CN217425659U - Current transformer dotted terminal detection circuit based on double-tube self-excited oscillator - Google Patents
Current transformer dotted terminal detection circuit based on double-tube self-excited oscillator Download PDFInfo
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- CN217425659U CN217425659U CN202221248375.6U CN202221248375U CN217425659U CN 217425659 U CN217425659 U CN 217425659U CN 202221248375 U CN202221248375 U CN 202221248375U CN 217425659 U CN217425659 U CN 217425659U
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Abstract
The invention discloses a circuit for detecting the dotted terminal of a current transformer based on a double-tube self-excited oscillator, which comprises the double-tube self-excited oscillator, a photoelectric driving module and a detection module; the double-tube self-excited oscillator is used for generating alternating triangular wave signals or sawtooth wave signals; the photoelectric driving module is used for transmitting and isolating an electric signal between the double-tube self-excited oscillator and the detection module, and driving the detection module and the current transformer to be detected; the detection module is used for detecting whether the ports of the primary side and the secondary side of the connected current transformer to be detected are homonymous terminals or not through the on and off of the bulb. Compared with the prior art, the circuit for detecting the homonymous terminal of the current transformer based on the double-tube self-excited oscillator can quickly judge the homonymous terminal of the current transformer, has low requirements on the electrician theory and the operation skill of operators, greatly improves the detection efficiency, and is very favorable for batch production, use and maintenance of the current transformer.
Description
Technical Field
The invention relates to the field of electronic detection of current transformers, in particular to a circuit for detecting the homonymous terminal of a current transformer based on a double-tube self-excited oscillator.
Background
Generally, the turn ratio of the primary side and the secondary side of the current transformer is large, the judgment of the homonymous end of the current transformer can provide important reference for the detection current and the detection phase of the current transformer, and along with the application of the current transformer in a large quantity, particularly in the batch production, use and maintenance processes, the quick and accurate judgment of the homonymous end of the current transformer has very important significance.
The inventor finds that the prior art for judging the same-name end of the current transformer has higher requirements on the electrician theory and the operation skill of an operator, needs to use instruments and equipment such as an alternating current power supply, a direct current power supply, a voltmeter, an ammeter or an oscilloscope, and needs to frequently disconnect and connect wires, so that the device adopting the prior art is low in efficiency and very unfavorable for batch production, use and maintenance.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a circuit for detecting the homonymous terminal of a current transformer based on a double-tube self-excited oscillator, and the specific technical scheme is that,
the device comprises a double-tube self-excited oscillator, a photoelectric driving module and a detection module;
the double-tube self-excited oscillator is a self-excited oscillator circuit comprising two triodes and is used for generating alternating triangular wave signals or sawtooth wave signals; the charging and discharging circuit comprises a biasing resistor R1, a charging and discharging resistor R2, a charging and discharging capacitor C1, a triode Q1 and a triode Q2; the triode Q1 is a PNP type triode, and the triode Q2 is an NPN type triode; the emitter of the triode Q1 is connected with a power supply VCC1, the base of the triode Q1 and one end of a bias resistor R1 are connected with one end of a charging and discharging capacitor C1, the collector of the triode Q1 is connected with the base of the triode Q2, the other end of the charging and discharging capacitor C1 is connected with one end of the charging and discharging resistor R2, the other end of the charging and discharging resistor R2 is connected with the collector of the triode Q2, the connection point of the charging and discharging resistor R2 is set as a port Sm, and the emitter of the triode Q2 and the other end of the bias resistor R1 are connected with a power supply ground GND 1;
the photoelectric driving module is used for transmitting and isolating an electric signal between the double-tube self-excited oscillator and the detection module, matching different working power supply voltages between the double-tube self-excited oscillator and the detection module and driving the detection module and the current transformer to be detected; the circuit comprises a current-limiting resistor R3, a photoelectric coupler U1 and a triode Q3; the photoelectric coupler U1 is a triode type photoelectric coupler, and the triode Q3 is an NPN type triode; the anode of a diode in the primary side of the photoelectric coupler U1 is connected with a power supply VCC1, the cathode of a diode in the primary side of the photoelectric coupler U1 is connected with one end of a current-limiting resistor R3, the other end of the current-limiting resistor R3 is connected with the port Sm, the collector of a triode in the secondary side of the photoelectric coupler U1 and the collector of a triode Q3 are connected with the power supply VCC2, the emitter of a triode in the secondary side of the photoelectric coupler U1 is connected with the base of a triode Q3, and the emitter of the triode Q3 is set as a port Sn and used for driving the detection module in the form of a switching signal;
the detection module is used for detecting whether the ports of the primary side and the secondary side of the connected current transformer to be detected are homonymous terminals or not through the on and off of the bulb; comprises a bulb D1, a regulating resistor R11 and a current limiting resistor R22; the adjusting resistor R11 is an equivalent two-port adjustable resistor; one end of a bulb D1 is connected with the port Sn, the port Sn is connected with a set port S _ port1, the other end of the bulb D1 is connected with a set port P _ port1, one end of an adjusting resistor R11 is connected with a set port P _ port2, one end of a current-limiting resistor R22 is connected with a set port S _ port2, and the other ends of the adjusting resistor R11 and the current-limiting resistor R22 are connected with a power ground GND 2; in addition, the port P _ port1 and the port P _ port2 are respectively used for connecting two ports on the primary side of the current transformer to be tested, and the port S _ port1 and the port S _ port2 are respectively used for connecting two ports on the secondary side of the current transformer to be tested.
