CN215733447U - Alternating-current overvoltage protection circuit - Google Patents
Alternating-current overvoltage protection circuit Download PDFInfo
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- CN215733447U CN215733447U CN202121796107.3U CN202121796107U CN215733447U CN 215733447 U CN215733447 U CN 215733447U CN 202121796107 U CN202121796107 U CN 202121796107U CN 215733447 U CN215733447 U CN 215733447U
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Abstract
The utility model relates to the technical field of overvoltage protection, in particular to an alternating-current overvoltage protection circuit which comprises a voltage comparison circuit, a control circuit, a direct-current relay and a direct-current power supply circuit, wherein two input ends of the voltage comparison circuit are respectively connected with an L line and an N line of alternating current, the voltage comparison circuit outputs a comparison result to the control circuit, the control circuit is connected with the direct-current relay, the control circuit controls the on-off of a coil of the direct-current relay according to the comparison result, the direct-current relay comprises a normally open contact which is connected with a power device in series, the control circuit controls the coil of the direct-current relay to be powered off when the voltage comparison circuit detects overvoltage, and the direct-current power supply circuit is used for converting the alternating current into direct current to supply power to the direct-current relay. The alternating-current overvoltage protection circuit provided by the utility model can disconnect a loop of the electric equipment when overvoltage occurs, so that the electric equipment is prevented from being burnt by the overvoltage, and the alternating-current overvoltage protection circuit is low in cost and high in stability.
Description
Technical Field
The utility model relates to the technical field of overvoltage protection, in particular to an alternating-current overvoltage protection circuit.
Background
When industrial electric equipment is wired, a worker needs to connect electric equipment with a phase line and a zero line led out from a power transformer, under a normal condition, the electric equipment normally works under corresponding voltage, but the condition that the electric equipment is burnt due to overvoltage caused by wiring errors or zero line breakage often exists.
For example, as shown in fig. 1, R01 and R02 represent two electric devices, respectively, where two ends of the electric device R01 are connected to the phase line L1 and the neutral line N, two ends of the electric device R02 are connected to the phase line L2 and the neutral line N, the phase voltage is 220V, and the line voltage is 380V, so that both electric devices normally operate at a voltage of 220V. However, in practical situations, if the total zero line of the line is disconnected, as shown in fig. 2, the electric device R01 and the electric device R02 are connected in series, and the voltage across the two ends of the series is 380V, at this time, if the load of the electric device R01 is much higher than the load of the electric device R02, the voltage divided by the electric device R01 exceeds 220V, and thus the electric device R01 is burnt out by overvoltage. Therefore, it is desirable to provide an ac overvoltage protection circuit for protecting the electrical equipment.
SUMMERY OF THE UTILITY MODEL
The utility model provides an alternating-current overvoltage protection circuit for solving the technical problem that electric equipment in the prior art has potential hazards of overvoltage burning, and the alternating-current overvoltage protection circuit is used for disconnecting a loop where the electric equipment is located when overvoltage occurs, so that the electric equipment is prevented from being damaged by the overvoltage.
The technical scheme adopted by the utility model is as follows:
an ac overvoltage protection circuit comprising:
the two input ends of the voltage comparison circuit are respectively connected with an L line and an N line of alternating current, and the voltage comparison circuit outputs a comparison result to the control circuit;
the control circuit is connected with a direct current relay and controls the on-off of a coil of the direct current relay according to the comparison result;
the direct current relay comprises a normally open contact which is connected with the electric equipment in series, and the control circuit controls the coil of the direct current relay to be powered off when the voltage comparison circuit detects overvoltage;
and the direct current power supply circuit is used for converting the alternating current into direct current to supply power to the direct current relay.
Further, the voltage comparison circuit includes a first voltage-dividing resistor, a second voltage-dividing resistor, a voltage comparison chip IC1 and a diode D1, wherein a first end of the first voltage-dividing resistor is connected to an L line, a second end of the first voltage-dividing resistor is connected to a first end of the second voltage-dividing resistor, a second end of the second voltage-dividing resistor is connected to an N line, a second end of the first voltage-dividing resistor is further connected to a first input end of the voltage comparison chip IC1, a second input end of the voltage comparison chip IC1 is connected to the N line, an output end of the voltage comparison chip IC1 is connected to the control circuit, and the diode D1 is connected to the first voltage-dividing resistor and the second voltage-dividing resistor in series.
