CN201478788U - Overvoltage and overcurrent protection circuit for input of light-current system - Google Patents
Overvoltage and overcurrent protection circuit for input of light-current system Download PDFInfo
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- CN201478788U CN201478788U CN2009201827622U CN200920182762U CN201478788U CN 201478788 U CN201478788 U CN 201478788U CN 2009201827622 U CN2009201827622 U CN 2009201827622U CN 200920182762 U CN200920182762 U CN 200920182762U CN 201478788 U CN201478788 U CN 201478788U
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Abstract
The utility model relates to an overvoltage and overcurrent protection circuit for the input of a light-current system. Before being connected with the system, an input line first passes through a voltage-sampling circuit and a first precision rectifier circuit and then enters a zero passage-judging circuit and an overvoltage-judging circuit at the same time, the zero passage-judging circuit and the overvoltage-judging circuit produce a control signal which controls an input switch by means of a switch controller to switch on, so that the input line is connected with the system, the current of the connected system enters an overcurrent-judging circuit via a current-sampling circuit and a second precision rectifier circuit, and the overcurrent-judging circuit produces a control signal which passes through a relay holding circuit and then controls the input switch by means of the switch controller to switch off. The utility model has the following advantages that: since the scheme in which the line is not connected with the system until the voltage of the line to be connected is judged first is adopted, the impact of transient high switch-on voltage is prevented, and the overvoltage-judging circuit constantly monitors the voltage of the line in order to prevent the slowly increasing voltage of the line from damaging the system. The relay holding circuit adopted for overcurrent protection can more effectively and reliably carry out protection.
Description
[technical field]
The utility model is about a kind of over-voltage over-current protection circuit, particularly the over-voltage over-current protection circuit of weak electricity system input.
[background technology]
Over-voltage over-current protection circuit is that the protection system circuit is not subjected to the impact of big voltage, electric current or misconnection forceful electric power and causes damage.In the weak electricity system circuit, more overvoltage, current foldback circuit adopt voltage stabilizing didoe, voltage clamp circuit, current-limiting circuit and fuse to wait and limit input voltage, electric current at present.
1, adopt voltage stabilizing didoe and thermistor to realize overvoltage, overcurrent protection; as shown in Figure 1; its principle is that voltage stabilizing didoe is connected in parallel on the protected circuit two ends; not during overvoltage, voltage stabilizing didoe is high-impedance state at input voltage, and its leakage current is very little; in case during the input voltage overvoltage; voltage stabilizing didoe provides low impedance path in moment, and with the low-voltage of voltage clamp in safety, thereby protective circuit is avoided the overvoltage infringement.Thermistor is connected with protected circuit, in case there is over-current state to occur, excessive electric current changes resistance by the protection component heating, is high-impedance state by low resistance state transition, thereby the restriction electric current makes protected circuit avoid overcurrent and damages.After over current fault was got rid of, the protection component cooling changed low resistance state into by high-impedance state automatically, recovers operate as normal.
2, voltage clamp circuit as shown in Figure 2, adopts metal-oxide-semiconductor to absorb high pressure, and the input voltage clamper in the voltage range of safety, can be realized the protection to positive and negative input voltage.
The overvoltage that existing these class methods can bear, overcurrent narrow range will be in case when misconnection forceful electric power or civil power, will make protective circuit and circuit system together burn.Especially some signal acquiring system; usually adopt the mode that inserts terminal to insert power supply input and signals collecting; although having differences such as sign between the two comes; but still have the situation of misconnection, in case, whole signal acquiring system is burnt with signals collecting end misconnection power supply; if be designed to be able to protect high pressure by existing protected mode; then its protection component requires power big, when protecting simultaneously is to adopt to absorb overvoltage, overcurrent composition, and circuit is caused burden.
In sum, mainly there is following shortcoming in existing weak electricity system input over-voltage over-current protection circuit:
1, do not have the judgement of access, can't bear moment and connect high pressure.
