Title of Invention

TAP CHANGER

Abstract

The invention relates to a tap changer which, to eliminate constructional complication in the case of applications requiring load changeover merely in the lower and medium switching performance range, has simplified switching and drive means. To this end, the tap changer has only two vacuum switching cells as electrical switching means. Fixed selector contacts are arranged in alternation in parallel paths and are connected by two movable mechanical contacts in fixed relationship to one another. A mechanical changeover contact is actuated by a force storage device released after a preceding biasing and the two vacuum switching cells of each phase are actuated at the same time.

Full Text

Tap changer The invention relates to a tap changer for uninterrupted switching over between different winding taps of a tapped transformer in accordance with the introductory part of the first patent claim. Such tap changers are already known from WO 94/02955. Tap changers serve the purpose, by changing the translation ratio under load, of being able to set the voltage, active power and idle power of electrical mains. In the case of a single-phase tap changer known from WO 94/02955, the fixed tap contacts, which are each electrically connected with a winding shunt of the tapped transformer, are arranged in a vertical line. Moreover, two individual linearity movable selector contacts are provided, which, independently of one another, scan the fixed selector contacts. The actuation of the movable selector contacts takes place in the known tap changer by a drive mechanism which essentially consists of a continuously drivable pull-up slide and a driven part which can be pulled up by means of a spring energy store. After release of the spring energy store, the driven part then abruptly follows the preceding continuous movement of the pull-up slide. One of the movable selector contacts is fixedly arranged at the pull-up slide and the other movable selector contact is disposed at the driven part. Provided as electrical switching means in this known single-phase tap changer are at least two, usually three, vacuum switching cells which are fixedly arranged at the driven part together with at least one transition resistance and thus execute the abrupt movement thereof after release. There is known from DE 42 16 034 C1 a further tap changer which similarity comprises fixed selector contacts arranged in one path and has movable contacts which are accommodated in one housing and need only one drive. This tap changer is a single-phase arrangement, i.e. the mentioned housing encloses all components which are required for the connecting of a phase and forms a so-called single-phase tap changer module. Thus, for a three-phase management three such complete tap changer modules with three separate housings then have to be used. These known tap changers have proved themselves for the realization of greater switching performance and are in use in large numbers. However, for certain simpler cases of use with only small system voltages and switching performance they are too complicated. In that case it is to be considered at the outset that the known tap changer represents a single-phase module; for the usual three-phase use, three such complete tap changers then have to be operated in common and thus also three complete drive mechanisms, force storage devices and actuating mechanisms are required. A further disadvantage consists in that the driven part of the known tap changer, which executes an abrupt vertical movement on each switching over, has a quite considerable mass due to the numerous components attached thereto. Thus, costly means for damping of movement and also for gravitational force compensation are required. The synchronous actuation of the individual vacuum switching cells during the switching-over sequence also requires highly accurate and relatively complicated actuating means. It is the object of the invention to indicate a tap changer according to category, which allows a reliable load changeover in the lower and medium switching performance range up to tap voltages in the order of magnitude of about 500 V with the simplest and most robust possible mechanical construction and with use of only two vacuum switching cells as electrical switching means. This object is met by a tap changer with the features of the first patent claim. The subclaims relate to particularly advantageous developments of the invention. The simple and robust construction is particularly advantageous with the tap changer according to the invention. The mechanical and also the electrical switching means for all phases to be switched are combined in a single housing. Thus, only a single drive mechanism is necessary for all phases; similarly, only a single force storage device is present, and all vacuum switching cells of all phases as well as all mechanical switching contacts are fixedly arranged on a single base plate. Moreover, the tap changer according to the invention has only low moved masses, simply because, as explained, the remaining components are fixedly arranged and do not have to execute the movements of the movable selector contacts. A further advantage of the tap changer according to the invention is that the two movable selector contacts are sooner movable independently of one another, but are fixed in common and unchangeably in