Electric Power Research Institute Incorporated

Westinghouse Electric Corporation

United States of America As Represented by the Secretary of the Air Force

Phillip W Eckels

George T Mallick, Jr

Donald C Litz

James R Logan

Michael R Jugan

Joachim V Heberlein

Adolphus Patterson

El-Eraky A Ibrahim

William G Moore

The present invention provides a straightforward sensor and method for quench detection in a superconducting coil, magnet or inductor. The superconducting sensor of the present invention consists of a probe having a twisted loop of superconducting wire in a protective sheath which is co-wound with the superconducting coil, and a readout device. A very small amount of energy is applied to the superconducting loop of wire in the probe by the readout device and its resistance is monitored by readout device. When joule heating occurs in the superconducting coil as a result of a portion becoming normal, the heat is transferred to a corresponding portion of the probe causing a portion of the superconducting wires therein to become normal. This causes the resistance in the superconducting wires to change and this change is detected or measured by the readout device which is magnetically coupled to the wires of the probe.

Superconducting sensor for quench detection in a superconductor

A superconducting rotor cooling system for an electrical generator includes a free vortex type pump which is located within and forms an integral part of the rotor assembly. The free vortex pump takes advantage of the centrifugal force of rotation of the cooling fluid to help the rotor winding compartment to remain in a superfluid helium state. Improved cooling results from combined natural convection, as occurs in a conventional rotor, and the superfluid heat transport which occurs at the velocity of sound.

Superconducting rotor cooling system

A high current density component of a dynamoelectric machine rotor is cooled by the use of thermosyphons that carry heat from the heat generating element to a cooler part of the rotor. A homopolar generator is shown with a rotor having a core covered by a copper shell that when so cooled by thermosyphons can be operated with substantially longer pulse intervals than previously.

Homopolar generators with thermosyphons for improved cooling

A vapor trap is placed in fluid communication with the vapor exhaust pipe of a supercooled rotor between, and in fluid communication with, the helium reservoir of the supercooled rotor and the portion of the exhaust pipe which is in contact with the torque tube of the rotor. By preventing a reverse flow of heated helium gas through the exhaust pipe toward the helium reservoir, the vapor trap of the present invention improves the operation of the rotor's vapor pump. Operating in a manner similar to liquid traps, the present invention blocks the passage of heated helium vapor in a reverse direction and thus improves the overall operation of the supercooled rotor.

Vapor trap for supercooled rotor

Vapor cooled leads to superconductive windings of a superconducting rotor are made more faultworthy by a regenerator portion of the conductive leads, through which the exiting vapor passes and is warmed so that, under fault conditions, the vapor does not cause icing of collector rings or damage to seals proximate the vapor return path.

Superconducting rotor with vapor cooled cryogenic leads having a

A radiation heat shield which comprises a plurality of helical grooves distributes possible thermal expansions around its circumference. These potential thermal expansions could be caused by transient conditions or other abnormal operational modes which could reduce the flow of coolant through particular fluid passages of the radiation shield. By incorporating a plurality of helical fluid passages, these potential thermal expansions are distributed around the circumference of the radiation shield and the resulting distortion moments tend to cancel each other and, provided that a sufficient number of turns is possible, eliminate the imbalance.

Radiation shield with helical fluid passages

A liquid coolant transfer device that has a stationary tube fit within a rotating conduit and a threaded throwback seal on the surface of the rotating element is further provided with a seal and bearing device in the form of a washer affixed to the conduit at the end of the threaded insert and extending across the gap between the rotating and stationary tubes for preventing liquid coolant flow therethrough even during severe flooding caused by faults within the electrical machine with which it is connected.

Coupling for cryogenic liquid transfer into rotating apparatus

The end turn region of a superconducting rotor is provided with end region support blocks that together provide channels for coil location. Within the support block channels there are intermittent supports in the form of insulating spacers extending radially both to the front and to the rear of the coil and also bottom spacers, with sheets of side insulation between the front and rear spacers and the adjacent support blocks. The intermittent supports provide access of coolant to the superconductor. They may also be formed in a manner to tilt the end region toward the pole piece for better mechanical support. A top insulating spacer is provided with cooling channels and is utilized with banding to provide secure compressive support for the end windings. Apertures in the support blocks and grooves in the spacers provide collant circulation.

