Superconductor technology: apparatus – material – process – High temperature devices – systems – apparatus – com- ponents,... – Electrical energy storage device – inductor – transformer,...
Patent
1991-04-29
1994-08-02
Donovan, Lincoln
Superconductor technology: apparatus, material, process
High temperature devices, systems, apparatus, com- ponents,...
Electrical energy storage device , inductor, transformer,...
336DIG1, 505705, 505850, 505851, 505880, 361 19, 361141, 335216, H01F 100, H02H 700, H01H 4700
Patent
active
053349644
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a current limiting choke coil including a coil through which current flows and particularly to a current limiting choke coil with a metal oxide ceramic superconductive core.
Super conducting switching devices are known (U.S. Pat. No. 2,946,030). Such a prior art device includes, in addition to the winding penetrated by alternating currents, a control coil for direct currents having a switching element actuated by feeding current into the control coil. If the control coil does not carry any direct current, the switching element has a very low impedance so that a high current is able to flow in the alternating current circuit. By feeding an appropriate direct current into the control winding, the superconductivity of the core is removed so that the device has a high impedance which reduces the alternating current. Also known are metal oxide ceramic superconductors (IEEE Spectrum, Volume 25, No. 5, May, 1988; K. Fitzgerald, "Superconductivity: Fact vs. Fancy", pages 30-41.
BACKGROUND OF THE RELATED ART
Upon a malfunction, high power energy supply electrical systems are subjected to extremely high electrodynamic stresses as a result of short circuit currents. Although a circuit breaker associated with sections of a malfunctioning system can interrupt a short circuit current, full short circuit current will flow in each case. Hence, expanding electrical power generation and transmission involves increasing short circuit powers resulting in increased electromechanical forces in the operating media in the event of malfunctions. These increased electromechanical forces occur primarily at locations of high power concentration and at system coupling points. Often over-sized bus bars, switching devices and transformers are employed in order to accommodate a future increase in short circuit power. Existing system components that are too weak must possibly be reinforced in the course of system expansion or replaced by new devices. Costs of expanding the electrical power capability of the systems involving high power concentration can be reduced if the short circuit currents can be limited. In a three-phase system this is accomplished with simple air chokes as described in Techn. Mitt. AEG-TELEFUNKEN [Technical News from AEG-TELEFUNKEN]61 (1971), No. 1, pages 58-63. These chokes exhibit a current proportional voltage difference which, although they appear to be limited in the case of a short circuit, in many cases under normal load takes on values which are too high to maintain stability of system operation. More favorable than simple chokes are devices having a non-linear current-voltage characteristic. This includes a limiting coupler as described in ETZ-A 87 (1966), pages 681-685. This coupler operates as a series resonant circuit which is tuned to the system frequency and, in normal operation, constitutes a very small resistance. A non-linear resistance combination in parallel with the capacitance of the resonant circuit takes care that, upon a malfunction, the resonance condition is cancelled and the inductance limits the current. However, the limiting coupler, developed as a coupling between two high power systems, has not found acceptance as a short circuit current limiter, primarily because of the high cost of the capacitor battery in the resonant circuit.
The development of superconductors for use at high current densities and with large magnetic fields has led to numerous solutions and proposals for current limiting switching devices. The publication El. Rev. Int., Vol. 202 (1978) No. 5, pages 63-65, reports of a short circuit current limiter having three pairs of transductors whose iron cores are magnetically saturated in normal operation with the aid of a superconductive current loop in that they are flooded by a normally direct field and exhibit a low inductive resistance. However, in the case of a short circuit, the increased alternating current amplitude cancels out the direct current flowing in the individual transductors
REFERENCES:
patent: 2946030 (1960-07-01), Slade
patent: 3091702 (1963-05-01), Slade
patent: 3094628 (1963-06-01), Jiu
patent: 3143720 (1964-08-01), Rogers
patent: 4894360 (1990-01-01), Leupold
patent: 4988669 (1991-01-01), Dersch
patent: 5140290 (1992-08-01), Dersch
"Superconductivity: Fact vs. Fancy," IEEE Spectrum, 25 (1988) May, No. 5, New York, N.Y., USA, pp. 30-41.
Winterberg, "Magnetically Insulated Transformer for Attaining Ultrahigh Voltages," The Review of Scientific Instruments, Dec. 1970, vol. 41, No. 12, pp. 1756-1763.
Fischer Roland
Schneider Rudolf
Voigt Heinz
Donovan Lincoln
Licentia Patent-Verwaltungs-GmbH
Ryan Stephen T.
LandOfFree
Current limiting choke coil does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Current limiting choke coil, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Current limiting choke coil will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-67385