CN201113378Y

CN201113378Y - Electronic current-limiting device

Info

Publication number: CN201113378Y
Application number: CNU2007200534907U
Authority: CN
Inventors: 杨文和
Original assignee: DONGGUAN DALANG JINZHUN ELECTRIC APPLIANCE PLANT
Current assignee: DONGGUAN DALANG JINZHUN ELECTRIC APPLIANCE PLANT
Priority date: 2007-06-29
Filing date: 2007-06-29
Publication date: 2008-09-10
Anticipated expiration: 2017-06-29

Abstract

The utility model belonging to the emergency protective circuit arrangement technical field relates to an electronic current limiter, and aims to solve the problems of the prior art including difficult control of parameters, difficult production, instability and low precision. The electronic current limiter comprises a power source change-over circuit (1), a current testing circuit (2) and a testing control circuit (3), wherein the testing control circuit (3) is provided with a mutual inductor T1; a primary coil, an electric light connecting terminal OUT1 and an electric light connecting terminal OUT2 are connected in series with an input circuit terminal CN1 and an input circuit terminal CN2; the primary coil is connected in series with a rectifier diode D3 to form a voltage signal output end; the testing control circuit is provided with a unidirectional silicon control Q1 and a relay; the output end of the power source change-over circuit is connected with a relay coil J which is connected in series with the cathode and the anode of the unidirectional silicon control; the control electrode and the cathode of the unidirectional silicon control are connected with the voltage signal output end which is connected in parallel with a reset switch K1; and the normally closed contact of a relay switch S1, the primary coil and the light connecting terminals are connected in series with the input circuit terminals.

Description

Electronic current limiter

Technical field

The utility model belongs to emergency protective circuit device technique field, is a kind of electronic current limiter that illuminating lamp is limited bearing power.

Background technology

According to the requirement that the user uses, such as the light fixture of many lamp holders, its total power consumption must not surpass certain wattage, as 190 watts.Existing load limits the control circuit of power to illuminating lamp, and great majority are to utilize the universal integrated circuit IC of models such as LM324 or LM358 to design.The circuit block diagram of this control circuit can be divided into: sample circuit, current rectifying and wave filtering circuit, amplify comparison circuit and output control circuit, amplifying comparison circuit generally takes a sample with manganese-copper filament, adopting signal operational amplifier to amplify handles, perhaps adopt the instrument transformer sampling, control the conducting and the shutoff of controllable silicon and relay again with comparator output, thereby turn off load and reach the purpose of rationing the power supply, but because of the magnetic core above the instrument transformer has discreteness, difficult parameters is to control to unanimity in the production, so being reduced, productivity ratio is difficult for producing, and cost is very high, adopt the method for operational amplifier also can cause cost to raise simultaneously, ration the power supply control circuit production cost and maintenance cost of existing in a word light modulation is too high, and unstable properties, and accuracy is not high.

The utility model content

It is a kind of simple in structure that the purpose of this utility model is to provide, the reliability height, and cost is low, when the restriction bearing power become greater to certain value, the electronic current limiter in the loop of can cutting off the electricity supply.

For realizing the purpose of this utility model, described electronic current limiter comprises being connected on input circuit end CN1, the CN2, AC power is converted to the power-switching circuit of dc supply; Input circuit end CN1, CN2 are carried out the current detection circuit that induction by current detects; Output signal according to current detection circuit is carried out the detection control circuit that break-make is switched to electrical network; Described detection control circuit is provided with instrument transformer T1, the primary coil of described instrument transformer T1 and electric light RL link OUT1 and OUT2 are serially connected among input circuit end CN1, the CN2, the secondary coil of described instrument transformer T1 is connected in series with rectifier diode D3, forms voltage signal output end; Described detection control circuit is provided with one-way SCR Q1 and relay, output at described power-switching circuit is connected to and the negative electrode of one-way SCR Q1 and the relay coil J of anode series, the control utmost point and the negative electrode of described one-way SCR Q1 are connected on described voltage signal output end, described voltage signal output end also is connected to reset switch K1, and the normally-closed contact of the switch S 1 of described relay and described primary coil and lamp link OUT1 and OUT2 are serially connected with among described input circuit end CN1, the CN2.

