CN107064592B - AC dynamic detection device and method, safety device and current display device - Google Patents
AC dynamic detection device and method, safety device and current display device Download PDFInfo
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- CN107064592B CN107064592B CN201710308925.6A CN201710308925A CN107064592B CN 107064592 B CN107064592 B CN 107064592B CN 201710308925 A CN201710308925 A CN 201710308925A CN 107064592 B CN107064592 B CN 107064592B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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Abstract
The invention discloses an alternating current dynamic detection device and method, a safety device and a current display device, wherein the alternating current dynamic detection device comprises a first direct current power supply circuit, a second direct current power supply circuit, a voltage stabilizing reference circuit, a micro-potential sampling circuit, a power frequency alternating current amplifying circuit, a detection circuit, a calibration circuit, a signal display and an electromagnetic conversion COS phi amplifying sampling measuring circuit; the voltage output end of the first direct current power supply circuit is connected with the power input end of the power frequency alternating current amplifying circuit, the voltage output end of the second direct current power supply circuit is connected with the power input end of the signal display, the voltage input end of the voltage stabilizing reference circuit is connected with the second direct current power supply circuit, and the voltage output end of the voltage stabilizing reference circuit is connected with the reference voltage input end of the signal display; the output end of the sampling voltage signal of the micropotential sampling circuit is connected with the input end of the power frequency alternating current amplifying circuit, and the output end of the power frequency alternating current amplifying circuit is connected with the input end of the signal display through the detection circuit and the calibration circuit in sequence. The invention has the advantages of large measuring range, high sensitivity and direct and convenient measurement.
Description
Technical Field
The present invention relates to an ac power detecting device, and more particularly, to an ac power dynamic detecting device, an ac power dynamic detecting method, a safety device, and a current display device.
Background
The measurement of alternating current is an important measurement object in electrical measurement metering, and the conventional method for measuring alternating current has the following steps: the serial resistance voltage dividing method with universal meter, electromagnetic conversion method with mutual inductor, phase mutual inductor detection and electric-magnetic-measuring method with horizontal wheel kilowatt-hour meter. Among them, the resistance voltage dividing method of universal meter and special meter has the highest resolution (taking four-bit half as an example) of 100 microvolts, and the traditional resistance measuring method is 200Ω.
The method has mature products in various instruments, industry and household application and has large use scale. These unavoidable drawbacks exist with the above methods for more scientific, long-term energy-saving, continuous online measurement, in particular mass, large-scale distributed monitoring: the problems of small measuring range, low sensitivity, unscientific, large body, weight, consumable, energy consumption and high manufacturing cost are solved. Because the external voltage dividing resistor with high resistance voltage division or the electromagnetic conversion device is necessarily required to be sampled by a laid energy consumption component, the alternating current can be measured, and thus, the continuous measurement range is small, the sensitivity is low, the weight is high, the body size is large, the consumption is high, and the energy consumption is high; in addition, the resource loss is also obvious, such as silicon steel sheets, insulating materials, copper materials and the like required by the electromagnetic converter.
Disclosure of Invention
The invention provides an alternating current dynamic detection device and method, a safety device and a current display device, which overcome the defects of the alternating current detection device in the prior art.
The technical scheme adopted for solving the technical problems is as follows: an alternating current dynamic detection device comprises a first direct current power supply circuit, a second direct current power supply circuit with power supply voltage lower than that of the first direct current power supply circuit, a voltage stabilizing reference circuit, a micro-potential sampling circuit, a power frequency alternating current amplification circuit for at least two-stage amplification, a detection circuit, a calibration circuit and a signal display; the voltage output end of the first direct current power supply circuit is connected with the power input end of the power frequency alternating current amplifying circuit, the voltage output end of the second direct current power supply circuit is connected with the power input end of the signal display, the voltage input end of the voltage stabilizing reference circuit is connected with the second direct current power supply circuit, and the voltage output end of the voltage stabilizing reference circuit is connected with the reference voltage input end of the signal display; the micro-potential sampling circuit is connected with the tested alternating current, the output end of a sampling voltage signal of the micro-potential sampling circuit is connected with the input end of the power frequency alternating current amplifying circuit, and the output end of the power frequency alternating current amplifying circuit is connected with the input end of the signal display through the detection circuit and the calibration circuit in sequence;
the system also comprises an electromagnetic conversion COS phi amplifying and sampling measuring circuit for measuring the electric degree and phase signals of the alternating current flowing through the micro-potential sampling circuit, and the electromagnetic conversion COS phi amplifying and sampling measuring circuit is connected with the power frequency alternating current amplifying circuit when the micro-potential sampling circuit is not connected or disconnected with the power frequency alternating current amplifying circuit.
