RU2128392C1 - Method and installation for impregnating and drying pieces of electrical equipment - Google Patents

Abstract

FIELD: electrical and electromechanical engineering; impregnating electrical machine windings. SUBSTANCE: method involves preheating of parts, their impregnation with relevant compound followed by their drying; preheating by electric current includes automatic series connection of part contact groups to current regulator, and then current is intermittently passed at preset ON-time and OFF-intervals. During current flow parts are heated up and their parameters are checked; during OFF-intervals, their pre-impregnation temperature is measured. Upon impregnation, parts are subjected to drying by direct heating of their metal surfaces simultaneously feeding hot air circulating in closed duct of air conduit. Desired air temperature is maintained by means of triac power regulator. Special draft ventilation channel provides for optimal concentration of impregnating compound vapors in drying chamber. Installation implementing this method has preheater unit, impregnating unit, and drying chamber; novelty is that preheater unit is provided with automatically connected contact groups for series connection and heating of parts with regulated current and that impregnating unit has sealed tank with flexible transparent indicating tube communicating with tube feeding impregnating compound to bath and with tube maintaining desired level in bath; the latter is provided with transfer tube that is threaded and has level-indicating scale, adjusting screw, and nozzle; scale rule is installed in bath. EFFECT: increased capacity of continuous process; improved quality of impregnated parts due to their active inspections for condition. 2 cl, 3 dwg

Description

 The inventive group of inventions, one of which is a method and another device for its implementation, relates to the technology of electrical engineering, in particular to technology and equipment for the impregnation and drying of electrical products, namely the windings of electrical machines, and can be used in the electrical industry.

 A known method and installation for the impregnation and drying of the windings of electrical machines (see Bromberg V.A. et al. Mechanization of the production of electrical insulating materials, insulating-wrapping and drying-impregnating works. M-L .: Gosenergoizdat, 1961, p. 100), in which the product passes through the pre-drying chamber, the impregnation section and the drying chamber. The installation comprises a preliminary drying chamber in the form of a channel, a drying chamber with air ducts, an impregnation unit connected to the outlet of the channel of the preliminary drying chamber and the inlet of the drying chamber, and an air duct system with two channels. However, this method does not provide sufficient impregnation of the winding with an impregnating composition, which degrades the quality of the product, and the installation is characterized by a rather complex design.

 These disadvantages are absent in the method and installation for the impregnation and drying of electrical products, mainly the windings of electrical machines (see ed. Certificate of the USSR N 714583, class H 02 K 15/12), taken as a prototype, in which the products are preheated, impregnation with an appropriate composition and subsequent drying. In this case, the installation comprises a pre-heating unit, an impregnation unit and a drying chamber.

 The prototype has the following disadvantages.

At the preheating stage:
- low preheating rate;
- lack of heating of the winding of the products from the inside, which reduces the quality of drying before impregnation and impairs the quality of impregnation;
- the temperature of the metal part and the winding of the product is the same, which is undesirable for impregnation by rolling (the metal must be cold so that the compound does not freeze in the bath);
- lack of active control of the condition of products and, accordingly, the timely rejection of unusable products. At the stage of drying the impregnated products: due to the different temperatures at the beginning and at the end of the chamber, as well as the lack of air temperature control, the selection of the optimal drying mode is worsened.

 In addition, the known installation is characterized by low efficiency due to large heat losses (as a result of the lack of recirculation, almost all heated air is emitted into the ventilation) and low air velocity (slow heat transfer). The installation as a whole is distinguished by the complexity of the design due to the presence of a large number of mechanical components (for example, turning angles of the conveyor, fans, air heaters), lack of versatility with respect to the selection of impregnating composition, inefficient cooling of finished products due to the short cooling area at the outlet.

 The inventive group of inventions solves the problem of creating a high-performance, uninterrupted process and equipment for impregnating and drying electrical products, ensuring high quality impregnation of rotors of generators using active control, to monitor the health of products.

 When implementing the group of inventions, such a technical result is achieved as the possibility of prompt and smooth temperature change to select the optimal temperature regime and preheating time. This ensures a high pre-heating rate, which is set by the magnitude of the current flowing through the product. Active control i.e. checking products for serviceability directly in automatic mode allows you to reject faulty products before impregnation and drying directly at the installation, excluding impregnation of defective products, and also to exclude additional jobs for checking products. Due to the higher heat capacity compared to the winding, the metal parts of the rotor are not heated very much at the preheating stage, which makes it possible to exclude its heating and solidification when rolling the rotors in a bath with a compound. At the stage of drying the impregnated products, the combination of local heating with heating elements and blowing with hot air circulating in a closed cockatoos increases the efficiency and quality of operation of the drying chamber. Moreover, the use of a seven-power power controller ensures the accuracy of installation and maintaining the air temperature at all points of the drying chamber, increases the quality and reduces the drying time. Due to the creation of a special exhaust ventilation channel that provides the optimal combination of hot and cold air flows in the drying chamber, the vapor concentration of the impregnating composition does not exceed the permissible values. In addition, the design of the installation has a high "survivability": in the event of a failure of several minor mechanical and electrical components, the installation remains operational.

