JPH07174803A - Superconductive coil quenching detection device - Google Patents

Abstract

PURPOSE:To easily detect any quenching occurring at the distant arbitrary coil section of a superconducting coil by leading out two intermediate taps from the superconducting coil and connecting it to fixed terminals of a 3-terminal variable resistor. CONSTITUTION:Intermediate taps 17 and 18 in addition to coil ends 5 and 6 are led out from a superconducting coil 1, led in a quench circuit 4, respectively, and connected to fixed terminals 19 and 20 of a 3-terminal variable resistor 21. A rough bridge balance is achieved by adjusting the resistance value of a bridge resistor 12, and a bridge circuit is balanced by adjusting the partial potential point of the resistor 21. For example, if any quenching occurs between the coil end 5 and the tap 17, a normal conducting resistance component occurs at that coil section, a normal conducting voltage is generated, and the balance condition of the bridge circuit is broken. When the voltage generated due to unbalance continuously exceeds the limit for the required period of time or longer, a protective method connected to detection output ends 11 and 12 determines the occurrence of a quenching and outputs a quenching detection signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quench detecting device for a superconducting coil.

[0002]

2. Description of the Related Art A circuit diagram of a quench detecting device for a superconducting coil according to the prior art is shown in FIG. The superconducting coil 1 to be detected is connected to the DC power source 2 via the DC circuit breaker 3 and is connected in parallel with the protection resistor 16 via the protection switching switch 15. The coil ends 5 and 6 of the superconducting coil 1 and the intermediate tap 7 are guided to the quench detection circuit 4.

The quench detection circuit 4 has voltage input terminals 8, 1
0 and detection output terminals 9 and 11 are provided. Lead wires derived from the coil ends 5 and 6 of the superconducting coil 1 are connected to the voltage input ends 8 and 10, respectively, and the two bridge resistors 12 and 13 connected in series are connected to each other on the other hand.
Both ends of are connected. The bridge resistor 12 is a variable resistor, and the bridge resistor 13 is a fixed resistor. The lead wire derived from the intermediate tap 7 of the superconducting coil 1 is connected to the first detection output end 9, and the common connection point of the two bridge resistors 12 and 13 is the second detection output end 11.
Make up. A bridge circuit for quench detection is configured by two portions of the superconducting coil 1 (hereinafter, referred to as “coil portion”) divided by the intermediate tap 7 and two bridge resistors 12 and 13.

Next, the operation of the detection circuit shown in FIG. 3 will be described. First, in the detection circuit of FIG.
That is, consider the case where the quench does not occur in the superconducting coil 1. With the protection switch 15 open, the DC breaker 3 is closed, a voltage for adjustment is applied from the DC power supply 2 to the superconducting coil 1, and a current is passed. If the magnitude of the current flowing through the superconducting coil 1 is i and the inductance of the superconducting coil 1 is L, then L × (di /
An inductive voltage of magnitude dt) is generated. Therefore, an ammeter M is connected between the detection output terminals 9 and 11 so that the bridge circuit is balanced under the above conditions, that is, the detection output terminals 9 and 11.
The value of the variable bridge resistor 12 is adjusted so that the swing (current value) of the ammeter M connected between 11 becomes zero.

Next, consider a case where a quench occurs in a part of the superconducting coil 1 for some reason while a current is flowing in the superconducting coil 1 in a superconducting state. When the quench occurs in at least a part of the superconducting coil 1, the superconducting coil 1 becomes at least partially equivalent to the state in which the normal conducting resistance component is inserted, and as shown in FIG. It becomes as if the corresponding resistor 25 is connected in the superconducting coil 1. At this time, the resistance 25
A current flowing in the resistor 25 causes a normal conduction voltage across the resistor 25. The generation of this normal conducting pressure breaks the equilibrium condition of the bridge circuit and generates a voltage between the detection output terminals 9 and 11. When the voltage exceeds the predetermined value for a predetermined time or more, it is determined that the quench has occurred, and the quench detection signal is output.

