RU2494517C2 - Three-cycle amplitude-width-discontinuous method to dry insulation of electrical machines - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: proposed three-cycle amplitude-width-discontinuous method for drying of insulation of electrical machines and devices of locomotives includes their forced blowdown with an air flow before heating and after heating, thermal heating, monitoring of operating temperature and condition of insulation. The difference consists in the fact that drying is performed in cycles at high temperature. In the first cycle the surface layers of insulation are dried with the air flow heated to the limit permissible temperature for this class of insulations. For insulation class B - 130°C, for F - 155°C, for H - 180°C. This temperature is set in the end of the operating period of the first cycle and is controlled in the oscillating mode till the end of the operating period of the third cycle. Such mode provides for moisture removal from upper layers of insulation in the first cycle and from lower layers of insulation in the second and third cycles. In the end of the third cycle the electric heater 1 (see fig.1) is switched off, and an electric motor 4 of the fan drive is started for full power in order to fully normalise insulation.

EFFECT: creation of most optimal mode of drying, insulation, providing for its reliability.

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Description

The invention relates to electrical engineering and can be used mainly for maintenance and repair of electrical machines.

A known method of maintaining the insulation of electrical machines and apparatus of locomotives (1). The proposed method for preserving the insulation of electric machines and locomotive apparatuses includes forcing them by air flow, heat heating, and subsequent monitoring of the working air temperature and insulation condition. The method is characterized in that the forced supply of air through electric machines and apparatuses is carried out from the environment, the temperature of which is increased stepwise with alternating purge with the ambient temperature and 2-5 times longer heating time, controlling the working air temperature and the insulation state, additionally, stepwise drying is carried out discretely to a temperature of 90-100 ° C of electric machines and apparatuses that previously had a reduced insulation state before repair.

Disadvantages:

- in this mode of drying the insulation consumes a large amount of energy;

- there is increased wear of the insulation and its reliability is reduced;

The closest analogue is the patent (2). The proposed method for drying the insulation of electric machines and apparatus of locomotives includes forced blowing them with the air flow, heat heating, control of the operating temperature and condition of the insulation. Drying is carried out in steps. At the first stage, the surface insulation layers are dried with an air stream heated to a temperature of 90-100 ° С, at the second stage, the insulation windings are dried with an air stream at a reduced temperature of 50-60 ° С. At the third stage of drying, they carry out an air flow without heating, until the insulation resistance indicator reaches the standards established by the repair rules.

The disadvantages include:

- drying of insulation at low temperatures several times increases the time for the normalization of insulation;

- the duration of the normalization process reduces the quality of insulation.

A three-cycle amplitude-latitudinal-discontinuous method of drying the insulation of electric machines and locomotive devices is proposed. The proposed method for drying the insulation of electric machines and apparatuses of locomotives includes forcing them by air flow before and after heating, heat heating, monitoring the operating temperature and condition of the insulation, characterized in that the drying is carried out in cycles. In the first cycle, the surface layers of insulation are dried with an air stream heated to the maximum permissible temperature for a given class of insulation. For insulation class B - 130 ° С, for F - 155 ° С, for Н - 180 ° С. This temperature is set at the end of the working period of the first cycle and is regulated in oscillatory mode until the end of the working period of the third cycle.

The invention is illustrated by diagrams. Figure 1 shows the "Scheme of air heating in an electric air heater", which shows: 1 - electric heater (TENY), 2 - outlet pipe, 3 - inlet pipe, 4 - fan motor, 5 - fan impeller casing, 6 - mobile trolley, 7 - control unit, 8 - corrugation of the outlet pipe. Figure 2 shows a diagram of a three-cycle amplitude-latitudinal-discontinuous mode of energy supply from the electric heater.

According to the proposed method, the insulation is dried in cycles in the following sequence:

In the first cycle, the electric heater 1 and the fan motor 4 are turned on at full power (maximum amplitude). Upon reaching the air flow temperature to the maximum permissible value, the electric heater turns off and the temperature decreases slightly.

In the second cycle, the electric heater 1 is turned on again, but with a lower level of energy supply with respect to the first cycle, and the electric motor 4 switches to a lower level of energy supply. The total energy supply level should be sufficient to restore the temperature of the air flow to the maximum permissible value. Upon reaching the air flow temperature to the maximum permissible value, the electric heater turns off and the temperature decreases slightly.

In the third cycle, the heater 1 is turned on again, but with a lower level of energy supply in relation to the second cycle, and the electric motor 4 is switched to the lowest level of energy supply. Upon reaching the air flow temperature to the maximum permissible value, the electric heater is turned off, and the electric motor

switches to full power and works until the end of the cycle in order to fully normalize the insulation.

The tests performed in depot conditions showed a significant reduction in electricity costs up to 30 ... 35% and a 2 ... 3 times reduction in the time to normalize insulation.

Reducing energy costs and improving the quality of the process is due to the fact that drying is carried out with an oscillating energy supply.

In the first cycle, there is a process of removing moisture from the upper layers of insulation, in the second and third - from the lower layers of insulation. In this regard, increased reliability of insulation.

Literature

1. RF patent №2138899, IPC H02K 5/12, H01F 4702. Application of 06/20/1997

2. RF patent №2324278, IPC H02K 15/12. Application dated 12/11/2006

Claims (1)

A three-cycle amplitude-latitudinal-discontinuous method of drying the insulation of electrical machines and apparatuses, according to which they are forced to purge them with an air stream before and after heating, heat heating, control of the operating temperature and insulation state, characterized in that the drying is carried out in cycles at high temperature with a decrease in the energy supply level in each subsequent cycle, and in the first cycle, the surface layers of insulation are dried by an air stream heated to the maximum permissible temperature for yes insulation class: В - 130 ° С, F - 155 ° С, Н - 180 ° С, moreover, the temperature is set at the end of the working period of the first cycle and is regulated in an oscillating mode until the end of the working period of the third cycle, and this mode provides moisture removal from the upper layers of insulation in the first cycle and from the lower layers of insulation in the second and third cycles, and at the end of the third cycle the electric heater is turned off, and the fan drive motor is turned on at full power in order to fully normalize the insulation.

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