Further, the light bulb D1 is replaced by an indicator light composed of two anti-parallel light emitting diodes.
Further, the transistor Q3 is replaced by an equivalent darlington transistor accordingly.
The circuit for detecting the homonymous terminal of the current transformer based on the double-tube self-excited oscillator has the advantages that the homonymous terminal of the current transformer can be quickly judged, the requirements on the electrician theory and the operation skill of operators are not high, frequent disconnecting and wiring are not needed, the detection efficiency can be greatly improved, and the circuit is very favorable for batch production, use and maintenance of the current transformer.
Drawings
Fig. 1 is a typical schematic diagram of a circuit for detecting a dotted terminal of a current transformer based on a dual-transistor self-excited oscillator.
Fig. 2 shows another alternative of the present invention for replacing the bulb.
Fig. 3 is a schematic diagram of a dual-tube self-excited oscillator according to the present invention.
Fig. 4 is a schematic view of the photovoltaic driving module according to the present invention.
Fig. 5 is a schematic diagram of a local equivalent operation circuit for detecting the dotted termination method of the current transformer.
Fig. 6 is a schematic diagram of a local equivalent operation circuit of the method for detecting the synonym termination of the current transformer.
Fig. 7 shows another alternative embodiment of the invention, which replaces the transistor Q3.
Fig. 8 is a specific example of the method for detecting the same-name terminal of the current transformer.
Fig. 9 is a specific example of the method for detecting the synonym termination of the current transformer according to the invention.
Detailed Description
In order that the above objects, features and advantages of the present invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings.
As shown in fig. 1, a typical schematic diagram of a circuit for detecting a dotted terminal of a current transformer based on a dual-transistor self-excited oscillator according to the present invention includes a dual-transistor self-excited oscillator, a photo-electric driving module and a detection module;
the double-tube self-excited oscillator is a self-excited oscillator circuit comprising two triodes and is used for generating alternating triangular wave signals or sawtooth wave signals; the charging and discharging circuit comprises a biasing resistor R1, a charging and discharging resistor R2, a charging and discharging capacitor C1, a triode Q1 and a triode Q2; the triode Q1 is a PNP type triode, and the triode Q2 is an NPN type triode; an emitter of the triode Q1 is connected with a power supply VCC1, a base of the triode Q1 and one end of a bias resistor R1 are connected with one end of a charging and discharging capacitor C1, a collector of the triode Q1 is connected with a base of the triode Q2, the other end of the charging and discharging capacitor C1 is connected with one end of the charging and discharging resistor R2, the other end of the charging and discharging resistor R2 is connected with a collector of the triode Q2, a connection point of the charging and discharging resistor R2 is set as a port Sm, and the emitter of the triode Q2 and the other end of the bias resistor R1 are connected with a power supply ground GND 1;
the photoelectric driving module is used for transmitting and isolating an electric signal between the double-tube self-excited oscillator and the detection module, matching different working power supply voltages between the double-tube self-excited oscillator and the detection module and driving the detection module and the current transformer to be detected; the circuit comprises a current-limiting resistor R3, a photoelectric coupler U1 and a triode Q3; the photoelectric coupler U1 is a triode type photoelectric coupler, and the triode Q3 is an NPN type triode; the anode of a diode in the primary side of the photoelectric coupler U1 is connected with a power supply VCC1, the cathode of a diode in the primary side of the photoelectric coupler U1 is connected with one end of a current-limiting resistor R3, the other end of the current-limiting resistor R3 is connected with the port Sm, the collector of a triode in the secondary side of the photoelectric coupler U1 and the collector of a triode Q3 are connected with the power supply VCC2, the emitter of a triode in the secondary side of the photoelectric coupler U1 is connected with the base of a triode Q3, and the emitter of the triode Q3 is set as a port Sn and used for driving the detection module in the form of a switching signal;