The invention adopts a further technical scheme that: an alternating current dynamic detection method comprises the following steps:
fixedly connecting two sampling points to a section of sampling lead along the length direction, and enabling the sampling lead and the sampling points to be positioned in a tested alternating current loop;
the voltage difference of the two sampling points is amplified at least in two stages through a power frequency alternating current amplifying circuit, the output of the power frequency alternating current amplifying circuit is connected with the input end of a signal display through a detection circuit and a calibration circuit in sequence, and the signal display displays the measured value of alternating current between the sampling points; the power supply voltage of the power frequency alternating current amplifying circuit is larger than that of the signal display;
measuring the alternating current between two sampling points by using a standard instrument to obtain a reference value;
comparing the measured value with a reference value, and adjusting a calibration circuit until the measured value is matched with the reference value;
the electroplating and phase signals of alternating current between sampling points are measured by an electromagnetic conversion COS phi amplifying sampling measuring circuit.
Further, the electromagnetic conversion COS phi amplifying, sampling and measuring circuit comprises a small transformer and a phase meter, wherein one end of a coil of the small transformer is grounded, when the output end of a sampling voltage signal of a sampling wire is disconnected with the input end of the power frequency alternating current amplifying circuit, the other end of the coil of the small transformer is connected with the input end of the power frequency alternating current amplifying circuit, the sampling wire penetrates into the coil of the small transformer, and the input end of the phase meter is connected with the output end of the power frequency alternating current amplifying circuit, so that the phase meter obtains electroplating and phase signals.
The invention adopts a further technical scheme that:
a safety device comprises a crimping mechanism, a locking piece, a driving mechanism, a voltage comparison circuit and the alternating current dynamic detection device, wherein the crimping mechanism is provided with a crimping piece which can be pressed down and reset, and when the crimping piece is pressed down, a power-off switch connected in a protected load loop is driven to be closed;
the micro-potential sampling circuit is connected with a protected load in series, the output end of the calibration circuit is connected with one input end of the voltage comparison circuit, the output end of the voltage stabilizing reference circuit is connected with the other input end of the voltage comparison circuit, the output end of the voltage comparison circuit is connected with the driving mechanism, and the locking piece is connected with the driving mechanism so as to be driven by the driving mechanism to lock or release the pressed compression joint piece.
Further, the driving mechanism comprises a reset elastic piece, a photoelectric switch and a magnet, the locking piece is an electromagnet, the positive input end of the photoelectric switch is connected with the output end of the voltage comparison circuit, the negative input end of the photoelectric switch is grounded, and the two output ends of the photoelectric switch are connected with a coil of the electromagnet and a power supply in series; the iron core of the electromagnet is positioned between the crimping piece and the magnet, and when the iron core is magnetized, the iron core is attracted with the magnet and releases the pressed crimping piece, and when the iron core is demagnetized, the iron core is reset through the reset elastic piece.
Further, a first wedge block is arranged on the side face of the crimping piece, a second wedge block is arranged at the end part of the iron core, and the first wedge block is correspondingly matched with the second wedge block.
Further, the voltage comparison circuit comprises a double operational amplifier and a peripheral circuit; the photoelectric switch is an optical isolation triac driver, the positive input end of the photoelectric switch is connected with the output end of the voltage comparison circuit, and the negative input end of the photoelectric switch is grounded.
