JP3132589B2 - Switchgear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching device such as a relay for opening and closing an electronic device.

[0002]

2. Description of the Related Art FIG. 7 is an electric circuit diagram using a conventional switchgear. In FIG. 7, the switching device 3 includes a main contact 31 connected between the power supply 1 and the load 2, and an operation coil 37 connected to the main contact 31 via a mechanism (not shown) to open and close the main contact 31. Has become. Control switch 5
Is closed and the control power supply 4 is applied to the operation coil 37, the main contact 31 is closed after a predetermined application time, and the control switch 5 is opened to shut off the control power supply 4. It is opened.

[0003]

In general, a relatively large noise prevention capacitor of, for example, about 1 microfarad is connected between power supply terminals of an electronic device in order to prevent leakage of internal circuit noise such as switching noise to the outside. In many cases. The load 2 in FIG. 7 shows such a case, in which a noise preventing capacitor 2A is connected between the power supply terminals of the internal circuit 2B.

In such a load, when the main contact of the switchgear is closed, the charging time of the noise prevention capacitor is very short, for example, about 10 microseconds at the moment when the main contact is closed. Large current flows up to. The input current of the electronic device is, for example, about 1 amp. Normally, a switching device having a main contact capacity corresponding to the input current is used. There is a problem that welding occurs at the main contacts of the switchgear and the life of the main contacts is significantly shortened.

On the other hand, conventionally, for example, a non-contact relay is used, but a non-contact relay capable of supplying such a large current even in an extremely short time is expensive.
In addition, there is a problem that the outer shape becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost and small-sized switchgear for welding a main contact caused by a charging current when a capacitive load is closed, such as an electronic device to which a noise preventing capacitor is connected. Is to prevent it.

When the capacitive load is opened, for example, the electric charge charged in the noise preventing capacitor is discharged through the internal circuit, so that there is almost no welding at the main contact.

[0008]

In order to achieve the above-mentioned object, a switchgear according to the present invention is connected between a power supply and the power supply terminal.
A main contact connected between the control coil and a load having a noise-preventing capacitor, and closed when a control power is supplied to the operation coil after a predetermined power-on operation time; the main contact this a first resistor and a switching element, respectively in parallel to the main contact is connected in series, and turning on the control power to the operating coil
Immediately before closing the point, the switching element is turned on,
Ri Do and a control circuit for turning off and shutting off the control power immediately the switching element before the open circuit of the main contact, before
The switching element is turned on before the main contact is closed.
To charge the capacitor through the first resistor.
That so. The control circuit includes, for example, a photodiode of a photocoupler including a photodiode and a phototransistor connected in series to an operation coil, a second resistor connected in series to a switching element, and the photocoupler. Of the photocoupler and the third resistor, and a connection point between the phototransistor of the photocoupler and the third resistor is connected to a control terminal of the switching element, or in series with an operation coil. A connected fourth resistor, a photodiode of a photocoupler including a photodiode and a phototransistor, a second resistor connected in series with a switching element, and a phototransistor and a third resistor of the photocoupler, respectively; And the photocoupler A connection point between the transistor and the third resistor is connected to a control terminal of the switching element, and a MOSFET or a thyristor is used as the switching element. Further, the control circuit includes, for example, a photodiode of a photocoupler including a photodiode and a phototriac connected in series to an operation coil, a second resistor connected in series to a switching element, and the photocoupler. And a third resistor, wherein a connection point between the phototriac of the photocoupler and the third resistor is connected to a control terminal of the switching element, or is connected in series to an operation coil in parallel. A fourth resistor, a phototriac of a photocoupler including a photodiode and a phototriac, a second resistor connected in series with a switching element, and a phototriac and a third resistor of the photocoupler. Consisting of a photo of the photocoupler Raiakku and the third resistor connection points to be connected to a control terminal of the switching element,
A triac is used as a switching element. Furthermore, a diode is connected in parallel with the reverse polarity to the operation coil in each of the switchgears.

[0009]

The switching device according to the present invention includes a first resistor and a switching element such as a MOSFET, a thyristor or a triac connected in series with a main contact in parallel, and this switching element as soon as control power is supplied to an operation coil. A control circuit for turning on and immediately turning off the switching element when the control power supply is cut off, for example, from a photodiode and a phototransistor or a photodiode and a phototriac connected in series with an operation coil or in parallel via a fourth resistor. And a second resistor and a phototransistor or phototriac of the photocoupler and a third resistor respectively connected in series with the switching element. And a connection point between the third resistor and a control circuit connected to a control terminal of the switching element. Therefore, when the control power supply is applied to the operation coil, the switching element is immediately turned on, and the small current limited by the first resistor and the capacitive load, for example, the noise prevention capacitor for about 1 millisecond. Charge. The main contact is closed about several milliseconds after the switching element is turned on, but the noise prevention capacitor has already been charged in about 1 millisecond as described above. No welding will occur.