their position relative to one another. This further simplifies the overall mechanical arrangement and additionally enables a space-saving mode of construction. According to a particularly advantageous development of the invention the actuation of these movable selector contacts takes place in particularly simple manner by a linear Maltese segment or two such Maltese segments. In fact, it is already known as such from US-PS 3 673 364 and 3 824 355 to displace movable contacts along a linear path by a rack. These known solutions do not, however, relate to tap changers operating under load, but concern tap changers switching free of .load (de-energized tap changer). A further difference with respect to this embodiment of the invention is that the known racks are actuated by a gearwheel disposed in constant mesh, whereas the Maltese segment of the described embodiment of the tap changer according to the invention is drivable by a Maltese drive which enters into engagement only in a specific setting. This solution with a Maltese segment thus allows, in particularly simple manner, the conversion of a continuous rotational movement of a drive motor or a drive shaft into a longitudinal movement, which is displaced in time, with a freewheel; the known solutions with their rigid connection between driving and driven part are not, in principle, suitable for that purpose. According to a further particularly advantageous embodiment the two movable selector contacts of each phase are fixedly arranged in common on a carrier frame in such a manner that only this carrier frame is movable by the described Maltese segment. The invention will be explained in more detail by way of example in the following with reference to drawings. In the figures: Fig. 1 shows a tap changer according to the invention in schematic illustration from the front, Fig. 2 shows a partial illustration of the base plate of this tap changer from the back. Fig. 2a shows a corresponding illustration in which, for clarification of the arrangement, the roller guide, which is still to be explained, has been omitted, Fig. 3 shows a partial illustration of the base plate of this tap changer from the front, Fig. 4 shows a schematic illustration of the co-operation of fixed selector contacts and movable contacts, Fig. 5 shows the electrical circuit, on which the tap changer according to the invention is based, in detail, and Fig. 6 shows a changeover sequence in the case of a changeover from the winding tap n-2 to the winding tap n-1. Initially the basic construction of a tap changer according to the invention shall be explained by reference to Figure 1. The entire apparatus is disposed in a housing 1, which has a rear, electrically insulating housing plate 2. Three contact carriers 3 of electrically insulating material, which each carry fixed selector contacts 4, are fastened parallel to one another at this rear housing plate 2. In that case a respective contact carrier 3 is provided for one phase; the individual contact carriers 3 are arranged parallel to one another and the fixed selector contacts 4 are arranged in identical manner for each of the three phases. As apparent from the figure, the individual fixed selector contacts 3 are provided to be offset in each instance relative to one another alternately on a lefthand and a righthand part of the contact carrier 3. The connecting of the fixed selector contacts 4 will be explained further below. Longitudinal guides 5, at each of which a respective Maltese segment 6 is guided to be vertically movable, are provided at the side walls of the housing 1. A carrier frame 7 of electrically insulating material, which carries two movable contacts 8 and 9 for each phase, is fastened between the two lateral Maltese segments 6. The movable contacts 8 and 9 of each phase respectively correspond with the fixed selector contacts 4 of the corresponding phase. The movable contacts 8 and 9 can thus connect different fixed selector contacts 4 by longitudinal displacement of the Maltese segments 6 and thus the carrier frame 7 within the longitudinal guides 5. The movable contacts 8 and 9 are in that case dimensioned in their longitudinal extent in such a manner that on common movement thereof in each switching step one of them reaches a new fixed selector contact on each occasion without the other leaving the previous fixed selector contact. This is illustrated again in Figure 4; a) shows the setting before a movement of the carrier frame 7 and thus of the movable contacts 8 and 9; and b) shows the setting after an executed switching step. Returning to Figure 1: laterally in the housing 1, a drive motor 10 is provided at a fastening 11 and connected with a gear 12. Exiting from this gear 12 is a first drive shaft 13 of electrically insulating material, which horizontally penetrates the housing and is mounted at the lower end in a bearing 15. This first drive shaft 13 has at each of the two ends a respective Maltese drive 16, which corresponds with the respective Maltese segment 6. The gear 12 is in that case designed so that for each switching-over for which the drive motor 10 is actuated, the first drive shaft 13 executes a rotation of 360 degrees. In that case the two Maltese drives 16 engage in the respective Maltese segments 6 and displace these and thus the can-ier frame 7 fastened therebetween through a specific travel upwardly or downwardly depending