2, signal inserts the system that all adopts terminal to be connected with the power supply input, in case signals collecting end misconnection power supply will cause protective circuit and circuit system together to burn.
3, the protected location of introducing adopts the mode that absorbs overvoltage, overcurrent composition, during protection circuit is impacted.
[utility model content]
Technical problem to be solved in the utility model is to provide a kind of to be possessed moment and connects high pressure, input overvoltage, overcurrent protection, can delay time simultaneously from the weak electricity system input over-voltage over-current protection circuit that recovers and do not influence during protection line status.
The utility model solves the problems of the technologies described above by the following technical programs: a kind of weak electricity system input over-voltage over-current protection circuit comprises voltage sample circuit, current sampling circuit, first precise rectification circuit, zero passage decision circuitry, overvoltage decision circuitry, second precise rectification circuit, overcurrent decision circuitry, time-delay holding circuit, on-off controller and input connection switch; Described first precise rectification circuit is connected on after the voltage sample circuit, the zero passage decision circuitry be connected between described first precise rectification circuit and the on-off controller after the overvoltage decision circuitry is in parallel, described current sampling circuit, second precise rectification circuit, overcurrent decision circuitry, time-delay holding circuit, on-off controller and input are connected switch and are connected successively, and described input is connected switch and is connected between incoming line and the outlet line;
Before the incoming line connecting system, at first pass through voltage sample circuit, first precise rectification circuit, enter zero passage decision circuitry, overvoltage decision circuitry more simultaneously, zero passage decision circuitry and overvoltage decision circuitry produce a control signal and connect switch closure by on-off controller control input, incoming line is connected with system, system power after the connection enters the overcurrent decision circuitry after via current sampling circuit, second precise rectification circuit, and the overcurrent decision circuitry produces a control signal and connects switch by on-off controller control input again by the time-delay holding circuit and disconnect.
This utility model can further be specially:
Described voltage sample circuit adopts two pure resistance element connected in series, and the voltage signal dividing potential drop on the incoming line is gathered, and the signal that collects is sent into first precise rectification circuit.
Described zero passage decision circuitry is by capacitor C 4, resistance R 20, R22, R24, R26, operational amplifier U4B, diode D6 forms, one of described resistance R 20 terminates to the output of described first precise rectification circuit, the other end of resistance R 20 is received the electrode input end of operational amplifier U4B by resistance R 22, capacitor C 4 is connected resistance R 20, between node between the R22 and the power supply ground, resistance R 24 is connected between the negative input and power supply ground of operational amplifier U4B, resistance R 26 is connected between the negative input and power supply of operational amplifier U4B, the negative pole of diode D6 is connected on the output of operational amplifier U4B, and the positive pole of diode D6 is connected to on-off controller.
Described overvoltage decision circuitry comprises capacitor C 3, resistance R 19, R21, R23, R25, operational amplifier U4A, diode D7, one of described resistance R 19 terminates to the output of described first precise rectification circuit, the other end of resistance R 19 is received the negative input of operational amplifier U4A by resistance R 21, capacitor C 3 is connected resistance R 19, between node between the R21 and the power supply ground, resistance R 25 is connected between the electrode input end and power supply ground of operational amplifier U4A, resistance R 23 is connected between the electrode input end and power supply of operational amplifier U4A, the negative pole of diode D7 is connected on the output of operational amplifier U4A, and the positive pole of diode D7 is connected to on-off controller.
Described overvoltage decision circuitry also comprises capacitor C 5, diode D5, capacitor C 5 be connected between the electrode input end and output of operational amplifier U4A after diode D5 is in parallel, wherein the positive pole of diode D5 connects the electrode input end of operational amplifier U4A, and negative pole connects the output of operational amplifier U4A.
Described overvoltage decision circuitry also comprises LED 3, resistance R 27, the output of a termination operational amplifier U4A of resistance R 27, and the negative pole of other end sending and receiving optical diode LED3, the positive pole of LED 3 connects power supply.
