JPH0195434A - Superconductive current safety breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a superconducting current safety breaker used as a safety device in the event of superconductor breakdown in a device using superconductors.

BACKGROUND OF THE INVENTION In recent years, devices using superconductivity have been developed. Superconductivity occurs below a critical current, critical temperature, and critical magnetic field, but when at least one of these three conditions exceeds this value, a transition from a superconducting state to a normal conducting state occurs. At this time, a large current is flowing in the superconducting state and the resistance value increases, causing heat generation that can cause the superconducting wires inside the device to melt.

The rapid expansion of the refrigerant may cause an explosion, resulting in equipment failure. For this reason, superconducting current safety breakers have conventionally been used that detect superconducting current and cut off the current when it reaches a critical current.

A conventional superconducting current safety breaker will be explained below.

Figure 3 is a diagram showing the configuration of a conventional superconducting current safety breaker, in which 6 is a superconducting wire, 6 is a relay, 7 is a resistor, 8 is an amplifier, and 9 is a comparison between the output of the amplifier 8 and the DC power supply VC. This is a comparator that performs

The operation of the superconducting current safety breaker configured as above will be explained below.

First, when current is flowing through the coil section of relay 6,
The contact portion of the relay 6 is closed, and a superconducting current is flowing through the superconducting wire 6. The voltage across a resistor 7 connected in series with the superconducting wire 6 is input to an amplifier 8 . Here, the resistance value R of the resistor 7 and the amplification degree μ of the amplifier 8 are set to have the following relationship, assuming that the critical current Ic is set.

Vc=μΦIG*R The output of the amplifier 8 is input to the comparator 9 and compared with the DC current v0. When the output of amplifier 8 exceeds vc, that is,
When the superconducting current exceeds the critical current.

The output of the comparator 9 is turned off, the contact portion of the relay 6 is opened, the current flowing through the superconducting wire 6 is cut off, and failure of the device is prevented.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, since the DC power supply VC was constant, it is not possible to always cut off with an appropriate current in response to changes in the critical current due to changes in the magnetic field or temperature applied to the superconducting wire. The problem was that it could not be done.

The present invention solves the above-mentioned conventional problems.

The purpose of the present invention is to provide a superconducting current safety breaker that can always interrupt the current at an appropriate time in response to changes in the current flowing in a superconducting wire, the applied magnetic field, and the temperature.

Means for Solving the Problem To achieve this object, the superconducting current safety breaker of the present invention uses a superconducting material for the movable contact.

A ferromagnetic material is attached to the movable contact, and a magnet is provided in the moving direction of the movable contact.

Effect With this configuration, when the superconducting wire used in the circuit that detects destruction of the superconducting state and cuts off the current is in the superconducting state, the movable contact is also in the superconducting state. The movable contact is pressed against the contact by the magnetic flux of the provided magnet, and the circuit is not in the make state. When the superconducting wire used in the circuit becomes normal conductive, the movable contact is also destroyed from the superconducting state. When normal conduction occurs, the ferromagnetic material attached to the movable contact is attracted to the magnet, and the circuit enters a break state. In this way, the superconductivity of the movable contact is destroyed under the same conditions as the superconducting state of the superconducting wire used in the circuit that detects the destruction of the superconducting state and attempts to cut off the current. It is possible to always cut off the current at an appropriate time in response to changes in the current flowing through the superconducting wire, the applied magnetic field, and temperature.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to one drawing.

FIG. 1 is a block diagram showing a make state of a superconducting current safety breaker according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a breaking state of the superconducting current safety breaker of the present invention. 1st
2, 1 is a magnet, 2 is an iron piece, 3 is a superconducting movable contact, and 4 is a superconducting wire.

The operation of the superconducting current safety breaker configured as above will be explained below.