on the rotational direction and thus on the switching direction of the tap changer. Due to this displacement of the cannier frame 7 upwardly or downwardly, the two movable contacts 8 and 9 of each phase are also moved in common upwardly or downwardly. In that case, one of these movable contacts - as already explained - on each occasion leaves the previously fixed selector contact with which it was in contact and contacts a new fixed selector contact 4, whilst the respective other movable contact, does indeed also move through the longitudinal dimension thereof, but still remains in contact with the previous fixed selector contact 4. The movable contacts 8 and 9 respectively wipe, by their free ends, electrically conductive contact tracks 17 and 18 of each phase, which tracks extend parallel to one another and are in turn each electrically connected with a first fixed contact 25 or a second fixed contact 26. This will be explained later. The individual contact tracks 17 and 18 are, in turn, spatially fixed in the housing 1 by means of a crossbeam 52. Apart from the already-described first drive shaft 13, a second drive shaft 14 also exits from the gear 12 and extends vertically upwardly in the housing 1. This second drive shaft 14 executes a rotation of 180 degrees for each switching-over and is connected with a pull-up slide 19 of a force storage device. This force storage device has as essential components just this pull-up slide 19, which is biased by the second drive shaft 14 against the force of force store springs 20, and in addition a driven part 21 which, after release, follows the longitudinal movement of the pull-up slide 19. Such force storage devices, in which a pull-up slide is moved in longitudinal direction by the rotational movement of a shaft and thus biased and in which a driven part after release abruptly executes a similar longitudinal movement, are already known in principle, so that further details do not need to be described here. For example, force storage devices of this category are described in explanatory manner in DE-PS 28 06 282 and also DE-PS 39 19 596. The driven part 21 is connected with a driven coupling 22, by which the abrupt horizontal longitudinal movement is transmitted, after release, to an actuating slide 23 of electrically insulating material. The function of this actuating slide 23 is also explained further below. Initially, however, a base plate 24 of similar electrically insulating material, which is arranged in the housing 1, shall be discussed, at which plate a respective first fixed contact 25 and second fixed contact 26 as well as fixed root contact 27 are provided for each phase. Moreover, a movable changeover contact 28. which comprises a contact member 31 by means of which a respective one of the two fixed contacts 25 and 26 is electrically connectible with the root contact 27, is arranged thereat in a mount 29; the entire arrangement has the function of an electrical changeover switch. The movable changeover contact 28 has in its upper part an actuating groove 32 actuable by an actuating member 30, which is fastened to the actuating slide 23, with an actuating pin 33. On horizontal movement of the actuating slide 23 after release of the driven part 21 of the force storage device, the actuating pin 33 consequently engages in the actuating groove 32 and pivots the entire movable changeover contact 28 about its mount 29, whereby a switching over between the electrical connection of a respective one of the two fixed contacts 25 and 26 as well as the root contact 27 takes place. At the side, which faces the rear housing plate 2, of the base plate 24 there are fastened further components which will now be explained in more detail by reference to Figures 2, 2a and 3. First of all, two vacuum switching cells 34 and 35 for each phase are fastened to the base plate 24 by means of mounting brackets 36 and 37. Moreover, a transition resistance 49 for each phase is arranged thereat in the lower region of the base plate 24. The upwardly projecting actuating plungers 50 and 51 of the two vacuum switching cells 34 and 35 are each provided with a respective pendulatingly mounted actuating arm 38 or 39. Each actuating arm 38 or 39 has at its free end a respective roller 40 or 41. In that case the actuating arms 38 and 39 are so shaped in their geometry that the two rollers 40 and 41 of each phase lie one above the other in a vertical line. The two rollers 40 and 41 each run in a respective profile 43 or 44 of a roller guide 42, which, for each phase, is fastened to the actuating slide 23. Moreover, the roller guide 42 has a further, additional profile 53 in which a further roller 54 is guided. This further roller 54 is fastened directly to the base plate 24 and guides the actuating slide 23 in its horizontal movement after release of the force storage device. In addition, a locking plate 47, which is similarity fastened to the actuating slide 23, is provided with a common longitudinal guide 48 for each phase, in which the two rollers 40 and 41 are similarly guided. Due to this additional locking plate 47 it is ensured that the actuating arms 38 and 39 can move vertically, in particular on displacement of the actuating slide 23 and thus of the roller guide 42, by their profiles 43 and 44 and thereby actuate the actuating plungers 50 and 51 of the vacuum switching cells 34 and 35, but cannot deflect