Superconducting coil protective system

A superconducting coil protective method for protecting a superconducting coil connected in parallel to a power source generating an output voltage, comprising the steps of:

• detecting occurrence of quenching in the superconducting coil and generating a quenching signal indicative of the occurrence of quenching;
• reducing an output voltage from the power source in response to the quenching signal from the quenching detecting means to reduce the output voltage to be at least substantially zero;
• causing a first commutation of a current from the superconducting coil to a current interrupting means connected in parallel to the superconducting coil upon the reduction of the output voltage from the power source;
• and
• causing a second commutation of the first-commutated current to a protective resistor connected in parallel to the current interrupting means upon the opening of the current interrupting means, whereby energy of the second-commutated current is dissipated in the protective resistor.

A superconducting coil protective system for use which an output voltage generating power source said protective system comprising:

• a superconducting coil;
• quenching detecting means for detecting occurrence of quenching in said superconducting coil and for generating and transmitting a quenching signal indicative of the occurrence of quenching;
• voltage control means for reducing voltage across said superconducting coil in response to the quenching signal;
• current interrupting means connected to said superconducting coil for causing a first commutation of a current from said superconducting coil to said current interrupting means upon the reduction of the voltage across said superconducting coil to a first voltage, and for interrupting said first commutated current;
• a first switch connected in series with said current interrupting means and in series with said superconducting coil, said first switch being closed in response to the quenching signal transmitted from said quenching detecting means;
• and
• a protective resistor connected in parallel to said current interrupting means so that energy is dissipated in said protective resistor when said first commutated current is interrupted.

A superconduting coil protective system comprising:

• a power source;
• a superconducting coil;
• quenching detecting means for detecting occurrence of quenching in said superconducting coil and for generating and transmitting a quenching signal indicative of the occurrence of quenching;
• voltage control means for reducing output voltage from said power source in response to said quenching signal;
• current interrupting means connected to said superconducting coil for causing a first commutation of a current from said superconducting coil to said current interrupting means upon the reduction of the output voltage from said power source to a first voltage, and for interrupting said first commutated current;
• a first switch connected in series with said current interrupting means and in series with said superconducting coil, said first switch being closed in response to the quenching signal transmitted from said quenching detecting means,
• a first protective resistor connected in parallel to said current interrupting means;
• a second protective resistor and a switch connected in series comprising a series branch, the series branch being connected in parallel with said first protective resistor.

A superconducting coil protective system comprising:

• a power source;
• a superconducting coil;
• quenching detecting means for detecting occurrence of quenching in said superconducting coil and for generating and transmitting a quenching signal indicative of the occurrence of quenching;
• voltage control means for reducing output voltage from said power source in response to said quenching signal;
• current interrupting means connected to said superconducting coil for causing a first commutation of a current from a said superconducting coil to said current interrupting means upon the reduction of the output voltage from said power source to a first voltage, and for interrupting said first commutated current, said current interrupting means comprising a circuit breaker;
• a first switch connected in series with said current interrupting means and in series with said superconducting coil, said first being closed in response to the quenching signal transmitted from said quenching detecting means;
• a first protective resistor connected in parallel to said current interrupting means;
• a second protective resistor and a switch connected in series comprising a series branch, the series branch being connected in parallel with said first protective resistor.