CN1078757C - Over-current, leakage, electric shock protection device - Google Patents

Abstract

The invention provides an over-current, leakage and electric shock protector, especially a protector on socket and extension line, mainly comprising a relay, an SCR capable of controlling the relay circuit, a trigger circuit of the SCR, a constant current detection circuit, and a micro-current sensing amplifying circuit, wherein the common contact of the relay is connected to a main power line terminal, and the normally closed contact forms the output end of the power line, and the normally open contact and a warning lamp are bridged on another main power line, the trigger circuit uses the signal of the detection circuit or the micro-current sensing amplifying circuit as the trigger source, when over-current, short circuit, leakage or someone electric shock, the trigger circuit starts to drive the SCR to open the power supply on the load.

Description

Over-current, leakage, electric shock protection device

The present invention mainly provides a protection device with electric shock, leakage, overload, and short circuit that can automatically cut off power on an AC power supply, especially a safety device applied to sockets and power extension sockets.

Among the well-known accidents, electric shock and fire are the two main causes. And the reason that fire takes place has very high rate and is that electric wire is caused by fire, and its main reason is that improper use electrical equipment, when circuit current is too large, fails to be detected and cut off in time.

At present, the extension socket has a device that cuts off the power due to excessive current, but its mechanical action mode, response sensitivity and effect are not ideal, and it is not suitable for electric shock caused by carelessness or ignorance when consumers use the socket, or when The loads on the socket, such as motors, electric heaters, air conditioners, range hoods, refrigerators, etc., have no way to provide the protection function of automatically cutting off the power supply when leakage occurs due to insulation damage.

When consumers use multiple electrical equipment at the same time, the current on the line will often increase due to overload or short circuit. If there is no fuse switch on the switchboard or it fails to act in time due to poor quality or aging, the main power supply will trip. Fires caused by electric wires may occur.

In view of this, the inventor has carefully designed and developed for a long time, and made a thorough solution and improvement to the above-mentioned deficiency, and invented the socket of overcurrent, leakage and electric shock protection device, and its main purpose is to provide a An overcurrent or short circuit protection device installed on the socket or extension cord socket. Its electronic design allows the rated power to be adjusted and can respond immediately within a few microseconds, so that the circuit system can be instantly protected when a short circuit or overload occurs. Automatically cut off the power.

Another object of the present invention is to provide a protection device for leakage or electric shock installed on the socket and the extension socket. It enables the circuit system to automatically cut off the power supply in the event of electric leakage or electric shock to the body.

In order to achieve the above object, the present invention is implemented in the following manner. The first feature of the present invention is mainly composed of a relay, an SCR capable of controlling the relay, a SCR trigger circuit, and a constant current detection circuit, wherein the relay The common contact (N.G.) is connected to a main power line end, while the normally closed contact (N.C.) forms the output end of the power line, and the normally open contact (N.O.) is connected across the other main power supply with a warning device On-line, and the trigger circuit uses the signal of the constant current detection circuit as the trigger source. When the constant current detection circuit senses that the current of the line is too large or exceeds the rated value or is short-circuited, the trigger circuit will be activated to drive the SCR action. , when the SCR is turned on, the normally closed contact (N.C.) of the relay is opened to disconnect the power supply on the load. The warning device of the overcurrent protection device can be a warning light, wherein the constant current detection circuit can use a comparator (CT) as a detector for circuit current detection change, and a reset switch is connected in series with the base of the SCR.

Another feature of the present invention is mainly composed of a relay, an SCR capable of controlling the relay, an SCR trigger circuit, and a micro-current sensing amplifier circuit with a Hall element, wherein the common contact (N.G.) of the relay is connected To a main power line end, and the normally closed contact (N.C.) forms the output end of the one power line, and the normally open contact ((N.O.) is connected across the other main power line as a warning device, and the trigger circuit is With the signal of the micro-current sensing amplifier circuit as the trigger source, when the micro-current sensing amplifier circuit senses leakage or someone gets an electric shock, the trigger circuit will be activated to drive the SCR action. When the SCR is turned on, the relay’s The normally closed contact (N.C.) is opened to disconnect the power supply on the load. The warning device of the leakage protection device can be a warning light, wherein the amplifying circuit of the micro current sensing uses a Hall current transducer (CT2) as the current A change detector. In addition, a reset switch is connected in series with the base of the SCR.

