JPS60175403A - Superconductive device - Google Patents

Abstract

PURPOSE:To prevent a quenching from occurring by flowing a constant current to a superconductor, periodically superposing a pulse current, predicting whether the quenching occurs or not, and performing a protective operation. CONSTITUTION:A constant-current power surce 1 supplies a current through a breaker 6 to a superconductor 3. The current value is variable, and can continuously control an arbitrary current from zero to a rated value. A pulse current is superposed on the superconductor by a pulse power source 2 in addition to the constant-current power source. A balance circuit 4 inserted in parallel with the superconductor forms a bridge circuit together with the superconductor, a voltage detector 5 operates even if a slight variation in the voltage occurs, and can output an alarm signal 8. The power source 1 reduces the current by the alarm signal, and even if the alarm signal still continues to flow, the breaker 6 is opened, and the energy of the superconductor is completely consumed by a protective resistor 7.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a superconducting device, and particularly to a superconducting quadruple unit with a transition prediction device suitable for use in a nuclear fusion device or an energy storage device.

[Background of the invention] Super? The 2ta device cools a conductor such as Nb or 4Sn using liquid helium or the like to bring it into a superconducting state with zero voltage resistance.

A strong magnetic field can be generated with ideally zero power consumption. However, during the operation of a superconducting device, part or all of the superconductor transitions to a normal conducting state (electrical resistance 4 zero) due to thermal factors, etc.
That is, in the case of quenching, heat generation due to joule loss in the quenched portion may cause boiling of the coolant and, in turn, damage to the superconducting device.

Conventionally, the voltage between the superconductor terminals was measured, and when the voltage, which is normally zero, exceeded a certain level, the current was cut off to protect the superconducting device.

Since the protection operation is not performed unless the quench state is reached when the required current is applied, the transition has not always been predicted.

[Purpose of the invention]

The present invention was made in view of the above-mentioned circumstances, and its purpose is to be able to predict the occurrence of quench before it occurs and take actions such as avoiding quench in superconducting equipment operation. The present invention provides a superconducting device with a transition prediction device.

[Summary of the invention]

The present invention allows a constant current to flow through a superconductor.

If the superconductor momentarily quenches due to one superimposed pulse current by periodically superimposing a pulse current, protective actions such as stopping the operation are taken as there is a risk of permanent quenching if the constant current value continues, and conversely, This superconducting device has a function to determine that the superconducting device is operating with sufficient margin if the pulse current does not instantaneously quench.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. 6 FIG. 1 is a block diagram of a superconducting device with a transition prediction device to which the present invention is applied. Constant current power supply 1 supplies current to superconductor 3 via circuit breaker 6 . The current value is variable, and any current from 0 to the rated current can be controlled continuously. A pulse current is superimposed on the superconductor by a pulse current WX2 in addition to the constant current power supply. The pulse current width and height are determined by the superconducting device Ii! It is necessary to determine the tfli, but the width is several ms and the height is approximately 5% of the rated current value. A balance circuit 4 inserted in parallel with the superconductor forms a bridge circuit together with the superconductor, and the voltage detector 5 operates even with a slight voltage change, making it possible to output an alarm signal 8. The constant current power supply performs a current reduction operation in response to the alarm signal, and if the alarm continues to be output, the circuit breaker 6 is opened and the protective resistor 7 is used to safely consume the energy of the superconductor.

The operation of the above device will be explained with reference to FIG. Figure 2 (a
) is a graph of the current l in the superconductor, (b) is the balance circuit output voltage V, and (c) is the voltage V generated by the constant current power supply to flow current through the superconductor. The shaded area in graph (a) is the quench region, where quenching occurs locally when the superelectric current value increases and enters this range. In general, a localized quenching state only occurs after a certain period of time (several tens of m8 or more, depending on the device) before it causes a general quenching. Therefore, in the current superposition of the pulse current width in the present invention, the quenched state has a current value of It disappears as the current returns to the constant current value.

First, as shown in (a), in order to start up the constant current power supply, the constant current power supply outputs the maximum voltage V. The waveform of I on which the pulse current from the pulse power source is superimposed is as shown in (a'). On the other hand, the balance circuit output V becomes (b), (2) and (2) when (2) does not fall into the quench region.

Only the voltage due to the inductance of the superconductor is displayed, but when I enters the quench region at time IA, a non-zero resistance portion occurs in a part of the superconductor at time b, so the alarm setting level VA is set. A value exceeding this occurs. At that point, the alarm is activated by a constant current power source, and 2 is sent, ・l decreases at a glance as shown in (c), and ■ decreases as shown in (a). 1 has fallen sufficiently and the alarm is not outputted again, the output voltage of the constant current power supply becomes the voltage value v0 for passing a constant current through the superconductor, and the subsequent operation continues. This current value is the maximum desired current value within a range that does not cause quenching of the superconductor.

Next, in FIG. 3, when the superconducting apparatus is performing constant material operation, the operation of this apparatus when the quench head load does not change due to external factors will be explained. As in Fig. 2, superconductor current I, balance circuit output V, and constant current power supply output voltage V are shown in (a) to (c), respectively. It is assumed that the quench region changes after time th autumn.

In FIG. 3, time 1. Up to this point, ■ does not fall into the quench region, and therefore \1 does not reach the 1゛ alarm level V^, so ■ becomes V because the rated current does not flow. Since the quench area is difficult to gradually decrease after time tB,
The pulse current is applied to the superimposed I 4j quench region,
■ exceeds the warning level. Therefore, an alarm signal is sent to the constant current power supply JL, and due to the current reduction, the constant current power supply output voltage V changes as shown in the diagram, and finally, after time to, the rated current is applied with the quench region stopping decreasing. The constant current power supply output voltage V for this purpose will continue.

As described above, the embodiments of the present invention have been explained with the drawings, but as a modified example, it is possible to omit the pulse power supply and obtain one effect of the present invention by adding a pulse current superimposition function to the constant current power supply. It is possible.

〔Effect of the invention〕

As described above, according to the present invention, in the operation of a superconducting device, a superconducting device equipped with a transfer prediction device that predicts the occurrence of quench before it occurs, and performs operations such as quench avoidance, etc.
Google is movable.

[Brief explanation of drawings]

11''2I is a block diagram of a superconducting device with a transition prediction device to which the present invention is applied, and FIGS. 2 and 3 are graphs for explaining the operation of the superconducting device. 1... Constant current power supply, 2... Pulse power supply, 3... Superconducting water 4... Balance circuit, 5... Voltage detector, 6...
- Breaker 7... Protection R resistor, 8 - Alarm signal. Agent Street Attorney Akio Takahashi Figure 3 (α)

Claims (1)

[Claims] ■ In a superconducting device that cools a superconductor below a critical temperature to reduce its electrical resistance to zero and allows current to flow with minimal power consumption, in parallel with a constant current power supply with a variable droplet value to flow a constant current through the superconductor, A pulsed power source is turned on to flow a pulsed current through a superconductor, and when the pulsed current is applied by the pulsed power source and the superconductor instantaneously transitions to a normal conducting state, that is, quenches, the voltage generated between the superconductor terminals is detected. A superconducting device characterized by comprising a voltage detector that emits a transition prediction signal.