The invention adopts a further technical scheme that: a current display device is used for displaying the current of high-voltage alternating current and comprises a first direct current power supply circuit, a second direct current power supply circuit, a voltage stabilizing reference circuit, a power frequency alternating current amplifying circuit, a detection circuit, a calibration circuit, a signal display and a high-voltage transformer, wherein the power frequency alternating current amplifying circuit is used for performing at least two-stage amplification; the voltage output end of the first direct current power supply circuit is connected with the power input end of the power frequency alternating current amplifying circuit, the voltage output end of the second direct current power supply circuit is connected with the power input end of the signal display, the voltage input end of the voltage stabilizing reference circuit is connected with the second direct current power supply circuit, and the voltage output end of the voltage stabilizing reference circuit is connected with the reference voltage input end of the signal display; the output end of the power frequency alternating current amplifying circuit is connected with the input end of the signal display through the detection circuit and the calibration circuit in sequence;
the high-voltage transformer comprises an insulating bracket, a silicon steel wire wound on the periphery of the insulating bracket, and a coil penetrating through the inside of the insulating bracket and crossing the silicon steel wire, wherein one end of the coil is grounded, the other end of the coil is connected with the input end of the power frequency alternating current amplifying circuit, and a high-voltage load wire to be tested penetrates into the center of the insulating bracket. Compared with the prior art, the invention has the following beneficial effects:
1. the invention adopts the first direct current power supply circuit to independently supply power to the power frequency alternating current amplifying circuit, adopts the second direct current power supply circuit with the power supply voltage lower than that of the first direct current power supply circuit to independently supply power to the signal display, not only can meet the respective working requirements of the power frequency alternating current amplifying circuit and the signal display, but also can obviously improve the amplification factor of the power frequency alternating current amplifying circuit to ensure that the amplification factor of the power frequency alternating current amplifying circuit is more than or equal to 10000 times, thereby the invention can detect the alternating current with lower sampling resistance (nano ohm and below), thereby enlarging the measuring range of the invention, greatly improving the measuring sensitivity of the invention and reducing the temperature effect; compared with the measuring device in the prior art, the measuring device is more energy-saving and emission-reducing, and has the advantages of good safety, low cost, small volume, light weight and more direct and convenient measurement.
2. The invention also comprises an electromagnetic conversion COS phi amplifying sampling measuring circuit which is used for measuring the electric power and phase signals of the alternating current, and can realize low-resistance on-line dynamic detection of the alternating current, so that the active power and the reactive power of the alternating current can be identified.
3. The electromagnetic conversion COS phi amplifying sampling measuring circuit comprises the phase meter and a small-sized transformer, can measure the electric power and the phase, and has the characteristics of simple circuit structure, simplicity and convenience in operation, low cost and the like.
4. The first direct current power supply circuit and the second direct current power supply circuit are respectively taken from power frequency electricity, and the power frequency electricity is subjected to step-down rectification filtering to obtain usable direct current, so that the use is convenient;
5. the safety device comprises a body, a crimping piece, a locking piece, a driving mechanism, a voltage comparison circuit and the alternating current dynamic detection device provided by the invention, can replace an alternating current fuse, an overcurrent switch and a leakage switch in the prior art, and solves the problems of slow reaction time, poor precision and unrepeatable alternating current fuse of the alternating current fuse, the overcurrent switch and the leakage switch.
6. The current display device can be used for measuring high-voltage alternating current, and the high-voltage transformer is simple in structure, small in size and low in cost.
The invention is described in further detail below with reference to the drawings and examples; however, the ac dynamic detection device and method, the safety device and the current display device of the present invention are not limited to the embodiments.
Drawings
FIG. 1 is a schematic block diagram of embodiment 1 of the present invention;
fig. 2 is a schematic circuit diagram of embodiment 1 of the present invention;
FIG. 3 is a schematic view showing a partial structure of an AC safety device according to embodiment 3 of the present invention;
fig. 4 is a schematic block diagram of a current display device according to embodiment 4 of the present invention;
fig. 5 is a schematic view of the structure of the high-voltage transformer of embodiment 4 of the present invention.
