PUBLIC POWER CORPORATION ENGINEERING & CONSTRUCTION OF TRANSMISSION PROJECTS DEPARTMENT

Transcription

1 PUBLIC POWER CORPORATION ENGINEERING & CONSTRUCTION OF TRANSMISSION PROJECTS DEPARTMENT SPECIFICATION SS-25 / 14 POWER TRANSFORMERS 150/ kV, 40/50 MVA WITH AUTOMATIC LOAD-RATIO CONTROL CONNECTION Dyn1 ATHENS - GREECE ---*--- NOVEMBER 2000

2 -2- SECTION A BASIC TECHNICAL CHARACTERISTICS kV System Characteristics 1.1. Three phase system, 50 cycles per second Rated voltage : 150kV 1.3. Highest voltage : 170kV 1.4. Impulse voltage (1.2 / 50µs) : 750kV 1.5. Level of three phase short circuit current : 30kA at 170kV 2. Altitude 1000m. above sea level. 3. Type of Cooling OA/FA, Natural oil - Natural air / Forced air 4. Capacity Ratings kva Cooling Temperature Rise o C (40 o C max. ambient, 30 o C average over 24 hours) continuous 40,000 * self 55 o C * (1) (average by resistance) 50,000 * Forced air 55 o C * (1) (average by resistance) * Items throughout this Specification designated by this symbol are basis of performance guarantees. (1) 65 o C temperature rise can also be accepted under the condition that the manufacturer will provide evidence that the insulating materials used are suitable to meet this requirement.

3 -3-5. Rated Voltage and Winding Connections 5.1. TABLE 1 Rating of windings and taps High Voltage ( H ) in Volts Medium Voltage ( M ) in Volts Rated kva 40,000 * 40,000 * Rated Voltage line-to-line Volts 150,000 * 15,750 * No load or 21,000 * No load Winding Volts (for wye operation) 9,100 and 12,120 Connection D yn1 Insulation Class in kv Line Neutral Line Neutral of windings of bushings (I) Transformers shall have an over-voltage capability of 10% at no load and 5% above rated secondary voltage at rated kva without exceeding the limiting temperature rise at load power factor of 80% or higher. (I) For bushings specification refer to pages 7, 8 and 12.

4 TABLE 2 ON LOAD TAP CHANGER WITH (17) SEVENTEEN POSITIONS (OLTC) Other voltages (Taps) at rated capacity. Voltage regulation 150kV + 7.5% % in steps of 1.25% , , , , , , , V ,125 or , V ,375 No Load , , , , , , ,250 If an OLTC is offered, which is not known and have not been used in the past by PPC (known and tested OLTCs are these of MR's, AEG's, ABB's, ELIN's and ELPROM's) then, the following two conditions must be met, providing of course, that it is acceptable otherwise by PPC. a. A guarantee period of four (4) years for OLTC damages or damages to the transformer due to OLTC malfunctioning must be provided. b. A single phase OLTC must be given free of charge for an order of up to fifteen (15) transformers and two (2) single phase OLTC, if the order is for more than fifteen (15) transformers. 6. No-load tap changer The power transformer will be equipped in addition to the on-load tap changer, with a manually operated by external hand-weel two position no-load tap changer, so arranged as to give two nominal low voltage ratings, namely and 21 kv at will. No-load tap changer is considered to be operated de-energized.

5 -5-7. Transformer s Core Type Three (3) - limb core 8. Angular Displacement and Required Transformer Arrangement The angular displacement shall be as in sketch given herebelow i.e. connection group Dyn1. The H.V. vectors shall lead the L.V. vectors by 30 degrees. The transformer arrangement shall also be as indicated below. R R R H1 H2 H3 G E C max 6m. X0 X1 X2 X3 G R R R Maximum distance 8,5 m. H2 H1 H3 The height of the transformer including the conservator tank shall not exceed 9 meters. X2 X1 Xo X3 (H) - High voltage bushing (X) - Low voltage bushing (C) - Conservator (G) - Grounding Terminals (R) - Radiators (E) - Cooling control cabinet Notice: The arrangement shown for the radiators is not obligatory. Manufacturers may propose their own standard arrangement. 9. Maximum Efficiency Maximum efficiency is desired at approximately the following load: 34,000 kw (Refer to evaluation of losses).