The control signal of described zero passage decision circuitry and the output of overvoltage decision circuitry is successively by resistance R 29, voltage stabilizing didoe DZ2, and triode Q3 control switch controller, one of resistance R 29 output that terminates at described zero passage decision circuitry and overvoltage decision circuitry wherein, the other end is received the positive pole of voltage stabilizing didoe DZ2, the negative pole of voltage stabilizing didoe DZ2 is received the base stage of triode Q3, the emitter of triode Q3 connects power supply, and the collector electrode of triode Q3 connects described on-off controller.
Described time-delay holding circuit comprises diode D2, resistance R 4, R5, R6, capacitor C 2, triode Q2, resistance R 7, diode D1, operational amplifier UB1, capacitor C 1, resistance R 2;
The negative pole of described diode D2 is taken over the output of stream decision circuitry, positive pole is received the negative input of operational amplifier UB1, resistance R 4 is connected between the electrode input end and power supply of operational amplifier UB1, resistance R 5 is connected between the electrode input end and power supply ground of operational amplifier UB1, the collector electrode of triode Q2 is connected the anode of diode D2, the emitter of triode Q2 connects power supply ground, the base stage of triode Q2 is connected with resistance R 7, the other end of resistance R 7 is connected between the negative pole of the negative pole of capacitor C 1 and diode D1, the positive pole of diode D1 connects power supply ground, the positive pole of capacitor C 1 connects the output of operational amplifier UB1, resistance R 6 is connected between the collector electrode and power supply of triode Q2, the positive pole of capacitor C 2 connects the collector electrode of triode Q2, negative pole connects power supply ground, and the output of operational amplifier UB1 is connected to on-off controller by resistance R 2.
Described time-delay holding circuit also comprises resistance R 1, R3, LED 1, LED2, be connected between the output and power supply of operational amplifier UB1 after described LED 1 and resistance R 1 series connection, wherein the negative electrode of LED1 is connected with the output of operational amplifier UB1, be connected between the output and power supply ground of operational amplifier UB1 after described LED 2 and resistance R 3 series connection, wherein the anode of LED2 is connected with the output of operational amplifier UB1.
Described on-off controller is made up of triode Q1, voltage stabilizing didoe DZ1, the break-make that K switch 1 adopts relay control input is connected in input, the control signal that overvoltage decision circuitry, zero passage decision circuitry and time-delay holding circuit produce is by the base stage of voltage stabilizing didoe DZ1 input triode Q1, the emitter of triode Q1 connects power supply, and the collector electrode of triode Q1 connects the relay coil that K switch 1 is connected in input.
Advantage of the present utility model is: the utility model weak electricity system input over-voltage over-current protection circuit, take to judge earlier to be access in line voltage distribution, again with the scheme of line access system.Adopt zero passage decision circuitry and overvoltage decision circuitry simultaneously, prevent the impact of moment connection high pressure, the infringement protected object.The overvoltage decision circuitry is monitoring circuit voltage constantly, prevents the line voltage distribution infringement system that slowly raises.The time-delay holding circuit is adopted in overcurrent protection, control protection time-delay.Connect instantaneous way, can more effective, reliable execute protection.The mode that switch adopts relay is connected in input, and the sampling device adopts the pure resistance element, and signal polarity on the circuit and phase place are not impacted, and during protection circuit is not caused the burden of absorption.
[description of drawings]
The utility model will be further described in conjunction with the embodiments with reference to the accompanying drawings.
Fig. 1 is the existing circuit diagram that adopts voltage stabilizing didoe and thermistor to realize overvoltage, overcurrent protection.
Fig. 2 is existing voltage clamp circuit.
Fig. 3 is the theory diagram of the utility model weak electricity system input over-voltage over-current protection circuit.
Fig. 4 is the overvoltage decision circuitry of the utility model weak electricity system input over-voltage over-current protection circuit and the circuit diagram of zero passage decision circuitry.