 The specified technical result is achieved by the fact that in the method of impregnation and drying of electrical products, mainly windings of electrical machines, in which the products are preheated, impregnated with an appropriate composition and subsequent drying, at the stage of preliminary current heating, the products are connected in series with automatically connected contact groups to to the current stabilizer and periodically pass current with a predetermined time of current presence and pause, thereby achieving rapid heating of the winding inside with a cold metal part. When passing current, the products are heated and actively monitored in the preheating zone for breaks, short circuits, and short circuits to the case, and during a pause, the temperature of the products is monitored at the position before impregnation, which is stored until the next measurement cycle and based on which the cycle is controlled pre-heating with the possibility of smooth and quick installation of the required temperature of the products, on the basis of which a signal is formed allowing the conveyor to move and move products in the impregnation zone. After impregnation of the product, it is subjected to a drying operation, which includes direct heating of the metal part of the product with electric heating elements with simultaneous drying with a stream of hot air circulating through the closed duct of the duct, while the air temperature, the same at all points of the drying chamber, is supported by a seven-power power controller with the possibility of its operational change . In addition, a special exhaust ventilation channel provides an optimal concentration of vapor of the impregnating composition in the drying chamber.

 The installation for impregnation and drying of electrical products, mainly windings of electrical machines, including a pre-heating unit, an impregnation unit and a drying chamber, is characterized in that the pre-heating unit has automatically connected contact groups for sequential connection and heating of products with a stabilized current, and the impregnation unit contains hermetically closed tank with a flexible transparent indicator tube connected to an impregnation bathtub for supplying the composition to the bathtub and a support tube Nia predetermined level in the tub, the latter is provided with a threaded adapter tube and scale level, and the adjusting screw tip and bath set measuring range.

 The essence of the proposed group of inventions is illustrated by the drawings: in FIG. 1 shows a General view of the installation for the impregnation and drying of electrical products; in FIG. 2 is a diagram of the movement of air flow inside the installation; figure 3 shows the impregnation unit.

 Installation for impregnation and drying of the windings of the rotors of the generators (Fig.1, 2) contains a pre-heating unit 1, an impregnation unit 2, a drying chamber 3 and a cooling zone 4. A main conveyor 6 is mounted on the frame 5, on the chain of which satellites for installing the rotors 7 are mounted The rotation of the conveyor is carried out by the drive 8, located on the table 9, attached to the main frame 5. At the bottom of the frame 5 is pneumatic equipment (not shown). For the rotation of the rotors in the impregnation and drying zone, there is a conveyor for the rotation of the rotors (not shown), driven by a rotor rotation drive 10. To preheat the rotor windings at the initial six positions on the left and right of the installation, contact left and right groups 11 are placed.

 The impregnation unit 2 is placed on the frame 5. The impregnation unit (Fig. 3) contains an impregnating bath 12 with a measuring ruler 13 fixed to the back wall with a compound level scale in the bath, a hermetically sealed opaque storage tank 14 with a stopper 15 for refilling the impregnating composition and a flexible transparent indicator tube 16, flexible tubes 17 and 18 connecting the bath 12 to the tank 14. The tube 17 is designed to supply the compound to the bath 12. The tube 18 serves to maintain a given level of compound in the bath and is equipped with a transition tube 19 with thread and scale the level of the compound, as well as the adjusting screw 20 and the tip 21. The tubes 17 and 18 are attached to the bath 12 by the holder 22.

 The tank 14 cannot be made of a transparent material (for example, glass or plastic), because he needs regular mechanical cleaning of the frozen compound. Flexible transparent tube 16 provides a visual indication and control of the amount of compound in the tank 14. In it, on the basis of communicating vessels, the same level of compound is established as in the tank 14.

 Turning the adjusting screw 20 changes the level of the compound by a certain amount. The tip 21 provides high accuracy of maintaining the level of the compound in the bath 12. It has been experimentally proved that without the tip, the level of the compound varies within 10 mm, while the tip reduces the fluctuations of the specified level to 2.5-3 mm.

 Tubes 17 and 18 are made transparent, which increases ease of use, because it makes visual adjustment of the supply and maintenance of the compound level in the bath. The level in the tube 18 during operation is constantly changing, and the tube is hidden inside the installation. As a result, it cannot be used as an indicator to determine the level of the compound in the tank 14.

 To raise and lower the bath 12 is a pneumocylinder 23 (figure 1).

 For drying the impregnated rotors in the drying chamber 3 (FIGS. 1, 2), electric heaters 24 are installed, as well as a closed hot air duct 25 with an integrated hot air preparation unit containing a hot air fan 26 and an air heater 27. The exhaust ventilation system is formed by partitions 28, a window 29, connecting the ventilation channel with the drying chamber, the walls of the installation, the cold air duct (in Fig.2 - solid lines with arrows), dampers 30 and 31.

 The installation is connected to the factory ventilation system at the connection points 32.

