JPS5937678A - Electric device - 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 an electrical device that prevents an adverse effect on the surrounding area due to a rise in temperature when an excessive current flows through a current-carrying body.

Generally, in a high-voltage power converter using a thyristor, the series number of the elements is determined by taking into consideration all normal operating voltages. Sporadically applied lightning impulses, switching surges, etc. are limited to a predetermined voltage by arresters.

In the conventional type, each thyristor element (
Arrester (At) (Ts) (T,) (Tll)
A, ) (AI) and snubber circuit (Sl) (St)
(S,) are connected in parallel. In this case, even if an overvoltage such as a lightning impulse is applied from the outside to each thyristor element (Tl) (Te1) (TI), the arrester (A,) CA*) (All) and snubber circuit connected in parallel (81) (st) (8g) Since the limited first voltage VML is not applied, each silicon risk element (Tl) (T,) ('rs) is protected.

“However, when a conduction command is issued to each thyristor (T1) (TJ (Ts), if only the thyrisk element (T8) does not conduct due to a failure in the dot-string circuit, the thyristor element (Tl) * remains. When the other thyristors are conductive, a load current determined by the external circuit conditions is forced to flow through the arrester (At) connected in parallel with the thyristor element (T□), and its terminal voltage is the voltage of the arrester p - (AX). −
The value is determined by the current characteristics.

Usually, arresters do not have the ability to carry an excessive current such as the load current for a long period of time, so they overheat and have an adverse thermal effect on the surrounding area. Furthermore, if the arrester overheats and mechanically breaks, the flying fragments may cause injury to the surrounding area. Therefore, as shown in Figure 2, if an excessive current flows through the arrester, connect both ends of the arrester electrically. It has been proposed to be configured to connect to

That is, in FIG. 2, an overvoltage limiting element (1) such as a zinc oxide type arrester is brought into contact with a low melting point metal (3) such as solder, and the overvoltage limiting element (1) is placed between a pair of electrodes (5) and (6).
1) and the low melting point metal (3) are electrically connected in series, pressed to one lj Ji +51 by a spring (8), and connected to the other electrode (6) by a shunt (9), and melted. Both current-carrying parts (5a) (6a) are electrically connected by the low melting point metal (3), and both the current-carrying parts (5a) (6a) facing each other are connected electrically.
is placed below the low melting point metal (3).

In the above configuration, if an excessive current flows through the overvoltage limiting element 1), the electrode (5)→overvoltage limiting element (1)→→
The low melting point metal (3) passes through the circuit of metal (3) → shunt (9) → electrode (6). As a result, the temperature of the overvoltage limiting element (1) increases, so the low melting point metal (3) melts and both It fell between the current-carrying parts (5a) and (6a), and both electrodes +51 (61
There is an electrical connection between the two. Therefore, the current flowing through the overvoltage limiting element (1) is reduced to both current-carrying parts (5a) (6a
), the overheating of the overvoltage limiting element (1) can be suppressed.

However, if a part of the overvoltage limiting element electrically breaks down and excessive current concentrates there, low-melting, low-melting metal in the vicinity will instantly melt and fall, but the area where the current is concentrated will Since the melting amount of the low-melting point metal differs depending on the type, the connection between the two current-carrying parts is often unstable.

This invention was made to eliminate the above-mentioned drawbacks.
To provide an electric device in which a large amount of low melting point metal is melted by providing a heat transfer plate having good heat conductivity and electrical conductivity between a current carrying body dedicated to an overvoltage limiting element and the low melting point metal.

The figures will be explained below. In Fig. 8, (1) is a current carrying body consisting of an overvoltage limiting element such as a zinc oxide element, C
2) is a heat transfer plate closely attached to one end of the current carrying body (1), and is made of a member with excellent heat transfer and electrical conductivity. (3) is a low melting point metal such as solder that is in close contact with the heat exchanger plate (2), (4
) is a conductive plate closely attached to a low-melting metal (3), and (5) is a first current-carrying part (5) closely attached to the other end of the current-carrying body (1).
5a), the first electrode (6) is the first current-carrying part (5a);
a) and a given interval? The second current-carrying part (6a
) is the second electrode. In addition, both current-carrying parts (5a)
(6a) is arranged below the low melting point metal (3) so that the molten low melting point metal (3) can fall and establish an electrical connection. (7) is an insulating orientation in which the current-carrying body (1) is retracted and both electrodes 15+(6) are held, and both current-carrying parts (5a
) (6a) and forms a reservoir 9 (7a). (8) is a spring disposed between the plate (4) and the second electrode (6), which presses the overvoltage limiting element (1) against the electrode (5) of the second electrode (1). (0) is a shunt electrically connected to the plate (4) and the second electrode (6).

Next, the operation will be explained. 2 in Figure 8, even if an excessive current flows locally in the current carrying body (1), the heat transfer plate (2) is gradually heated, so that the low melting point metal (3) and heated. Therefore, since the low melting point metal +3) melts and falls almost simultaneously, the reservoir (7a) is filled with a large amount of low melting metal 12), and the gap between the current carrying parts (5a) and (6a) is Ensuring current carrying capacity.

In the above embodiment, an overvoltage limiting element such as a zinc oxide arrester was explained, but if an excessive current flows during an accident and causes overheating,
Similar effects are expected.

According to this invention, there is a heat transfer plate that has heat conductivity and conductivity between the current carrying body and the low melting point metal. By providing this, the entire low melting point metal is heated evenly, so a large amount of low melting point metal melts almost simultaneously, and the current flow between the two electrodes increases.
can be sufficiently secured.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a power conversion device, FIG. 2 is a cross-sectional view showing a conventional electric device, and No. 8 (2) is a cross-sectional view showing an embodiment of the present invention. In the figure, (1) is a current carrying body, (2)
is a heat exchanger plate, (3) is a low melting point metal, (5) is the 10th electrode,
(M) is the second electrode. Note that the same reference numerals in each figure indicate the same or equivalent parts. Agent Makoto Kuzuno - Figure 1 Figure 3

Claims (2)

[Claims] (1) Between a pair of electrodes having respective current-carrying parts facing each other with a predetermined interval, a current-carrying body and a low-melting body (all electrically connected to the metal) are arranged in series, and the above-mentioned low-melting body In the structure in which the melting point metal is located above both of the current carrying parts, a heat transfer plate having excellent heat conductivity and electrical conductivity is closely attached between the current carrying body and the above melting point metal (metal). An electrical device characterized in that: (2) The electric device according to claim 1, wherein the current-carrying portion has a low melting point metal attached thereto.