JPS5839225A - Protecting circuit for dc high voltage load - 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 The present invention relates to a protection circuit for a DC high voltage load such as a particle accelerator.

In particle accelerators that use DC high voltage, such as electron accelerators and ion accelerators, flash shorts occur between the electrodes in the acceleration tube, and this is necessary to avoid damage to the electrodes due to the arc generated at that time. It is necessary to extinguish the arc as quickly as possible.

Therefore, conventionally, as shown in FIG. 1, for example, a protection circuit has been used in which a high-speed operating vacuum tube 2 is provided in series with a load 1, and the current from a DC power source 6 is cut off by the vacuum v2. Note that 4 is a current detector and 5 is a control device.

Therefore, the protection circuit configured as described above is for the vacuum tube 2.
Although the cut-off operation of the vacuum tube 2 is extremely fast, the drawbacks of the vacuum tube 2 include the large loss when energizing the normal load 1 current, and the need for an auxiliary power source for the filament, grid, etc., making the circuit configuration larger. There is.

The object of the present invention is to sufficiently suppress the influence of momentarily increasing overcurrent on a DC high voltage load, and to obtain a protection circuit with excellent efficiency and a compact circuit configuration.

This invention will be explained based on the embodiment shown in FIG. 1
1 is a load such as a particle accelerator, and 12 is a DC power source that supplies DC high voltage to the load 11.

Reference numeral 16 denotes a switching element provided in parallel with the DC power supply 12, such as a thyristor or ignitron having a short-circuit and shunt function. 14 is a non-linear resistance element inserted into the load 11111 from the shunt point P in series with the load 11, and this element 14 exhibits high resistance at small currents and low resistance at large currents. For example, 8i0. It may be made of ceramic such as ZnO, or it may be one that utilizes the forward characteristics of a silicon diode or the reverse characteristics of a Zener diode. 15 is a switching control for controlling the switching of the switching element 16. device, 16
is a current detector connected in series with the load 11, and its output signal is sent to the switching control device 15.

The operation of the circuit configured as described above will now be explained. For example, in a load 11 such as a particle accelerator, when a flash short circuit occurs between electrodes in an acceleration tube, a short circuit current tends to flow from the power source 12 to the load side. This is quickly detected by the current detector 16 and its output signal is sent to the switching control device 15. As a result, a control signal such as an ignition pulse is sent from the switching control device 15 to the switching element 16. As a result, the switching element 16 is ignited, and the short circuit current is bypassed so that it does not flow to the load side.
When using a single star or ignitron, during bypass current conduction, the load 11
A terminal voltage of several tens to hundreds of square meters remains between the terminals. Regarding the arc between the electrodes in the accelerating tube, since the arc voltage is a relatively low value, the arc may not be extinguished due to the residual voltage. However, as shown in the figure, since the nonlinear resistance element 14 is provided in series with the load 11, the residual voltage is shared by the nonlinear resistance element 14, and the arc current is suppressed and the arc is stopped. disappear completely. The nonlinear resistance element 14 exhibits high resistance when the load current is small, and low resistance when the load current is large.
This has the effect of reducing power loss as much as possible when passing through 4.

Now, in the above-mentioned embodiment, a protection circuit having the simplest configuration was shown, but this protection circuit 4 may be configured as shown in FIG. That is, the switching element 17 is connected to an arc extinguishing circuit 17 formed by connecting a reactor L and a capacitor C in series so that the current flowing through the switching element 16 becomes oscillatory and the switching element 16 is completely automatically extinguished. Alternatively, a thyristor 18 may be provided in series with the load 11, and a voltage may be applied to the load 11 at any time. Note that when you do this,
The aim is for the load current or voltage to rise quickly (for example, several 10
(around μs).

By the way, in the embodiments shown in FIGS. 2 and 6, the non-stone wire resistance element 14 is provided in series with the load 11 in order to reduce the arc current and completely extinguish the arc.
As shown in the figure, the battery 20 is inserted in series with the load 11,
Furthermore, the same effect can be obtained even if the polarity is reversed.

5- Also, when configured as shown in Fig. 5, the above-mentioned 6th
The same effect as shown in the figure is achieved.

As can be understood from the above explanation, when an overcurrent that instantaneously increases is about to flow through the load, this is bypassed by the switching element, so damage to the load due to the overcurrent is avoided, and the load The arc can be completely extinguished by reducing the arc current by using a non-linear resistance element or a battery of reverse polarity connected in series with the arc.

As described above, according to the present invention, since the circuit constituent elements are small, this type of circuit can be downsized and the power loss can be reduced as much as possible.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional example, and FIGS. 2 to 4 are circuit diagrams showing embodiments of the present invention. 11... Load, 14... Non-linear resistance element, 12... DC power supply, 20...
・Battery 16...Switching element, P...
... Divergence point 6- O I Investigation 7 Figure 5 Large 5 Figure--= Blanket 12 procedural amendment (method) January 29, 1981 1, Indication of case 1981 Patent application No. 137921, Name of the invention: Protection circuit for DC high voltage loads 3. Relationship to the case of the person making the amendment Patent applicant Postal code: 615 Address: 47, Umezu Takaune-cho, Ukyo-ku, Kyoto-shi Column for a brief explanation of the drawings in the specification. 5. Contents of correction

Claims (1)

[Claims] / A switching element is provided in parallel with a DC power supply that supplies high DC voltage to the load, and a non-switching element is connected in series from the shunt point to the load side, which exhibits high resistance at small currents and low resistance at large currents. A DC high voltage load protection circuit characterized by the insertion of a linear resistance element. λ A protection circuit for a DC high voltage load, characterized in that a switching element is provided in parallel with a DC power source that supplies DC high voltage to the load, and a battery is inserted in series with reverse polarity from the shunt point to the load side.