CN215817497U - Three-phase protection circuit - Google Patents
Three-phase protection circuit Download PDFInfo
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- CN215817497U CN215817497U CN202121800847.XU CN202121800847U CN215817497U CN 215817497 U CN215817497 U CN 215817497U CN 202121800847 U CN202121800847 U CN 202121800847U CN 215817497 U CN215817497 U CN 215817497U
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Abstract
The utility model provides a three-phase protection circuit, and relates to the technical field of electronic circuits. This three-phase protection circuit includes: the number of the current-sharing capacitors is three, and each current-sharing capacitor is connected with any one phase power supply of the three-phase power supply; the three-phase bridge rectifier circuit is connected with the three current-sharing capacitors; the optical coupler is connected with the bridge rectifier circuit and used for detecting the three-phase state of the three-phase power supply according to the current data of the current-sharing capacitor and the bridge rectifier circuit and forming a warning instruction when the three-phase state is a phase-loss state; the signal transmission circuit is connected with the optical coupler and used for forming a power-off signal according to the warning instruction; and the protection circuit is connected with the signal transmission circuit and used for receiving a power-off signal sent by the signal transmission circuit and cutting off the connection between the three-phase power supply and the electric equipment. The technical scheme provided by the utility model can protect the electric equipment in time when the three-phase power supply is in a phase-failure state.
Description
Technical Field
The utility model relates to the technical field of electronic circuits, in particular to a three-phase protection circuit.
Background
Three-phase power supply is generally adopted in industrial power utilization, for example, more than 90% of power loads in a 380V alternating current system supply three phases, so that the power loads are damaged once single phase or two phases are interrupted due to faults. The current open-phase protection device mainly uses whether three-phase current is balanced or not as a criterion for phase failure, and the open-phase protector can only be used for protecting electric equipment (such as a three-phase motor) in a three-phase power supply circuit, but cannot be generally used for open-phase protection.
Therefore, a protection circuit with higher reliability and wider application range is needed to protect the three-phase circuit.
SUMMERY OF THE UTILITY MODEL
In view of the above, the present invention provides a three-phase protection circuit for protecting an electric device in a three-phase power supply circuit.
In view of the above object, the present invention provides a three-phase protection circuit, including:
the number of the current-sharing capacitors is three, and each current-sharing capacitor is connected with any one phase power supply of the three-phase power supply;
the three-phase bridge rectifier circuit is connected with the three current-sharing capacitors;
the optical coupler is connected with the bridge rectifier circuit and used for detecting the three-phase state of the three-phase power supply according to the current data of the current-sharing capacitor and the bridge rectifier circuit and forming a warning instruction when the three-phase state is a phase-loss state;
the signal transmission circuit is connected with the optical coupler and used for forming a power-off signal according to the warning instruction;
and the protection circuit is connected with the signal transmission circuit, is arranged between the three-phase power supply and the electric equipment and is used for receiving a power-off signal sent by the signal transmission circuit and cutting off the connection between the three-phase power supply and the electric equipment.
Furthermore, the signal transmission circuit comprises a first resistor, a second resistor, a first time base circuit, a relay, a phase-lack signal delay sub-circuit and a direct-current power supply; wherein,
the first end of the first resistor is connected with the anode of the direct-current power supply, the second end of the first resistor and the first end of the optical coupler are connected with the first end of the second resistor, the second end of the optical coupler and the second end of the second resistor are connected with the cathode of the direct-current power supply, and the first end of the first resistor and the second end of the second resistor are used for forming a high-potential signal at the second end of the first resistor in a phase-failure state;
the input end of the first time base circuit is connected with the second end of the first resistor, the output end of the first time base circuit is connected with the first end of the relay, the second end of the relay is connected with the anode of the direct-current power supply, and a low potential signal is output by the high potential signal of the second end of the first resistor through the first time base circuit, so that the relay is excited;
the input end of the phase-lack signal delay sub-circuit is connected with the output end of the first time base circuit, and the output end of the phase-lack signal delay sub-circuit is connected with the input end of the first time base circuit and used for keeping the input end of the first time base circuit at a high potential.