6 Noise Level It is required that transformers shall have audible sound levels not exceeding the values given in the latest NEMA standard TR Impedance Voltage The impedance voltage between H.V. winding and L.V. winding shall be not less than 15.2% at kva at any tap of the on-load tap changer (O.L.T.C.). 12. No-Load Current No-load current shall be as possible consistent with economical design. Percent no-load current shall not exceed 12 times the specified percent no-load loss under sine wave excitation at rated voltages and frequency and shall not increase more than 2 1/2 times this value at rated frequency and 110 percent (110%) rated voltage. 13. Tap Changing Mechanism On-load tap changer (O.L.T.C.) of the resistance type with transfer switches, selector switches and reversing switches for voltage regulation from +7,5% to -12,5% in steps of I,25% or smaller. The O.L.T.C. shall be on the High Voltage side of the transformer. The transfer switches shall be placed in a separate oil tank. The O.L.T.C. shall be motor operated controlled by an automatic loadratio control system supplied by seller consisting of the necessary current transformers, voltage regulating relay, line-drop compensator etc. Available D.C. supply: 110 V. Available voltage supply: substation voltage transformer 15000/100 V 20000/100 V The line-drop compensator shall have two elements X and R for reactance and resistance compensating. Both of these elements shall be adjustable to obtain values corresponding to the voltage drop in the 15 or 20 kv primary distribution lines. To avoid excessively frequent operation of the O.L.T.C. a time delay device is necessary to be provided with possibilities of adjustment from 10 to 100 sec. A step by step device must be incorporated in the control circuit to ensure one tap-change only, even when the control switches are held continuously in the 'ON' position. The O.L.T.C. shall be equipped with auxiliary contacts for remote position indication as well as with an operation counter. Provision shall be made for a switchboard change over switch with at least (3) three positions i.e. (a) OFF, (b) automatic load ratio control, (c) remote-local manual load-ratio control.

7 -7- The motor drive mechanism of the O.L.T.C. shall be fed by three (3) phase voltage 220/380V, 50Hz. The motor and the O.L.T.C. mechanism shall be protected through a circuit breaker against overload, under voltage and loss of one 220/380V phase voltages. The O.L.T.C. mechanism shall be protected by a suitable earthquake proof Buchholz relay. If a sudden interruption of the current feeding the motor occurs, the switch must not stay between two positions. All relays, switches, fuses etc., of the O.L.T.C. shall be mounted in a weather-proof control cabinet mounted on transformer. A heat resistance shall be provided in the cabinet supplied by 220V A.C. and controlled by a thermostat. 14. Over-voltage Capability The transformer shall have an over-voltage capability of 10% at no-load and 5% above rated secondary voltage at rated kva without exceeding the limiting temperature rise at load power factor 80% or higher. 15. Winding Temperature Equipment The following temperature equipment shall be furnished with the transformer One thermal replica relay, AKM type of Sweden supplied from a current transformer on the low voltage bushing X1 and consisting of heating coil and dial type thermometer with maximum pointer and with at least two (2) normally open adjustable contacts, one for starting the fans and one for tripping One thermal replica relay, AKM type of Sweden supplied from a current transformer on the low voltage bushing X3 and consisting of heating coil and dial type thermometer with maximum pointer and with at least two (2) normally open adjustable contacts, one for giving alarm and one for tripping. The thermal time constant of the above thermal replica relays should match the Transformer thermal time constant. 16. Bushings For terminals HI, H2, H3, MICAFIL of Switzerland, type CTF (Guaranteed by manufacturers for BIL 750 kv and chopped wavespeak value 865kV, 3µs time to flash-over. Minimum creepage distance 4,000mm). Other H.V. bushings equivalent and fully interchangeable to those of MICAFIL may, also, be accepted at Purchaser's option (F+G, ABB, HAEFELY, PASSONI & VILLA). The low voltage bushings (X1, X2, X3, X0) shall have BIL = 150kV and creepage distance > 600mm.

8 Bushing Current Transformers TABLE 3 Terminals Number Ratio Accuracy & Burden H1, H2, H / 1 X1, X H1, H2, H /1 X VA, ANSI 2.5L 500, (1) for relaying (1A rated secondary current). As required for thermal replica relays supply. 50VA, ANSI 2.5L 1000, (1) for relaying (1A rated secondary current). As required for the automatic load ratio control. (1) Accuracy class 5P20, according to IEC Standards, is also acceptable. 18. Spill Gaps TABLE 4 On Terminals Spill gap adjustment (inches) From To Factory Setting H1, H2, H X1, X2, X Total gap distance specified for X1, X2, X3 is made up by two gaps in series. 19. Terminal Clamp Connectors TABLE 5 Terminals Suitable for Direction Take-off H1, H2, H3 185mm 2 stranded copper conductor Vertical X1, X2, X3 80mm tube Horizontal Terminals shall be provided with flexible clamp connectors.

