High energy overcurrent protective device
AssigneeThe United States of America as represented by the United States Department of Energy
InventorWalter F. Praeg
Life of this patent
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Abstract
Electrical loads connected to capacitance elements in high voltage direct current systems are protected from damage by capacitance discharge overcurrents by connecting between the capacitance element and the load, a longitudinal inductor comprising a bifilar winding wound about a magnetic core, which forms an incomplete magnetic circuit. A diode is connected across a portion of the bifilar winding which conducts a unidirectional current only. Energy discharged from the capacitance element is stored in the inductor and then dissipated in an L-R circuit including the diode and the coil winding. Multiple high voltage circuits having capacitance elements may be connected to loads through bifilar windings all wound about the aforementioned magnetic core.
Claims7
A device for protecting a direct current system against discharge of a capacitance element in which energy is stored, the system having a load electrically connected to the capacitance element, said device including an inductor having an inductance, comprising:
- a magnetic circuit including a first portion of ferromagnetic material having a first magnetic permeability and a second portion having a second magnetic permeability less than the first magnetic permeability of said first portion;
- at least one coil disposed about said first portion of said magnetic circuit electrically connected between said capacitance and said load such that said magnetic circuit is not magnetically excited during first operating conditions of said direct current system;
- said coil further connected between said capacitance and said load for conducting a discharge of said capacitance element during second operating conditions of said direct current system that magnetically excites said magnetic circuit setting up a magnetic field in said first portion of said magnetic circuit;
- an eddy current shield of electrically conductive material disposed about said first portion of said magnetic circuit, for containing a magnetic field in said first portion of said magnetic circuit;
- said inductor and said capacitance element comprising an oscillatory circuit L-C circuit energized by the discharge of said capacitance element;
- said device further including a diode connected across a first portion of said one coil which conducts current of a first polarity only, said diode conducting a first portion of the energy of a discharge of said capacitance element which is dissipated in said inductor, whereby the first portion of the energy of a discharge of said capacitance element is diverted from the load during second operating conditions of said direct current system.
Dependencies are inferred from the claim text.