First, the makeup state will be explained. A superconducting current is flowing through the superconducting wire 4. At this time, since the superconducting movable contact 3 is made of a superconducting material having the same characteristics as the superconducting wire 4, the superconducting movable contact 3 is also in a superconducting state. The iron piece 2 attached to the superconducting movable contact 3 tries to be attracted to the magnet 1, but due to the Meissner effect, the superconducting movable contact 3 in the superconducting state is pressed against the superconducting wire 4, as shown in FIG. The makeup state is maintained.

Next, the break state will be explained. Now, if the temperature and magnetic field surrounding the superconducting material change and the critical current becomes smaller than the flowing current, the superconducting state of the superconducting wire 4 and the superconducting movable contact 3 is destroyed and they shift to normal conductivity. When in the superconducting state, the superconducting movable contact 3 was repelled by the magnet 1 due to the Meissner effect, but this repulsive force disappears due to the destruction of the superconducting state, so the superconducting movable contact 3 attracts the iron piece 2 attached to the superconducting movable contact 3. The force causes the superconducting movable contact 3 to separate from the superconducting wire 4, resulting in a broken state as shown in FIG.

Next, we will explain the market transition from a break state to a make state. After the superconducting state is destroyed, if the temperature drops sufficiently again, the superconducting movable contact 3 automatically returns to the make state shown in FIG. 1 due to the Meissner effect.

As described above, according to this embodiment, the superconducting state is prevented from being destroyed by using a superconducting material for the movable contact, attaching a ferromagnetic material to the movable contact, and providing a magnet in the moving direction of the movable contact. It is possible to always cut off the current at an appropriate time in response to changes in the temperature and magnetic field applied to the current flowing in the superconducting wire used in the circuit that detects and cuts off the current.

In addition, in the embodiment, the magnet 1 may be a permanent magnet or an electromagnet.

In addition, due to the shape 1 dimension 1d of the iron piece 2 attached to the superconducting movable contact 3, the iron piece 2 receives an attractive force that is smaller than the repulsive force that the superconducting movable contact 3 receives due to the Meissner effect, and the Meissner effect does not work. Needless to say, the design is such that the superconducting contact 3 is attracted to the magnet 1 side when

Effects of the Invention As described above, the present invention uses a superconducting material for the movable contact,
The superconducting state of a superconducting wire used in a circuit that detects destruction of the superconducting state and attempts to cut off the current by attaching a ferromagnetic material to the movable contact and providing a magnet in the moving direction of the movable contact. Since the superconductivity of the movable contact breaks down under the same conditions as the superconducting wire used in the circuit, it has the advantage of being able to always cut off the current at the appropriate time in response to changes in the current flowing in the superconducting wire used in the circuit, the applied magnetic field, and the temperature. This makes it possible to realize a superconducting current safety breaker.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the make state of the superconducting current safety breaker in an embodiment of the present invention, FIG. 2 is a front view showing the breaking state of the superconducting current safety breaker in the embodiment of the present invention, and FIG. 3 is a conventional view. FIG. 2 is a circuit diagram showing the configuration of a superconducting current safety breaker. 1... Magnet, 2... Piece of iron, 3. River...
Superconducting movable contact, 4... Superconducting wire, 6...
...Superconducting wire, 6...Relay, 7...
Resistor, 8...Amplifier, 9...Comparator. Name of agent: Patent attorney Toshio Nakao and one other person
-Magnet? ---Kinyi 3-ff s-ko movable #r 纺Fig. 1 4-Kinmo! I line diagram 2

Claims (3)

[Claims] (1) A superconducting current safety breaker characterized in that a movable contact is made of a superconducting material, a ferromagnetic material is attached to the movable contact, and a magnet is provided in the moving direction of the movable contact. (2) The superconducting current safety breaker according to claim 1, wherein a superconducting material having the same characteristics as the movable contact is used as the contact material. (3) The movable contact is made of a superconducting material having the same characteristics as a superconducting wire used in a circuit that detects destruction of a superconducting state and interrupts current. Superconducting current safety breaker.