The present invention has the protection functions of overcurrent, short circuit, electric leakage and electric shock, and its electronic design has greater advantages than the mechanical action mode, and it has higher sensitivity, less error and rated The value can be adjusted flexibly, which can protect the load on a single circuit without affecting the power supply of other circuits, which has beneficial effects.

Fig. 1 is the protective circuit diagram of overcurrent or short circuit of the present invention;

Fig. 2 is the protective circuit diagram of electric leakage or electric shock of the present invention;

Fig. 3 is the circuit diagram when Fig. 1 and Fig. 2 of the present invention are combined;

Figure 4 is a schematic diagram of the detection of leakage current.

Description of figure number:

1 Relay (AC Relay) 2 SCR

3 Trigger circuit 4 Constant current detection circuit

5 Reset switch S.W 6 Micro current sensing amplifier circuit

Common contact of N.G. relay N.C. relay normally closed contact

NO relay normally open contact CT ₁ comparator

CT ₂ current transducer (or Hall element type current sensor)

In order to further understand the present invention, a preferred embodiment will now be described in conjunction with the accompanying drawings:

Please refer to shown in Fig. 1, the overcurrent or short circuit protection circuit of the present invention, it mainly comprises relay (ACRealy) 1, a SCR2 that can control relay, a trigger circuit 3 that can drive SCR, and has a rated current detection circuit 4 as the trigger signal source of the trigger circuit 3; wherein the common contact N.G. of the relay 1 is connected to a main power line end, and the normally closed contact (N.C.) forms the output end of the power line, and the normally open contact (N.O.) Then connect it to another main power line via a warning light L (or other warning device).

The above-mentioned constant current detection circuit 4 uses a comparator (CT ₁ ) as a detector for circuit current variation.

In addition, the present invention has a reset switch (SW) 5, by which the SCR2 can be disconnected.

Under normal use, the line current is normal, SCR2 is not conducting, the relay (AC Relay) 1 remains inactive, and the AC power supply is kept connected to the load through the NC normally closed contact. When the power supply of the load exceeds the set current due to abnormality, the output terminal V _o1 of the secondary side of the comparator CT ₁ is: ${\mathrm{<figure-callout\; id="1"\; label="V\; o"\; filenames="C9910053500081.png"\; state="\{\{state\}\}">V</figure-callout>}}_o=K\frac{I_o}{r}{R}_L$

K = coupling coefficient I ₀ = line current

n = Secondary side box number R _L = Secondary side load

When the output terminal of V ₀₁ passes through the voltage dividing resistor, when its output voltage is greater than V _ZD , the diode OR gate makes SCR2 conduct, the AC Relay operates, the normally closed contact NC becomes disconnected (OFF), and the power supply is cut off , blocking line current (I) continues to rise.

Fig. 2 is a protection circuit diagram related to electric leakage or electric shock in the present invention. It mainly includes a relay (AC Relay) 1, an SCR2 that can control the action of the relay, and a trigger circuit 3 that can drive the SCR2, and has a micro current sensing amplifier circuit 6 as the trigger signal source of the trigger circuit 3; The common contact (N.G.) of relay 1 is connected to a main power line end, and the normally closed contact (N.C.) forms the output end of the power line, and the normally open contact N.O is crossed by a warning light (or other warning device). Connect to another mains power source.

The above-mentioned micro-current sensing amplifying circuit 6 uses a current transduction CT ₂ as a detector of circuit current change; this CT ₂ adopts a high-sensitivity Hall element type current sensor (or called a current transducer) , especially suitable for the measurement of small currents, and can increase a number of winding turns 7 on the CT ₂ core to improve the sensitivity.

In addition, the present invention has a reset switch (SW) 5, and the SCR2 can be disconnected by the operation of the reset switch (SW) 5 .

