EP0783198A1 - Détection de la formation de gaz de décomposition dans les transformateurs - Google Patents

Détection de la formation de gaz de décomposition dans les transformateurs Download PDF

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Publication number
EP0783198A1
EP0783198A1 EP96100103A EP96100103A EP0783198A1 EP 0783198 A1 EP0783198 A1 EP 0783198A1 EP 96100103 A EP96100103 A EP 96100103A EP 96100103 A EP96100103 A EP 96100103A EP 0783198 A1 EP0783198 A1 EP 0783198A1
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EP
European Patent Office
Prior art keywords
temperature
pressure
volume
contact
liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP96100103A
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German (de)
English (en)
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EP0783198B1 (fr
Inventor
Jürgen Bastian
Anne Isobel Bastian
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Individual
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Individual
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Publication date
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Priority to DE59600566T priority Critical patent/DE59600566D1/de
Priority to AT96100103T priority patent/ATE171314T1/de
Priority to EP96100103A priority patent/EP0783198B1/fr
Priority to US08/771,842 priority patent/US5900538A/en
Publication of EP0783198A1 publication Critical patent/EP0783198A1/fr
Application granted granted Critical
Publication of EP0783198B1 publication Critical patent/EP0783198B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/02—Details
    • H01H33/53—Cases; Reservoirs, tanks, piping or valves, for arc-extinguishing fluid; Accessories therefor, e.g. safety arrangements, pressure relief devices
    • H01H33/55—Oil reservoirs or tanks; Lowering means therefor
    • H01H33/555—Protective arrangements responsive to abnormal fluid pressure, liquid level or liquid displacement, e.g. Buchholz relays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/26—Details
    • H01H35/28—Compensation for variation of ambient pressure or temperature