Fig. 5 is the circuit diagram of the time-delay holding circuit of the utility model weak electricity system input over-voltage over-current protection circuit.
Fig. 6 be the utility model weak electricity system input over-voltage over-current protection circuit be the circuit diagram that switch is connected in on-off controller and input.
[embodiment]
See also shown in Figure 3; the utility model weak electricity system input over-voltage over-current protection circuit comprises voltage sample circuit 1, current sampling circuit 2, first precise rectification circuit 3, zero passage decision circuitry 4, overvoltage decision circuitry 5, second precise rectification circuit 6, overcurrent decision circuitry 7, time-delay holding circuit 8, on-off controller 9 and input connection switch 10.
Described first precise rectification circuit 3 is connected on after the voltage sample circuit 1, be connected between described first precise rectification circuit 3 and the on-off controller 9 after zero passage decision circuitry 4 and overvoltage decision circuitry 5 are in parallel, described current sampling circuit 2, second precise rectification circuit 6, overcurrent decision circuitry 7, time-delay holding circuit 8, on-off controller 9 and input are connected switch 10 and are connected successively, and described input is connected switch 10 and is connected between incoming line and the outlet line.
Before line access system, at first by voltage sample circuit 1, first precise rectification circuit 3, enter zero passage decision circuitry 4, overvoltage decision circuitry 5 more simultaneously, voltage conditions satisfy simultaneously existing voltage again under the situation in safe range zero passage decision circuitry 4 and overvoltage decision circuitry 5 just can produce a control signal and connect switches 10 closures by on-off controller 9 control inputs, incoming line is connected with system.System power after the connection enters overcurrent decision circuitry 7 after via current sampling circuit 2, second precise rectification circuit 6, when system power surpasses permissible value, just disconnect by on-off controller 9 control input connection switches 10 again by time-delay holding circuit 8 by overcurrent decision circuitry 7 generations one control signal.Time-delay holding circuit 8 connects from recovery after impelling system delay, prevents from still to locate guard mode after overcurrent from removing.
Described voltage sample circuit 1 adopts two pure resistance elements that the voltage signal dividing potential drop on the circuit is gathered, and the signal that collects obtains positive voltage through first precise rectification circuit 3, realizes nonpolarity judgement.
As shown in Figure 4, the signal through voltage sample circuit 1 is gathered is input to zero passage decision circuitry 4 and overvoltage decision circuitry 5 behind first precise rectification circuit 3.
Described zero passage decision circuitry 4 is made up of capacitor C 4, resistance R 20, R22, R24, R26, operational amplifier U4B, diode D6.One of described resistance R 20 terminates to the output of described first precise rectification circuit 3, the other end of resistance R 20 is received the electrode input end of operational amplifier U4B by resistance R 22, capacitor C 4 is connected between the node and power supply ground between resistance R 20, the R22, resistance R 24 is connected between the negative input and power supply ground of operational amplifier U4B, resistance R 26 is connected between the negative input and power supply of operational amplifier U4B, the negative pole of diode D6 is connected on the output of operational amplifier U4B, and the positive pole of diode D6 is connected to on-off controller 9.Wherein resistance R 24, R26 provide the zero passage comparative voltage, and capacitor C 4, resistance R 20, R22 form filter circuit, and diode D6 realizes isolating with the control signal of overvoltage decision circuitry 5.