Furthermore, the optical coupler comprises a first diode and a triode, the anode of the first diode of the optical coupler is connected with the cathode of the diode of the common cathode group in the three-phase bridge type rectifying circuit, the cathode of the first diode of the optical coupler is connected with the anode of the diode of the common anode group in the three-phase bridge type rectifying circuit, the collector of the triode is connected with the second end of the first resistor, and the emitter of the triode is connected with the cathode of the direct current power supply.
Further, the open-phase signal delay sub-circuit comprises a second time-base circuit and a second diode; wherein
The input end of the second time base circuit is connected with the output end of the first time base circuit, the output end of the second time base circuit is connected with the anode of the second diode, and the cathode of the second diode is connected with the input end of the first time base circuit and used for inverting the low potential signal of the output end of the first time base circuit into a high potential signal and keeping the input end of the first time base circuit at a high potential.
Furthermore, the relay comprises a relay coil, an iron core, an armature, a normally closed relay contact and a normally open relay contact, after the relay is electrified, the relay coil generates an electromagnetic effect, the armature is attracted to the iron core under the electromagnetic effect, the normally closed relay contact is disconnected, and the normally open relay contact is closed.
Furthermore, two ends of the normally closed contact of the relay are connected with a protective capacitor.
Furthermore, the protection circuit comprises an electric control switch connected with the normally closed contact of the relay, the three-phase power supply is connected with the electric equipment through the electric control switch, and the three-phase power supply is used for disconnecting the normally closed contact of the relay and the electric control switch when the relay is electrified and cutting off the connection between the three-phase power supply and the electric equipment.
Further, the electrically controlled switch is a contactor coil.
And furthermore, the three-phase power supply is respectively connected with the three normally closed main contacts of the contactor, and is used for disconnecting the three normally closed main contacts of the contactor and cutting off the connection between the three-phase power supply and the electric equipment when the coil of the contactor loses power.
Furthermore, the signal transmission circuit further comprises a reset switch, wherein a first end of the reset switch is connected with the input end of the first time base circuit, and a second end of the reset switch is connected with the negative electrode of the direct-current power supply and used for setting the input end of the first time base circuit to be at a low potential when the reset switch is closed.
From the above, it can be seen that the three-phase protection circuit provided by the utility model is a phase-failure protection circuit based on a voltage detection principle, a three-phase power supply is detected through a current-sharing capacitor, a three-phase bridge rectifier circuit and an optical coupler, when any phase of the three-phase power supply is in a phase-failure state, the input end of a signal transmission circuit is at a high potential, a relay coil in the signal transmission circuit is excited, a normally closed contact of a relay in the protection circuit is disconnected, and then the connection between the three-phase power supply and a power consumption device is cut off. The detection method is simple and reliable, and can generally protect the electric equipment.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic circuit diagram of a three-phase protection circuit according to an embodiment of the present invention.
Description of reference numerals: A. a first phase in a three-phase power supply; B. a second phase in the three-phase power supply; C. a third phase of the three-phase power supply; KM3, three normally closed main contacts of a contactor; c1, a first current sharing capacitor; c2, a second current sharing capacitor; c3, a third current sharing capacitor; c4, a fourth capacitance; c5, a fifth capacitance; c6, a sixth capacitor; c7, a seventh capacitance; VD1, a first diode; VD2, second diode; VD3, third diode; VD4, fourth diode; VD5, fifth diode; VD6, a sixth diode; VD7, a seventh diode; VD8, an eighth diode; VD9, ninth diode; VD10, twelfth polar tube; VD11, eleventh diode; VD12, a twelfth diode; PC1, optocoupler; p1, a first time base circuit; p2, a second time base circuit; r1, a first resistor; r2, a second resistor; r3, third resistor;
r4, fourth resistor; KA1, relay coil; KA2 and a normally open contact of a relay; KA3, normally closed contact of a relay; KM1, contactor coil; KM2, a contactor normally open contact; SB, a reset switch; SB1, load stop switch; SB2, load starting switch; HL, a light-emitting diode.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.