 Temperature control in the drying chamber 3 is carried out by temperature sensors 33.

 To cool the rotors in the cooling zone 4, a fan 34 of cold air is installed on the vibration mounts, which turns on only when necessary in the hot season.

 The method of impregnation and drying of the windings of the rotors of the generators is as follows.

 The installation is turned on and in the loading zone 35 is loaded with rotors 7.

 Electric heaters 24 and air heater 27 start heating the drying chamber 3. When the set temperature is reached, a signal for allowing the movement of the conveyor 6 is generated. Then, the power control devices go into the mode of maintaining the set drying temperature of the rotors. The heating is controlled by a seven-power power controller (located in the control cabinet 36), receiving temperature information from the temperature sensor 33. In case of excess of temperature, the unit is switched off abnormally.

 When loading, when the rotors are at the position before impregnation, the preheating unit 1 is turned on. The rotors 7, connected in series using contact groups 11, are connected to the current stabilizer (located in the control cabinet 36). The current is passed cyclically with a given current and pause time.

 Pre-heating operation cycle 1: operation - 6 sec, pause - 1 sec.

 When current is passed, the rotor windings are quickly heated (metal parts remain cold) and active control in the preheating zone with visual indication of an open, short circuit (or reduced resistance), short circuit to the housing. In the event of a malfunction, an emergency lock is activated, to remove which it is necessary to remove the defective rotor. During a pause, the temperature of the rotors is monitored at the position before impregnation, which is stored until the next measurement cycle and on the basis of which the preheating cycle is controlled (via the preheating control unit), with the possibility of quick and smooth control of the temperature of the products before impregnation.

 A signal is formed allowing the movement of the conveyor and, consequently, the movement of the rotors in the impregnation zone.

 Then, in the impregnation unit 2, the rotors are impregnated by rolling them in a rising bath 12 with a compound. After the time relay is activated, the bath is lowered. The next rise of the bath occurs after the step of the conveyor 6 and the impregnation cycle is repeated.

 During normal operation of the installation, the conveyor takes one step per minute.

 Next, the impregnated rotors 7 enter the drying chamber 3, where they undergo a drying operation. Cold after impregnation of the metal parts of the rotors must be quickly heated. For this, they are directly heated by electric heaters 24 and a stream of hot air created by a fan 26 and an air heater 27 circulating at a sufficiently high speed through a closed channel of the air duct 25.

 Due to the fact that the windows of the partitions 28 are smaller than the window 29, maximum resistance to the movement of cold air passing through the installation is created (short arrows in FIG. 2), i.e. if possible, the path to the parasitic flow is blocked. While hot air (in figure 2 - long intermittent arrows) containing harmful compound vapors leaves almost unhindered through the exhaust ventilation duct (in figure 2 - a continuous line with arrows). Thus, a minimum amount of cold and maximum hot air flows are created, which move along a predetermined exhaust ventilation channel between the walls of the installation through the air ducts and the shutter 31, by means of which the magnitude of this flow is regulated. In the drying chamber, as a result of the circulation of hot air, the same air temperature is reached at all points of its volume.

 If necessary, it is possible to smoothly and quickly change the temperature.

 Thanks to the use of emergency locks from overheating and the presence of visual indications, constant monitoring of the drying process in the drying chamber is ensured and mass rejection in the operation of the installation is prevented.

 The dried rotors are cooled in the cooling zone 4 at the outlet of the installation. Fan 34 is used in the hot season when free cooling is not enough.

Claims (2)

 1. The method of impregnation and drying of electrical products, mainly the windings of electrical machines, in which they pre-heat the products, impregnate them with an appropriate composition and subsequent drying, characterized in that at the pre-heating stage the series-connected products are connected to a current stabilizer and the current is periodically passed with a predetermined time the presence of current and pause, while transmitting current, the products are heated and the electrical parameters of the products are actively monitored in the pre-load zone eva, and during a pause, they monitor the temperature of the products, on the basis of which the preheating cycle is controlled with the possibility of smooth and operational control of the temperature of the product before the impregnation operation and the formation of a conveyor movement permission signal, and after the impregnation of the product, they undergo a drying operation that involves direct heating of the metal parts of products with simultaneous drying by a stream of hot air circulating through a closed duct channel, while the temperature air, identical at all points of the drying chamber, is supported by a seven-power power regulator with the possibility of its operational change, in addition, by moving the air flow through a given exhaust ventilation channel, the optimal concentration of vapor of the impregnating composition in the drying chamber is maintained.  2. Installation for the impregnation and drying of electrical products, mainly the windings of electrical machines, including a pre-heating unit, an impregnation unit and a drying chamber, characterized in that the pre-heating unit has automatically connected contact groups for sequential connection and heating of products with a stabilized current, and the impregnation unit contains a hermetically sealed tank with a flexible transparent indicator tube connected to an impregnating bath tube for feeding the composition into the bath and a tube for holding in the bath at a given level, while the latter is equipped with a level scale, an adjusting screw and a tip, and a measuring ruler is installed in the bath.

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