Definitions

  • Whether a fault current occurring in a transformer can be detected and which methods and devices can be used depends mainly on whether, based on the respective type of construction, the fault current has a detectable effect and whether a temporary or permanent effect appears as a fault can kick.
  • a further limitation is the delay in response, which is due to the fact that cracked gas bubbles can only be detected with a time delay by means of a gas collecting container, which has led to the inclusion of pressure wave sensitivity for error detection.
  • Buchholz relay in its function as a pressure wave detector.
  • the Buchholz relay has a damage-reducing rather than a damage-preventing role: switching off the transformer generally prevents the bursting event, but does not always avoid damage to the transformer itself.
  • the listed devices for fault indication have in common that they should or can either indicate fault currents in a late phase of their escalation or else unusual operating states, in particular overload.
  • the pressure measurement could be reduced to the normal operating pressure, i.e. refer to the constant temperature that causes it.
  • the monitoring of the pressure would therefore be particularly easy to carry out, since every pressure increase would indicate an error, each pressure drop would indicate a leak.
  • Construction-specific, optimal use of legal relationships as a general aim of the invention temperature-related volume monitoring in breathing and gas cushion transformers; Temperature-related pressure monitoring with hermetic transformers.
  • the breathing transformer with expansion tank is mechanically moved, preferably the measurement technology for the integrally filled hermetic transformer.
  • the respective liquid volume is related to the temperature that alone determines this volume in undisturbed operation.
  • the method can also be used for the gas cushion transformer. With the latter type, however, the method of temperature-related pressure monitoring can also be used with restrictions.
  • the respective pressure in the liquid can be related to the respective temperature with this type of transformer, as detailed below.
  • the method is particularly suitable for the integrally filled transformer, since with the same elasticity of the boiler and the exclusion of falsifying factors, the pressure increase in this case is greater than that of the gas cushion. If the temperature and volume remained the same, the pressure would be constant, and the measured pressure value only had to be compared with the value of the last measurement, with no temperature or volume reference being necessary.
  • DGPT d éte Frankfurt g az / p ression / t empérature for monitoring - optionally - gas development, pressure or temperature with a single one Device
  • function-like devices for the protection of transformers of various designs.
  • the present invention enables a low-current fault to be detected and developed. According to the prior art, the detection of high-current errors or the issuing of a warning signal or the shutdown which takes place is effected by various devices, various principles being used.
  • the present invention is a supplement to these devices. It is primarily about recognizing low-current, non-high-current, errors aligned. Since there is agreement that a current-causing fault only occurs very rarely without it having been preceded by a low-current fault - assuming that the fault has its origin in a defect on the transformer side - the invention is intended to detect the low-current fault which avoids current-causing faults will.
  • the invention described below mainly relates to integrally filled transformers.
  • the non-mechanical variant (claims 4-6) can only be used in other hermetic transformers if there are influences causing false indications, e.g. strong sunlight can be excluded.
  • points 1 and 2 relate generally to the aim of the invention and construction, point 3 relates only to the non-mechanical variant.
  • the composition of the cracked gases is determined by the type of fault and the liquid, and since different gases dissolve at different speeds in different insulating liquids, different faults are detected at different speeds, but basically within the escalation that can be processed by measurement and switching technology and well below the threshold a fault current in which the current-limiting fuses would operate.
  • FIGS. 1 to 3H The constructive implementation of the utilization of the principle for diagnostic and damage prevention purposes using simple mechanical devices is shown schematically in FIGS. 1 to 3H.
  • Numeral 1 denotes a floating piston, numeral 1a a bellows analogous to this. Floating pistons and bellows determine the direction of movement of the volume-dependent contact element A.
  • Numeral 2 denotes a temperature-driven (temperature-dependent) component, for example a bimetal element, which is used for the direction of movement of the temperature-dependent contact element B in Fig. 1 / H / i or B 1 and B 2 in the other schematic drawings.
  • Numeral 3 in Fig. 2 / E represents the connection to the expansion vessel.
  • Numeral 4 in Fig. 3 / N 2 indicates an oil leak.
  • Number 5 represents the transformer tank cover of a hermetic transformer.
  • 1, 1 / H and 1 / H / i show the undisturbed operation of an alternately loaded transformer.
  • the volume of the liquid is determined solely by the respective average temperature of the liquid; while maintaining the distances to B 1 and B 2, the contact element A moves upwards when heated and downwards when cooled.
