JPS5843977B2 - Powder safety circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety circuit for electric circuits using a powder arrester, and in particular, suppresses lightning surge voltage in telephone circuits in people's homes, thereby preventing fuses from breaking. The idea is to provide a fuse that will break in response to mold temperature surges.

Conventionally, the security circuit of a telephone subscriber has a line L1 . The arrester A1.L2 is connected in series in advance. A2 is installed, arrester A1
．． The neutral point of A2 is grounded at ground E, and before that the fuse F1. F2 was provided.

The purpose of this circuit is that when a lightning surge occurs, the arrester A1. A2 suppresses the voltage and warms the mold - when a deer enters, the arrester and the fuse X'AI + F 1 + A2
+F2 was working at the same time and cutting off the circuit.

However, in reality, if the fuse is made to withstand lightning surges or higher, it will not blow even when there is a mold temperature surge, so it is usually 6A DC.
During lightning strikes, the fuses would break as the arresters operated, causing hundreds of disconnections a day in mined areas.

Furthermore, recently, semiconductor components that are susceptible to surges are being used to provide advanced functions to telephones, so there has been an increase in the number of cases in which the telephones themselves are damaged by secondary surges caused by the activation of the protector.

In order to prevent this phenomenon, the simplest thing to do is to add an additional set of arresters A to the circuit shown in Fig. 1, as shown in Fig. 2.
3. Arrester A3゜A4 against lightning surge against A4
works and arrester A1. A2 does not work, and arresters A, A2 work against the mold temperature surge, and arrester A3. A4 does not work and fuse F1. It was thought that F2 would be disconnected.

This shows the difference in properties between lightning surge and mold temperature surge as A1. A2
and A3. This is based on the principle that this is reflected in the difference in the characteristics of the arrester used in the A4.

However, as long as a simple gap discharge is used, there is no material that can withstand the high energy density of arc discharge, and the electrodes are deformed and deteriorated and the surrounding insulators are contaminated.As a result, the variation in operation becomes more than 100%, and the arrester design characteristics was not maintained and the desired effects could not be achieved.

For this reason, attempts have been made to adjust the order of operation by inserting a reactance element in the middle of the two-stage arrester, as shown in the section X in Figure 2, but this method has not been successful in controlling the arrester operation. However, there is nothing that is currently in practical use.

The present invention was developed by one of the inventors using a powder arrester that he had previously invented.The powder arrester selectively operates against lightning surges with many high-frequency components, and against mold temperature surges with many low-frequency components. In contrast, the carbon arrester is activated to reduce the probability of fuse rupture due to lightning surge.

A powder arrester is a device in which sized insulating powder (e.g. aluminum oxide powder, spherical, 30±10 microns in size) is placed between the discharge gap and enclosed in a small amount of moisture. This is what I did.

The amount of water contained is such that it can be obtained by simply enclosing it in a saturated state at a temperature about 10 degrees higher than the operating temperature when manufacturing a powder arrester.

This powder arrester (i) ensures operation by leakage current on the powder surface before operation, (1i) prevents damage to the electrode by not concentrating energy due to the presence of powder, and (
m) Contamination of the insulator is prevented by masking the discharge products with the powder, thus reducing the variation in operation by approximately 1/10.
This is what I did.

Fig. 3 shows an embodiment of the present invention, in which powder arresters So and S2 are connected in series between the lines L1 and L2, sandwiching the fuses F1 + F2 shown in Fig.1. The neutral point is commonly grounded with the carbon arrester A1 y A2.

A 1 s A2 is a carbon arrester that uses carbon electrodes as discharge electrodes and has a discharge gap of 0.075 mm between the carbon electrodes, and operates at an average of 400 V at commercial frequencies and at an average of 700 V during lightning surges.

S1+82 is a powder arrester with a gap of 0.1 mm that operates at an average of 600 V at commercial frequencies and at an average of 300 V at lightning surges.

In general, carbon arresters have a structure in which gas or air is used as a medium and the discharge gap between the electrodes is less than 0.1 mmJfi, and there are many low frequency components and the surge rise waveform is gentle and does not vary for commercial frequencies. However, in response to lightning surges, the discharging electrode undergoes physical and chemical changes due to the manually applied discharge energy density, resulting in abnormal discharge or short circuits, resulting in greater variations in operation.

On the other hand, with powder arresters, the discharge gap is filled with insulating powder, so it has relatively high voltage resistance against commercial frequencies, and the insulation inside the discharge gap is able to withstand lightning surges. Since the discharge path is dispersed by the material powder, discharge delay can be reduced, surge resistance can be increased, abnormal discharge can be prevented, and variations in operation can be reduced.

When a lightning surge is applied between the ground E and the line, the powder arrester immediately leaks high-frequency components through the powder surface and excites the current carrier, so the arrester A 1 y A2 does not operate and the arrester S1. Only S2 operates.

On the other hand, when mold temperature occurs, this mainly consists of low frequency components, so rather than excitation of the powder surface, the gap of the carbon arrester is operated, and the arrester S1. S2 is not activated, only arrester A1 + A2 is activated, and fuses F1. F2
operate to interrupt the circuit.

Of course, since A1yA2 is a conventionally used arrester, it has the above-mentioned drawbacks, but the high frequency component of the surge is always transferred to the arrester S1. Since it is bypassed at S2, the probability of deterioration is small.

FIG. 4 shows an embodiment of the music according to the present invention, in which the S3
．． Two powder arresters of S4 are connected in series and used as one, and the line L1. It is installed between L2 and its neutral point is separately grounded at E2.

Arrester S3. The installation point of S4 is the powder arrester S1 mentioned above.
．． It is appropriate to place the subscriber line lead-in utility pole and wiring terminal box slightly away from S2.

The purpose of this is to suppress surges before they enter the subscriber line when they enter from the line, and to protect the line cable when surges enter from the ground of El.

S3. The powder arrester used in the S4 has a slightly wider gear width, and has an I o o ov range for commercial frequencies and 500 for lightning surges.
It is desirable to operate at a voltage approximately twice as high as V.

As explained above, according to the present invention, in a simple discharge gap, the operating voltage is controlled by the gear tooth width, whereas in powder arresters, the gear tooth width, moisture content, material and surface characteristics of the powder are designed. This makes it possible to change the operation caused by surge waveforms without degrading the characteristics, so it is possible to permanently maintain the function that the fuse does not blow during lightning surges and blows during mold temperature surges. Ta.

Since the solid powder arrester suppresses the deterioration of its characteristics, there are few abnormal discharges, and therefore this circuit is
It is suitable for the safety of circuits that use semiconductor components because there are few secondary surges.

[Brief explanation of the drawing]

Fig. 1 shows a general subscriber safety circuit, Fig. 2 shows a conventional fuse breakage prevention circuit, Fig. 3 shows an embodiment of the powder safety circuit of the present invention, and Fig. 4 shows a small embodiment of the song of the present invention. . T...Telephone, A1-A4 + S1 + S2・
...Arrester, Fl, F2... Hughes.

Claims (1)

[Claims] 1 Telephone line L1. Fuses are installed on the L2 side, two carbon arresters are connected in series between the lines on the telephone side that sandwich the fuses, and an insulating powder that has a substantially uniform spherical shape is installed between the lines on the line side that sandwich the fuses. At least one powder arrester is installed in which two powder arresters are connected in series, and the neutral point of the carbon arrester and the neutral point of the powder arrester are connected in series. A powder safety circuit characterized by being grounded.