9 Other Required Manufacturing Features and Particulars of the Transformer. a. Transformer shall be equipped with necessary fans, conduit, wiring and control for automatic operation of forced air equipment through the action of the winding temperature device. Provision for manual control shall be made. b. Oil level gauge shall be provided with low oil level alarm contacts. Oil temperature indicator shall be provided with hot oil alarm and trip contacts and shall be so arranged as to give correct indication of temperatures above the contact position. Alarm and trip contacts shall be ungrounded. c. Transformer shall be provided with an earthquake proof Buchholz relay similar to type 10 of VEM. GERMANY, with electrically separate alarm and tripping contacts. The on-load tap changing mechanism shall be also protected by an earthquake proof Buchholz relay similar to type: RS.2001 of Reinhausen. d. All small wire connections from alarm contacts, temperature indicating coils, current transformers, control and other devices, shall be brought to terminal blocks in the cooling control cabinet from which control cables to the control room are be connected. All wiring shall be color coded, moisture resistant wire in galvanized steel conduit. All terminals shall be suitably identified. Cooling control cabinet shall be provided with heat resistance controlled by suitable thermostat. All L.V. control circuits shall be tested with 2kV RMS voltage for 1min. and all C.T. secondaries with 2.5kV RMS voltage for 1min. e. Tank shall be of the "BELL TYPE" with bolted flange connection to the transformer bottom, and suitable for filling with oil under a vacuum of 28'' of mercury. f. Gasketed joints for bushings, manholes and radiators shall be designed so that the gasket will not be exposed to the weather and shall be provided with mechanical stops to prevent crushing of gasket. Recessed corprene (or equivalent) gaskets are preferred. g. Transformer shall be completely self contained, conservation, radiators, cooling fans, air ducts or accessories shall be supported by the transformer tank or sub-base and shall not require separate foundations or support. h. Radiators shall be detachable and tank connections shall be provided with valves, so that radiators may be removed without draining oil from tank. Each radiator shall be provided with lifting eyes and drain valves or plugs. A filling plug shall be provided at the highest point of the upper radiator header.

10 -10- i. The radiators shall be attached and supported only by the body of the transformer. j. Transformer shall be suitable for platform mounting with swivel wheels of narrow flange suitable for moving the transformer filled with oil. The wheels shall be of a type and shall be so arranged that they can be rotated 90 degrees for changing the direction of transformer's motion. The rail gauze shall be 1435mm between rails. k. The tanks of the transformer shall have jack bosses and lifting lugs suitable for handling the entire weight of the transformer with oil and shall have pulling eyes or other arrangement for attaching pulling rig for moving the transformer. l. Transformer must be designed for possible transport by railroad in a low bed railroad wagon providing all clearances required by continental railway systems. m. Transformer shall be shipped with core and coils assembled in the tank filled with oil. n. The transformer tank must be equipped with a sudden pressure relief device. o. Oil conservators or expansion tanks shall be of rugged design and of sufficient capacity to maintain an oil seal through a temperature range of 100 o C. Each such tank shall be equipped with a silica gel breather and a pump with a drain valve. Pipe connection between main transformer case and conservator or expansion tank shall include the above mentioned gas operated relay of Buchholz type, a shut off valve, and shall be arranged with a flanged joint of pipe union connection between main transformer base and shut off valve. The shut-off valve may be omitted where the conservator has a capacity less than 55 u.s. gal of oil. Mounting shall permit removal of conservator or expansion tank. p. Filtering connections shall be of 2'' gas thread internal diameter. Two filtering connections shall be provided. q. Transformers shall fulfill all requirements of this specification in continuous operation, when filled with oil in good condition, of qualities commonly accepted for transformer insulation oil in accordance to the latest IEC Standards, non-toxic and biodegradable (without PCB s etc.) and damage to the environment. Transformers shall be furnished complete with oil. r. The H.V. bushings shall be provided with a capacitance tap for power factor testing. The L.V. bushings shall not be provided with such taps. s. The fans shall be mounted on the radiators of the transformer. t. All cables must be located on the transformer body.