Next, when the control power supply is cut off, the switching element is turned off immediately, and the main contact is opened after a cutoff operation time of about several milliseconds after the switching element is turned off. Therefore, a small current limited by the first resistor flows through the switching element only for about several milliseconds from when the switching element is turned on to when the main contact is closed.
The current capacity of the switching element may be extremely small.

Since the main contact breaking operation time is generally shorter than the closing operation time and may operate very quickly, a flywheel diode is connected to the operating coil in parallel with the opposite polarity, and the control power supply is turned off. The switching element is more reliably turned off before the main contact is opened because the decay of the current flowing through the operation coil when the switching is interrupted is delayed to extend the interruption operation time.

[0012]

FIG. 1 is an electric circuit diagram using an embodiment of the switchgear of the present invention. The switchgear of the present invention shown in FIG.
Are different from the conventional switchgear shown in FIG. 1 in that a current-limiting resistor 32 connected in series to a main contact 31 and a switching element 33 made of, for example, a MOSFET are connected.
And a photodiode 35B of a photocoupler 35 composed of a photodiode and a phototransistor connected in series with the operation coil 37, and a current limiting resistor 34 and a photocoupler 35 connected in series with the switching element 33, respectively. A phototransistor 35A and a resistor 36 for the gate of the switching element 33 are provided.
Is located at a point connected to the gate of the switching element 33. Then, the photocoupler 35, the resistor 34, and the resistor 3
Reference numeral 6 denotes a control circuit of the switching element 33.

When the control switch 5 is closed, the operation coil 37 is closed.
When the control power supply 4 is turned on, the photodiode 35B of the photocoupler 35 connected in series is simultaneously energized, and the phototransistor 35A of the photocoupler 35 is turned on.
Turns on. When the phototransistor 35A is turned on, the switching element 33 is immediately turned on, and the load 2, for example, the noise prevention capacitor 2A is charged via the resistor 32. Now, assuming that the voltage of the power supply 1 is 100 V, the capacitance of the noise prevention capacitor 2A of the load 2 is 1 microfarad, and the resistance value of the resistor 32 is 1 kΩ, the noise prevention capacitor 2A has a current of about 0.1 amperes. It is charged in about milliseconds. After the control power supply 4 is turned on, the main contact 31 is closed after a turn-on operation time of about several milliseconds. However, the charging of the noise prevention capacitor 2A is already completed in about 1 millisecond as described above. Therefore, welding does not occur on the main contact 31, and the shortening of its life is prevented.

Next, when the control power supply 4 is cut off, the switching element 33 is immediately turned off, and after a switching operation time of about several milliseconds after the switching element 33 is turned off, the main contact 3 is turned off.
1 is open. Therefore, the switching element 33 has a resistance.
32 , a small current of about 0.1 A, for example, flows only for a few milliseconds from when the switching element is turned on to when the main contact 31 is closed.
The current capacity of 33 may be very small. Therefore, it is low-cost and compact.

When the capacitive load is opened, for example, the electric charge charged in the noise preventing capacitor 2A is discharged through the internal circuit 2B, so that the main contact 31 is hardly welded.

FIG. 2 is a circuit diagram showing another embodiment of the switchgear of the present invention. The switchgear of the present invention shown in FIG.
2 is different from the switchgear of the present invention shown in FIG. 2 in that the photocoupler 35 connected in series to the operation coil 37 in FIG.
In that a current limiting resistor 38 and a photodiode 35B of a photocoupler 35 are connected in series in parallel with the operation coil 37 instead of the photodiode 35B.

The same operation as that of FIG. 1 can be obtained with the circuit shown in FIG.

FIGS. 3 and 4 are circuit diagrams showing still another embodiment of the switchgear of the present invention.
1 is different from the embodiment shown in FIGS. 1 and 2 in that a switching element 33 composed of a thyristor is used instead of the switching element 33 composed of a MOSFET.

The circuit shown in FIG. 3 and FIG.
The same operation as described above is obtained.

FIGS. 5 and 6 are circuit diagrams showing still another embodiment of the switchgear of the present invention.
In the embodiment shown in FIG. 1, a photocoupler 40 composed of a photodiode 40B and a phototriac 40A is used instead of the photocoupler 35 composed of the photodiode 35B and the phototransistor 35A shown in FIGS. Switching element 3
Switching element 33 made of triac instead of 3
Is used in each case.

In the embodiments shown in FIGS. 1 to 4, the power supply 1 is a DC power supply, while in the embodiments shown in FIGS. 5 and 6, the power supply 1 is an AC power supply.
The circuits shown in FIGS. 5 and 6 can obtain the same operation as that of FIG. 1 except that the power supply 1 is an AC power supply.

In each of the embodiments shown in FIGS. 1 to 6, a flywheel diode 39 is further connected to the operating coil 37 in parallel with the opposite polarity. Since the shut-off operation time of the main contact 31 is generally shorter than the closing operation time and may operate very quickly, when the flywheel diode 39 is connected to the operation coil, the operation coil 37 is turned off when the control power supply 4 is cut off. Therefore, the switching element 33 is more surely turned off before the main contact 31 is opened because the current flowing through the main contact 31 is delayed and the cutoff operation time is lengthened.