It is to be noted that technical terms or scientific terms used in the embodiments of the present invention should have the ordinary meanings as understood by those having ordinary skill in the art to which the present disclosure belongs, unless otherwise defined. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.
Referring to fig. 1, the three-phase protection circuit of the present invention is further described, including: the number of the current-sharing capacitors is three, and each current-sharing capacitor is connected with any one phase power supply of the three-phase power supply; the three-phase bridge rectifier circuit is connected with the three current-sharing capacitors; the optical coupler is connected with the bridge rectifier circuit and used for detecting the three-phase state of the three-phase power supply according to the current data of the current-sharing capacitor and the bridge rectifier circuit and forming a warning instruction when the three-phase state is a phase-loss state; the signal transmission circuit is connected with the optical coupler and used for forming a power-off signal according to the warning instruction; and the protection circuit is connected with the signal transmission circuit, is arranged between the three-phase power supply and the electric equipment and is used for receiving a power-off signal sent by the signal transmission circuit and cutting off the connection between the three-phase power supply and the electric equipment.
In the above scheme, further, the three-phase bridge rectifier circuit includes a first group of rectifier diodes, a second group of rectifier diodes, and a third group of rectifier diodes.
The first group of rectifying diodes comprises a third diode VD3 and a fourth diode VD4, and the anode of the third diode VD3 is connected with the cathode of the fourth diode VD 4. The second group of rectifying diodes comprises a fifth diode VD5 and a sixth diode VD6, and the anode of the fifth diode VD5 is connected with the cathode of the sixth diode VD 6. The third group of rectifying diodes comprises a seventh diode VD7 and an eighth diode VD8, and the anode of the seventh diode VD7 is connected with the cathode of the eighth diode VD 8. Cathodes of the third diode VD3, the fifth diode VD5 and the seventh diode VD7 are connected to form a common cathode group, and anodes of the fourth diode VD4, the sixth diode VD6 and the eighth diode VD8 are connected to form a common anode group.
Further, the three current sharing capacitors are respectively a first current sharing capacitor C1, a second current sharing capacitor C2 and a third current sharing capacitor C3. One end of the first current-sharing capacitor C1 is connected with A, and the other end of the first current-sharing capacitor C1 is connected with the anode of a third diode VD 3; one end of a second current-sharing capacitor C2 is connected with B, and the other end of the second current-sharing capacitor C2 is connected with the anode of a fifth diode VD 5; one end of a third current-sharing capacitor C3 is connected with C, and the other end of the third current-sharing capacitor C3 is connected with the anode of a seventh diode VD7, so that three-phase load balance is formed, energy consumption is reduced, and the circuit is more stable and reliable.
Furthermore, although the first current-sharing capacitor C1, the second current-sharing capacitor C2, and the third current-sharing capacitor C3 are already step-down by the rectifier bridge, the voltages at the two ends of the capacitors cannot suddenly change, so the instantaneous voltages borne by the diodes VD3 to VD8 may reach the amplitude value of the three-phase line voltage, the amplitude value of the three-phase line voltage is 1.414 × 380 — 573(V), and the maximum reverse peak voltage of the selected diodes is greater than the amplitude value of the three-phase line voltage for the protection circuit. In the present embodiment, the diode type in the three-phase bridge rectifier circuit is 1N4007, and the maximum reverse peak voltage thereof is 700V.
Furthermore, two ends of a diode in the optical coupler PC1 are respectively connected with the bridge rectifier circuit, two ends of a triode of the optical coupler PC1 are connected with the signal transmission circuit, and the signal transmission circuit is connected with the protection circuit. The protection circuit is used for forming a warning signal according to the current conditions detected by the three current-equalizing capacitors and the bridge rectifier circuit, and receiving the warning signal to cut off the connection between the three-phase power supply and the electric equipment, so that the protection of the three-phase circuit is realized.
