General Electric Company

Electric Power Research Institute Incorporated

Madabushi V Chari

Evangelos Trifon Laskaris

Michele Dollar Ogle

Anthony F Armor

Gerald Burt Kliman

Bizhan Dorri

Donald W Jones

Michael Anthony Palmo, Jr

Sameh Ramadan Salem

Sterling C Barton

Ahmed K Kalafala

Henry W Kudlacik

Swarn S Kalsi

John D'Angelo

Sheppard Salon

Gary Bedrosian

Paul Reece

George W Turnbull

O-Mun Kwon

Harold E Collings

System and methods for monitoring electric machines are provided. A magnetic field associated with the electric machine is measured at one or more points external to the electric machine, wherein a respective magnetic field value is associated with each of the one or more points. The one or more measured magnetic field values are compared to one or more corresponding expected values, and a determination of whether a fault is present in the electric machine is made based at least in part on the comparison.

Non-invasive monitoring and diagnosis of electric machines by measuring external flux density

A superconductive magnet with magnetic shielding has an annularly-cylindrical-shaped housing whose first end wall and outer cylindrical wall are magnetizable (e.g., iron) walls and whose inner cylindrical wall is a non-magnetizable wall. At least one main superconductive coil is positioned within the housing and carries an electric current in a first (e.g., clockwise) direction. An annular first permanent magnet is positioned outside the housing longitudinally proximate the first end wall. The first permanent magnet has a number of equivalent ampere turns and has a magnetic field direction oriented parallel to the axis pointing towards the second end wall so that its magnetic field longitudinally pulls the stray magnetic field of the superconductive coil(s), which leaves the magnet's bore, inward to be captured by the iron first end wall.

Superconducting magnet with magnetic shielding

An open magnet having two magnet assemblies arranged in a spaced-apart, parallel relationship to define a working space therebetween is provided for magnetic resonance imaging. Each assembly has an annular superconductive coil and a ferromagnetic field enhancer encircled by the superconductive coil. The field enhancers are substantially cylindrical ferromagnetic pole pieces which are encircled by a respective one of the superconductive coils. The magnet assemblies are attached to a C-shaped support frame which is rotatively mounted to a pedestal member. The frame can thus be rotated between vertical and horizontal imaging positions. The field enhancers are shaped so as to maximize homogeneity in the imaging volume while keeping their weight and volume to a minimum. The specific shape of the field enhancers is determined with a nonlinear optimization design method.

Open (non-enclosed) magnets for magnetic resonance imaging

An open magnet having a frustoconical shaped inner bore is provided for MR imaging. The magnet has a plurality of axisymmetric superconducting coils of differing diameters which are disposed along an axis in order of successively increasing diameters so as to define the frustoconical shape. This shape permits a patient access opening which is much larger than that in conventional cylindrical magnets. The overall length is much less than the length of conventional systems. The combination of wide opening and short length facilitates patient access and presents a feeling of openness. Furthermore, the device can be tilted with respect to horizontal to increase the openness.

Frustoconical magnet for magnetic resonance imaging

A toroidal circumferentially wound superconducting coil is provided for generating a constant magnetic field with a significant radial field component. A room-temperature resistive coil wound circumferentially and connected to launch activating means is coaxial with the superconductive coil. Interaction of the current in the resistive coil with the radial field component of the superconductive coil produces an axial force on the resistive coil and in turn on the launch activating means. The axial force is controllable in magnitude and direction by controlling the magnitude and direction of the current supplied to the resistive coil.

Electromagnetic launcher

A resistive magnet is provided having a cylindrical radio frequency/gradient coil assembly. A first and second cylindrically shaped main coil is situated coaxially on either side of the radio frequency/gradient coil assembly with the radio frequency/gradient coil assembly and the first and second main coils having the same inside diameter defining a magnet bore. A cylindrical correction assembly coil surrounds the radio frequency/gradient coil assembly. Means for securing the first and second main coil to the cylindrical correction assembly is provided. The radio frequency/gradient assembly provides axial support for the first and second main coil assembly. For additional cylindrical main coils surround the correction coil.

Compact whole body resistive magnetic resonance imaging magnet

A shield for a MR magnet is provided comprising a cylindrical shell of magnetic material surrounding the MR magnet. The cylindrical shell is situated so that its longitudinal axis is coaxial with the magnetic axis of the MR magnet. Two disk shape end caps of magnetic material are secured to either end of the cylindrical shell. The end caps each define a central aperture extending longitudinally through the disk, with the radial extent of each of the apertures sized so that the perturbation of the field in the working volume of the MR magnet due to the cylindrical shell is compensated for.

Aperture sized disc shaped end caps of a ferromagnetic shield for

An apparatus for supporting a stator winding in a superconductive generator. The apparatus includes a plurality of integral stator bars positioned in the air-gap between the yoke and the rotor and a plurality of non-conductive supporting teeth interspaced between the stator bars. The supporting teeth are rigidly attached to the yoke of the generator and are engaged by a plurality of wedge members. The wedge members and the supporting teeth secure the stator bars in a rigid supporting arch.

Apparatus for supporting a stator winding in a superconductive generator

An auxiliary field winding for a superconductive AC electrical machine. The auxiliary field winding is adapted to provide a controlled and rapidly varying magnetic field to an armature winding in addition to that produced by the main field winding for improving the dynamic stability of the machine. The main field winding is superconductive and is adapted to provide a substantially steady-state magnetic field to the armature. The two windings permit the machine to rapidly accommodate changes in the load made on the machine during operation.

Auxiliary field winding for a superconductive alternating current

A terminal box for a dynamoelectric machine utilizes a flux shield system wherein a plurality of flux shields are interposed between the wall of the terminal box and a high voltage bushing. Cooling fluid is passed through the flux shield system to maintain all parts at a safe, low temperature. In one embodiment of the invention, a first inner flux shield member of high electrical conductivity and low magnetic permeability is spaced from but surrounding the bushing. A second outer flux shield member of low electrical conductivity and high magnetic permeability is spaced between the first shield member and the terminal box wall. Passages and openings are provided to allow cooling fluid to circulate over the respective shield members and the wall of the terminal box without providing a path for transmission of flux from the area surrounding the bushing to the terminal box wall. The fluid flow path and the suction ducts for removing coolant from the terminal box are arranged to ensure maximum flow of cooling fluid over the most heated portions of the terminal box wall.

Generator terminal box with multiple flux shielding and forced

An improved apparatus is provided to cool the flux shields of dynamoelectric machines. In one embodiment of this invention, cooling fins are attached to a flux shield at localized areas of heating of the flux shield referred to as hot spots to reduce the temperatures there to acceptable levels. These fins may be provided with a tapered portion which minimizes the fluid losses associated with the flow of cooling gas over the fins. In another embodiment of the present invention, an annular rim, bored to provide cooling gas passages therethrough, is fixed to the flux shield along an inner portion thereof, to effect the transfer of heat from the flux shield to a flow of the cooling gas through the passages. Finally, in a third embodiment of the present invention, an electrically non-conducting annular baffle is disposed around the flux shield adjacent an inner surface thereof to direct a flow of cooling gas across the inner surface of the flux shield thereby cooling the same.

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Burnt Hills, NY, United States of America

Madabushi V Chari