During use, input circuit end CN1, CN2 are connected on the power supply, electric light RL is connected on electric light link OUT1 and the OUT2.Power supply passes through power-switching circuit on the one hand, the output direct-current working volts, for other circuit provides dc supply, pass through the normally-closed contact and the primary coil of electric light RL, switch S 1 on the other hand, produce an induced voltage on the secondary coil of instrument transformer T1, this voltage is along with changing by the load current among the electric light RL.When the load current variation is increased to certain value; the voltage signal of voltage signal output end output is added on the control utmost point and negative electrode of one-way SCR Q1; make negative electrode and the anode of one-way SCR Q1 be in conducting state; the relay coil J action of switching on; the normally-closed contact of switch S 1 is disconnected; thereby disconnect the power supply of supplying with electric light RL, play the excessive protective effect of restriction electric current.At this moment, if push reset switch K1, make the control utmost point of one-way SCR Q1 and negative electrode connect between short circuit, negative electrode and anode just switch to cut-off state, relay coil J outage, make the normally-closed contact closure of switch S 1, electric light RL can be serially connected in again among input circuit end CN1, the CN2 and work, and realizes power-on-reset.

Description of drawings

The drawing of accompanying drawing is described as follows:

Fig. 1 is the circuit block diagram of the utility model electronic current limiter.

Fig. 2 is for realizing the circuit theory diagrams of Fig. 1.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the utility model electronic current limiter is described in further detail:

Electronic current limiter described in the utility model comprises being connected on input circuit end CN1, the CN2, AC power is converted to the power-switching circuit (1) of dc supply.Described power-switching circuit (1) is provided with resistance R 2 and the diode D1 that is serially connected on input circuit end CN1, the CN2, after capacitor C 1 and resistance R 1 serial connection and in the two ends of resistance R 2, the positive pole of diode D2 is connected on the negative pole of diode D1, the negative pole of voltage stabilizing didoe D4 is connected on the negative pole of diode D2, the positive pole of voltage stabilizing didoe D4 be connected to ground at positive pole and the input circuit end CN2 of diode D1.At the two ends of voltage stabilizing didoe D4 and meet energy storage filter capacitor C2.Capacitor C 2 two ends are the dc output end of power-switching circuit (1).When power supply be added in input circuit end CN1, when CN2 is last, for AC power, the capacitive reactance of capacitor C 1 is much bigger with respect to resistance R 1, R2, therefore when alternating voltage is in positive half cycle, electric current is added in after capacitor C 1, resistance R 1, R2 are through diode D2 rectification and carries out voltage stabilizing on the voltage stabilizing didoe D4, obtains galvanic current and presses.The power-switching circuit of this power supply (1) mainly concentrates on the capacitor C 1 pressure drop of power supply, thereby avoided adopting transformer to carry out step-down and the volume that causes is big, circuit complexity, the problem that cost is high.The power-switching circuit of this power supply (1) is an easy DC voltage-stabilizing output circuit, though have certain voltage fluctuation and ripple at direct-flow output signal, is enough to satisfy the operating voltage that detects control circuit (3).

Input circuit end CN1, CN2 are carried out the current detection circuit (2) that induction by current detects.Described detection control circuit (3) is provided with instrument transformer T1, the primary coil of described instrument transformer T1 is the lead that passes magnetic core, primary coil and electric light link OUT1 and OUT2 are serially connected among input circuit end CN1, the CN2, the secondary coil of described instrument transformer T1 is connected in series with rectifier diode D3, forms voltage signal output end.Operating position according to bulb load, the design secondary coil is exported about 1.5 volts alternating voltage, because primary coil is the lead that passes magnetic core, turn ratio between itself and the secondary coil is relatively large, when the generation of the electric current in the elementary coil a bit changes, the voltage of secondary coil output just can produce very big variation, therefore has bigger signal and changes ratio, conveniently carries out induction by current and detects.The secondary coil two ends of described instrument transformer T1 also are connected to resistance R 3, and this resistance R 3 makes the secondary coil two ends output voltage of instrument transformer T1 realize steady relatively.

Output signal according to current detection circuit (2) is carried out the detection control circuit (3) that break-make is switched to electrical network, and this detection control circuit (3) is provided with one-way SCR Q1, relay, reset switch K1, diode D5.

Output at described power-switching circuit (1) is connected to and the negative electrode of one-way SCR Q1 and the relay coil J of anode series, and the control utmost point and the negative electrode of described one-way SCR Q1 are connected on described voltage signal output end.

Described voltage signal output end also is connected to reset switch K1, and the normally-closed contact of the switch S 1 of described relay and described primary coil and lamp link OUT1 and OUT2 are serially connected with among described input circuit end CN1, the CN2.

After being added with conducting voltage between the control utmost point of one-way SCR Q1 and the negative electrode, negative electrode and anode then are in conducting state, otherwise then are in cut-off state.Therefore when be in conducting state between negative electrode and the anode, the direct voltage of the output of power-switching circuit (1) then is added on the relay coil J, makes the switch S 1 of relay move, and converts disconnection to by normally closed.Otherwise when being in cut-off state between negative electrode and the anode, switch S 1 converts closure to by disconnection.

Described voltage signal output end also is connected to energy storage capacitor C4.The parameter value of energy storage capacitor C4 is 100 microfarads, and it is level and smooth to make that the flip-flop of voltage signal output end becomes, and utilizes level and smooth flip-flop voltage to carry out break-make as the control utmost point to one-way SCR Q1 with negative electrode and controls.