the detection module is used for detecting whether the ports of the primary side and the secondary side of the connected current transformer to be detected are homonymous terminals or not through the on and off of the bulb; comprises a bulb D1, a regulating resistor R11 and a current limiting resistor R22; the adjusting resistor R11 is an equivalent two-port adjustable resistor; one end of a bulb D1 is connected with the port Sn, the port Sn is connected with a set port S _ port1, the other end of the bulb D1 is connected with a set port P _ port1, one end of an adjusting resistor R11 is connected with a set port P _ port2, one end of a current-limiting resistor R22 is connected with a set port S _ port2, and the other ends of the adjusting resistor R11 and the current-limiting resistor R22 are connected with a power ground GND 2; in addition, the port P _ port1 and the port P _ port2 are respectively used for connecting two ports on the primary side of the current transformer to be tested, and the port S _ port1 and the port S _ port2 are respectively used for connecting two ports on the secondary side of the current transformer to be tested.
As shown in fig. 2, in another alternative of the present invention, at least one of the light bulb D1 and the light bulb D2 is replaced by an indicator light composed of two anti-parallel light emitting diodes.
As shown in fig. 3, which is a schematic diagram of the dual-transistor self-excited oscillator of the present invention, a primary side branch of the photocoupler U1 may be regarded as an equivalent load, and is connected between the power source VCC1 and the port Sm, so as to form a typical self-excited oscillator circuit including two triodes, and two ends of the equivalent load are alternating triangular wave or sawtooth wave signals.
As shown in fig. 4, which is a schematic diagram of the photovoltaic driving module according to the present invention and is described with reference to fig. 3, assuming that an equivalent load is additionally connected to the port Sn, the working process is,
(1) when the voltage difference between the power supply VCC1 and the port Sm is higher than the conduction voltage of a light emitting diode in the primary side of the photoelectric coupler U1, a low impedance state is formed between a collector and an emitter of a triode in the secondary side of the photoelectric coupler U1, so that the secondary side of the photoelectric coupler U1 is conducted, forward bias is provided for a base and an emitter of the triode Q3, a low impedance state is formed between the collector and the emitter of the triode Q3, so that the triode Q3 is conducted, namely the port Sn outputs high level;
(2) when the voltage difference between the power supply VCC1 and the port Sm is lower than the conduction voltage of a light emitting diode in the primary side of the photoelectric coupler U1, a high impedance state is formed between a collector and an emitter of a triode in the secondary side of the photoelectric coupler U1, so that the secondary side of the photoelectric coupler U1 is turned off, the base and the emitter of the triode Q3 lose forward bias, a high impedance state is formed between the collector and the emitter of the triode Q3, so that the triode Q3 is cut off, namely the port Sn outputs a low level;
in summary, the output voltage waveform of the port Sn is an alternate switching signal; because the input signal and the output signal of the photoelectric driving module are mutually isolated, the photoelectric driving module can be technically suitable for current transformers with different powers or different working voltages to detect.
Because the number of turns of the primary side and the number of turns of the secondary side of the current transformer are different greatly, in order to improve the batch detection efficiency of the same type of current transformers, a fault-free current transformer with the same type and known homonymy end is found to determine the parameter of the regulating resistor R11, and then the homonymy end is detected in batch; the method comprises the following operation steps of carrying out,
(1) the port P _ port1 and the port P _ port2 are respectively connected with two ports on the primary side of a known current transformer TA, the port S _ port1 and the port S _ port2 are respectively connected with two ports on the secondary side of the known current transformer TA, namely, the two ports on the primary side with less turns of the current transformer TA are respectively connected with the port P _ port1 and the port P _ port2, and the two ports on the secondary side with more turns are respectively connected with the port S _ port1 and the port S _ port 2;
(2) determining parameters of an adjusting resistor R11; so as to achieve the effect that when the current transformer TA is in the same name termination method, the bulb D1 is not lighted; when the current transformer TA is in the different name end method, the bulb D1 is lighted;
(3) and then, detecting the homonymous terminals of the same type of current transformers in batches.