laterally. This locking plate 47 is arranged between the roller guide 42 and actuating slide 23; as it is covered by the roller guide 42 in the illustration according to Figure 2, this roller guide 42 has been omitted in Figure 2a. The two rollers 40 and 41 are in every case dimensioned in such a manner that they simultaneously run in one of the profiles 43 and 44 and additionally on the longitudinal guide 48. Springs 45 and 46 are in addition provided at the actuating plungers 50 and 51 in per se known manner to provide compensation for contact burning. In the following, the function of the described components will be further described with respect to their interaction in the case of a switching over. For initiation of a load changeover from in each instance one fixed selector contact 4 to an adjacent other selector contact, the electric drive motor 10 is actuated and produces by way of the gear 12 two mutually independent movements of the two drive shafts 13 and 14. The rotational direction of each of the two drive shafts 13 and 14 depends on the direction the load changeover, i.e. on whether a changeover in the direction "higher" or in the direction "lower" takes place. The first drive shaft 13 executes, in each load switching-off, a rotation of 360 degrees and after a specific rotational angle the two Maltese drives 16 engage in the respective Maltese segments 6 and displace the carrier frame 7 and thus the respective movable contacts 8 and 9 in such a manner that one of the two movable contacts reaches the new fixed selector contact to be selected. In addition, there is provided in the gear 12 a freewheel, which is known per se and not illustrated more closely, of the first drive shaft 13, by which it is achieved that in the case of reversal of switching direction and thus reversal of rotational direction of the drive shafts the first drive shaft 13 and thus the Maltese drives 16 rotate not through the full 360 degrees, but only through a smaller angle in such a manner that no engagement of the Maltese drives 16 in these Maltese segments 6 takes place and thus also no movement of the movable contacts 8 and 9. This principle, which is conventional in tap changers, can also be explained on the basis of Figures 4 and 6: on the first reversal of switching direction the movable contacts 8 and 9 remain on the respective fixed selector contacts 4 which they have just contacted, whilst a biasing of the force storage device by the second drive shaft 14 and after the release thereof an actuation of the movable changeover contact 28 and the vacuum switching cells 34 and 35 takes place. In the case of multiple switching in the same direction, there against, the described freewheel is ineffective and initially the movable contacts 8 and 9 are brought into their new position before - again after release of the force storage device - the mechanical and electrical switching means are actuated. At the same time a second drive shaft 14 executes a rotation of 180 degrees and biases the pull-out slide 19. After complete biasing, the driven part 21 is released by latches, which are not illustrated in more detail, and abruptly executes a movement in horizontal direction. In that case the movement always takes place, in alternation, initially to the right and in the next changeover to the left, etc. This is based' on the fact that the driven part, after release, is always moved alternately into its lefthand or right-hand end position. The respective horizontal movement of the driven part 21 is transmitted by way of the driven coupling 22 to the actuating slide 23, which is similarly impelled on each occasion in alternation initially to the right and in the next changeover initially to the left. Not only the mechanical switching elements on the front side of the base plate 24, but also the vacuum switching cells 34 and 35 on the rear side of the base plate 24 are thereby actuated: on the front side of the base plate 24, the actuating pin 33 engages in the actuating groove 32 each time and pivots the movable changeover contact 28, which thereby interrupts the electrical connection of the first fixed contact 25 with the root contact 27 and, instead thereof, electrically connects the second fixed contact 26 with the root contact 27 and vice versa. As already explained, the two fixed contacts 25 and 26 are disposed in electrical connection by way of the two contact tracks 17 and 18 with the respective fixed selector contacts 4, which have just been actually contacted by the movable contacts 8 and 9, in such a manner that through the actuation of the movable changeover contact 28 a changeover from one movable contact 8 to the other movable contact 9 and thus from formerly contacted fixed selector contact to the new fixed selector contact takes place. On the rear side of the base plate 24, the roller guide 42, which similarly moves back and forth, actuates the vacuum switching cells 34 and 35 on each occasion through the profiles 43 and 44, which move with it and in which the rollers 40 and 41 of the actuating arms 38 and 39 are guided. , Through appropriate geometric shaping of the profiles 43 and 44, more specifically through the horizontal offset thereof, the actuating sequences are thereby accurately defined In addition, the already-explained locking plate 47 prevents, by its longitudinal guide 48, an undesired lateral pivoting out of the rollers 40 and 41 