JPS5933803A - Sensor for detecting quenching of superconductive coil - Google Patents

Abstract

PURPOSE:To detect exactly the generation of quenching by detecting generated voltage on the basis of electric resistance generating on a superconductive wire element attached closely to a superconductive wire for a superconductive coil and connected with a current feeder line and a voltage measuring line, respectively, on either end thereof. CONSTITUTION:A small current flows on a current feeder line 13. In the normal state, both superconducting wire 11 and superconductive element 12 are low-temperature without generation of resistance, hence, without generation of voltage on both ends of the supercondcutive wire element 12, and voltage is not detected on a voltage detector. Once the superconductive coil quenches, the temperature of the surface of the superconductive wire 11 raises, and the temperature of the spuerconductive wire element 12 closely attached to this superconductive wire 11 is above the critical temperature, resistance generates on the superconductive wire element 12, which produces voltage between both ends thereof. Accordingly, by conducting the generated voltage to the voltage detector through the voltage measuring wire 14, quenching generating on the superconductive coil is deteted exactly by the indication of the voltage detector.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a quench detection sensor for a superconducting coil.

Conventionally, there has been a detector of this type as shown in FIG. 1 of the accompanying drawings.

That is, in the figure, the symbol / is a voltage measurement line, 3 is a quench detector, L/, Lj are the self-inductances of the /a part and /b part of the superconducting coil /, and E is /, 1lii indicate the induced voltage generated by the self-inductance L/, LJ.

Since the conventional device is configured in this way, when a current flows through the superconducting coil l, the self-inductance L/, L
J generates an induced voltage E/, l(j.

In this case, if there is a voltage difference between the induced voltages E/ and EJ, the higher induced voltage is divided by a resistor in the quench detector J to make it smaller, and the quench detector for both induced voltages E/ and EJ Make the voltage difference within 3 zero.

Under these conditions, the superconducting coil l is activated, but if the superconducting coil l quenches during excitation, resistance initially occurs in a part of the superconducting wire, so the voltage generated by that resistance is , is detected by the quench detector 3, thereby detecting the occurrence of quench and cutting off the coil current of the superconducting coil. In this way, by cutting off the current in the superconducting coil l, the superconducting coil /
This suppressed heat generation and prevented the superconducting coil l from burning out.

Since the conventional quench detector is configured as described above, if a quench occurs near the connection point with the voltage measurement line 2a at the center of the superconducting coil l, and the speed at which the quench spreads is , /b are both equivalent, then
The voltages E/ and E due to the resistances generated in portions /a and /b are also equal, and therefore the difference between the voltages E/ and EJ is close to zero, and as a result, it is impossible for the quench detector 3 to detect a quench. There was a drawback that the superconducting coil 3 could be burnt out.

The detection sensor of the present invention eliminates the shortcomings of conventional devices, and provides reliable quench detection for superconducting coils that reliably detects the occurrence of quench and protects the superconducting coil from burning out. Its purpose is to provide sensors.

In order to achieve this object, the present invention provides a superconducting element wire that is closely attached to a superconducting wire wound around a superconducting coil and has a current carrying wire and a voltage measuring wire connected to both ends of the superconducting wire; The superconducting wire is characterized in that it is comprised of a voltage detector connected to a voltage measurement line to detect the generated voltage based on the electrical resistance generated in the superconducting element wire.

Hereinafter, the present invention will be explained based on FIG. 3 of the accompanying drawings showing one embodiment thereof.

In the figure, the symbol /l is a superconducting wire constituting a superconducting coil, and the symbol /l is a superconducting wire attached closely to the superconducting wire, and both ends of the superconducting wire are is connected to a current-carrying wire /3 that passes a predetermined current through the superconducting wire /3 and a voltage detector (not shown) that detects the voltage generated by the electrical resistance generated in the superconducting wire /1. It is connected to the voltage measurement line lμ. Note that (3) the superconducting wire is in close contact with the superconducting wire by attaching the superconducting wire with the current carrying wire 13 and the voltage measuring wire 141 connected to the surface of the superconducting wire in such a way that no induction occurs. It is done by pasting. Further, the current flowing through the current-carrying wire 13 is sufficiently smaller than the critical current of the superconducting wire 1.2.

The quench detection sensor of the present invention is constructed as described above, and its operation will be explained next.

First, as mentioned above, a small current is passed through the current-carrying wire 13, but under normal conditions, superconducting wire /1 and superconducting strand /2 are both at low temperatures, so there is no current in superconducting wire 13. No resistance is generated, so no voltage is generated across the superconducting wire 12, and as a result, no voltage is detected by a voltage detector (not shown).

However, whenever the superconducting coil quenches and the surface temperature of the superconducting wire increases, and the temperature of the superconducting strands in close contact with the superconducting wire exceeds its critical temperature,
Resistance occurs in the superconducting strand lλ, and due to this resistance a voltage appears between its ends. Therefore, by guiding this generated voltage to the voltage detector through the voltage measurement line /l, the occurrence of quench in the superconducting coil can be reliably detected by the display on the voltage detector. This cuts off the power supply to the superconducting coil, thereby reliably preventing burnout of the superconducting coil due to excessive heat generation in the superconducting coil.

The quench detection sensor of the present invention is constructed and operates as described above, but instead of attaching the superconducting strands /l directly to the superconducting wire /l, as shown in FIG. As a result, an additional effect of making it easier to attach the superconducting wire to the electrical insulator occurs.

The quench detection sensor of the present invention is configured and operates as described above, so that no matter where quench occurs in the superconducting coil, it always detects the quench reliably.
Therefore, it is possible to prevent and protect the superconducting coil from burning out, and therefore, it is possible to provide a highly reliable quench detection sensor.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit explanatory diagram of an example of a conventional quench detection device for a superconducting coil, FIG. 2 is a schematic explanatory diagram of a main part of an embodiment of a quench detection sensor of the present invention, and FIG. 3 is a schematic diagram of an example of a quench detection sensor of the present invention. FIG. 2 is a perspective view schematically illustrating the main parts of the embodiment. //・Superconducting coil, /l・・Voltage measurement wire, //・
・Superconducting wire, 12...Superconducting wire, /3...Current carrying wire 1.2/...Electrical insulator. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Shin Kuzuno - (7) Figure 1 q Figure Ara 2

Claims (2)

[Claims] (1) A superconducting element wire that is attached closely to a superconducting wire wound around a superconducting coil and has a current carrying wire and a voltage measuring wire connected to both ends thereof, and a superconducting wire that is connected to the voltage measuring wire and A quench detection sensor for a superconducting coil, comprising a voltage detector that detects the generated voltage based on the electrical resistance generated in the strands. (2) A quench detection sensor for a superconducting coil according to claim 1, wherein the superconducting wire is covered with a green material.