11 Tests Standard withstand voltages Impulse tests (Refer to ANSI C Impulse tests shall be made on each unit ordered and shall precede the low voltage frequency tests. The standard impulse test consists of applying on H.V. and L.V. winding line terminals H1, H2, H3 and X1, X2, X3 and in the following order one reduced full wave, two chopped waves and one full wave using a 1.2/50 microseconds wave of negative polarity, the O.L.T.C. being on the /21kV position for the H.V. side tests and on the /21kV position for the L.V. side tests. - Reduced Full Wave: For this test, the applied voltage wave shall have a crest value between 50 and 70 percent of 750kV for the H.V. terminals and 150 kv for the L.V. terminals. - Chopped wave: For this test the applied voltage wave shall be chopped by a suitable air gap. It shall have a crest voltage 865kV for the H.V. terminals and 175kV for the L.V. terminals and time to flash-over not less than 3 microseconds respectively. - Full wave: For this test, the voltage wave shall have a crest value 750kV for the H.V. terminals and 150kV for the L.V. terminals and no flash-over of the bushing or test gap shall occur Impulse tests on transformer neutral (on each unit ordered) The test on the neutral shall precede the test on the line terminals. The test consists of applying on the neutral terminals Xo and in the following order one reduced full wave and two full waves of 150kV crest value Applied voltage tests (on each unit ordered) (1 min. 50 c.p.s.) - H.V. winding 325kV - L.V. winding 50kV Induced potential test (on each unit ordered) The induced potential test shall be made by applying between the terminals of the low voltage winding 42kV r.m.s. 120 cycles for 60 sec., or equivalent 6000 cycles test, the O.L.T.C. being on the /21 kv position.

12 Bushings (Type Test) a) Insulation class H.V. : 161 kv L.V. : 25 kv L.V. Neutral : 25 kv b) 50 cps. 1 min Dry Withstand Test H.V. : 385 kv L.V. : 70 kv L.V. Neutral : 70 kv c) 50 cps. 10 sec. Wet Withstand Test H.V. : 315 kv L.V. : 70 kv L.V. Neutral : 70 kv d) Full wave Impulse Withstand Test (1.2/50 microsec. wave) H.V. : 750 kv L.V. : 150 kv L.V. Neutral : 150 kv The values under b, c and d are understood to apply to separate tests of bushings (not mounted on transformer) Temperature tests Temperature tests shall be made according to ANSI standards on one unit of each type when one or more units are ordered Corona discharge Test (Measurement or partial discharges) A corona discharge test shall be made during the induced potential test specified in paragraph on each unit ordered. There shall be no evidence of internal corona at rated voltage and the RIV (Radio Influence Voltage) of the full test voltage shall not exceed 500 microvolts. Ultrasonic methods may be used to determine the source of any significant corona Noise Level Test Noise level test shall be carried out according to ANSI C57.12 standard on one unit of each order.

13 Manufacturer s Drawings The Seller shall furnish (3) three copies for approval and (5) five copies as well as one (1) transparency of final drawings at or before the time of shipment of the following: a. Assembled transformer outline drawing b. Bushings outline drawing c. Nameplate drawing d. Cooling circuit control wiring diagram e. Current transformers control wiring diagram f. Current transformers characteristic curves showing open circuit secondary saturation, ratio and phase angle correction. g. Detailed arrangement and mounting of spill gaps. h. Instruction manuals covering installation, operation and maintenance. i. Terminals. j. Automatic load-ratio control system operation diagram and detailed wiring diagram. 23. Photographs Five (5) copies of photographs (21x28mm) with binding edge on the 28mm dimension, shall be furnished at or before the time of shipment for the following views: Side and Top Tanked and untanked Fully Assembled 24. Data to be Supplied by Bidder Bidders are required to submit, attached to their offers, outline drawing showing overall dimensions of the complete transformer as well as any information sketches and data for a complete description of the proposed equipment. In addition Bidders shall supply all technical data requested in SECTION B "INFORMATION BY SELLER" attached hereto, as well as any proposed departures from the present Specification and the reasons therefore. Submission of SECTION B incomplete shall constitute sufficient ground at the option of Purchaser for rejection of the offer.