and thus of the entire actuating arms 38 and 39. In the figures to which reference was previously made, the electrical connections between the individually described components are not illustrated in every case. In Figure 1 there are illustrated merely the contact tracks 17 and 18 of each phase, which are electrically connected with the respective movable contacts 8 and 9 and in turn are each connected with a respective one of the two fixed contacts 25 and 26. The electrical connecting lines going to the fixed selector contacts 4, the vacuum switching cells 34 and 35, the fixed contacts 25 and 26, the root contact 27 and the load shunt are, for reasons of clarity, there against not illustrated. The electrical connection between the individually described components is apparent, with respect to the interrelationship, from Figure 5. Figure 6, finally, describes on the basis of the schematic circuit according to Figure 5 a load changeover, by way of example, from n-2 to n-1, more specifically the sequence of successive actuation of the individual components. The respective current-conducting parts of the electrical circuit are represented by thicker lines. As the arrangement of components exactly corresponds with that in Figure 5, the reference symbols are omitted in Figure 6 for reasons of clarity. A load changeover consists of the following successively elapsing switching steps: a) shows the initial situation, in which the fixed contact n-2 is connected. In this setting, the movable changeover contact 28 connects the first fixed contact 25 with the root contact 27 and produces the connection to the load shunt L by way of the closed first vacuum switching cell 34. The second vacuum switching cell 35 is open. b) the movable contacts 8 and 9 have moved in common; the movable contact 8 still remains at the fixed selector contact n-2, but the movable contact 9 has reached the new fixed selector contact n-1 to be connected. This is illustrated in Figure 4; a change in the circuit in the illustration relative to a) has thus not yet resulted. c) the second vacuum switching cell 35 closes and a part of the load current now additionally flows by way of the transition resistance 49. d) the first vacuum switching cell 34 opens and the entire load current now flows by way of the transition resistance 49 and the second vacuum switching cell 35. e) the movable changeover contact 28 is pivoted and now connects the second fixed contact 26 with the root contact 27. f) the first vacuum switching cell 34 is closed and takes over the load current; in addition, the circuit idle current now flows. g) the second vacuum switching cell 35 opens again and the load current now flows from the new fixed selector contact n-1 by way of the first vacuum switching cell 34 to the load shunt L; the new stationary setting is reached and the load changeover is concluded. The invention has been explained in the foregoing on the basis of a three-phase tap changer. Instead thereof, it is possible within the frame of the Invention to provide only a single-phase tap changer, in which then only one of the previously described three separate subassemblies, consisting in each case of fixed selector contacts 4, movable contacts 8 and 9, changeover switches 25, 26, 27 and 28 and two vacuum switching cells 34 and 35, is provided. Nothing is thereby changed at the circuit and the changeover sequence, even less so with regard to the mode and manner of actuation of the individual components by the first and second drive shafts 13 and 14. Patent Claims 1. Tap changer for uninten-upted switching over between different winding taps of a tapped transformer wherein fixed selector contacts, which are electrically connected respectively with the individual winding taps, are arranged along a line, wherein the fixed selector contacts are actuable by two movable contacts which are longitudinally displaceable, wherein two vacuum switching cells are provided as electrical switching means for each of the phases to be switched, wherein a drive is provided which is triggered on each actuation of the tap changer, and wherein a force storage device is provided which is biased by the drive and actuated after triggering of the electrical switching means, characterised in that the fixed selector contacts (4) respectively required for all the phases to be switched, the movable contacts (8, 9), the two vacuum switching cells (34, 35), all further switching and actuating means, the single drive (10) and the similarly single force storage device are arranged in a common housing (1), that the fixed selector contacts (4) of each phase are arranged in alternation in two parallel paths, that the two movable contacts (8, 9) of each phase are movable in common and without change in their position relative to one another, that each of the two movable contacts (8, 9) of each phase cones ponds with, respectively, the fixed selector contacts (4) arranged in one path, that each of the two movable contacts (8, 9) of each phase is electrically connected by a mechanical fixed contact (25, 26) of a changeover switch, the root contact (27) of which is connected with a load shunt (L) by way of a first vacuum switching cell (34), and that one of the two movable contacts (8) is similarity connected with the load shunt (L) additionally by way of a series connection of a transition resistance (49) and a second vacuum switching cell (35). 