  • Fig. 1 / H / i causes the direction of equality of the two contact elements to the continuous contact between the two contact elements (in analogy state inversion, due to the I of the contact elements B 1 and B 2 ntegration in B).
  • Fig. 2 / E and 2 / H of the accident is shown in each case reformed gas formation due to leakage or arc: the temperature un-dependent increase in the volume causes Berühung of the contact elements A and B 1 caused thereby alarm or the transformer is switched off .
  • Fig. 2 / E schematically illustrates the operation of a transformer with E xpansionsgefäß, Fig. 2 / H in H ermetiktransformator represents.
  • FIG. 3 / N 2 and 3 / H the liquid loss fault is shown, with FIG. 3 / N 2 showing the mode of action in an nitrogen-loaded, FIG. 3 / H in an integrally filled hermetic transformer.
  • Fig. 1 / H / i shows the constructive and the respective state of the contact elements defining a consequence of the I ntegration of the contact elements B 1 and B 2 in B.
  • the float or floating piston 1 When the mean operating temperature and thus the liquid volume increase, the float or floating piston 1 is pushed upwards and pulls the contact plate (contact element A) upwards; at the same time, the rise in the mean operating temperature with the appropriate design and location of the bimetal element 2 causes the associated contact elements B 1 and B 2 to move upward at the same speed and while maintaining the spacing of the contact elements from one another.
  • the bimetal temperature sensor 2 is therefore to be placed so that the temperature prevailing there is the average temperature of the insulating medium. If the average operating temperature falls, the process proceeds in the opposite direction (Fig. 1, Fig. 1 / H).
  • contact A and B 1 will close a circuit (Fig. 2, Fig. 2 / E, Fig. 2 / H). If the volume does not decrease as a result of a leak (Fig. 3, Fig 3 / N 2 , Fig. 3 / H) the contacts A and B 2 move towards each other until they touch and the circuit is closed, whereby, as in the case of contacting A and B 1, an alarm is triggered or the switch-off of the transformer is effected.
  • the sensitivity of the temperature-related volume monitoring depends on whether the prevailing conditions are actually recorded. In particular, it must be ensured that the formation of fission gas increases the volume of the floating piston or the bellows bottom. In addition, false triggering due to vibrations and changes in the properties of the equipment (aging) must be excluded.
  • a plunger actuated directly or indirectly by a movable piston in a gas cylinder could be used (applies to contact elements B 1 and B 2 , or B in 1 / H / i).
  • Volume changes of the integrally filled hermetic transformer can only be used diagnostically if either the volume changes are recorded as pressure changes or a design change is carried out which provides the temperature-dependent contact element with a volume-dependent correspondence.
  • a bellows 1a with a tension and compression spring, which extends from the underside of the cover 5 into the transformer and is closed on the oil side and is open or closed to the outside (the version which is closed to the outside is shown), the movements of which are so coordinated that they represent the temperature-related volume changes, which leads to a uniform movement of the three contact elements or two contact elements in Fig. 1 / H / i.
  • the ratio of bellows height: bellows width and the choice of spring force must be determined empirically, especially since the volume and pressure ratios bring about a slight shift by introducing the bellows and the resulting change in volume. (Without a tension and compression spring, an inelastic bellows would assume an undesirable position due to the buoyancy.)
  • sack-like structures equipped with a tension and compression spring would also be conceivable, whereby weldable plastics, possibly as laminates with a gas barrier layer, could be used.
  • a closed version of a bellows can also be used.
  • the use of a tension and compression spring is not absolutely necessary in the case of a gas-tight bellows that remains in a vertical position, but because of the tendency of the gas to advance the volume expansion of the liquid, it has a compensatory and corrective-stabilizing effect and thus enables tighter tolerances.
  • the version with an open bellows is preferred.
  • the opening must be protected from environmental influences, for example by fitting a U-shaped tube that is curved downwards and sealed against the transformer cover.
  • Transformers that are not integrally filled are generally characterized by low elastic and plastic deformability. However, if plastic deformation occurs, it is essential to re-calibrate to avoid false triggering due to the apparent decrease in liquid volume.
  • the ideal internal pressure variable hermetic transformer is not plastically deformable and can be deformed indefinitely. Plastic deformations due to overpressure and material fatigue can occur in real hermetic transformers. Plastic deformations are generally considered to be irreversible. It is theoretically possible to fill a hermetic transformer so that there is overpressure at all temperatures. Plastic deformations limit elastic deformability. They are fundamentally undesirable and can be reduced to a minimum by appropriate design measures. It will in the following, however, because they cannot be excluded in principle.