Described overvoltage decision circuitry 5 is by capacitor C 3, resistance R 19, R21, R23, R25, capacitor C 5, diode D5, operational amplifier U4A, LED 3, resistance R 27, diode D7 forms, one of described resistance R 19 terminates to the output of described first precise rectification circuit 3, the other end of resistance R 19 is received the negative input of operational amplifier U4A by resistance R 21, capacitor C 3 is connected resistance R 19, between node between the R21 and the power supply ground, resistance R 25 is connected between the electrode input end and power supply ground of operational amplifier U4A, resistance R 23 is connected between the electrode input end and power supply of operational amplifier U4A, the negative pole of diode D7 is connected on the output of operational amplifier U4A, and the positive pole of diode D7 is connected to on-off controller 9.Capacitor C 5 be connected between the electrode input end and output of operational amplifier U4A after diode D5 is in parallel, wherein the positive pole of diode D5 connects the electrode input end of operational amplifier U4A, negative pole connects the output of operational amplifier U4A, the output of one termination operational amplifier U4A of resistance R 27, the negative pole of other end sending and receiving optical diode LED3, the positive pole of LED 3 connects power supply.Wherein capacitor C 3 constitutes filter circuit with resistance R 19, R21, and resistance R 23, R25 provide the normality comparative voltage, and capacitor C 5, diode D5 constitute clamp circuit, realizes preventing critical fluctuation.LED 3, resistance R 27 are formed the guard mode indication, and diode D7 realizes isolating with the control signal of zero passage decision circuitry 4.The control signal control switch controller 9 of zero passage decision circuitry 4 and 5 outputs of overvoltage decision circuitry.
In the present embodiment, described zero passage decision circuitry 4 is passed through resistance R 29 successively with the control signal of overvoltage decision circuitry 5 outputs, voltage stabilizing didoe DZ2, and triode Q3 control switch controller 9, one of resistance R 29 output that terminates at described zero passage decision circuitry 4 and overvoltage decision circuitry 5 wherein, the other end is received the positive pole of voltage stabilizing didoe DZ2, the negative pole of voltage stabilizing didoe DZ2 is received the base stage of triode Q3, the emitter of triode Q3 connects power supply, the collector electrode of triode Q3 connects described on-off controller 9, wherein said voltage stabilizing didoe DZ2 service hoisting control signal voltage.
Described current sampling circuit 2 adopts the pure resistance element to connect with system.After system power flows through the pure resistance element, produce pressure drop at pure resistance element two ends, through behind second precise rectification circuit 6, export positive magnitude of voltage again, the size of this voltage is represented the size of system power.
System power converts magnitude of voltage to through current sampling circuit 2, by described overcurrent decision circuitry 7, carries out the judgement system electric current and whether surpasses the protection value behind second precise rectification circuit 6.
See also shown in Figure 5; it is the circuit diagram of described time-delay holding circuit 8; the control signal that is produced by overcurrent decision circuitry 7 is input to time-delay holding circuit 8 by diode D2; in case overcurrent decision circuitry 7 produces protection (low level) control signal; time-delay holding circuit 8 will produce control signal control switch controller 9; impel input to connect switch 10 and disconnect, described time-delay holding circuit is by diode D2; resistance R 4; R5; R6; capacitor C 2; triode Q2; resistance R 7; diode D1; operational amplifier UB1; capacitor C 1; resistance R 1; R2; R3; LED 1; LED2 forms.
The negative pole of described diode D2 is taken over the output of stream decision circuitry 7, positive pole is received the negative input of operational amplifier UB1, diode D2 is used for conducting the low level signal of overcurrent decision circuitry 7, resistance R 4 is connected between the electrode input end and power supply of operational amplifier UB1, resistance R 5 is connected between the electrode input end and power supply ground of operational amplifier UB1, resistance R 4, R5 provides control trigger point comparative voltage, the collector electrode of triode Q2 is connected the anode of diode D2, the emitter of triode Q2 connects power supply ground, the base stage of triode Q2 is connected to an end of resistance R 7, the other end of resistance R 7 is connected between the negative pole of the negative pole of capacitor C 1 and diode D1, the positive pole of diode D1 connects power supply ground, the positive pole of capacitor C 1 connects the output of operational amplifier UB1, resistance R 6 is connected between the collector electrode and power supply of triode Q2, the anode of capacitor C 2 connects the collector electrode of triode Q2, negative electrode connects power supply ground, be connected between the output and power supply of operational amplifier UB1 after described LED 1 and resistance R 1 series connection, wherein the negative electrode of LED1 is connected with the output of operational amplifier UB1, be connected between the output and power supply ground of operational amplifier UB1 after described LED 2 and resistance R 3 series connection, wherein the anode of LED2 is connected with the output of operational amplifier UB1, and the output of operational amplifier UB1 is connected to on-off controller 9 by resistance R 2.Wherein instantaneous circuit is kept, is connected in resistance R 6, R7, capacitor C 1, C2, triode Q2, diode D1 formation control protection time-delay.LED 1, resistance R 1 indication normal operating condition, LED 2, resistance R 2 indication overcurrent protection states, control signal transfers to on-off controller 9 through resistance R 2.