14 Spare Parts for Transformers Bidders should quote the following spare parts giving item prices: Item No. D E S C R I P T I O N 1. One high voltage bushing complete. 2. One low voltage bushing complete. 3. Complete set of gaskets for all bushings, covers, radiator flanges, manholes and hand-holes for one transformer. 4. Cooling fan and motor set. 5. Set of replacement parts for each type of part likely to be damaged upon operation of the relays, contactors, instruments, safety devices etc. 5a. Automatic Voltage regulation relay. 6. Set of replacement parts for the O.L.T.C. likely to be damaged during operation (Complete set of arcing contacts for the transfer switch etc.) to be listed in detail and prices given separately. 7. Set of replacement parts for the load-ratio control system. 8. One complete set of H.V. and L.V. winding for one phase. The windings shall be adjusted in height with end insulating disks ready for installation, delivered in tank with oil. The Purchaser reserves the right to determine, when signing the Contract, the spare parts which Seller shall furnish on the basis of the prices set forth in his proposal. For this reason it is imperative that all offers should include the item price of each spare part. Otherwise the Purchaser reserves the right to reject the offer.

15 Packaging of transformer accessories The transformer accessories must be packed inside robust wooden boxes of maximum gross weight of five (5) tons. The above requirment does not include the bushings of the transformer, which must be packed separately, one bushing per one wooden box.

16 -16- SPECIFICATION SS-25 / 14 POWER TRANSFORMERS 150/ kV, 40/50 MVA WITH AUTOMATIC LOAD-RATIO CONTROL SECTION B Information by Seller 1. Type of transformer (short description) : Transformer s Power without operation of cooling fans :. * MVA 3. Transformer s Power with operation of cooling fans :. * MVA 4. Transformers connection :.. 5. Core type :.. 6. No-load ratio at principal tap No. 7 of the on-load tap changer :.. 7. Performance data (shall be guaranteed by Seller as follows) : 7.1. Voltage i. at rated voltage 15.75kV ii. at 110% rated voltage i. at rated voltage 21kV ii. at 110% rated voltage No-Load Loss (Watts) * Exciting Current % of Rating kva (40,000) * The No-Load Losses (Watts), measured after impulse tests shall be considered as basis for the performance guaranteed Total losses and impedance at principal tap 150/21kV

17 -17- (not including cooler equipment power requirements) a. Winding loaded from 150kV to 21kV. Load kva Total loss kw * (1) Impedance % * (2) 50,000 40,000 30,000 20,000 b. Winding loaded from 150kV to 15.75kV. Load kva Total loss kw * (1) Impedance % * (2) 50,000 40,000 30,000 20,000 (1) No tolerance above stated values. For penalties see page 21. (2) Tolerances provided by IEC publ. 76 are permitted on the condition that no impedance voltage at any tap shall have an actual value less than 19% at 50,000kVA. In case the actual impedance voltage is less than 19% at any tap the transformer shall be rejected Copper Losses The guaranteed values of copper losses refer to 85 o C. 8. Windings temperature rise (for ambient temperature 40 o C) a. Self cooled at 40,000kVA :. O C * b. Forced air cooled at 50,000kVA :. O C * 9. Approximate cooling requirements a. Forced air (total for fans) :.. kw b. Number of coolers :.. c. Fan power : kw per cooler d. Pump power : kw per cooler e. Total required power for the cooling system :.. kw 10. On-load tap changer (O.L.T.C.)

18 -18- a. Number of positions :. b. Voltage difference between steps :.. V c. Nominal current of O.L.T.C. :.. A d. Type of O.L.T.C. and manufacturer s name : Bushing current transformers (Ratio, accuracy class and burden) a. On terminals H 1, H 2, H 3 :.. b. On terminals X 1 and X 3 :.. c. On terminal X 2 : High voltage insulators (Type, B.I.L., rated voltage and current, creepage path etc.) : Low voltage insulators (Type, B.I.L., rated voltage and current, creepage path etc.) : Spill gap adjustment : a. On terminals H 1, H 2, H 3 : from.. to.. b. On terminals X 1, X 2, X 3 : from.. to Flexible clamp connectors (included in the supply) : Tests (acceptance of specified tests) : Impedance voltage for 50MVA a. At tap position 1 :. % b. At tap position 17 :. % 18. Flux density at rated voltage : Maximum permissible short circuit duration : 5... sec. 20. Noise level (It is specified that transformers shall have audible sound levels not exceeding the values given in NEMA standards for transformers, last publication) : Full-load regulation a. at rated service and p.f. = 1 :.. b. at p.f. = 0.85 : Efficiency