Further, the voltage comparison chip IC1 employs TL 431.
Furthermore, a capacitor C1 for interference resistance is connected between the first input end and the second input end of the voltage comparison chip IC1, and a capacitor C2 for jitter elimination is further arranged between the output end and the second input end of the voltage comparison chip IC 1.
Further, the dc power supply circuit includes a voltage reduction capacitor C3, a rectifier diode D2, a voltage regulator device TVS1 and a filter capacitor C4, a first end of the voltage reduction capacitor C3 is connected to an L line, a second end of the voltage reduction capacitor C3 is connected to a cathode of the voltage regulator device TVS1 and an anode of the rectifier diode D2, an anode of the voltage regulator device TVS1 is connected to an N line, a cathode of the rectifier diode D2 is connected to a first end of the filter capacitor C4 and a first end of a coil of the dc relay, a second end of the filter capacitor C4 is connected to the N line, and a second end of the coil of the dc relay is connected to the N line.
Further, the direct current supply circuit further comprises an inductor L1 for eliminating surge, and the inductor L1 is connected with the voltage reduction capacitor C3 in series.
Further, a voltage regulator tube ZD1 is also connected in series with the coil of the direct current relay, the cathode of the voltage regulator tube ZD1 is connected with the second end of the coil of the direct current relay, and the anode of the voltage regulator tube ZD1 is connected with an N line.
Further, the control circuit comprises a switching device Q1, a first pin of the switching device Q1 is connected to the output end of the voltage comparison chip IC1, a second pin and a third pin of the switching device Q1 are respectively connected to two ends of the coil of the dc relay, when the voltage difference between the first input end and the second input end of the voltage comparison chip IC1 is greater than a threshold value, the voltage comparison chip IC1 is turned on, the switching device Q1 is turned on, and the coil of the dc relay is turned off.
Further, the switching device Q1 is a PNP triode, the first pin of the switching device Q1 is the base of the PNP triode, the second pin of the switching device Q1 is the emitter of the PNP triode, and the third pin of the switching device Q1 is the collector of the PNP triode.
Further, the output terminal of the voltage comparison chip IC1 is connected to the cathode of the rectifier diode D2 through a resistor R21.
Compared with the prior art, the technical scheme of the utility model has the following beneficial effects: according to the utility model, the phase line and the zero line of alternating current to be accessed to the electric equipment are detected through the voltage comparison circuit, if the voltage is detected to be normal, the loop of the electric equipment is conducted, the electric equipment can work normally, if the overvoltage is detected, the loop of the electric equipment is disconnected, and the electric equipment does not work, so that the electric equipment does not work during the overvoltage, and phenomena such as burning and the like are avoided; moreover, the direct-current relay is adopted, the direct-current relay is simple in structure, low in cost, stable in attraction and long in service life, the direct-current relay is powered by the direct-current power supply circuit, the direct-current power supply circuit directly obtains electricity from alternating current, the alternating current is converted into direct current required by the direct-current relay, an additional power supply is not needed, and the cost is saved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic diagram of two electric devices in normal operation;
FIG. 2 is a schematic diagram of the operation of two electric devices in the case of a zero line disconnection;
FIG. 3 is a flow chart of the AC overvoltage protection circuit of the present embodiment;
FIG. 4 is a schematic diagram of an AC overvoltage protection circuit of the present embodiment;
fig. 5 is a schematic diagram of TL 431.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
As shown in fig. 3-4, the present embodiment provides an ac overvoltage protection circuit, which includes a voltage comparison circuit, a control circuit, a dc power supply circuit and a dc relay, wherein two input terminals of the voltage comparison circuit are respectively connected to an L line and an N line (i.e., a phase line and a zero line) of an ac power, the voltage comparison circuit compares voltages of the L line and the N line, and outputs a comparison result to the control circuit, for example, when a difference between the input voltages is greater than a set threshold, a low level is output, and when a difference between the input voltages is less than the set threshold, a high level is output.