Superconducting rotor with end turn region intermittent support and

A cryogenic lead is described which comprises a plurality of tubular conductors arranged in parallel association and connected to two conductive blocks. Each tubular conductor is a laminar assembly of an inner conductive sleeve and an outer sleeve which acts as a thermal mass to absorb heat from the inner sleeve during thermal perturbations. A fluid refrigerant is directed through the tubular conductors. Each tubular conductor has at least one flow restrictor disposed within its inner sleeve to reduce the relative effect of changes of refrigerant viscosity on pressure drop within the tubular conductor and to block the transmission of thermal radiation through the tubular conductor.

High-current cryogenic leads

An apparatus is provided for rapidly restarting the flow of coolant through the cold electromagnetic shield of a superconducting rotor following a thermal transient episode. A vortex diode inhibits coolant flow in the undesirable reverse direction and encourages the reestablishment of a normal thermosyphon cooling loop flow quickly following the termination of a thermal transient such as that caused by transmission line faults. The present invention requires no moving parts and may therefore be permanently sealed in the superconducting rotor without risk of costly repair efforts caused by components failure.

Fast starting cold shield cooling circuit for superconducting generators

A cryogenic liquid coolant transfer device enhances flow of a liquified gas in the inboard direction by the incorporation of a threaded insert in the rotating inlet pipe of a superconducting rotor. The threads of the device also facilitate the reverse flow of liquid helium back into a stationary supply tube during fault conditions. The objective of the insert, during both normal and abnormal conditions, is to inhibit the flow of liquid coolant into the clearance gap that exists between rotating and stationary parts of the liquified gas transfer system.

Liquid coolant transfer device

A rotor for a superconducting generator with improved thermal transient response is disclosed and claimed. In particular, a cylindrical radiation shield disposed about said rotor is given the twin-functions of protecting the rotor from radiant heat from the ambiance, as well as warming the coolant during abnormal operating conditions to ensure minimal damage from thermal transients. Thermohydraulic stabilization of the coolant flow through axial passages in the shield is achieved by the use of risers located within the flow path at the discharge end of the shield.

Superconducting generator with improved thermal transient response

Cryostability is achieved by a superconductive rotor of a dynamoelectric machine constructed in accordance with the invention. The superconductive rotor comprises: a rotor shaft; a support rim; a plurality of slot teeth formed at the outer periphery of said rim, said teeth located between and defining a plurality of rotor slots; and a plurality of slot assemblies, one within each rotor slot. Each slot assembly comprises: a plurality of stacks of superconductors, each superconductor within a stack having insulation on only two of its sides and being disposed one on top of another in generally radial direction relative to the rotor shaft; a plurality of insulative separators, one between each pair of stacks; a top insulative strip and a bottom insulative strip, respectively radially above and below said conductor stacks; and a side panel on either side of the slot assembly and next to a slot tooth. Cooling channels are disposed on the surfaces of the separators, the side panels and the top and bottom strips so as to establish at least one coolant path along which coolant may be circulated to, within and from the slot assembly by natural convection.

Dynamoelectric machine with cryostable field winding

A vapor trap is provided for use in a liquid coolant supply pipe of a superconductive generator. The supply pipe has interiorly located, a flow constriction, an annular liquid coolant dam, and means for blocking the vapor flow through the central portion of the supply pipe. These act cooperatively to prevent the coolant vapor within the generator from flowing back through the supply pipe. This would be an undesirable condition most likely to occur during transient operating conditions when the normal flow of liquid coolant is temporarily stopped.

Vapor trap and regulator for superconductive turbogenerators

A superconducting generator is disclosed herein and includes a super cooled rotor assembly and two interconnected torque tubes constructed of a material having a thermal coefficient of linear expansion which is negligible at and below a predetermined cryogenic temperature. During normal operation of the generator, predetermined axial sections of these torque tubes are maintained at or below this cryogenic temperature. This minimizes thermal expansion of these sections and eliminates damage therefrom should the generator operate in an abnormal way which causes the torque tube sections to drop significantly in temperature. At the same time, other axial sections of the torque tubes are maintained at temperatures above this cryogenic temperature during normal operation of the generator but are coupled to an external source of heat to minimize any drop in temperature of these sections during abnormal operation.

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Penn Hills, PA, United States of America

Phillip W Eckels