  • the proportion of the transformer internal volume increase attributable to the plastic deformation causes a slight reduction in the target pressure. This depends on the type of construction and the load cycles. The more rigid the transformer, the less plastic and elastic deformation and the greater the pressure fluctuation. In a transformer in which, for example, the cooling fins and tank are made of die-cast aluminum and form a whole, the plastic deformation can be neglected. Plastic deformation is known to transformer operators; when it occurs, it requires refilling one or more times with small amounts of the respective insulating liquid in order to restore the target delivery pressure. (Normally this is not done, since the restoration of the delivery condition target pressure is only desirable for test purposes.) Therefore, the corrected target pressure curve p ' should be created depending on the plastic deformation.
  • the corrected setpoint pressure curve describes the course of the transformer internal pressure as a function of the mean temperature of the insulating liquid and the elastic deformability of the transformer, the total volume increase as a result of the temperature increase being taken into account.
  • the corrected desired pressure curve (p 'should) be determined empirically or (electronic) to create due to temperature-related pressure measurements over again when a drop in the actual pressure at the insufficient kompensieten desired pressure values gives (p set ⁇ p' to ⁇ p '' to , etc.). In practice, depending on the load cycle extremes and choice of materials, this case will occur rarely or frequently.
  • the location and number of temperature measuring points must be determined empirically, except in the event that the representativity of the temperature measured in the thermometer pocket of the transformer or at another location which is favorable in terms of measurement technology is ensured for the mean temperature of the insulating liquid.
  • a correction factor may have to be taken into account. The latter is type-specific and can therefore only be determined empirically. The smaller the transformer, the smaller the temperature differences in the liquid in it - provided there is sufficient possibility of convection.
  • Temperature-related volume monitoring (claims 1 to 3) has no disadvantage compared to conventional mechanical monitoring of pressure and / or temperature (e.g. patents from Smith and Sangster) due to the fact that it functions purely mechanically.
  • the disadvantage is compared to the metrological-electronic method (claims 4 to 6), which is characterized in that it can be automatically verified (claim 4).
  • the automatic re-calibration which is repeated again and again, may only take place in the case of a drop that is significant in terms of measurement technology (significant in terms of measurement technology must be defined empirically) - not with an increase! - the measured and recalculated values are below the theoretical (original) target pressure values - and only within arbitrarily defined limit values that result from empirically obtained data. Small leaks are detected by the temperature-related pressure monitoring analogue to plastic deformations and cause an automatic re-calibration. There is no re-calibration in the opposite direction.
  • the described method and the associated arrangement not only cover all functions that are performed with the devices which react to dynamic pressure changes and function analogously to the Buchholz relay in the case of the internal pressure-variable hermetic transformer, with or without a gas cushion; in addition, the monitoring of the operating state of the transformer is made possible by means of a computer.
  • any back pressure exerted by the hermetic liquid container causes an increase in pressure which can be measured in the liquid.
  • This pressure increase is caused by the expansion of the liquid, which in turn is a consequence of the temperature increase.
  • a pressure increase of 0.1 bar in a hermetic transformer with a certain elasticity corresponds to a temperature increase of y K
  • a pressure increase of 0.2 bar corresponds to a correspondingly greater temperature increase of 2 y K.
  • these correspondences only apply to a very narrow pressure and temperature range, because the elasticity of the transformer, especially the integral-filled, very limited.
  • the volume of liquid is determined by the mean temperature, the choice of the most favorable measuring point depends on the design and the viscosity of the liquid, and the plastic deformability is construction and material-specific, the mean temperature and the plastic deformation can only be determined empirically .
  • the representativity of the temperature measurement (e.g. thermometer pocket) must be checked before setting up a target pressure curve.
  • the delivery condition-target pressure curve can be assumed up to the tolerable internal pressure of 1.2bar or 1.3bar (overpressure of 0.2- 0.3 bar) with the simple means of heating the liquid and applying little external pressure.
  • the prevailing external pressure should be slightly above the prevailing internal pressure.
  • Example integrally filled, stretchable transformers or hermetic transformers with gas cushion.
  • a gradual pressure increase can be carried out the respective values are brought about without heating the liquid by adding the appropriate amount of insulating liquid.
  • the quantity to be added is determined by the thermal expansion coefficient. This requires the basis of a temperature reference curve with entered values.
  • a correction factor may have to be taken into account, since the heating of the liquid causes an uncompensated disproportionate pressure increase due to the greater expansion of the gas and this expansion component is not partially compensated for by the gas partially dissolving.