19 -19- a. at 150 / 15.75kV p.f. = 1 p.f. = 0.85 at 50,000kVA at 40,000kVA at 20,000kVA at 10,000kVA b. at 150 / 21kV p.f. = 1 p.f. = 0.85 at 50,000kVA at 40,000kVA at 20,000kVA at 10,000kVA 23. Over-voltage capability a. at no-load :.. b. at rated kva : Type of tank (to be described by Bidder in tender) : Supervisory and protection equipment (to be listed by Bidder in tender) : Construction drawings of the transformer : Net weights and dimensions - Core and coils :.. kgs - Case and fittings :.. kgs - Oil :.. kgs - Total weight including bushings, radiators (coolers) and conservator tank :.. ton - Untanking weight (heaviest piece) :.. kgs - Over-all height :. m - Height over case :. m - Untanking height (with H.V. bushings, without lifting beam) :. m - Projected floor dimensions related to line through H.V. bushings :

20 -20- Parallel to :. m Right angles to :. m 28. Approximate shipping weights - Normal method of shipment (in oil or gas) : in oil.. - Heaviest part to handle, if shipped in oil :. kgs. - Total shipping weights, if shipped in oil :. kgs. 29. Approximate shipping Specification - Transformer in tank with oil : m 3 - Accessories shipped separately : m Are the radiators attached and supported by the body of the transformer? : Are the fans mounted on the radiators? : Exceptions, if any, to the present Specification and the reasons thereof :......

21 -21- SPECIFICATION SS-25 / 14 POWER TRANSFORMERS 150/ kV, 40/50 MVA WITH AUTOMATIC LOAD-RATIO CONTROL SECTION B Information by Seller ANNUAL COST Transformer rating kva : 40,000 / 50,000 Basic loading kva : 40,000 Basic loading kw : 34,000 Transformer first cost (The transformer total first cost will be computed by the Purchaser who will consider the Seller C+F price, as amended after the evaluation of the proposed terms of payment. This cost will also include the corresponding custom duties, proportion of the spare parts required and any other charge which Purchaser will consider necessary). : k =... No-load loss (at rated voltage 150/21kV) : A = kw Copper loss at 40,000kVA (windings loaded from 150 to 21kV) : B = kw Total loss : A + B = kw Transformer annual cost 1. Transformer carrying charges (at 9.37 per cent) : 937. k = Capacity loss (at 83,30 per kw-year) : 83,30. (A+B) =.. Energy loss ( per kwh) a. No-load loss for 8760 hours : A =... b. Copper loss (Load factor 50%, Loss factor 30%, Loss hours 2630) : B =..... Total annual cost : (the Sum) =....

22 -22- SPECIFICATION SS-25 / 14 POWER TRANSFORMERS 150/ kV, 40/50 MVA WITH AUTOMATIC LOAD-RATIO CONTROL SECTION B Information by Seller Penalty for excess losses With regard to load and no-load losses, a transformer is considered as successfully inspected if the losses ascertained during inspection do not exceed the maximum tolerances specified in the IEC standards, versus the losses guaranteed by Seller. Otherwise the transformer is rejected. On each successfully inspected transformer, any difference in the losses versus the guaranteed ones (without tolerance), shall be negative or zero. If such difference is positive, i.e. the losses ascertained during inspection exceed the guaranteed ones (without tolerance), a penalty shall be imposed on Seller consisting of : ,63 per kw of no-load losses in excess ,73 per kw of load losses in excess The corresponding amount for excess load losses shall be balanced by the corresponding amount for reduced, if any, no-load losses and vice-versa. However if this algebraic sum is negative the Seller is not entitled to any additional payment, whilst if this sum is positive the penalty shall be imposed. AA/CV/October 1981 AA/CV/August 1985 CV/DL/March 1989 AA/CV/γπ/JULY 1990 AA/CV/GP/JULY 1991 CV/em/JULY 1994 CV/ak/NOV AG/ak/May 1996 KV/ak/December 1997 SS-25/13 / KB/ak/July 1998 SS-25/14 / AG/ak/October 1999 SS-25/14 / AG/sk/Noevember 2000