See also Fig. 6, it is the circuit diagram that switch 10 is connected in on-off controller 9 and input, overvoltage decision circuitry 5, the control signal that zero passage decision circuitry 4 and time-delay holding circuit 8 produce is connected switch 10 by on-off controller 9 control inputs, described on-off controller 9 is by triode Q1, voltage stabilizing didoe DZ1 forms, the break-make that K switch 1 adopts relay control input is connected in input, overvoltage decision circuitry 5, the control signal that zero passage decision circuitry 4 and time-delay holding circuit 8 produce is by the base stage of voltage stabilizing didoe DZ1 input triode Q1, the emitter of triode Q1 connects power supply, and the collector electrode of triode Q1 connects the relay coil that K switch 1 is connected in input.Voltage stabilizing didoe DZ1 service hoisting control signal voltage, when control signal was high level, the coil of K switch 1 is connected in input must not electricity and can't be closed, and incoming line is connected with protected system disconnection.
In sum, the technical solution adopted in the utility model technique effect corresponding with it is as described below.
1, circuit is inserted at first judge whether voltage is arranged on the line attachment and whether exceed the ceiling voltage that system allows, promptly adopt zero passage decision circuitry and overvoltage decision circuitry before the protected system, realize judging before the access to line voltage distribution.The zero passage decision circuitry disconnects protected system earlier and being connected with circuit, when having only voltage is arranged on the circuit, is that ability is connected protected system with circuit in safe range the time by the voltage on the overvoltage decision circuitry judgement circuit simultaneously.The method can be when preventing that misconnection from going into high pressure, and overvoltage protection is in the time that determines execute protection, and the connection high pressure of moment causes protected system damage.
When 2, being in safe range as if access voltage, circuit is connected with system, this moment is by overcurrent decision circuitry judgement system electric current, in case system power surpasses the safety margins value, then incoming line and system are disconnected, after process is kept a period of time, recover to insert, then disconnect connection at once if still be in over-current state.Realize quick execute protection, the self-recovering function of guard mode is kept in time-delay, prevents from still to locate guard mode after overcurrent from removing.
3, when normal operating conditions or guard mode, protective circuit can not influence the signal condition on the circuit, influences the phase place of signal etc. as absorption signal, introducing perception or capacitive, inserts switch for this reason and adopts relay control to insert.The voltage acquisition input adopts the high impedance precise rectification circuit, and the current acquisition device adopts pure resistance, low resistance element.Realize not influencing line status.
The utility model weak electricity system input over-voltage over-current protection circuit is monitored the voltage on the line attachment constantly; and be under input voltage situation in allowed limits to the monitoring of electric current; monitor current again after circuit connected; quick execute protection is adopted in overcurrent protection, and the mode that guard mode is kept in time-delay realizes from recovering.So be prerequisite, protect more reliably that protected system is safer with the input voltage.Protective circuit can not cause the influence that absorbs or change signal properties to the signal on the circuit under protection and normal operating conditions simultaneously.
