Title of Invention

"TRANSFORMER ARRANGEMENT WITH COOLING CIRCUIT"

Abstract

This invention relates to a transformer arrangement with cooling circuit, in particular for use as railway transformer arrangement, comprising at least one transformer accomodated in a housing, a cooler and a circulating pump, and the transformer comprises at least one coil of at least one primary winding and one secondary winding which are arranged concentrically an a core, and a coaling medium circulates through the housing„ the pump & the cooler in such a manner that the cooling medium is, after having been cooled by the cooler, fed to the coil, without being mixed with cooling medium in the housing, characterized in that at least one coil (5) is designed as a layered winding arrangement with primary winding and secondary winding respectively wound concentrically in layers, and between the individual layers are provided coaxially arranged cooling channels with a clearance of less than 4 an in width through which the cooling medium is ducted in essentially laminary flow, and the coil comprises an inner and an outer support pipe between which windings are accommodated and which are sealed by pressure flanges whilst establishing an upstream distribution chamber which is linked to the cooling channels.

Full Text

Transformer arrangement with cooling circuit The invention relates to a transformer arrangement with cooling circuit, especially to be used as a railway transformer arrangement according to the preamtle of the main claim. Railway transformers are known which are configured as disc winding devices, the primary and secondary windings being configured as discs which are disposed axially beside one another on the core. Transformers of this kind are provided with a cooling system in which the cooling medium, here transformer oil, is poured via nozzles under high pressure between and onto the disc-shaped windings. The oil is withdrawn via a pump, led to a cooling apparatus and then used again for cooling. A known disc winding device of this type with a cooling system has the disadvantage that cold oil injected onto or between the windings mixes very quickly with the hot oil present in the transformer, such that a large amount of oil, e.g. 1000 1 has to be led in the circuit, when only 400 1 are effectively necessary. Moreover, with a disc winding device high axial short-circuit forces arise for which allowance must be made with corresponding tension elements. The object underlying the invention is to create a transformer arrangement which has small dimensions and makes available an effective cooling system. This object is achieved according to the invention by the characteristic features of the main claim in conjunction with the features of the preamble. Through the measures quoted in the subordinate claims, advantageous developments and improvements are possible. Because the transformer is configured as a layer winding device, in which cooling ducts are provided between the winding layers, through which ducts the cooling medium can flow purposefully and substantially in a laminar fashion, a transformer arrangement of very low constructional height can be made available, which has an extraordinarily high cooling efficiency. The transformer coil is here configured almost in the form of a heat exchanger, the cooling ducts of which can be very thin, e.g. inner widths of less than 3 mm. By this means, a small, amount of circulating oil is required, the speed is low and the pressure drops are likewise low. Because the amount of oil warmed up by the loss-generator, i.e. the transformer coil, is led back, after being recoolea, through the cooling apparatus directly, without mixing with the oil located in the housing, to cool the coil, the efficiency is increased. The advantage arising here lies in the respective di fference from the mixing temperature occurring from the recooled liquid and the liquid which is determined -3- by the amount of liquid located in the boiler and its potential for balancing the temperature. Adjusting the temperatures with the boiler liquid can only take place in the region of the short admission ducts in the boiler. As a result of the low amount of cooling medium to be circulated, the assemblies such as the circulating pump and the cooling apparatus can be configured smaller. Since the pressure drops are low with the controlled guiding of the cooling medium through the cooling ducts, during which guiding, cold oil is deliberately brought into the hot coil, the cooling medium is introduced into the housing at low pressure e.g. atmospheric pressure, whereby the housing can be configured as a low-pressure boiler, the result of which is that it can be built more easily than is the case in prior art. An embodiment of the invention is shown in the/drawing and is explained more fully in the following description. The figures show: Fig. 1 the constructional elements, connected with one another to form a cooling circuit, of the transformer arrangement according to the invention with a cooling system. Fig. 2 a longitudinal section through a transformer. Fig. 3 a cross-section through the transformer according to the invention and Fig. 4 a schematic representation of the transformers received in the housing, with flow division. In Fig. 1 is represented a transformer arrangement with a cooling system, which