  • the method of temperature-related pressure measurement is possible not only for integrally filled transformers but also for those with a gas cushion.
  • the restrictions listed above, in particular sun exposure, must be observed.
  • An alternative to this is to adhere to a waiting period before the initial verification of a building type, in order to carry out the verification only after gas saturation has taken place.
  • the method described has a slight inaccuracy factor which is due to the disproportionate expansion of the gas with respect to the liquid.
  • this inaccuracy factor is not significant in terms of measurement technology; if the gas is in contact with the liquid, it is partially compensated for by the higher gas solubility with a simultaneous increase in pressure and temperature.
  • expansion caused by strong solar radiation or the increase in pressure caused by this can simulate a fault current. If this danger is present, the mechanical variant of the invention, namely the temperature-related liquid volume monitoring, will prove to be more reliable.
  • the course of the multiple solubility curves is determined by the type of fault, the insulating liquid and the respective gases. This fact does not limit the principle of operation itself, but relativizes the sensitivity of the measuring system.
  • the actual pressure is recorded and digitized using a pressure probe.
  • the digitized value is compared with the associated digitized target pressure value. This comparison happens constantly, e.g. every 10 sec. If the actual pressure falls below the set pressure value, the set pressure value is automatically re-calibrated to compensate for the plastic deformation that has occurred or a possible loss of liquid.
  • the once created and compensated for each time of measurement temperature-dependent target pressure curve (p 'should ⁇ p' 'should ⁇ p''' is intended, etc.) provides the reference values with which the actual values are compared. This is done by comparing the digitized values, either computer-dependent or independent.
  • the pressure measurement is very reliable, the measurement accuracy is very high; Even inexpensive non-dedicated pressure gauges measure pressure changes of ⁇ 1mbar and use the measured values for digital display after conversion.
  • the invention pursues the purpose of also and in particular detecting errors - in their non-mechanical design in hermetic transformers - to which the current-limiting fuses cannot respond. This also includes the nominal current ranges in which the current-limiting fuse does not work reliably.
  • errors that are difficult to detect in particular such as a creeping turn short in a so-called gas dissolving or gas absorbing oil, can also be detected early and in particular in a hermetic transformer.
  • temperature-related pressure monitoring offers the possibility of releasing gas unselectively in the event of a pressure rise that is not caused by the liquid temperature, possibly after an alarm, since it is irrelevant in the temperature range above the dew point of the gases concerned, whether the gas cover is made from pure nitrogen or from cracked gases enriched nitrogen.
  • Temperature-related pressure monitoring is unsuitable for transformers with gas cushions where exposure to the sun cannot be ruled out.
  • temperature-related volume monitoring (mechanical variant) is recommended, especially since this variant also includes a leakage oil monitor function.
  • mechanical variant in order to enable a sufficiently reliable error display, e.g. false indications caused by vibrations can be avoided.
  • re-calibration is cumbersome and can only be carried out by hand; self-adjustment is impossible.
  • the liquid that is free of cracked gas when filling will always have a higher flash point than that saturated with cracked gases.
  • the saturation limit for fission gases is temperature-dependent.
  • the formation of fission gases, which go into solution without delay, does not cause a measurable increase in pressure and is therefore not immediately detectable. However, this is not relevant to loss prevention. It is therefore irrelevant that the temperature-related pressure monitoring for extremely low-energy faults works best in a medium saturated with fission gas. Escape of fission gases from the saturated liquid during cooling causes a spread between the actual pressure values and the target pressure values and thus, if necessary, an error message or shutdown. The temperature-related monitoring of the (target) volume or (target) pressure prevents a dangerous drop in the flash point.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Fluid Mechanics (AREA)
  • Power Engineering (AREA)
  • Housings And Mounting Of Transformers (AREA)
  • Examining Or Testing Airtightness (AREA)
  • Emergency Alarm Devices (AREA)
EP96100103A 1996-01-05 1996-01-05 Détection de la formation de gaz de décomposition dans les transformateurs Expired - Lifetime EP0783198B1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE59600566T DE59600566D1 (de) 1996-01-05 1996-01-05 Überwachung der Spaltgasbildung in Transformatoren
AT96100103T ATE171314T1 (de) 1996-01-05 1996-01-05 Überwachung der spaltgasbildung in transformatoren
EP96100103A EP0783198B1 (fr) 1996-01-05 1996-01-05 Détection de la formation de gaz de décomposition dans les transformateurs
US08/771,842 US5900538A (en) 1996-01-05 1996-12-23 Monitoring of decomposition gases in transformers by referencing volume or pressure to temperature