In the switching device of the present invention, as described above, a small current limited by the resistor 32 is applied to the switching element 33 for an extremely short time, that is, from when the switching element 33 is turned on to when the main contact 31 is closed. Since the current flows only for an extremely short time of about several milliseconds, the present invention can be applied to a large-capacity switchgear without using a particularly large-capacity element as a switching element.

The resistors 32, 34, 36, and 38 are referred to as first, second, third, and fourth resistors, respectively.

[0025]

According to the switchgear of the present invention, a resistor and a switching element which are respectively connected in series to the main contact in parallel are provided, and the switching element is turned on just before the main contact is closed, or the main contact is opened slightly. Before the main contact is closed, the charging of the capacitive load, for example, the noise prevention capacitor is completed before the main contact is closed with a small current limited by the resistor. In addition, shortening of contact life is prevented. A small current limited by the resistor flows through the switching element for only a few milliseconds from when the switching element is turned on to when the main contact is closed. And a compact device. Therefore, the present invention can be applied to a large-capacity switchgear without using a large-capacity element as a switching element, and the effect is very large.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram using an embodiment of a switchgear of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the switchgear of the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the switchgear of the present invention.

FIG. 4 is a circuit diagram showing still another embodiment of the switchgear of the present invention.

FIG. 5 is a circuit diagram showing still another embodiment of the switchgear of the present invention.

FIG. 6 is a circuit diagram showing still another embodiment of the switchgear of the present invention.

FIG. 7 is an electric circuit diagram using a conventional switchgear.

[Explanation of symbols]

Reference Signs List 1 power supply 2 load 3 switchgear 31 main contact 32 first resistor 33 switching element (MOSFET, thyristor, triac) 34 second resistor 35 photocoupler (composed of photodiode and phototransistor) 35A phototransistor (photocoupler 35 35B Photodiode (of photocoupler 35) 36 Third resistor 37 Operating coil 38 Fourth resistor 39 Diode 40 Photocoupler (composed of photodiode and phototriac) 40A Phototriac (of photocoupler 40) 40B Photo Diode (of photocoupler 40) 4 Control power supply

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-313817 (JP, A) JP-A-62-82816 (JP, A) JP-A-2-65313 (JP, A) JP-A-58-58 3322 (JP, A) JP-A 4-118528 (JP, U) JP-A-59-80950 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 9/54 H01H 47 / 00 H03K 17/725 H03K 17/73

Claims (9)

(57) [Claims] 1. A noise suppressor connected between a power supply and the power supply terminal.
A main contact that is connected between a load having a shut-off capacitor and that closes after a predetermined turning-on time when control power is supplied to the operating coil, and that opens after a predetermined shut-off time when the control power is cut off; When a control power is applied to the first resistor and the switching element connected in series to the operation coil, the switching element is turned on immediately before the main contact is closed , and the control power is shut off. Then Ri Do and a control circuit for turning off immediately the switching element before the open circuit of the main contact, the main contact is closed
Before switching on, the switching element is turned on and the first
A switching device for charging the capacitor via the resistor . 2. The switchgear according to claim 1, wherein the control circuit is connected in series with a photodiode of a photocoupler comprising a photodiode and a phototransistor connected in series to the operation coil, and in parallel with the switching element. A second resistor, a phototransistor of the photocoupler, and a third resistor. A connection point between the phototransistor of the photocoupler and the third resistor is connected to a control terminal of the switching element. Switchgear characterized by. 3. The switchgear according to claim 1, wherein the control circuit comprises: a fourth resistor and a photodiode of a photocoupler comprising a photodiode and a phototransistor connected in series with the operation coil; A second resistor respectively connected in series with the element in parallel, a phototransistor of the photocoupler and a third resistor;
And a connection point between the phototransistor of the photocoupler and the third resistor is connected to a control terminal of the switching element. 4. The switchgear according to claim 1, wherein the switching element comprises a MOSFET. 5. The switchgear according to claim 1, 2 or 3, wherein the switching element comprises a thyristor. 6. The switchgear according to claim 1, wherein the control circuit is connected in series with the photodiode of the photocoupler comprising a photodiode and a phototriac connected in series with the operation coil, and in parallel with the switching element. A second resistor, a phototriac of the photocoupler, and a third resistor, and a connection point between the phototriac of the photocoupler and the third resistor is connected to a control terminal of the switching element. And switchgear. 7. The switchgear according to claim 1, wherein the control circuit comprises: a phototriac of a photocoupler including a fourth resistor, a photodiode, and a phototriac connected in series with each other in parallel with the operation coil; A second resistor connected in series with the element in parallel, and a phototriac and a third resistor of the photocoupler, and a connection point of the phototriac of the photocoupler and the third resistor is connected to the switching element of the switching element. A switchgear connected to a control terminal. 8. The switchgear according to claim 7, wherein the switching element comprises a triac. 9. The switchgear according to claim 1, wherein a diode is connected in parallel with the operation coil in reverse polarity.