is to be mounted as a railway transformer in a small constructional height under the carriage floor of a train-set. Here the available installation height is for example 450 to 550 mm. The system shown in Fig. 1 comprises at least one transformer received in a housing or boiler 1, not shown in Fig. 1, a circulating pump 2, a cooling apparatus 3 with a fan and corresponding connection lines 4, which lead the warm cooling medium from the boiler to the circulating pump 2 and to the cooling apparatus and guide the cold cooling medium, i.e. transformer oil, back again into the boiler 1. Pressure measuring appliances P and temperature measuring appliances T are provided to monitor the cooling system, and furthermore a flowmeter Q can be inserted in the lines 4. Monitoring of the cooling system takes place substantially through checking the temperatures of the fluid cooling the transformers- An inadmissible temperature here signals faults which can be caused by coil faults, on pump failure or reduced output, on contamination of cooler or duct or on inadmissible overload or driving operation. Two transformers are disposed parallel beside one another in the boiler or housing 1, the corresponding coils sitting on two arms of a core. In Figs. 2 and 3, a coil of the transformer is represented in longitudinal section and cross-section, this coil being constructed according to the principle of a heat exchanger. The coil 5 has an inner carrier pipe 5, onto which a high-voltage winding 7 is wound concentrically as the primary winding, which is designed for example for a high voltage of 25kV. The high-voltage winding 7 consists of a plurality of layers, between which spacer blocks 8 are attached. These spacer blocks 8 extend over the whole length of the high-voltage winding 7, blocks 8 also being preferably arranged between the inner carrier pipe 6 and the first layer. On the high-voltage winding 7, the traction winding 9 sits as the secondary winding which also comprises a plurality of layers and which is designed for example for a low voltage of 2000 V. Between high-voltage winding 7 and traction winding 9 is provided a separation pipe 10, which ensures the insulation between the two windings. Blocks 8 are also provided between the layers of the traction winding. The blocks 8 define the size or the inner width of cooling ducts 11, it being possible for the inner width to be less than 4 mm, preferably less than 3 mm. The high-voltage winding 7 and the traction winding 9 can also be manufactured separately from one another, and then be subsequently inserted into one another. The windings are received in an outer carrier pipe 12, the inner carrier pipe 6 and the outer carrier pipe 12 protruding on both sides beyond the windings 7, 9. The windings are fixed by radially disposed thrust pieces 13 and by respectively one annular pressure flange 14 closing the end of the carrier pipes 6, 12. Between pressure flanges 14 and the ends of the windings is thus produced respectively a distribution chamber 15, formed from space segments between the thrust pieces 7 and which serves simultaneously as high-voltage protection against earth and stray fields and prevents stray fields from penetrating the yoke. The thrust pieces 15 have holes 16 through which segments of the distribution chamber 15 are connected with one another. Moreover the pressure flanges 14 have flow-through apertures 17 for the cooling medium. The carrier pipes 6, 12 and the separation pipe 10 and the spacer blocks 8 for the cooling ducts 11 are manufactured from glass-fibre composite materials which satisfy their requirements in terms of insulation strength and mechanical strength. -6- The coil represented in Figs. 2 and 3 is placed together with an identically constructed coil onto the two arms of a core and inserted into the housing 1 or the boiler, the core being held together via tension elements configured as press irons, and connected with the housing. The press irons are here configured as hollow sections which have flow-through apertures which in turn are connected with the flow-through apertures 17 of the coils 5. Preferably, the housing also has hollow sections which serve to supply and take away the cooling medium into and from the press irons and, if necessary, as secondary flows into the interior of the housing. Coils and core are attached in the housing, it being possible for additional constructional elements such as throttles or the like to be received in the housing. In Fig. 4 is shown schematically the flow pattern in the housing 1, which according to Fig. 1 is connected on the one hand with the cooling apparatus 3 and on the other hand with the circulating pump 2. According to Fig. 4, two coils 5 are disposed parallel on respectively one arm 18 of the core, and cold oil is led via the return line 4 to the housing 1 from the cooling apparatus 3, in accordance with arrow 19. The pressure at which the oil is here supplied is low; it is for example 0.15 bar. The oil reaches the press iron configured as a hollow section, which is indicated by the reference numeral 20 and flows via the flow-through apertures 17 in the flanges 14 into the distribution chambers 15. From the distribution chambers 15, the oil is led in a substantially laminar flow through the cooling ducts 11 of the coils 5, as is indicated by arrows 21. Through the laminar