Furthermore, the control circuit is connected with a direct current relay, the direct current relay is powered by a direct current power supply circuit, the direct current relay comprises a normally open contact, the normally open contact is connected with the electric equipment in series, the control circuit controls the on-off of a coil of the direct current relay according to a comparison result of the voltage comparison circuit, when the voltage comparison circuit detects that the difference value of input voltage is smaller than or equal to a set threshold value (at the moment, the voltage between an L line and an N line does not exceed 220V), the control circuit controls the coil of the direct current relay to be electrified, the normally open contact of the direct current relay is closed, and the electric equipment works normally; when the voltage comparison circuit detects that the difference value of the input voltage is larger than a set threshold value (at the moment, the voltage between the L line and the N line exceeds 220V), the control circuit controls the coil of the direct current relay to be powered off, the normally open contact of the direct current relay is disconnected, and the loop where the electric equipment is located is disconnected and does not work.
Like this, this embodiment detects the phase line and the zero line of the alternating current that the consumer will insert through voltage comparison circuit, if detect voltage normal then the consumer place return circuit switch on, the consumer can normally work, if detect overvoltage then the consumer place return circuit disconnection, the consumer is out of work, so can guarantee that the consumer is out of work when overvoltage, avoids taking place phenomenons such as burning out. Moreover, the direct current relay is adopted in the embodiment, the direct current relay is simple in structure, low in cost, stable in attraction and long in service life, the direct current relay is powered by the direct current power supply circuit, the direct current power supply circuit directly takes electricity from alternating current, the alternating current is converted into direct current required by the direct current relay, an extra power supply is not needed, and the cost is saved.
The voltage comparison circuit of this embodiment includes a first voltage-dividing resistor, a second voltage-dividing resistor and a voltage comparison chip IC1, the first voltage-dividing resistor and the second voltage-dividing resistor can be set according to requirements, in this embodiment, a selection resistor R1, a resistor R2 and a resistor R3 are connected in series to form the first voltage-dividing resistor, and a selection resistor R4 and a resistor R5 are connected in parallel to form the second voltage-dividing resistor. Furthermore, a first terminal of the first voltage-dividing resistor is connected to the L line (i.e., AC1 in fig. 4), a second terminal of the first voltage-dividing resistor is connected to a first terminal of the second voltage-dividing resistor, a second terminal of the second voltage-dividing resistor is connected to the N line (i.e., AC2 in fig. 4), a second terminal of the first voltage-dividing resistor is further connected to a first input terminal of the voltage comparison chip IC1, a second input terminal of the voltage comparison chip IC1 is connected to the N line, and an output terminal of the voltage comparison chip IC1 is connected to the control circuit. The voltage comparison circuit further comprises a diode D1, the diode D1 is connected with the first voltage-dividing resistor and the second voltage-dividing resistor in series, specifically, the diode D1 can be connected between the L line and the resistor R1 in the forward direction, and due to the unidirectional conductivity of the diode, the voltage comparison circuit only carries out comparison in the positive half period of the alternating current, and misoperation is avoided.
Preferably, the voltage comparison chip IC1 of this embodiment employs a TL431, as shown in fig. 5, the TL431 has a power amplifier U1, a transistor Q2 and a reference source Vref of 2.5V inside, and when a voltage difference between a first input terminal (i.e., a first pin) and a second input terminal (i.e., a second pin) is greater than 2.5V, the transistor Q2 is turned on, and an output terminal (i.e., a third pin) of the TL431 is communicated with the second input terminal. Returning to fig. 4, by setting the values of the first voltage-dividing resistor and the second voltage-dividing resistor, when the voltage difference between the first input terminal and the second input terminal of the voltage comparison chip IC1 is greater than the threshold value, i.e., 2.5V, the output terminal and the second input terminal of the voltage comparison chip IC1 can be connected; when the voltage difference between the first input end and the second input end of the voltage comparison chip IC1 is less than or equal to the threshold value, namely 2.5V, the output end and the second input end of the voltage comparison chip IC1 are disconnected. Therefore, different comparison results can be output to the control circuit according to the magnitude of the input voltage, and the TL431 is small in package and low in cost, so that the cost of the protection circuit of the embodiment is further reduced.
In order to improve the stability of the protection circuit, in this embodiment, a capacitor C1 for resisting disturbance is further connected between the first input terminal and the second input terminal of the voltage comparison chip IC1, and when external disturbance occurs, the capacitor C1 prevents voltage from sudden change, thereby preventing malfunction. Further, a capacitor C2 for jitter elimination is further disposed between the output terminal and the second input terminal of the voltage comparison chip IC1, so that the output signal, i.e., the comparison result, is more stable.