Claims (10)
1. a weak electricity system input over-voltage over-current protection circuit is characterized in that: comprise voltage sample circuit, current sampling circuit, first precise rectification circuit, zero passage decision circuitry, overvoltage decision circuitry, second precise rectification circuit, overcurrent decision circuitry, time-delay holding circuit, on-off controller and input connection switch;
Described first precise rectification circuit is connected on after the voltage sample circuit, the zero passage decision circuitry be connected between described first precise rectification circuit and the on-off controller after the overvoltage decision circuitry is in parallel, described current sampling circuit, second precise rectification circuit, overcurrent decision circuitry, time-delay holding circuit, on-off controller and input are connected switch and are connected successively, and described input is connected switch and is connected between incoming line and the outlet line;
Before the incoming line connecting system, at first pass through voltage sample circuit, first precise rectification circuit, enter zero passage decision circuitry, overvoltage decision circuitry more simultaneously, zero passage decision circuitry and overvoltage decision circuitry produce a control signal and connect switch closure by on-off controller control input, incoming line is connected with system, system power after the connection enters the overcurrent decision circuitry after via current sampling circuit, second precise rectification circuit, and the overcurrent decision circuitry produces a control signal and connects switch by on-off controller control input again by the time-delay holding circuit and disconnect.
2. weak electricity system input over-voltage over-current protection circuit as claimed in claim 1; it is characterized in that: described voltage sample circuit adopts two pure resistance element connected in series; voltage signal dividing potential drop on the incoming line is gathered, and the signal that collects is sent into first precise rectification circuit.
3. weak electricity system input over-voltage over-current protection circuit as claimed in claim 1; it is characterized in that: described zero passage decision circuitry is by capacitor C 4; resistance R 20; R22; R24; R26; operational amplifier U4B; diode D6 forms; one of described resistance R 20 terminates to the output of described first precise rectification circuit; the other end of resistance R 20 is received the electrode input end of operational amplifier U4B by resistance R 22; capacitor C 4 is connected resistance R 20; between node between the R22 and the power supply ground; resistance R 24 is connected between the negative input and power supply ground of operational amplifier U4B; resistance R 26 is connected between the negative input and power supply of operational amplifier U4B; the negative pole of diode D6 is connected on the output of operational amplifier U4B, and the positive pole of diode D6 is connected to on-off controller.
4. weak electricity system input over-voltage over-current protection circuit as claimed in claim 1; it is characterized in that: described overvoltage decision circuitry comprises capacitor C 3; resistance R 19; R21; R23; R25; operational amplifier U4A; diode D7; one of described resistance R 19 terminates to the output of described first precise rectification circuit; the other end of resistance R 19 is received the negative input of operational amplifier U4A by resistance R 21; capacitor C 3 is connected resistance R 19; between node between the R21 and the power supply ground; resistance R 25 is connected between the electrode input end and power supply ground of operational amplifier U4A; resistance R 23 is connected between the electrode input end and power supply of operational amplifier U4A; the negative pole of diode D7 is connected on the output of operational amplifier U4A, and the positive pole of diode D7 is connected to on-off controller.
5. weak electricity system input over-voltage over-current protection circuit as claimed in claim 4; it is characterized in that: described overvoltage decision circuitry also comprises capacitor C 5, diode D5; capacitor C 5 be connected between the electrode input end and output of operational amplifier U4A after diode D5 is in parallel; wherein the positive pole of diode D5 connects the electrode input end of operational amplifier U4A, and negative pole connects the output of operational amplifier U4A.
6. as claim 4 or 5 described weak electricity system input over-voltage over-current protection circuits; it is characterized in that: described overvoltage decision circuitry also comprises LED 3, resistance R 27; the output of one termination operational amplifier U4A of resistance R 27; the negative pole of other end sending and receiving optical diode LED3, the positive pole of LED 3 connects power supply.
