RU1774285C - Liquid dielectric testing device - Google Patents

Abstract

SUMMARY OF THE INVENTION: the device comprises a base, an electrode rod, a pocket for a thermometer. The device allows control of breakdown loads, dielectric loss tangent, permittivity, resistivity and electrical conductivity of liquid dielectrics. 2 silt

Description

The invention relates to electrical engineering and can be used to monitor the performance of liquid dielectrics, for example transformer oil.

Existing devices (see Bazhanov S.A., Voskresensky V.F. Preventive tests of insulation of high voltage equipment .- M .: Energi, 1977, p. 288) do not simultaneously monitor the main electrical insulating indicators of liquid dielectrics (breakdown voltage, dielectric loss tangent, permittivity, resistivity and conductivity).

A disadvantage of the devices is non-universality in the measurement of electrical insulating characteristics of liquid dielectrics.

A device for controlling the electrical insulating characteristics of liquid dielectrics (see USSR Author's Certificate No. 572697. CL G 01 N 27/06 // G 01 R 27/22, 1977) containing a measuring electrode, a high voltage electrode isolated from it, a base and pins for connection to a measurement circuit.

A disadvantage of the known device is the impossibility of measuring the breakdown voltage and the operational control of liquid dielectrics directly in electric devices.

The purpose of the invention is to expand the functionality of the device by measuring breakdown voltage.

To achieve this, the device is equipped with a base on which an electrode system is installed, including a measuring and high-voltage electrodes, rod electrode, as well as a pocket for a thermometer and a valve for venting air. The gap between the measuring and high voltage electrodes is ensured by means of insulating structures.

Fig. 1 shows a device for monitoring liquid dielectrics in two projections.

The device comprises a base 1, to which, using leads 2-4, an electrode system is attached, including a measuring electrode 5 made in the form of a plate, a high-voltage electrode 6 made in the form of two plates, an electrode-rod 7, and also a pocket 8 for a thermometer and a valve 9 for venting air.

Ј

X)

2

hO 00

ate

Terminal 2 is connected to the measuring electrode plate 5, terminal 3 is connected to the high voltage electrode plates 6, and terminal 4 is connected to the rod electrode 7. The gap between the plates 5 and 6, equal to 2 mm, is provided by insulating bushings 10 and gaskets 11, which are fixed by means of screws 12, nuts 13 and washers 14. The gap between the rod 7 and the plate 6 is established by means of nuts 15. Terminals 2-4 are connected to bushing insulators 16 and 17 to which the measuring circuit is connected.

The device operates as follows.

The electrode system of the device and the pocket 8 for the thermometer are lowered into a controlled fluid, which fills the gap between the plates 5, b and the rod 7. A thermometer is inserted into the pocket 8. The electrode system is connected through bushing insulators 16, 17 to a measuring circuit to monitor the electrical insulating performance of liquid dielectrics. When monitoring the breakdown voltage, insulators 16 are used, the remaining indicators are insulators 16 (connected to terminal 3) and 17.

The device allows controlling the breakdown voltage, dielectric loss tangent, permittivity, resistivity and electrical conductivity of liquid dielectrics.

The breakdown voltage Unp (kV) is determined as the arithmetic mean of six measurements.

The dielectric loss tangent, is determined by the formula

(tgu

Co ci

tg do),

where Ci, tg 5i are the capacitance and the dielectric loss tangent, respectively, when filling the interelectrode gap of the device with a controlled fluid;

Co, tg & are the capacitance and the dielectric loss tangent, respectively, when filling the device’s electrode gap with air;

The parasitic capacitance of the device is due to the presence of insulating structures, capacitance of wires, etc.

SpSo Јk - SK Zs-1

where Ck is the capacitance when filling the interelectrode gap of the device with a liquid dielectric with a known value of EC.

The relative permittivity is determined as follows:

about

Ci - cn

So - Sp

The specific volume electrical resistivity rf (Ohm-m) is determined by the expression

  0.113 CoRv U12,

where Rv is the measured volumetric electrical resistance value.

Electrical conductivity gg (x)

twenty

A1 d / V Rv S

where d is the gap between the plates of the electrode system;

S is the area of overlap of the plates of the electrode system.

To eliminate the interaction of the electrodes 5, 6 and insulating structures 10, 11c with a fluid-controlled plate 5, 6 of the electrode system are made, for example, of stainless steel grade

12X18H9T, and bushings 10 and gaskets 11 are made of fluoroplast-4.

A thermometer installed in pocket 8 is used to measure the temperature of the fluid being monitored.

The valve 9 is a screw with two mutually perpendicular holes, when it is unscrewed, air is released, for example, when the control device is installed in an oil-filled electric device.

The use of a rod-plane electrode system for measuring the breakdown voltage can significantly reduce the Unp value, which makes it possible to use the proposed device for monitoring the electric strength, for example, transformer oil directly in operating electric devices.

In the device, the insulators 16 are made of fluoroplast-4, the insulator 17 is standard, for example, type IKP-3.

An example of installing a control device in the oil regeneration circuit of a power transformer is shown in Fig.2.

The regeneration circuit includes a transformer tank 18 filled with oil, a thermosiphon filter 19 for continuous oil recovery, valves 20 for shutting off oil supply, an elbow 21 of the circulation pipe, flanges 22 for installing an elbow, a measuring chamber 23 (shown with the cover removed) for installing an control equipment, oil monitoring device 24.

The versatility of the device allows you to use it to measure the basic electrical insulating indicators of liquid dielectrics,

The possibility of free circulation of the controlled fluid between the electrodes of the open type measuring cell and the presence of an air vent valve allow controlling the performance of the LIQUID dielectric, for example, transformer oil directly in operating electric devices without laborious sampling and analysis in a testing laboratory.

By increasing the efficiency of monitoring the state of liquid insulation, the reliability of power transformers is increased, which increases the reliability of the supply of electrical energy consumers.

Claims (1)

SUMMARY OF THE INVENTION A device for monitoring liquid dielectrics comprising a measuring electrode, a high voltage electrode isolated from it, a base, and terminals for connecting i to a measuring circuit, characterized in that, in order to expand its functionality by measuring the breakdown voltage, it further comprises an installed on the. the base is an electrode rod, a thermometer pocket and an air valve, the high-voltage electrode being movably mounted. eighteen 17 12 CPud thirteen 22 2321 22 FIG. 2 79