JPH0717236Y2 - Surge absorption circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to a surge absorbing circuit used for protecting a device connected to an AC power supply from a surge voltage. .

(Prior Art) Conventionally, a power supply filter circuit is configured such that a noise removing capacitor is connected in series at both ends of an AC power supply, and a connection point of the noise removing capacitor is connected to a ground point. However, in such a power supply filter circuit, when an external surge voltage such as a lightning surge is applied to the input end of the AC power supply, an overvoltage exceeding the rated withstand voltage is applied to the noise removing capacitor, resulting in a short circuit state. There was a problem. Therefore, in general, in order to absorb the external surge voltage, a surge absorber such as ZNR is connected in parallel to each noise removing capacitor as a surge absorbing means.

FIG. 3 shows an example of such a surge absorbing circuit, which has an AC power supply AC, a fuse F1 connected to one AC power supply terminal (10), and the other AC power supply terminal ( 11) A series circuit of a fuse F2 connected to 11), noise elimination capacitors C1 and C2 connected between the non-power supply side terminals of the fuses F1 and F2, and a noise elimination capacitor C1 connected in parallel. Surge absorber ZI and surge absorber connected in parallel with the noise removing capacitor C2
Z2 and is connected from the middle point of the noise removing capacitors C1 and C2 to the ground point.

Here, the fuses F1 and F2 are used to protect the surge absorbers Z1 and Z2 from a short circuit failure or the like that occurs when a surge current larger than the rated allowable value flows into the surge absorbers Z1 and Z2.

With this configuration, both normal and common noises can be removed, the noise removal capacitors C1 and C2 can be protected from the application of excessive surge voltage, and the surge absorbers Z1 and Z2 are short-circuited. In this case, it is possible to prevent the fuses F1 and F2 from being blown and continuously flowing an excessive current to the surge absorbers Z1 and Z2.

FIG. 4 shows still another conventional example, and the configuration different from that shown in FIG. 3 has a midpoint between the noise removing capacitors C1 and C2 and a midpoint between the surge absorbers Z1 and Z2. The fuse F2 is inserted between and.

[Problems to be solved by the device]

However, in the conventional example shown in FIGS. 3 and 4, in order to protect the surge absorbing circuit when the surge absorbers Z1 and Z2 are short-circuited, the first surge absorber Z1 is connected to the AC power source AC. It is necessary to insert a fuse in each of the first closed circuit including the second surge absorber Z2 and the second closed circuit including the second surge absorber Z2. Ie, at least two fuses
F1 and F2 are required. Therefore, problems such as an increase in cost of the fuse and an increase in size of the fuse occur.

The present invention has been made to solve the above problems, and an object thereof is to provide a surge absorbing circuit capable of protecting a plurality of surge absorbers by a fuse inserted in one of the AC power supplies. It is in.

[Constitution of device]

(Means for Solving the Problem) According to the present invention, fuses are inserted between a plurality of surge absorbing means and an AC power source, and the fuses are inserted in respective closed circuits including the respective surge absorbing means. In this case, by sharing a part of the plurality of closed circuits, the fuse can also be used for disconnecting the plurality of closed circuits.

(Operation) The present invention uses a part of a plurality of closed circuits including the surge absorbing means from the AC power source as described above to obtain a surge absorbing effect and to cut off the fuse for closing the plurality of closed circuits. It can be used for both.

(Example) Hereinafter, the present invention will be described in detail based on an example.

FIG. 1 shows the basic structure of the present invention. The same structure as in the prior art example is designated by the same reference numeral, and the detailed description thereof is omitted.

The configuration different from the conventional example shown in FIG. 3 is that the second surge absorber Z2 is not connected to both ends of the noise removing capacitor C2 but is connected between the output terminals (21, 22).

With this configuration, the first surge absorber Z1
When a short circuit occurs, an excessive current flows to the first closed circuit from the AC power supply terminal (10) to the fuse F → the first surge absorber Z1 → the ground point, and the fuse F is inserted,
When the second surge absorber Z2 is short-circuited, the AC power supply terminal (1
0) to the fuse F → the second surge absorber Z2 → the AC power supply terminal (11). Even if the absorbers Z1 and Z2 are short-circuited, the surge absorption circuit can be reliably protected.

Further, the protection of the noise removing capacitor C1 from the surge voltage can be performed by the first surge absorber Z1 as in the conventional case, and the protection of the noise removing capacitor C2 is performed by the first surge absorber Z2 from the first surge absorber Z2. The surge absorber Z1 can be operated at a voltage less the breakover voltage.

FIG. 2 shows a second embodiment of the present invention, which uses the embodiment shown in FIG. 1 as a second power supply filter circuit 2 at the next stage of the power supply filter circuit 1. Is.

Here, the first power supply filter circuit 1 includes a third surge absorber Z3 connected from the AC power supply AC through a fuse F.
And a noise removing capacitor C3 connected in parallel with the third surge absorber Z3, and this noise removing capacitor
A filter L having a coil connected to one terminal of C3 and a coil connected to the other and configured to be coupled to each other, and a noise removing capacitor C4 connected to an output end of the filter L. It consists of

Therefore, with this configuration, the power supply filter circuit 2 can be protected and the power supply filter circuit 1 can be protected by the fuse F.

The present invention is not limited to the above embodiment, for example, the first surge absorber Z1 is connected in parallel with the noise removing capacitor C2, and the fuse F is connected to the AC power supply terminal (11) side. You may comprise. In short, the first and second surge absorbers Z1 and Z1 have a fuse F interposed between them and the AC power source AC, and the fuse F includes the surge absorbers Z1 and Z2. Any fuse may be used as long as the fuse F can also be used to cut off the both closed circuits by sharing a part of the both closed circuits. Although the capacitor is used as an example for removing noise, it may be combined with a resistor or an inductor.
It goes without saying that impedance is all that is required.

[Advantages of the Invention] As described above, the present invention provides a series circuit of a first impedance and a second impedance that is fed from an AC power supply and connected in parallel with the AC power supply, and one of the series circuit and the AC power supply. A first surge absorbing means connected in parallel with the first or second impedance connected to the non-power supply terminal side of the fuse, and the series circuit. The second surge absorbing means connected in parallel is provided, and the middle point of the series circuit is connected to the grounding point, so that the surge absorbing effect is obtained and the fuse is cut off into a plurality of closed circuits. Therefore, the fuse has a remarkable effect that the cost of the fuse is increased and the size of the fuse is prevented from increasing.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention, and FIG.
FIG. 3 is a circuit configuration diagram showing a second embodiment of the present invention, and FIGS. 3 and 4 are circuit configuration diagrams showing a conventional example of the present invention. AC ... AC power supply, C1 ... First impedance, C2 ... Second impedance, F ... Fuse, Z1 ... First surge absorbing means, Z2 ... Second surge absorbing means.

Claims (1)

[Scope of utility model registration request] 1. An AC power supply, a series circuit of a first impedance and a second impedance, which is fed from the AC power supply and connected in parallel with the AC power supply, and a series circuit and one terminal of the AC power supply. A fuse interposed between the first and second impedances connected in parallel with the first or second impedance connected to the non-power supply terminal side of the fuse, and in parallel with the series circuit. Second connected
The surge absorbing circuit according to claim 1, wherein the midpoint of the series circuit is connected to the ground point.