When the three phases are normal, the rectified current at a certain moment flows out from a current-sharing capacitor and a diode which are connected with the highest potential in the three phases, and flows back to the power supply through the diode in the optical coupler. When the three phases are normal, the output voltage of the rectifier bridge does not have a zero crossing point, the diode part in the optical coupler always has current passing, the triode part is in saturated conduction, the signal transmission circuit cannot transmit an open-phase signal to the protection circuit, and the electric equipment works normally.
When any phase in the three-phase power supply is in a phase-loss state, the output voltage of the rectifier bridge has a zero crossing point, when the voltage crosses the zero crossing point, the optical coupler is not conducted, at the moment, the signal transmission circuit receives a warning instruction sent by the optical coupler and transmits the warning instruction to the protection circuit, and the protection circuit generates a power-off signal so as to protect the electric equipment.
Through the scheme, the phase-failure state of the three-phase power supply can be detected, and the power supply and the electric equipment are timely disconnected in the phase-failure state, so that the electric equipment is generally protected.
In some embodiments, the signal transmission circuit comprises a first resistor, a second resistor, a first time base circuit, a relay, a phase-lack signal delay sub-circuit and a direct-current power supply; wherein,
the first end of the first resistor is connected with the anode of the direct-current power supply, the second end of the first resistor and the first end of the optical coupler are connected with the first end of the second resistor, the second end of the optical coupler and the second end of the second resistor are connected with the cathode of the direct-current power supply, and the first end of the first resistor and the second end of the second resistor are used for forming a high-potential signal at the second end of the first resistor in a phase state;
the input end of the first time base circuit is connected with the second end of the first resistor, the output end of the first time base circuit is connected with the first end of the relay, and the second end of the relay is connected with the anode of the direct-current power supply and used for outputting a low potential signal from the high potential signal of the second end of the first resistor through the first time base circuit so as to excite the relay;
the input end of the phase-lack signal delay sub-circuit is connected with the output end of the first time base circuit, and the output end of the phase-lack signal delay sub-circuit is connected with the input end of the first time base circuit and used for keeping the input end of the first time base circuit at a high potential.
The first time base circuit P1 and the second time base circuit P2 have eight pins in total, and pin 1 is GND (ground) which functions as ground and is low; pin 2 is a TRIG, which functions to give a high level at the output when the pin voltage drops to Vcc/3 (or a threshold voltage determined by the control terminal); pin 3 is OUT (output), which functions to output high + Vcc or low; pin 4 is RST (reset) and has the function that when the pin is connected with a high level, the timer works, and when the pin is grounded, the chip is reset and outputs a low level; pin 5 is CTRL (control), whose function is to control the threshold voltage of the chip. (default two threshold voltages are Vcc/3 and 2Vcc/3 when the pin is empty); pin 6 is THR (threshold), and the output terminal gives a low level when the pin voltage rises to 2Vcc/3 (or a threshold voltage determined by the control terminal); pin 7 is DIS (discharge), which functions as an internal OC gate for discharging the capacitor; pin 8 is Vcc (power supply) and its function is to provide a high level and power to the chip.
Further, the signal transmission circuit further comprises a third resistor R3, a fourth resistor R4, a ninth diode VD9, a twelfth diode VD10, an eleventh diode VD11, a twelfth diode VD12, a fifth capacitor C5, a sixth capacitor C6, a light emitting diode HL and a normally open relay contact KA 2. The positive electrode of the twelfth diode VD12 is connected with the positive electrode of the direct-current power supply, the negative electrode of the twelfth diode VD12 is connected with the first end of the first resistor R1, the second end of the first resistor R1 is connected with the positive electrode of the ninth diode VD9, the negative electrode of the ninth diode VD9 is connected with the pin 6 of the first time base circuit P1, the pin 1 of the first time base circuit P1 is connected with the negative electrode of the direct-current power supply, the pin 3 of the first time base circuit P1 is connected with the first end of the relay coil KA1, the second end of the relay coil KA1 is connected with the negative electrode of the twelfth diode VD12, the pin 4 and the pin 8 of the first time base circuit P1 are connected with the negative electrode of the twelfth diode VD12, the positive electrode 10 is connected with the first end of the relay coil KA1, and the negative electrode of the twelfth electrode diode VD10 is connected with the second end of the relay coil KA 1.
