Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K55/00—Dynamo-electric machines having windings operating at cryogenic temperatures
  • H02K55/02—Dynamo-electric machines having windings operating at cryogenic temperatures of the synchronous type
  • H02K55/04—Dynamo-electric machines having windings operating at cryogenic temperatures of the synchronous type with rotating field windings
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K15/00—Processes or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
  • H02K15/12—Impregnating, moulding insulation, heating or drying of windings, stators, rotors or machines
  • H02K15/125—Heating or drying of machines in operational state, e.g. standstill heating
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
  • Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

Definitions

• the invention relates to a device for heating cold parts of large thermal mass arranged in a thermally insulating cryostat housing for superconducting windings, with an electrical heater arranged in the cryostat housing and connectable to an external heating current source.
• the cold section When using superconducting windings, the cold section must be well thermally insulated to avoid thermal losses from the outside world (cryostat). So are z. B. the losses for a cryostat with a length of approx. 80 cm and a diameter of 30 cm slightly below 30 W. If maintenance work on the cold part becomes necessary, its temperature must be brought from the operating temperature, for example 20 K, to room temperature. If only the thermal losses of the order of magnitude that are necessarily minimized for operation are available for this purpose, this results in warm-up times on a weekly scale, which of course is not acceptable for practical operation. In order to accelerate the warm-up process, electrical heaters are therefore installed in the cold section so that additional warm-up capacity is available if necessary. Of course, these heaters must be supplied with electrical energy from the outside.
• the structure is usually such that the connections of the electrical heater are led out of the inner cryostat part by means of vacuum bushings.
• additional feedthroughs for the heaters are also required. Any vacuum penetration caused but an additional effort and thus costs.
• the number of operations must be kept as low as possible.
• the invention is therefore based on the object of designing a device of the type mentioned at the outset such that an additional electrical heater can be operated without increasing the number of bushings.
• the electric heater is designed as an ohmic heater and is connected in parallel with the superconducting windings, and that the heating current source is an AC power source connected to the outer superconductor supply lines.
• the heaters do not cause any significant additional losses in normal operation, they must be designed with high resistance compared to the superconducting magnet winding. However, one cannot simply select a very high ohmic resistance in order to keep the additional losses during the operation of the cryostat as small as possible, since with increasing resistance, the external losses also
• the resistance of the ohmic heater should therefore be selected such that, in normal operating conditions, the power loss that arises due to the DC operating voltage drop across the superconducting bond is significantly below the heat loss power of the cryostat, so a loss near zero should not be sought.
• a switchover device for connecting a direct current source to the outer supply lines when the transition temperature is reached of the superconducting windings, so that in addition to the ohmic heater, the then no longer superconducting windings can also be operated as an ohmic heater.
• the rotor winding 2 which is only indicated schematically, is provided, which is provided with direct current supply lines 3, 4 which are connected through
• Bushings 5 and 6 of the housing are guided to the outside and are applied to a DC voltage source 7.
• an ohmic heater that is to say a resistor 8 is provided according to the invention, which is connected in parallel with the superconducting coil windings of the rotor 2.
• An AC power source 9 which is connected to the external power connections 10 and 11 of the superconducting windings of the rotor 2, is used for the power supply for the heating case.
• the rotor has an inductance of 3 H in a specific embodiment.
• the voltage drop across the coil is typically less than 1 V.
• An ohmic heater 8 connected in parallel to the winding in the form of a resistor with a resistance value of 100 ⁇ thus causes an additional power loss of less than 10 mW and is therefore compared to the thermal losses of the cryostat from Z. B. 30 W negligible. If you want to heat, the
• the AC power source 9 connected which has a frequency of z. B should have 10 kHz.
• the impedance of the winding of rotor 2 is approximately 188 k ⁇ .
• An AC voltage of 200 V can thus easily be applied to the connections, which results in a heating power of 400 W in the ohmic heater 8. As this heating output does not depend on the temperature of the cold part (in contrast to the thermal losses, which decrease with decreasing
• the warm-up time is shortened by more than the factor resulting from the ratio of 400 W to 30 W. It should also be taken into account that in order to avoid excessive thermal gradients in the cold part and the associated mechanical loads, lower heating capacities may also be desirable, but this can be easily adjusted by reducing the applied voltage. As soon as the thermal gradients are no longer so large, the heating output can be easily increased again, which can be achieved automatically by means of a corresponding control program.
• the device according to the invention has the advantage that completely new heating devices do not necessarily have to be developed for the supply of the heating power, but that, for. B. can use modified (tube) power amplifiers from consumer electronics or ultrasound technology.
• modified (tube) power amplifiers from consumer electronics or ultrasound technology.
• the numerical values given above, in particular the frequency of the AC voltage, can only be seen as an example.
• a value of 50 or 60 Hz, i.e. mains frequency, can also be used as a heating current source. In the example above, about 10% of the heating current would go through the coil.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Containers, Films, And Cooling For Superconductive Devices (AREA)
• Superconductive Dynamoelectric Machines (AREA)
• Control Of Resistance Heating (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (2)

Family

ID=27634746

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (3)

Family Cites Families (12)

• 2003
  • 2003-01-30 US US10/503,060 patent/US20050122640A1/en not_active Abandoned
  • 2003-01-30 WO PCT/DE2003/000261 patent/WO2003065767A2/de not_active Ceased
  • 2003-01-30 DE DE50308113T patent/DE50308113D1/de not_active Expired - Lifetime
  • 2003-01-30 JP JP2003565208A patent/JP4005973B2/ja not_active Expired - Fee Related
  • 2003-01-30 EP EP03706271A patent/EP1470740B1/de not_active Expired - Lifetime

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