Described voltage signal output end also is connected to HF filtering capacitor C3.The parameter value of HF filtering capacitor C3 is 0.01 microfarad, when input circuit end CN1, CN2 produce a high-frequency interferencing signal, be added in HF filtering capacitor C3 at the high-frequency impulse of voltage signal output end output and become and be equivalent to short circuit and be absorbed, avoid causing the control utmost point of one-way SCR Q1 and the false triggering between the negative electrode being made switch S 1 convert disconnection to by normally closed.

Described voltage signal output end also is connected to adjustable resistance RT1.When power supply all cut off the power supply, the electric energy that adjustable resistance RT1 can make capacitor C3, C4 store was released.In case when overload, be when stored voltage is higher than the trigger voltage of the control utmost point of one-way SCR Q1 and negative electrode on the electric capacity after the outage, once more behind the incoming call, can be because of the voltage on the electric capacity still greater than the trigger voltage of controlling the utmost point and negative electrode, and make one-way SCR Q1 remain in conducting state, cause the normally-closed contact of switch S 1 to be transformed into disconnection, make electric light RL be in off-state always by closure.On the other hand, adjustable resistance RT1 still is the load of secondary coil of instrument transformer T1, by regulating the resistance value size of adjustable resistance RT1, make the conducting voltage that is added between the control utmost point and the negative electrode current value corresponding to the primary coil that flows through instrument transformer T1.

Described relay coil J two ends also are connected to the diode D5 that oppositely is connected in series with negative electrode and the anode of one-way SCR Q1.When one-way SCR Q1 ends, relay coil J two ends can produce a forward high pressure that is added on anode and the negative electrode, this moment, the positive pole owing to diode D5 was connected on the anode, therefore the forward high pressure can unload by diode D5 and put, in case the negative electrode of one-way SCR Q1 and anode moment convert cut-off state to, relay coil J two ends produce high pressure and are added in negative electrode and anode two ends and puncture and burn.

Be provided with among input circuit end CN1, the CN2 with the normally opened contact and the primary coil of described switch S 1 and be connected in series LED and resistance R 4.When the normally-closed contact of switch S 1 disconnects, the normally opened contact closure, electric light RL was disconnected LED and resistance R 4 and then replaced electric light RL and be serially connected among input circuit end CN1, the CN2 and luminous this moment, and prompting is transshipped.

Claims

1. electronic current limiter comprises:

Be connected on input circuit end CN1, the CN2, AC power converted to the power-switching circuit (1) of dc supply;

Input circuit end CN1, CN2 are carried out the current detection circuit (2) that induction by current detects;

Output signal according to current detection circuit (2) is carried out the detection control circuit (3) that break-make is switched to electrical network;

It is characterized in that:

Described detection control circuit (3) is provided with instrument transformer T1, the primary coil of described instrument transformer T1 and electric light link OUT1 and OUT2 are serially connected among input circuit end CN1, the CN2, the secondary coil of described instrument transformer T1 is connected in series with rectifier diode D3, forms voltage signal output end;

Described detection control circuit (3) is provided with one-way SCR Q1 and relay, output at described power-switching circuit (1) is connected to and the negative electrode of one-way SCR Q1 and the relay coil J of anode series, the control utmost point and the negative electrode of described one-way SCR Q1 are connected on described voltage signal output end, described voltage signal output end also is connected to reset switch K1, and the normally-closed contact of described relay switch S1 and described primary coil and lamp link OUT1 and OUT2 are serially connected with among described input circuit end CN1, the CN2.

2. electronic current limiter according to claim 1 is characterized in that described voltage signal output end and is connected to energy storage capacitor C4.

3. electronic current limiter according to claim 1 is characterized in that described voltage signal output end and is connected to HF filtering capacitor C3.

4. electronic current limiter according to claim 2 is characterized in that described voltage signal output end and is connected to HF filtering capacitor C3.

5. according to claim 1,2,3 or 4 described electronic current limiters, it is characterized in that described voltage signal output end and be connected to adjustable resistance RT1.

6. according to claim 1,2,3 or 4 described electronic current limiters, it is characterized in that described relay coil J two ends and be connected to the diode D5 that oppositely is connected in series with negative electrode and the anode of one-way SCR Q1.

7. according to claim 1,2,3 or 4 described electronic current limiters, it is characterized in that being provided with among input circuit end CN1, the CN2 with the normally opened contact and the primary coil of described switch S 1 and be connected in series LED and resistance R 4.

8. according to claim 1,2,3 or 4 described electronic current limiters, it is characterized in that the secondary coil two ends of described instrument transformer T1 and be connected to resistance R 3.