Furthermore, the anode of the eleventh diode VD11 is connected to pin 3 of the first time-base circuit P1, the cathode of the eleventh diode VD11 is connected to pin 2 of the second time-base circuit P2, pin 6 of the second time-base circuit P2 is connected to pin 2 of the second time-base circuit P2, pin 8 of the second time-base circuit P2 is connected to the cathode of the eleventh diode VD11, pin 4 of the second time-base circuit P2 is connected to pin 8 of the second time-base circuit P2, the first end of the third resistor R3 is connected to the cathode of the dc power supply, the second end of the third resistor R3 is connected to the first end of the fifth capacitor C5, and the second end of the fifth capacitor C5 is connected to the cathode of the twelfth diode VD 12.
Furthermore, one end of a sixth capacitor C6 is connected to the cathode of the twelfth diode VD12, the other end of the sixth capacitor C6 is connected to the cathode of the dc power supply, the first end of the relay normally-open contact KA2 is connected to the cathode of the twelfth diode VD12, the second end of the relay normally-open contact KA2 is connected to the first end of a fourth resistor R4, the second end of the fourth resistor R4 is connected to the anode of the light emitting diode HL, and the cathode of the light emitting diode HL is connected to the cathode of the dc power supply.
Specifically, the operating principle of the signal transmission circuit is as follows: when the three phases are normal, the triode is partially saturated and conducted, the current in the signal transmission circuit flows out from the original positive pole of the direct current, flows to the first resistor R1 through the twelfth diode VD12, then flows through the collector and the emitter of the triode from the second end of the first resistor R1, and finally flows back to the negative pole of the direct current power supply. At this time, the second terminal of the first resistor R1 is at a low potential, the input terminal of the first time base circuit is at a low potential, and the output terminal of the first time base circuit is at a high potential. The output end of the first time base circuit is connected with the first end of the relay coil, the second end of the relay coil is also at a high potential, the coil is not excited, the normally closed contact of the relay in the protection circuit is kept in a normally closed state, and the electric equipment works normally.
When any one of the three phases is in a phase-loss state, the current in the signal transmission circuit flows out from the positive electrode of the direct-current power supply, flows to the ninth diode VD9 through the twelfth diode VD12 and the first resistor R1, flows to the second resistor R2, and finally flows back to the negative electrode of the direct-current power supply, at this time, the second end of the first resistor R1 is at a high potential, the input end of the first time base circuit is at a high potential, and the output end of the first time base circuit is at a low potential. Because the second end of the relay coil in the relay is connected with the positive pole of the direct current power supply, and the first end is connected with the output end of the first time base circuit, one end of the relay coil is at a high potential, and the other end of the relay coil is at a low potential, and the potential difference is enough for the coil in the relay to be excited. Under the action of electromagnetic force, a normally closed contact of a relay in the protection circuit is disconnected, and then the connection between the three-phase power supply and the electric equipment is cut off.
In some embodiments, the optocoupler includes a first diode and a transistor, an anode of the first diode of the optocoupler is connected to a cathode of the diode of the common cathode set in the three-phase bridge rectifier circuit, a cathode of the first diode of the optocoupler is connected to an anode of the diode of the common anode set in the three-phase bridge rectifier circuit, a collector of the transistor is connected to the second end of the first resistor, and an emitter of the transistor is connected to a cathode of the dc power supply.
The positive electrode of the first diode VD1 is connected with the negative electrodes of VD3, VD5 and VD7, and the negative electrode of the first diode VD1 is connected with the positive electrodes of VD4, VD6 and VD 8.