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP96100103A EP0783198B1 (fr) 1996-01-05 1996-01-05 Détection de la formation de gaz de décomposition dans les transformateurs

Publications (2)

Publication Number Publication Date
EP0783198A1 true EP0783198A1 (fr) 1997-07-09
EP0783198B1 EP0783198B1 (fr) 1998-09-16

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP96100103A Expired - Lifetime EP0783198B1 (fr) 1996-01-05 1996-01-05 Détection de la formation de gaz de décomposition dans les transformateurs

Country Status (4)

Country Link
US (1) US5900538A (fr)
EP (1) EP0783198B1 (fr)
AT (1) ATE171314T1 (fr)
DE (1) DE59600566D1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102015204431A1 (de) * 2015-03-12 2016-09-15 Alstom Technology Ltd. Verfahren und Vorrichtung zur Überwachung einer Ölfüllung eines Leistungstransformators

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10118875C1 (de) * 2001-04-18 2002-09-12 Eppendorf Ag Verfahren zum kontrollierten Dosieren von Flüssigkeiten unter Verdrängung eines Gaspolsters
CZ292922B6 (cs) * 2001-07-23 2004-01-14 Josef Ing. Altmann Zařízení pro snížení kontaminace olejových náplní transformátorů plyny a vodou
CA2364277A1 (fr) * 2001-12-05 2003-06-05 Ioan A. Sabau Methode et appareil de reduction du degagement gazeux et de la degradation de l'huile isolante dans les transformateurs
CN1867799A (zh) * 2003-10-17 2006-11-22 梅塞尔集团有限公司 用气体充装压力容器的方法
EP1695001B1 (fr) * 2003-12-19 2009-07-08 Messer Group GmbH Procede pour remplir de gaz des recipients a gaz comprime
CN101223613A (zh) * 2005-07-17 2008-07-16 西门子公司 密封的电设备
ATE504843T1 (de) * 2008-12-05 2011-04-15 Abb Technology Ltd Durchführungsdiagnose
PL2688081T3 (pl) * 2012-07-20 2016-06-30 Abb Schweiz Ag Urządzenie zabezpieczające dla transformatora mocy i powiązany transformator mocy wykorzystujący takie urządzenie zabezpieczające
EP3706148B1 (fr) * 2019-03-06 2023-08-09 Hitachi Energy Switzerland AG Ensemble transformateur electrique, procede de determination d'un etat thermique d'un ensemble transformateur electrique, et dispositif de determination

Citations (4)

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US4223364A (en) * 1978-05-25 1980-09-16 Sangster Harold L Pressure and temperature responsive protective devices
US4654806A (en) * 1984-03-30 1987-03-31 Westinghouse Electric Corp. Method and apparatus for monitoring transformers
US4823224A (en) * 1988-01-21 1989-04-18 Qualitrol Corporation Rapid pressure rise circuit
DE4101718A1 (de) * 1991-01-22 1992-07-23 Vdo Schindling Druckschalter

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US4148086A (en) * 1977-06-07 1979-04-03 Landa Mikhail L Device for overload protection of electric apparatus
US4908730A (en) * 1988-10-14 1990-03-13 Kearney Surge arrester with shunt gap
US5281955A (en) * 1991-09-20 1994-01-25 C & D Charter Power Systems, Inc. Battery charge monitoring apparatus and method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4223364A (en) * 1978-05-25 1980-09-16 Sangster Harold L Pressure and temperature responsive protective devices
US4654806A (en) * 1984-03-30 1987-03-31 Westinghouse Electric Corp. Method and apparatus for monitoring transformers
US4823224A (en) * 1988-01-21 1989-04-18 Qualitrol Corporation Rapid pressure rise circuit
DE4101718A1 (de) * 1991-01-22 1992-07-23 Vdo Schindling Druckschalter

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102015204431A1 (de) * 2015-03-12 2016-09-15 Alstom Technology Ltd. Verfahren und Vorrichtung zur Überwachung einer Ölfüllung eines Leistungstransformators

Also Published As

Publication number Publication date
ATE171314T1 (de) 1998-10-15
EP0783198B1 (fr) 1998-09-16
US5900538A (en) 1999-05-04
DE59600566D1 (de) 1998-10-22

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