As shown in fig. 5, it is a schematic diagram of a local equivalent operating circuit of the current transformer for detecting the dotted terminal method of the present invention; during power-on, in the process that a signal on the port Sn is converted from a low level to a high level, two branches formed by a primary side and a secondary side of the current transformer TA are connected, the inductance of the primary side can inhibit the increase of current, an induced voltage Up can be generated between the two ends of the primary side, a voltage Us is induced on the secondary side through the current transformer TA, as shown in the attached figure 1, the conduction voltage drop of the triode Q3 is ignored, and the highest voltage on the port Sn is V CC2 According to kirchhoff's voltage law, the resulting quantitative relationship is
Subtracting the formula (1) from the formula (2)
For the purpose of analysis and regulation, assuming that the current flowing through the lamp is I, and assuming that the resistance of the current limiting resistor R22 is 0, there are
Transform equation (5) into
According to the formula (6), the connection according to fig. 5 is connected, the current I flowing through the lamp bulb is reduced by increasing the adjusting resistor R11, so that the detection purpose of "when the current transformer TA is in the same-name terminal connection, the lamp bulb D1 is not lighted" can be achieved, namely, the parameter of the adjusting resistor R11 is adjusted until the lamp bulb D1 is not lighted immediately.
Similarly, when the signal on the port Sn is converted from the high level to the low level, the analysis process and the result are similar to those described above, and details are not repeated.
As shown in fig. 6, which is a schematic diagram of a local equivalent operating circuit for detecting the synonym termination method of the current transformer according to the present invention, when a signal at a port Sn is converted from a low level to a high level during power-Up, two branches formed by a primary side and a secondary side of a current transformer TA are connected, an inductance at the primary side inhibits an increase of a current, an induced voltage Up is generated between the two ends of the current transformer TA, a voltage Us is induced at the secondary side through the current transformer TA, as shown in fig. 1, a conduction voltage drop of a triode Q3 is ignored, and a highest voltage at the port Sn is V CC2 According to kirchhoff's voltage law, the resulting quantitative relationship is
The equation (8) is subtracted from the equation (7) to obtain
For ease of analysis and adjustment, assume that the current flowing through the bulb is
Similarly, assume that the value of the current limiting resistor R22 is 0, and there is
Converting formula (11) into
In the formula (12), as illustrated in fig. 5, the resistance value of the modulated regulating resistor R11 remains unchanged, and as compared with the formula (6), the current flowing through the lamp bulb is obviously increased, so as to achieve the detection purpose of "when the current transformer TA is a different-name terminal method, the lamp bulb D1 is turned on".
Similarly, when the signal on the port Sn is converted from the high level to the low level, the analysis process and the result are similar to those described above, and details are not repeated.
In summary, according to the wiring and adjusting processes shown in fig. 5 and fig. 6, the parameters of the adjusting resistor R11 are determined, and the parameters are used for batch detection of the same type of current transformers to improve the working efficiency; the following procedure for the detection is that,
(1) the port P _ port1 and the port P _ port2 are respectively connected with two ports on the primary side of the current transformer TA to be tested, and the port S _ port1 and the port S _ port2 are respectively connected with two ports on the secondary side of the current transformer TA to be tested;
(2) when the detection module bulb emits light, the current transformer TA port connected with the port P _ port1 and the port S _ port1 of the detection module is a synonym terminal; when the bulb of the detection module does not emit light, it is described that the ports of the current transformer TA connected to the port P _ port1 and the port S _ port1 of the detection module are the same name.
As shown in fig. 7, in another embodiment of the present invention, the transistor Q3 is replaced correspondingly, the transistor Q3 is replaced correspondingly by an equivalent darlington transistor, so as to increase the load driving capability of the transistor, thereby adapting to the detection of a high-power current transformer.
As shown in fig. 8, in an embodiment of the method for detecting the homonymous terminals of a current transformer according to the present invention, the connection is performed according to the above principle, and after power is turned on, the light bulb D1 is not lit, which indicates that the TA ports of the current transformer connected to the P _ port1 and the S _ port1 of the detection module are homonymous terminals.