Further, when the three phases are normal, the optical coupler is in saturated conduction, current in a triode in the optical coupler flows from a collector to an emitter, and the input end of the signal transmission circuit is at a low potential. When any one of the three phases is in a phase-lacking state, the optical coupler is in a cut-off state, the current in the signal transmission circuit flows out from the positive pole of the direct-current power supply, flows back to the negative pole of the power supply through the twelfth diode VD12, the first resistor R1 and the second resistor R2, and at the moment, the input end of the signal transmission circuit is at a high potential.
In some embodiments, the open-phase signal delay sub-circuit comprises a second time-base circuit and a second diode; the input end of the second time base circuit is connected with the output end of the first time base circuit, the output end of the second time base circuit is connected with the anode of the second diode, and the cathode of the second diode is connected with the input end of the first time base circuit and used for inverting the low potential signal of the output end of the first time base circuit into a high potential signal and keeping the input end of the first time base circuit at a high potential.
Further, the dead zone voltage of the first diode in the optical coupler in the circuit is 1.2V, and when the output voltage of the rectifier bridge is less than 1.2V, the optical coupler is in a cut-off state. Namely, the phase-lack signal can be detected only when the output voltage of the rectifier bridge is less than 1.2V, and the time corresponding to the output voltage of less than 1.2V is short, so that a phase-lack signal delay sub-circuit is designed in the signal output circuit.
Further, the operation principle of the phase-lacking signal delay sub-circuit is as follows: when any phase of the three-phase power supply is in a phase failure and the voltage detected by the diode in the optical coupler is less than 1.2V, the optical coupler is switched off. The input end of the first time base circuit is at a high potential, the output end of the first time base circuit is at a low potential, and the relay coil is excited. Meanwhile, the input end of the second time base circuit is at a low potential, the output end of the second time base circuit is at a high potential, the high potential enables the input end of the first time base circuit to continuously maintain at the high potential through a second diode VD2, a coil in the relay is continuously excited, and a normally closed contact of the relay in the protection circuit is continuously disconnected.
In some embodiments, the relay comprises a relay coil, an iron core, an armature, a normally closed relay contact and a normally open relay contact, wherein when the relay is electrified, the relay coil generates an electromagnetic effect, the armature is attracted to the iron core under the electromagnetic effect, the normally closed relay contact is opened, and the normally open relay contact is closed.
Specifically, the phase-lack signal response between the signal transmission circuit and the protection circuit is accomplished by a relay. The relay mainly comprises a relay coil, an iron core, an armature, a normally closed contact and a normally open contact. The relay coil is connected in the signal transmission circuit, two ends of the normally closed contact are connected in the protection circuit, when the relay coil is excited, an electromagnetic effect is generated, the normally closed contact of the relay is disconnected, and no current passes through the protection circuit.
In some embodiments, a protective capacitor is connected across the normally closed relay contact.
Specifically, the seventh capacitor C7 is connected across the normally closed contact of the relay, which reduces sparking when the normally closed contact is opened.
In some embodiments, the protection circuit comprises an electronic control switch connected with the normally closed contact of the relay, and the three-phase power supply is connected with the electric equipment through the electronic control switch, so that when the relay is electrified, the normally closed contact of the relay and the electronic control switch are disconnected, and the connection between the three-phase power supply and the electric equipment is cut off.
Specifically, when the normally closed contact is disconnected and the protection circuit is powered off, the electric control switch is disconnected, that is, the connection between the three-phase power supply and the electric equipment is cut off, so that the electric equipment is protected.
In some embodiments, the electrically controlled switch is a contactor coil.
Further, the protection circuit further comprises a contactor normally-open contact KM2, a normally-closed switch SB1, a normally-open switch SB2, a seventh capacitor C7, a three-phase power supply and three normally-closed main contacts KM3 of the contactor. Wherein A looks power is connected to the first end of the normally open contact in the relay, and the first end of contactor coil is connected to the second end, and the first end of normally open switch SB2 is connected to the second end of contactor coil, and normally closed switch SB 1's first end is connected to normally open switch SB 2's second end, and C looks power is connected to normally closed switch SB 1's second end, and contactor normally open contact's both ends are connected with normally open switch SB 2's both ends.
