the measurement accuracy of absorptance and polarization coefficient.

The utility model is achieved in that the building-out capacitor method that adopts, and adds a building-out capacitor C at the input port of high tension megger test loop ₀Building-out capacitor C ₀An end link to each other with the L terminal, the other end links to each other with the G terminal.Do not add building-out capacitor, start shooting moment, high pressure Vs is added in sample resistance R immediately by capacitor C x ₀On, sample resistance R ₀Last transient voltage is very high, makes the holding circuit action, and high pressure interrupts, and test can't be carried out.Set up building-out capacitor C ₀, because building-out capacitor C ₀Dividing potential drop effect with capacitor C x can make building-out capacitor C ₀On voltage V ₀Slowly raise, enter steady-state value, holding circuit is not interrupted high pressure, and test can be carried out.Because building-out capacitor C ₀The instantaneous short circuit effect, make the electric current on the capicitive sample enough big, can make full use of the power supply capacity of megohmmeter.

For non-capicitive sample (for example electrical network lightning arrester etc.), in order to improve the response speed of megohmmeter, a switch can be set in that building-out capacitor is other, to cut off building-out capacitor.

Accompanying drawing 1. the utility model measuring principle circuit diagrams, wherein, Co-building-out capacitor, K-switch, R ₀-sample resistance, Cx-analog equivalent circuit capacitance, Rx-analog equivalent circuitous resistance, three test terminals of E, G, L-high tension megger, A-test loop.

Accompanying drawing 2. the utility model front panel synoptic diagram.Wherein, the 1-megaohm shows that the 2-hour hands show that 3-interrupts button, and 4-keeps button, the continuous button of 5-.

Accompanying drawing 3. the utility model rear panel synoptic diagram.Wherein, 6-C/R Gear-shift switch, 7-attaching plug.

Embodiment: utilize the GZ-5A type high tension megger of Chinese University of Science and Technology to experimentize C ₀Get 4.7 μ F, the electric capacity that can test capicitive sample does not add building-out capacitor more than 0.1 μ F, then can't measure.

The utility model has the advantages that: owing to do not need to be connected in series big resistance, thereby can take full advantage of the power supply capacity of high tension megger, improve the measurement accuracy of absorptance and polarization coefficient. Can make the high tension megger of short-circuit protection can carry out normal capicitive sample test. To pointer megameter, then can alleviate immediate current of boot-strap the recoil of pointer is hit. Simple in structure, practical, easy to make.

Claims (1)

1, a kind of high tension megger of accurate measuring capicitive sample property is characterized in that adding building-out capacitor at the input port of the test loop of the high tension megger that includes panel.

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