。此时因为二条主电线是现时贯穿电流换能器CT₂，流进和流出的电流两相抵消后，就只剩下泄漏电流io₂，此一漏电或触电电流因霍耳效应而形成一霍耳电压V_H，再经过高增益的OP放大器给予放大后，再经一极电晶体放大电路，以增大电流输出，传到二极管的OR闸，同理使SCR2动作，电源被切断，可避免因触电或漏电所造成的伤害。Under normal use, the line current is normal, SCR2 is not conducting, relay 1 remains inactive, and the AC power supply is connected to the load through the NC normally closed contact. This means that the power consumption is normal, and the warning light L is not on. When someone gets an electric shock or leaks electricity, please refer to Figure 4 first. Usually, one phase of the wiring of the power equipment is grounded. When the load of the main power supply has a leakage current to the ground, the resistance of r ₀ (the load resistance of the leakage) is about tens KΩ-hundreds of KΩ, and produce a small current

. At this time, because the two main wires are currently passing through the current transducer CT ₂ , after the inflow and outflow currents are canceled out, only the leakage current io ₂ remains, and this leakage or electric shock current forms a Hall effect due to the Hall effect. The ear voltage V _H is amplified by a high-gain OP amplifier, and then passed through a one-pole transistor amplifier circuit to increase the current output, and then transmitted to the OR gate of the diode. Similarly, SCR2 is activated, and the power supply is cut off, which can avoid Injuries caused by electric shock or leakage.

As shown in Figure 1 and Figure 2, when SCR2 is triggered to conduct due to an excessive current, the relay 1 is activated at the same time, the normally open contact (N.O.) is ON, and the warning light L is turned on, so as to inform the phenomenon of abnormal current and achieve a warning. Effect.

Figure 1 shows the protection circuit diagram for overcurrent or short circuit, Figure 2 shows the protection circuit diagram for leakage or electric shock, Figure 3 is a circuit diagram combining Figure 1 and Figure 2 with an OR gate of a diode, and has two circuit diagrams at the same time effect.

Finally, the user can restore the device to its original state by the following methods:

1. Press reset switch (SW) 5 to disconnect SCR2, and relay 1 returns to its original state.

2. Unplug the socket to disconnect the main power supply, causing SCR2 to be powered off, and relay 1 to return to its original state.

Since the present invention has the protection functions of overcurrent, short circuit, electric leakage and electric shock, it has higher sensitivity and less error when used on sockets and extension lines than traditional ones, and the rated value can be adjusted flexibly, which can protect the load on a single circuit It does not affect the power supply of other loops, it is very innovative, progressive and can be utilized by the industry. It really meets the requirements for application of new patents, and the application is hereby filed in accordance with the law.

Claims (8)

1. An overcurrent protection device, characterized in that: the protection device includes a relay, an SCR capable of controlling the relay, a trigger circuit capable of driving the SCR, and a constant current detection circuit as a signal source of the trigger circuit, wherein The common contact of the relay is connected to a main power line end, and the normally closed contact forms the output end of the one power line, and the normally open contact is connected across another main power line through a warning device. 2. The overcurrent protection device according to claim 1, wherein the warning device is a warning light. 3. The overcurrent protection device as claimed in claim 1, wherein the constant current detection circuit uses a comparator as a detector for detecting changes in circuit current. 4. The overcurrent protection device according to claim 1, wherein a reset switch is connected in series with the base of the SCR. 5. A protection device for leakage and electric shock, characterized in that the protection device includes a relay, an SCR capable of controlling the relay, a trigger circuit capable of driving the SCR, and a Hall element type micro Current sensing amplifying circuit; wherein the common contact of the relay is connected to a main power line end, and the normally closed contact forms the output end of the one power line, and the normally open contact is connected across another main power line through a warning device . 6. The leakage and electric shock protection device according to claim 5, wherein the warning device is a warning light. 7. The leakage and electric shock protection device according to claim 5, characterized in that the micro-current sensing amplifier circuit uses a current transducer as a detector for micro-current changes. 8. The leakage and electric shock protection device according to claim 5, wherein a reset switch is connected in series with the base of the SCR.

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