The direct current power supply circuit of this embodiment includes step-down capacitor C3, rectifier diode D2, voltage regulator device TVS1 and smoothing capacitor C4, L line is connected to the first end of step-down capacitor C3, the second end of step-down capacitor C3 is connected in the negative pole of voltage regulator device TVS1 and the positive pole of rectifier diode D2, N line is connected to the positive pole of voltage regulator device TVS1, rectifier diode D2 ' S negative pole is connected in the first end of smoothing capacitor C4 and the first end of direct current relay ' S coil S1, N line is connected to the second end of smoothing capacitor C4, N line is connected to the second end of direct current relay ' S coil S1. Due to the unidirectional conductivity of the diode, the current only passes through the rectifier diode D2 in the positive half period, which is equivalent to half-wave rectification, and the voltage is stabilized at 24V through the voltage stabilizing device TVS1 and the rectified voltage is smoothly stabilized through the filter capacitor C4, so that the direct current power supply of the direct current relay is realized.
Further, the direct current supply circuit further comprises an inductor L1 for eliminating surge, the inductor L1 is connected in series with the step-down capacitor C3, and the inductor L1 is specifically connected between the step-down capacitor C3 and the rectifier diode D2, so that the stability of the protection circuit is further improved.
Preferably, the coil S1 of the dc relay of this embodiment is further connected in series with a voltage regulator ZD1, a cathode of the voltage regulator ZD1 is connected to the second end of the coil S1 of the dc relay, and an anode of the voltage regulator ZD1 is connected to the N line. The direct current relay of the embodiment adopts HF3FF/024, the pull-in voltage of the direct current relay is 18V, the direct current relay can normally work only by the voltage of more than 18V after being conducted, and if the direct current relay works under 24V all the time, the loss of the direct current relay is large, so that the loss of the direct current relay can be reduced by arranging the voltage regulator tube ZD1, and the service life of the direct current relay is prolonged.
The control circuit of the embodiment comprises a switching device Q1, a first pin of the switching device Q1 is connected with an output end of a voltage comparison chip IC1 through a current-limiting resistor R23, a second pin and a third pin of the switching device Q1 are respectively connected with a first end of a coil S1 of a direct-current relay and an anode of a voltage regulator tube ZD1, when a voltage difference between a first input end and a second input end of the voltage comparison chip IC1 is larger than a threshold value, the voltage comparison chip IC1 is switched on, the switching device Q1 is switched on, at the moment, the coil S1 of the direct-current relay is equivalently short-circuited, the coil S1 of the direct-current relay is switched off, a normally-open contact RL1 is switched off, and the electric equipment RO1 does not work.
Further, the output terminal of the voltage comparison chip IC1 is further connected to the cathode of the rectifier diode D2 through the resistor R21, so that the operating current can be supplied to the voltage comparison chip IC1, and when the voltage difference between the first input terminal and the second input terminal of the voltage comparison chip IC1 is less than or equal to the threshold value, a high level is supplied to the first pin of the switching device Q1, so that the switching device Q1 is opened, the coil S1 of the dc relay is energized, the normally-open contact RL1 is closed, and the electric device R01 operates normally.
Preferably, the switching device Q1 is a PNP transistor, the first pin of the switching device Q1 is a base of the PNP transistor, the second pin of the switching device Q1 is an emitter of the PNP transistor, and the third pin of the switching device Q1 is a collector of the PNP transistor. Of course, other transistors or MOS transistors may be used in other embodiments.
In summary, the ac overvoltage protection circuit provided by this embodiment can disconnect the loop where the electrical device is located when an overvoltage occurs, so as to prevent the electrical device from being burned by the overvoltage, and the ac overvoltage protection circuit has low cost and high stability.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing circuits, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above examples are only for describing the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims (10)
1. An ac overvoltage protection circuit, comprising:
the two input ends of the voltage comparison circuit are respectively connected with an L line and an N line of alternating current, and the voltage comparison circuit outputs a comparison result to the control circuit;
the control circuit is connected with a direct current relay and controls the on-off of a coil of the direct current relay according to the comparison result;
the direct current relay comprises a normally open contact which is connected with the electric equipment in series, and the control circuit controls the coil of the direct current relay to be powered off when the voltage comparison circuit detects overvoltage;
and the direct current power supply circuit is used for converting the alternating current into direct current to supply power to the direct current relay.