With this detection output, the protection switch 15 is closed and the DC circuit breaker 3 is opened via a protection circuit (not shown). As a result, the magnetic energy possessed by the superconducting coil 1 is consumed as a circulating current from the superconducting coil 1 via the protective resistor 16 while being attenuated with a value of time constant = L / (resistance value of the protective resistor 16). As described above, since the current at the time of occurrence of quench flows through the protective resistance 16, the magnetic energy possessed by the superconducting coil 1 is consumed by the protective resistance 16, and the energy consumption, that is, the temperature rise in the superconducting coil 1 itself is correspondingly consumed. It is suppressed and here the superconducting coil 1 can be protected from thermal destruction.

[0007]

However, in the conventional quench detecting device for a superconducting coil, only the quench phenomenon occurring in either of the two coil portions directly connected to both sides of the intermediate tap 7 of one superconducting coil is detected. However, it does not detect the quench of the superconducting coil in an arbitrary range away from the coil center tap. This type of detection device is in principle not suitable for detecting quench of either of two superconducting coils connected in series.

Therefore, an object of the present invention is to provide a quenching apparatus for a superconducting coil capable of detecting a quench of the superconducting coil generated in an arbitrary coiled portion that is separated.

[0009]

A quench detecting device for a superconducting coil according to the present invention derives two intermediate taps from a superconducting coil to be detected and inserts a fixed terminal of a three-terminal variable resistor between the two intermediate taps. In addition to connecting, connect two bridge resistors in series between both coil ends of the superconducting coil to form a bridge circuit with the superconducting coil and the bridge resistor, and the movable terminal of the three-terminal variable resistor and both bridge resistors are common The connection point is the detection output end.

[0010]

The balance of the bridge circuit in the quench detecting device for a superconducting coil according to the present invention is controlled by a variable bridge resistance and 3
This is performed by adjusting the resistance value of at least one of the terminal variable resistors. When a quench occurs in a part of the superconducting coil forming a part of the bridge circuit, a voltage is generated between the detection output terminals of the bridge circuit in the balanced state, and the quench can be detected based on the voltage. in this way,
According to the present invention, it is possible to detect a quench occurring in an arbitrary coil portion that is apart from the superconducting coil.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a quench detecting device for a superconducting coil according to the present invention. The superconducting coil 1 to be detected is connected to the DC power supply 2 via the DC circuit breaker 3 and is connected in parallel to the protection resistor 16 via the protection switching switch 15. From the superconducting coil 1 to the coil end 5,
In addition to 6, intermediate taps 17 and 18 are derived and introduced into the quench detection circuit 4, respectively. The quench detection circuit 4 includes voltage input terminals 8 and 10 and a detection output terminal 11,
22 is provided. A lead wire derived from the coil end 5 is connected to the voltage input end 8, and a lead wire derived from the coil end 6 is connected to the voltage input end 10. A variable bridge resistor 12 is connected between the voltage input terminal 8 and the detection output terminal 11, and a fixed bridge resistor 13 is connected between the voltage input terminal 10 and the detection output terminal 11. The two intermediate taps 17 and 18 derived from the superconducting coil 1 are connected to fixed terminals 19 and 20 of a 3-terminal variable resistor 21, respectively. Movable terminal 23 of 3-terminal variable resistor 21
Is connected to the detection output terminal 22.

In FIG. 1, consider the case of normal operation, that is, the case where the superconducting coil 1 is not quenched.
With the protection switch 15 open, the DC circuit breaker 3
Closed, and a current is passed from the DC power supply 2 to the superconducting coil 1,
The current value is changed. On the other hand, in order to balance the bridge circuit, in addition to the adjustment of the variable bridge resistor 12 through the above-described current adjustment process, the resistance value of the movable terminal 23 of the three-terminal variable resistor 21, that is, the division ratio adjustment is performed. be able to. For this adjustment,
For example, an ammeter M is connected between the detection output terminals 11 and 22, and the resistance of at least one of the bridge resistor 12 and the three-terminal variable resistor 21 is set so that the deflection (current value) of the ammeter M becomes zero. Adjust the value.

According to the circuit configuration of FIG. 1, the bridge resistor 1
By adjusting the resistance value of 2, a rough bridge balance is obtained, and 3
By adjusting the voltage dividing point of the terminal variable resistor 21, the bridge circuit can be balanced while confirming positive and negative swings of the ammeter M.