7. weak electricity system input over-voltage over-current protection circuit as claimed in claim 1; it is characterized in that: the control signal of described zero passage decision circuitry and the output of overvoltage decision circuitry is successively by resistance R 29; voltage stabilizing didoe DZ2; and triode Q3 control switch controller; one of resistance R 29 output that terminates at described zero passage decision circuitry and overvoltage decision circuitry wherein; the other end is received the positive pole of voltage stabilizing didoe DZ2; the negative pole of voltage stabilizing didoe DZ2 is received the base stage of triode Q3; the emitter of triode Q3 connects power supply, and the collector electrode of triode Q3 connects described on-off controller.
8. weak electricity system input over-voltage over-current protection circuit as claimed in claim 1, it is characterized in that: described time-delay holding circuit comprises diode D2, resistance R 4, R5, R6, capacitor C 2, triode Q2, resistance R 7, diode D1, operational amplifier UB1, capacitor C 1, resistance R 2;
The negative pole of described diode D2 is taken over the output of stream decision circuitry, positive pole is received the negative input of operational amplifier UB 1, resistance R 4 is connected between the electrode input end and power supply of operational amplifier UB1, resistance R 5 is connected between the electrode input end and power supply ground of operational amplifier UB1, the collector electrode of triode Q2 is connected the anode of diode D2, the emitter of triode Q2 connects power supply ground, the base stage of triode Q2 is connected with resistance R 7, the other end of resistance R 7 is connected between the negative pole of the negative pole of capacitor C 1 and diode D1, the positive pole of diode D1 connects power supply ground, the positive pole of capacitor C 1 connects the output of operational amplifier UB1, resistance R 6 is connected between the collector electrode and power supply of triode Q2, the positive pole of capacitor C 2 connects the collector electrode of triode Q2, negative pole connects power supply ground, and the output of operational amplifier UB1 is connected to on-off controller by resistance R 2.
9. weak electricity system input over-voltage over-current protection circuit as claimed in claim 8; it is characterized in that: described time-delay holding circuit also comprises resistance R 1; R3; LED 1; LED2; be connected between the output and power supply of operational amplifier UB1 after described LED 1 and resistance R 1 series connection; wherein the negative electrode of LED1 is connected with the output of operational amplifier UB1; be connected between the output and power supply ground of operational amplifier UB1 after described LED 2 and resistance R 3 series connection, wherein the anode of LED2 is connected with the output of operational amplifier UB1.
10. weak electricity system input over-voltage over-current protection circuit as claimed in claim 1; it is characterized in that: described on-off controller is made up of triode Q1, voltage stabilizing didoe DZ1; the break-make that K switch 1 adopts relay control input is connected in input; the control signal that overvoltage decision circuitry, zero passage decision circuitry and time-delay holding circuit produce is by the base stage of voltage stabilizing didoe DZ1 input triode Q1; the emitter of triode Q1 connects power supply, and the collector electrode of triode Q1 connects the relay coil that K switch 1 is connected in input.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009201827622U CN201478788U (en) | 2009-09-03 | 2009-09-03 | Overvoltage and overcurrent protection circuit for input of light-current system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009201827622U CN201478788U (en) | 2009-09-03 | 2009-09-03 | Overvoltage and overcurrent protection circuit for input of light-current system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102427189A (en) * | 2011-12-31 | 2012-04-25 | 河南辉煌科技股份有限公司 | Signal acquisition isolator |
| US10263416B2 (en) | 2012-12-03 | 2019-04-16 | Huawei Technologies Co., Ltd. | Overvoltage protection apparatus and method |
-
2009
- 2009-09-03 CN CN2009201827622U patent/CN201478788U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102427189A (en) * | 2011-12-31 | 2012-04-25 | 河南辉煌科技股份有限公司 | Signal acquisition isolator |
| US10263416B2 (en) | 2012-12-03 | 2019-04-16 | Huawei Technologies Co., Ltd. | Overvoltage protection apparatus and method |
| US11404867B2 (en) | 2012-12-03 | 2022-08-02 | Huawei Techologies Co., Ltd. | Overvoltage protection apparatus and method |
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