2. The ac overvoltage protection circuit of claim 1, wherein the voltage comparison circuit comprises a first voltage-dividing resistor, a second voltage-dividing resistor, a voltage comparison chip IC1 and a diode D1, a first end of the first voltage-dividing resistor is connected to an L line, a second end of the first voltage-dividing resistor is connected to a first end of the second voltage-dividing resistor, a second end of the second voltage-dividing resistor is connected to an N line, a second end of the first voltage-dividing resistor is further connected to a first input end of the voltage comparison chip IC1, a second input end of the voltage comparison chip IC1 is connected to the N line, an output end of the voltage comparison chip IC1 is connected to the control circuit, and the diode D1 is connected in series with the first voltage-dividing resistor and the second voltage-dividing resistor.
3. The ac overvoltage protection circuit of claim 2, wherein the voltage comparison chip IC1 is TL 431.
4. The ac overvoltage protection circuit of claim 3, wherein a capacitor C1 for interference rejection is further connected between the first input terminal and the second input terminal of the voltage comparison chip IC1, and a capacitor C2 for jitter elimination is further provided between the output terminal and the second input terminal of the voltage comparison chip IC 1.
5. The AC overvoltage protection circuit as claimed in claim 4, wherein said DC power supply circuit includes a voltage-reducing capacitor C3, a rectifier diode D2, a voltage-stabilizing device TVS1 and a filter capacitor C4, a first end of said voltage-reducing capacitor C3 is connected to L line, a second end of said voltage-reducing capacitor C3 is connected to a cathode of said voltage-stabilizing device TVS1 and an anode of said rectifier diode D2, an anode of said voltage-stabilizing device TVS1 is connected to N line, a cathode of said rectifier diode D2 is connected to a first end of said filter capacitor C4 and a first end of a coil of said DC relay, a second end of said filter capacitor C4 is connected to N line, and a second end of a coil of said DC relay is connected to N line.
6. The AC overvoltage protection circuit of claim 5, wherein the DC power supply circuit further comprises an inductor L1 for eliminating surge, the inductor L1 is connected in series with the buck capacitor C3.
7. The alternating-current overvoltage protection circuit according to claim 6, characterized in that a voltage regulator tube ZD1 is further connected in series with the coil of the direct-current relay, the cathode of the voltage regulator tube ZD1 is connected with the second end of the coil of the direct-current relay, and the anode of the voltage regulator tube ZD1 is connected with an N line.
8. The AC overvoltage protection circuit of claim 7, wherein the control circuit comprises a switching device Q1, a first pin of the switching device Q1 is connected to an output terminal of the voltage comparison chip IC1, a second pin and a third pin of the switching device Q1 are respectively connected to two ends of a coil of the DC relay, when a voltage difference between a first input terminal and a second input terminal of the voltage comparison chip IC1 is greater than a threshold value, the voltage comparison chip IC1 is turned on, the switching device Q1 is turned on, and the coil of the DC relay is turned off.
9. The ac overvoltage protection circuit of claim 8, wherein the switching device Q1 is a PNP transistor, the first leg of the switching device Q1 is a base of the PNP transistor, the second leg of the switching device Q1 is an emitter of the PNP transistor, and the third leg of the switching device Q1 is a collector of the PNP transistor.
10. The ac overvoltage protection circuit of claim 9, wherein the output terminal of the voltage comparison chip IC1 is further connected to the cathode of the rectifier diode D2 through a resistor R21.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121796107.3U CN215733447U (en) | 2021-08-03 | 2021-08-03 | Alternating-current overvoltage protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121796107.3U CN215733447U (en) | 2021-08-03 | 2021-08-03 | Alternating-current overvoltage protection circuit |
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| Publication Number | Publication Date |
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| CN215733447U true CN215733447U (en) | 2022-02-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202121796107.3U Active CN215733447U (en) | 2021-08-03 | 2021-08-03 | Alternating-current overvoltage protection circuit |
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| CN (1) | CN215733447U (en) |
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- 2021-08-03 CN CN202121796107.3U patent/CN215733447U/en active Active
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