JPH01227408A - Quenching detector - Google Patents

Abstract

PURPOSE:To obtain a quenching detector of an AC superconductive coil not requiring a means for inductively and correctly dividing the coil and for correcting a noise with high accuracy by providing a bias current feeding part feeding a bias current to a superconductive coil, and a bias voltage detecting part detecting bias voltage. CONSTITUTION:A bias current feeding part 52 feeding a bias current IB to a superconductive coil 2 and a bias voltage detecting part 53 detecting bias voltage VQ of both ends of the superconductive coil 2 outputting a signal breaking main power supply 1 of the superconductive coil 2 are provided. For instance, a DC bias current IB is fed to the superconductive coil 2 by the bias current feeding part 52 for measuring both end voltage of the superconductive coil 2 in a voltage measuring part 51. Then, the bias voltage detecting part 53 unifies the voltage of the coil both ends and detects DC bias voltage VQ and issues an order of an open-circuit to a breaker 3 so as to break a circuit, in case when the DC bias voltage VQ exceeds a predetermined threshold.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a quench detector for detecting normal conductive dislocations (quenches) in superconducting coils, and in particular, to a quench detector for detecting normal conducting dislocations (quenches) in superconducting coils. Regarding the detector.

(Prior Art) FIG. 3 shows a circuit diagram using a conventional quench detector for a superconducting coil. In other words, only one power supply.

A current is supplied to the superconducting coil 2, and in the event of an abnormality such as quenching, the current supply is stopped by opening the circuit breaker 3. At this time, the quench detector 4 is used to detect the quench, and the voltage measurement sections 41 and 42 measure the voltage of each half of the superconducting coil 2, and the voltage comparison section 43 compares the voltages. It has the function of generating a signal to open the circuit breaker 3 when the difference exceeds a threshold value.

(Problems to be Solved by the Invention) By the way, when the quench detector 4 shown in FIG. 3 is applied to an AC superconducting coil, an induced voltage is generated in the superconducting coil 1. In order to detect the quench voltage superimposed on that voltage by comparing the voltages of the two parts of the coil, it is necessary to accurately divide the coil in terms of inductance.

However, since there are distortions in the voltage waveform, stray inductance in the measurement system, etc., there is a drawback that means for correcting these with high precision is required.

Also, since the voltage tap is drawn out from the middle of the coil, there is a possibility that insulation may deteriorate from there.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a quench detector for an AC superconducting coil that does not require accurate division of the coil in terms of inductance or means for correcting noise with high accuracy.

[Structure of the invention]

(Means for Solving the Problems) The quench detector of the present invention has a configuration including a bias current supply section that supplies a DC bias current to a superconducting coil, and a bias voltage detection section that detects the DC bias voltage. .

(Function) The operating principle of the quench detector of the present invention will be explained with reference to FIG.

Figure 2 shows the voltage waveform at both ends of the superconducting coil when the superconducting coil quenches while DC bias current is being supplied to the superconducting coil 6 In other words, the AC power supply voltage VA
A DC bias current and a bias voltage V due to the resistance generated by quenching are superimposed on C. This ■9
Since is the average value of the voltage waveforms at both ends of the coil, it is sufficient to take the average of several AC cycles, and the quench detection accuracy can be improved.

Furthermore, even if there is distortion in the power supply waveform, if it is periodic, quenching can be detected by simply finding the average value of the voltage. In addition, under normal conditions, the bias voltage vQ
is zero.

(Example) An example of the present invention will be described below with reference to the drawings. Components that are the same as those in the prior art are designated by the same reference numerals.

FIG. 1 shows a superconducting coil 2 to which a quench detector 5 according to the present invention is applied.

The quench detector 5 includes a voltage measurement section 51, a bias current supply section 52, and a bias voltage detection section 53.

The bias current supply section 52 supplies a DC bias current (8) to the superconducting coil 2, and the voltage measuring section 51 measures the voltage across the superconducting coil 2. Then, the bias voltage detection section 53 averages the voltages across the coil and detects the DC bias voltage VQ.

If the DC bias voltage vQ exceeds a preset threshold, an opening command is issued to the circuit breaker 3.

Break the circuit.

Quench detection is performed based on whether the average value of the voltages across the superconducting coil 2 exceeds a certain threshold.

In other words, even if the power supply waveform contains periodic distortion, since the average value of the waveform is used, the distortion is canceled and quench detection can be performed with high accuracy.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to realize a quench detector for AC superconducting coils that does not require accurately dividing a superconducting coil into equal inductances and does not require highly accurate correction means. .

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram when a quench detector according to an embodiment of the present invention is applied to a superconducting coil, Fig. 2 is a voltage waveform diagram explaining the operating principle of quench detection according to the present invention, and Fig. 3 is a circuit diagram of a conventional quench detector. It is a circuit diagram explaining a quench detector. 1... Power supply 2 ・Superconducting coil 3...
- Breaker 4...Quench detector 5...
Quench detector 41.42... Voltage measurement section 43...
- Voltage comparison unit 51... Voltage measurement unit 52... Bias current supply unit 53... Bias voltage detection unit T... Time V... Voltage VQ... Bias voltage VAC... AC power supply voltage agent Patent Attorney Nori Ken Chika Yudo Ken Daishimaru Figure 1

Claims (1)

[Claims] An alternating current that is characterized by comprising a bias current supply section that supplies a bias current to the superconducting coil, and a bias voltage detection section that detects the bias voltage at both ends of the superconducting coil and outputs a signal to cut off the main power supply of the superconducting coil. Quench detector for superconducting coils.