flow, pressure losses hardly occur in the coil and the cold oil is deliberately led in the narrow cooling gaps through the hot coil, whereby the heat is dissipated in a controlled manner without the disadvantages of - 7 - laminar flow. However, should it be so desired, the flow can, through deliberate measures, be led in a turbulent manner. When the oil leaves the coils, it can be led out deliberately or it can be used to cool secondary loss-generators, as can be for example received . in an additional chamber in the housing, as indicated by reference numeral 22. The oil leaves the housing 1, which can have additional space 23 for lead-throughs, and is led again to the cooling apparatus via the circulating pump 2, in accordance with arrow 23. With a coil of 700 to 800 mm in length, in a corresponding arrangement according to Fig. 4, for example a flow of 7 1 per second at a speed of only 50 cm per second (=145KW) takes place. All the armatures or apertures are connected via sliding seals to the duct system of the housing or to the liquid circuit. If necessary, oil can be led additionally through the boiler through parasitic bores. WE CLAIMS 1- Transformer arrangement with cooling circuit, in particular for use as railway transfarmer arrangement, comprising at least one transformer accommodated in a housing (1), a cooler (3) and a circulating pump (2), and the transformer comprises at least one coil (5) of at least one primary Minding (7) and one secondary winding (9) which are arranged concentrically on a core, and a cooling mediu« circulates through the housing (1) the pump (23) and the cooler (3) in such a manner that the cooling medium is, after having been coaled by the cooler (3), fed to the coil (5) without being Mixed Mith cooling medium in the housing, characterized in that at least one coil (5) is designed as a layered Minding arrangement Mith primary winding (7) and secondary winding (9) respectively Mound concentrically in layers, and between the individual layers are provided coaxially arranged cooling channels (ll) Mith a clearance of less than 4 mm in width through witch the cooling medium is ducted in essentially laminary flOw, and the coil (5) comprises an inner(6) and an outer support pipe (12) between which windings (7,9) are accommodated and which are sealed by presure flanges (14) whilst establishing an upstream distribution chamber (15) which is linked to the cooling channels. 2- Transformer arrangement as claimed in claim 1 wherein spacers (8) for forming cooling channels (11) are provided between the layers- -9- 3- Transformer arrangement as claimed in one of claims 1 to 2, wherein the housing (1) and/or clamping elements for clamping the core (18) of the transformer include hollow profiles for ducting the cooling medium. 4. Transformer arrangement as claimed in one of claims 1 to 3, wherein at least one coil (5) comprises the inner support pipe (6), a thereonta placed primary Minding including the cooling channels (11) , a separation pipe (10), a thereonto placed secondary winding (9) including cooling channels, and the outer support pipe (12), and in the distribution chamber (15) at the respective upstream or domnstream side of the cooling channels (11) are provided spaced pressure elements (13) with throughflow openings (16), and the distribution chambers (15) are sealed by prerssure flanages (14) with through flow openings (17). 5. Transformer arrangement as claimed in one of claims 1 to 4, wherein the cooling channels have a clearance of less than 3 mm. 6. Transformer arrangement as claimed in one of claims 1 to 3 wherein the housing 1 is designed as a low pressure vessel- This invention relates to a transformer arrangement with cooling circuit, in particular for use as railway transformer arrangement, comprising at least one transformer accomodated in a housing, a cooler and a circulating pump, and the transformer comprises at least one coil of at least one primary winding and one secondary winding which are arranged concentrically an a core, and a coaling medium circulates through the housing„ the pump & the cooler in such a manner that the cooling medium is, after having been cooled by the cooler, fed to the coil, without being mixed with cooling medium in the housing, characterized in that at least one coil (5) is designed as a layered winding arrangement with primary winding and secondary winding respectively wound concentrically in layers, and between the individual layers are provided coaxially arranged cooling channels with a clearance of less than 4 an in width through which the cooling medium is ducted in essentially laminary flow, and the coil comprises an inner and an outer support pipe between which windings are accommodated and which are sealed by pressure flanges whilst establishing an upstream distribution chamber which is linked to the cooling channels.

Documents:

00819-cal-1999-abstract.pdf

00819-cal-1999-claims.pdf

00819-cal-1999-correspondence.pdf

00819-cal-1999-description(complete).pdf

00819-cal-1999-drawings.pdf

00819-cal-1999-form-1.pdf

00819-cal-1999-form-18.pdf

00819-cal-1999-form-2.pdf

00819-cal-1999-form-26.pdf

00819-cal-1999-form-3.pdf

00819-cal-1999-form-5.pdf

00819-cal-1999-letters patent.pdf

00819-cal-1999-p.a.pdf

00819-cal-1999-priority document others.pdf

00819-cal-1999-priority document.pdf

00819-cal-1999-reply f.e.r.pdf