As shown in fig. 9, for an embodiment of the method for detecting the different-name terminals of the current transformer according to the present invention, the connection is performed according to the above-mentioned principle, and after power is turned on, the light bulb D1 is turned on, which indicates that the ports TA of the current transformer connected to the ports P _ port1 and S _ port1 of the detection module are different-name terminals.
Claims (3)
1. The circuit for detecting the dotted terminal of the current transformer based on the double-tube self-excited oscillator is characterized by comprising the double-tube self-excited oscillator, a photoelectric driving module and a detection module;
the double-tube self-excited oscillator is a self-excited oscillator circuit comprising two triodes and is used for generating alternating triangular wave signals or sawtooth wave signals; the charging and discharging circuit comprises a biasing resistor R1, a charging and discharging resistor R2, a charging and discharging capacitor C1, a triode Q1 and a triode Q2; the triode Q1 is a PNP type triode, and the triode Q2 is an NPN type triode; an emitter of the triode Q1 is connected with a power supply VCC1, a base of the triode Q1 and one end of a bias resistor R1 are connected with one end of a charging and discharging capacitor C1, a collector of the triode Q1 is connected with a base of the triode Q2, the other end of the charging and discharging capacitor C1 is connected with one end of the charging and discharging resistor R2, the other end of the charging and discharging resistor R2 is connected with a collector of the triode Q2, a connection point of the charging and discharging resistor R2 is set as a port Sm, and the emitter of the triode Q2 and the other end of the bias resistor R1 are connected with a power supply ground GND 1;
the photoelectric driving module is used for transmitting and isolating an electric signal between the double-tube self-excited oscillator and the detection module, matching different working power supply voltages between the double-tube self-excited oscillator and the detection module and driving the detection module and the current transformer to be detected; the circuit comprises a current-limiting resistor R3, a photoelectric coupler U1 and a triode Q3; the photoelectric coupler U1 is a triode type photoelectric coupler, and the triode Q3 is an NPN type triode; the anode of a diode in the primary side of the photoelectric coupler U1 is connected with a power supply VCC1, the cathode of a diode in the primary side of the photoelectric coupler U1 is connected with one end of a current-limiting resistor R3, the other end of the current-limiting resistor R3 is connected with the port Sm, the collector of a triode in the secondary side of the photoelectric coupler U1 and the collector of a triode Q3 are connected with the power supply VCC2, the emitter of a triode in the secondary side of the photoelectric coupler U1 is connected with the base of a triode Q3, and the emitter of the triode Q3 is set as a port Sn and used for driving the detection module in the form of a switching signal;
the detection module is used for detecting whether the ports of the primary side and the secondary side of the connected current transformer to be detected are homonymous terminals or not through the on and off of the bulb; comprises a bulb D1, a regulating resistor R11 and a current limiting resistor R22; the adjusting resistor R11 is an equivalent two-port adjustable resistor; one end of a bulb D1 is connected with the port Sn, the port Sn is connected with a set port S _ port1, the other end of the bulb D1 is connected with a set port P _ port1, one end of an adjusting resistor R11 is connected with a set port P _ port2, one end of a current-limiting resistor R22 is connected with a set port S _ port2, and the other ends of the adjusting resistor R11 and the current-limiting resistor R22 are connected with a power ground GND 2; in addition, the port P _ port1 and the port P _ port2 are respectively used for connecting two ports on the primary side of the current transformer to be tested, and the port S _ port1 and the port S _ port2 are respectively used for connecting two ports on the secondary side of the current transformer to be tested.
2. The circuit for detecting the dotted terminal of the current transformer based on the two-transistor self-excited oscillator of claim 1, wherein the light bulb D1 is replaced by an indicator light consisting of two anti-parallel light emitting diodes.
3. The circuit for detecting the homonymous terminal of the current transformer based on the dual-transistor self-oscillation oscillator of claim 1, wherein the transistor Q3 is replaced by an equivalent Darlington transistor correspondingly.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202221248375.6U CN217425659U (en) | 2022-05-24 | 2022-05-24 | Current transformer dotted terminal detection circuit based on double-tube self-excited oscillator |
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| CN202221248375.6U CN217425659U (en) | 2022-05-24 | 2022-05-24 | Current transformer dotted terminal detection circuit based on double-tube self-excited oscillator |
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