Next, consider a case in which a quench occurs in a part of the superconducting coil 1 for some reason while a current is being applied to the superconducting coil. For example, when a quench occurs between the coil end 5 of the superconducting coil 1 and the voltage tap 17, a normal conducting resistance component is generated in the coil portion, and a normal conducting pressure is generated. The generation of this normal conducting pressure destroys the equilibrium condition of the bridge circuit. When the voltage generated by this imbalance exceeds a predetermined value and continues for a relatively short predetermined time, it is determined that a quench has occurred by a protection means (not shown) connected between the detection output terminals 11 and 22. A quench detection signal is output.

With this detection output, the protection switch 15 is closed and the DC breaker 3 is opened via the protection means. As a result, the protection resistance 16 is connected in parallel to the superconducting coil 1, and the magnetic energy possessed by the superconducting coil 1 is time constant = L / (protection resistance 16
Resistance value (where L is the inductance of the superconducting coil 1) and is consumed as Joule loss of the flowing current while being attenuated. As described above, since the current at the time of occurrence of quench flows through the protective resistance 16, the magnetic energy possessed by the superconducting coil 1 is consumed by the protective resistance 16, and the energy consumption, that is, the temperature rise in the superconducting coil 1 itself is correspondingly consumed. Suppressed, where the superconducting coil 1 can be well protected from thermal destruction.

FIG. 2 shows a circuit diagram of another embodiment of the present invention. As shown, this embodiment has two superconducting coils 2
One quench detection circuit 4 is provided for 7, 28. The two superconducting coils 27 and 28 have a connecting portion 26
Are connected to each other in series. Superconducting coil 27
The coil end 30 of is connected to the voltage input end 8 and the voltage tap 31 is connected to the fixed end 19 of the three-terminal variable resistor 21. Similarly, the coil end 33 of the superconducting coil 28 is connected to the voltage input end 10, and the voltage tap 32 is connected to the fixed end 20 of the three-terminal variable resistor 21. The other components are the same as in the embodiment of FIG.

The quench detection circuit 4 itself of FIG. 2 is no different from that of FIG. 1, and the principles of adjustment for bridge circuit balancing and quench detection are the same as those of FIG. 1 already described. Even in the case of the coil configuration of FIG. 2, quench detection can be performed in exactly the same manner as in the case of FIG.

As described above, since the portion of the superconducting coil connected to the bridge portion can be arbitrarily changed, the quench generated in the arbitrary coil portion of each of the two superconducting coils can be easily detected.

[0019]

According to the present invention, it is possible to provide a quenching detection device capable of easily detecting a quenching which occurs in an arbitrary coil portion of a superconducting coil which is separated.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a quench detecting device for a superconducting coil according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the quench detection device according to the present invention.

FIG. 3 is a circuit diagram showing a conventional quench detection device for a superconducting coil.

FIG. 4 is a diagram for explaining the principle of quench detection.

[Explanation of symbols]

 1, 27, 28 Superconducting coil 2 DC power supply 3 DC breaker 4 Quench detection circuit 5, 6, 30, 33 Coil end 8, 10 Voltage input terminal 11, 22 Detection output terminal 12, 13 Bridge resistance 15 Protection switch 16 Protection resistor 17,18,31,32 Voltage tap 19,20 Fixed terminal of 3 terminal variable resistor 21 3 terminal variable resistor 23 3 Movable terminal of variable resistor

Claims (3)

[Claims] 1. A two-way tap is derived from a superconducting coil to be detected, a fixed terminal of a three-terminal variable resistor is connected between the two taps, and a series connection is made between both coil ends of the superconducting coil. Of the superconducting coil, in which a bridge circuit is formed by connecting the two bridge resistors of (1) and (2) to the movable terminal of the three-terminal variable resistor and the common connection point of the two bridge resistors. Quench detector. 2. The quench detection device for a superconducting coil according to claim 1, wherein at least one of the two bridge resistors is a variable resistor. 3. The quench detection device for a superconducting coil according to claim 1, wherein the superconducting coil is composed of two structurally separate coils, and the intermediate tap is led out from the middle of each coil.