2. Tap changer according to claim 1, characterised in that a first drive shaft (13) and a second drive shaft (14) exit from the single drive (10), that ail movable contacts (9, 10) of all phases to be switched are continuously actuated in common each time by the first drive shaft (13), and that a pull-up slide (19) of a force storage device known per se is actuated by the second drive shaft (14), the driven part (21) of which force storage device after release abruptly actuates all changeover switches, which each consist of two fixed contacts (25, 26), the root contact (27) and a movable changeover contact (28), and ail vacuum switching cells (34, 35) of each phase, which is to be switched, in a predetermined switching-over sequence. 3. Tap changer according to claim 2, characterised in that all movable contacts (8, 9) are fixedly arranged on a common earner frame (7), that the fixed carrier frame (7) is constructed to be longitudinally displaceable in such a manner that the fixed selector contacts (4) can be scanned by the movable contacts (8, 9), that the fixed carrier frame (7) is connected at each of two sides with a respective Maltese segment (6), and that the first drive shaft comprises two Maltese drives (16) which each correspond with a respective one of the Maltese segments (6) in such a manner that through rotation of the first drive shaft (13) the cannier frame (7) and thus all movable contacts (8, 9) are movable vertically upwardly and downwardly through a fixed switching step. 4. Tap changer according to claim 2 or 3, characterised in that provided in the housing (1) is a base plate (24) which carries at its front side the changeover switch, which respectively consists of the two fixed contacts (25, 26), the root contact (27) and a movable changeover contact (28), for each phase to be switched and at its rear side the respective two vacuum switching cells (34, 35) for each phase to be switched, that the driven part (21) is connected with an actuating slide (23) following its abrupt movement after release and that the actuating slide (23) carries on its front side means for actuation of the movable changeover contacts (28) and on its rear side means for actuation of the vacuum switching cells (34, 35). 5. Tap changer according to claim 4, characterised in that the means for actuation of the movable changeover contact (28) consists of a respective actuating part (30) with an actuating pin (33), wherein the latter engages in a respective actuating groove (32) of the respective changeover contact (28) mounted to be rotatable about a bearing (29). 6. Tap changer according to claim 4 or 5, characterised in that the means for actuation of the vacuum switching cells (34, 35) consist of a respective roller guide (42), that each of these roller guides (42) comprises two profiles (43, 44), in each of which a respective roller (40. 41) is guided, and that each roller (40, 41) respectively acts by way of an actuating arm (38, 39) on an actuating plunger (50, 51) of a vacuum switching cell (34, 35). 7. Tap changer according to claim 4, 5 or 6, characterised in that the two rollers (40, 41) of each phase are each guided in a respective further vertical longitudinal guide (48) of a respective locking plate (47), which is fastened to the actuating slide (23), in such a manner that they are fixed in their vertical position relative to one another. 8. Tap changer according to one of the preceding claims, characterised in that the electrical connection between the respective movable contacts (8, 9) and the respective fixed contacts (25. 26) of the respective changeover switch is effected each time by electrically conductive contact tracks (17, 18) in such a manner that the movable contacts (8, 9) each wipe, by a respective free end, a respective one of the contact tracks (17, 18), i.e. are electrically connected. 9. Tap changer according to one of the preceding claims, characterised in that the movable contacts (8, 9) are dimensioned in their longitudinal extent in the direction of movement in such a manner that on common movement thereof in each switching step one of them reaches a respective new fixed selector contact (4) without the other one of them leaving the previous fixed selector contact (4). 10. Tap changer according to one of claims 6 to 9, characterised in that additional means for horizontal guidance of the actuating slide (23) are provided in such a manner that the roller guide (42) connected with the actuating slide (23) has an additional horizontal profile (53) in which a further roller (54), which is fixedly connected with the base plate (24), is guided. 11. Tap changer for uninterrupted switching over between different winding taps of a tapped transformer substantially as herein described with reference to the accompanying drawings.

Documents:

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in-pct-2001-670-che-abstract.pdf

in-pct-2001-670-che-claims filed.pdf

in-pct-2001-670-che-claims granted.pdf

in-pct-2001-670-che-correspondnece-others.pdf

in-pct-2001-670-che-correspondnece-po.pdf

in-pct-2001-670-che-description(complete)filed.pdf

in-pct-2001-670-che-description(complete)granted.pdf

in-pct-2001-670-che-drawings.pdf

in-pct-2001-670-che-form 1.pdf

in-pct-2001-670-che-form 19.pdf

in-pct-2001-670-che-form 26.pdf

in-pct-2001-670-che-form 3.pdf

in-pct-2001-670-che-form 5.pdf

in-pct-2001-670-che-pct.pdf