Further, an electric control switch in the protection circuit can be a contactor coil, when any phase is in a phase-loss state, a normally closed contact of a relay in the protection circuit is disconnected, no current passes through the protection circuit, and the contactor coil is disconnected.
Further, the coil of the contactor is a large inductance element, when the coil in the relay is excited, a large spark is generated when the normally closed contact of the relay is opened, and the seventh capacitor C7 is connected to two ends of the normally closed contact of the relay, so that the spark generated when the normally closed contact is opened can be reduced.
The three-phase power supply is connected with the three normally closed main contacts of the contactor respectively and used for disconnecting the three normally closed main contacts of the contactor when the coil of the contactor loses power and cutting off the connection between the three-phase power supply and the electric equipment.
Specifically, a contactor coil in the protection circuit can control the on-off of three normally closed main contacts connected in a three-phase power supply. When the three phases are normal, the protection circuit works normally, the coil of the contactor is electrified and excited, three normally closed main contacts connected in the three-phase power supply are in a closed state, and the electric equipment runs normally. When the three-phase power supply is in a phase-loss state, the protection circuit is powered off, the coil of the contactor is powered off, the three normally-closed main contacts connected in the three-phase power supply are disconnected, and the connection between the power supply and the electric equipment is cut off.
In some embodiments, the signal transmission circuit further includes a reset switch, a first end of the reset switch is connected to the input terminal of the first time base circuit, and a second end of the reset switch is connected to a negative electrode of the dc power supply, and is configured to set the input terminal of the first time base circuit to a low potential when the reset switch is turned on.
Further, both ends of the reset switch are connected to a fourth capacitor C4.
Specifically, a first end of the reset switch is connected to the pin 2 of the first time base circuit, and a second end of the reset switch is connected to the negative electrode of the dc power supply. When the reset switch is closed, the pin 2 of the first time base circuit is set to be at a low potential, the output end of the first time base circuit is at a high potential, a coil in the relay is not excited, and the protection circuit works normally.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the utility model, also features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the utility model as described above, which are not provided in detail for the sake of brevity.
The embodiments of the utility model are intended to embrace all such alternatives, modifications and variances that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, substitutions, improvements and the like that may be made without departing from the spirit and principles of the utility model are intended to be included within the scope of the utility model.
Claims (10)
1. A three-phase protection circuit, comprising:
the number of the current-sharing capacitors is three, and each current-sharing capacitor is connected with any one phase power supply of the three-phase power supply;
the three-phase bridge rectifier circuit is connected with the three current-sharing capacitors;
the optical coupler is connected with the bridge rectifier circuit and used for detecting the three-phase state of the three-phase power supply according to the current data of the current-sharing capacitor and the bridge rectifier circuit and forming a warning instruction when the three-phase state is a phase-lacking state;
the signal transmission circuit is connected with the optical coupler and used for forming a power-off signal according to the warning instruction;
and the protection circuit is arranged between the three-phase power supply and the electric equipment and used for receiving the power-off signal sent by the signal transmission circuit and cutting off the connection between the three-phase power supply and the electric equipment.
2. The three-phase protection circuit according to claim 1, wherein the signal transmission circuit comprises a first resistor, a second resistor, a first time base circuit, a relay, a phase-lack signal delay sub-circuit and a direct-current power supply; wherein,
the first end of the first resistor is connected with the anode of the direct-current power supply, the second end of the first resistor and the first end of the optical coupler are connected with the first end of the second resistor, and the second end of the optical coupler and the second end of the second resistor are connected with the cathode of the direct-current power supply, so that a high-potential signal is formed at the second end of the first resistor in the phase-lacking state;
the input end of the first time base circuit is connected with the second end of the first resistor, the output end of the first time base circuit is connected with the first end of the relay, and the second end of the relay is connected with the positive electrode of the direct-current power supply and used for outputting a low-potential signal from the second end of the first resistor through the first time base circuit so as to excite the relay;
the input end of the phase-lack signal delay sub-circuit is connected with the output end of the first time base circuit, and the output end of the phase-lack signal delay sub-circuit is connected with the input end of the first time base circuit and used for keeping the input end of the first time base circuit at a high potential.
