SU1566445A1 - Method of electrosmotic drying of electric machine windings - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to drying the insulation of the windings of electric machines during their operation. The purpose of the invention is to intensify the process of electroosmotic insulation insulation. A pulsating voltage of the same polarity is applied to the constant electrostatic field created in the insulation. This causes the destruction of the ionic shells of water molecules and increases the mobility of the latter when they are directed towards the negative electrode. The invention makes it possible to reduce the power consumption during drying 4-5 times. 4 il.

Description

The invention relates to electrical engineering, in particular, to methods for drying the insulation of windings of electrical machines during their operation.

The purpose of the invention is to reduce energy consumption by intensifying drying.

Fig. 1 shows a graph of the drying rate of an electric motor's insulation when applying a pulsating field of the same polarity (1) to a constant field and a variable field (2) to a constant field and from a constant voltage source (3) at a maximum drying voltage of 320 AT; Fig. 2 is a graph of the rate of drying of the insulation of an electric motor when applied to a constant field with a voltage of 200 V and a pulsing of the same polarity with a different pulse shape with a voltage of 120 V;

90 Hz; Fig. 3 is a graph of the drying rate of the insulation of an electric motor at different levels of pulse voltage of one polarity (30, 120 and 250 V) at maximum voltage in all cases of 320 V and a frequency of 80 Hz; Fig. 4 is a graph of the drying rate of an electric motor's insulation when applied to a constant field with a voltage of 200 V and a pulsing of the same polarity with a voltage of 120 V at different frequencies (90 and 10 Hz and 1.5 kHz).

As a result of laboratory studies, it was found that the intensity of the method of electroosmotic drying, based on the combination of two fields - a constant and a pulsating one polarity, depends on the pulse shape, frequency

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pulses and amplitude of the pulsating component.

It was established experimentally that the optimal pulse shape is - a rectangle, the pulse repetition frequency lies in the range of 20-100 Hz, the amplitude of the pulsating component lies in the range of 25-50% of the maximum permissible drying voltage.jg

The method is implemented as follows.

The megohmmeter measures the resistance of all the isolation parts of an asynchronous motor. Moreover, minus 15 megohm meter served on the body. In subsequent control measurements, the indicated polarity should be observed, since the value of the insulation resistance changes with change20

polarity.

Depending on the initial insulation resistance R ,, the maximum drying voltage is established. Based on experimental data on the basis of the dielectric strength of insulating materials, it has been established that if R „, lies in the range of 20-60 kΩ, then the maximum drying voltage does not

implying wet isolation), the pulse shape is rectangular, the pulse repetition rate is 20-100 Hz.

Thus, the penetrating ability of water molecules in their directional movement towards the negative electrode increases due to the destruction of the ionic shells by imposing on the constant field a pulsating voltage of one polarity.

The economic effect of using the drying method in accordance with the invention is to save energy, the consumption of which is 4-5 times less compared to the known method of electroosmotic drying.

Claims (1)

Invention Formula The method of electroosmotic drying of the insulation of the windings of electric machines, in which a constant voltage is applied between the conductors of the windings and the case of the machine, connecting the positive pole of the constant voltage source to the conductors of the windings, should exceed 200 V; in case of Kie, and negative - to the case, about tl and nominal 60–100 kΩ, drying voltage 200–350 V; at 100-150 kOhm, the maximum drying voltage is 350-500 V and at R .., more than 150 kOhm, the maximum voltage g E drying life 500-700 V..35 In accordance with the established maximum permissible value of the drying voltage, two fields are created - constant and pulsating with one that, in order to reduce energy consumption by intensifying the drying, they turn on the source of pulsating voltage and additionally apply a pulsing voltage. with the same polarity as the constant, and the amplitude value of the pulsating implying wet isolation), the pulse shape is rectangular, the pulse repetition rate is 20-100 Hz. Thus, the penetrating ability of water molecules in their directional movement towards the negative electrode increases due to the destruction of the ionic shells by imposing on the constant field a pulsating voltage of one polarity. The economic effect of using the drying method in accordance with the invention is to save energy, the consumption of which is 4-5 times less compared to the known method of electroosmotic drying. Invention Formula The method of electroosmotic drying of the insulation of the windings of electric machines, in which a constant voltage is applied between the conductors of the windings and the case of the machine, connecting the positive pole of the constant voltage source to the conductors of the windings,  and negative - to the body, about t l and Compared with the fact that, in order to reduce energy consumption by intensifying drying, a source of pulsating voltage is successively connected to a source of constant voltage and a pulsating voltage is additionally applied with the same polarity as the constant amplitude of the pulsating voltage. polarity through a set-to-voltage set equal to 25-50% of the maximum permissible drying voltage, the shape of the impu is set to be rectangular, and a frequency of 20-100 Hz. including two sources, the level of the pulsating voltage being the maximum (caused by the initial resistance of the voltage is set to 25-50% of the maximum allowable value of the drying voltage, the shape of the pulses is set rectangular, and the frequency is 20-100 Hz. Rus