3. The three-phase protection circuit of claim 2, wherein the optocoupler includes a first diode and a transistor, an anode of the first diode of the optocoupler is connected to a cathode of the diode of the common cathode set in the three-phase bridge rectification circuit, a cathode of the first diode of the optocoupler is connected to an anode of the diode of the common anode set in the three-phase bridge rectification circuit, a collector of the transistor is connected to the second end of the first resistor, and an emitter of the transistor is connected to a cathode of the dc power supply.
4. The three-phase protection circuit according to claim 2, wherein the open-phase signal delay sub-circuit comprises a second time-base circuit and a second diode; wherein
The input end of the second time base circuit is connected with the output end of the first time base circuit, the output end of the second time base circuit is connected with the anode of the second diode, the cathode of the second diode is connected with the input end of the first time base circuit, and the second time base circuit is used for inverting the low potential signal of the output end of the first time base circuit into a high potential signal and keeping the input end of the first time base circuit at a high potential.
5. The three-phase protection circuit according to claim 2, wherein the relay comprises a relay coil, an iron core, an armature, a normally closed relay contact and a normally open relay contact, when the relay is energized, the relay coil generates an electromagnetic effect, the armature is attracted to the iron core under the electromagnetic effect, the normally closed relay contact is opened, and the normally open relay contact is closed.
6. The three-phase protection circuit according to claim 5, wherein a protection capacitor is connected to two ends of the normally closed contact of the relay.
7. The three-phase protection circuit according to claim 5, wherein the protection circuit comprises an electrically controlled switch connected to the normally closed contact of the relay, and the three-phase power supply is connected to the electric equipment through the electrically controlled switch, so that when the relay is powered on, the normally closed contact of the relay and the electrically controlled switch are disconnected, and the connection between the three-phase power supply and the electric equipment is cut off.
8. A three-phase protection circuit according to claim 7, wherein the electrically controlled switch is a contactor coil.
9. The three-phase protection circuit according to claim 8, wherein the three-phase power supply is connected to three normally closed main contacts of a contactor, respectively, and is configured to disconnect the three normally closed main contacts of the contactor to cut off the connection between the three-phase power supply and the electric equipment when the contactor coil is de-energized.
10. The three-phase protection circuit according to claim 2, wherein the signal transmission circuit further comprises a reset switch, a first end of the reset switch is connected to the input terminal of the first time base circuit, and a second end of the reset switch is connected to a negative electrode of the dc power supply, and is configured to set the input terminal of the first time base circuit to a low potential when the reset switch is turned on.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121800847.XU CN215817497U (en) | 2021-08-03 | 2021-08-03 | Three-phase protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121800847.XU CN215817497U (en) | 2021-08-03 | 2021-08-03 | Three-phase protection circuit |
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| Publication Number | Publication Date |
|---|---|
| CN215817497U true CN215817497U (en) | 2022-02-11 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202121800847.XU Active CN215817497U (en) | 2021-08-03 | 2021-08-03 | Three-phase protection circuit |
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| Country | Link |
|---|---|
| CN (1) | CN215817497U (en) |
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2021
- 2021-08-03 CN CN202121800847.XU patent/CN215817497U/en active Active
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Inventor after: Chang Lugang Inventor after: Bu Qingguo Inventor after: Xie Jiarui Inventor after: Bai Jincai Inventor before: Chang Lugang Inventor before: Zeng Wuqing Inventor before: Bu Qingguo Inventor before: Xie Jiarui Inventor before: Bai Jincai |