Detailed Description
Referring to fig. 1 and 2, an ac dynamic detection device of the present invention includes a first dc power supply circuit 1, a second dc power supply circuit 2 with a lower supply voltage than the first dc power supply circuit 1, a voltage stabilizing reference circuit 3, a micro-potential sampling circuit 4, a power frequency ac amplifying circuit 5 with at least two-stage amplification, a detection circuit 6, a calibration circuit 7, and a signal display 8; the voltage output end of the first direct current power supply circuit 1 is connected with the power input end of the power frequency alternating current amplifying circuit 5, the voltage output end of the second direct current power supply circuit 2 is connected with the power input end of the signal display 8, the voltage input end of the voltage stabilizing reference circuit 3 is connected with the second direct current power supply circuit 2, and the voltage output end of the voltage stabilizing reference circuit 3 is connected with the reference voltage input end of the signal display 8; the micro-potential sampling circuit 4 is connected with the tested alternating current, the output end of a sampling voltage signal of the micro-potential sampling circuit is connected with the input end of the power frequency alternating current amplifying circuit 5, and the output end of the power frequency alternating current amplifying circuit 5 is connected with the input end of the signal display 8 through the detection circuit 6 and the calibration circuit 7 in sequence. The model number of the signal display 8 is tc7106 or tc7107 or tc7129. The invention also comprises an electromagnetic conversion COS phi amplifying sampling measuring circuit for measuring the electric degree and phase signals of the alternating current flowing through the micro-potential sampling circuit 4, and the electromagnetic conversion COS phi amplifying sampling measuring circuit is connected with the power frequency alternating current amplifying circuit 5 when the micro-potential sampling circuit 4 is not connected or disconnected with the power frequency alternating current amplifying circuit 5.
In this embodiment, the micro-potential sampling circuit 4 includes a section of sampling wire R2, and the sampling wire R2 may be a copper wire with a circular cross section. During testing, one end of the sampling wire R2 is connected with a zero line N of a socket T1 connected with a power frequency power supply 11 through a plug P3, the other end of the sampling wire R2 is connected with resistors R3 and R4 (the two resistors are protection resistors) at the input end of a power frequency alternating current amplifying circuit 5, one end of the resistor R4 is grounded, and the other end of the resistor R3 is connected with a 3 pin (namely the same-direction input end of a first operational amplifier) of the first operational amplifier.
The electromagnetic conversion COS phi amplification sampling measurement circuit comprises a phase meter 9 and a small transformer 10, wherein one end of a coil of the small transformer 10 is grounded, when the output end of a sampling voltage signal of a sampling lead R2 is not connected or disconnected with the input end of the power frequency alternating current amplification circuit 5, the other end of the coil of the small transformer 10 is connected with the input end of the power frequency alternating current amplification circuit 5 (namely connected with resistors R3 and R4 at the input end of the power frequency alternating current amplification circuit 5), and the sampling lead R2 penetrates into the coil of the small transformer 10; the phase meter 9 is connected with the output end of the power frequency alternating current amplifying circuit 5. As a preferred mode, the sampling voltage signal output end of the sampling wire R2 and the other end of the coil of the small transformer 10 are connected to the input end of the power frequency ac amplifying circuit 5 through a single-pole double-throw switch 12, specifically, the moving end of the single-pole double-throw switch 12 is connected to the input end of the power frequency ac amplifying circuit 5, one of the fixed ends of the single-pole double-throw switch 12 is connected to the other end of the coil of the small transformer 10, and the other fixed end of the single-pole double-throw switch 12 is connected to the sampling voltage signal output end of the sampling wire R2.
In this embodiment, the first dc power supply circuit 1 is selected from the power frequency power 11, and forms a power supply voltage of ± (8-15) V, and takes a preferred value of ± 9V. The first direct current power supply circuit 1 comprises a step-down capacitor C1, a bleeder resistor R1 and a rectifying and filtering circuit, wherein the step-down capacitor C1 and the bleeder resistor R1 are connected in parallel, one end of the step-down capacitor C1 is connected with a live wire of 220V alternating current through a plug P3, the other end of the step-down capacitor is connected with the input end of the rectifying and filtering circuit, the positive voltage output end of the rectifying and filtering circuit is connected with the positive power input end of the power frequency alternating current amplifying circuit 5, and the negative voltage output end of the rectifying and filtering circuit is connected with the negative power input end of the power frequency alternating current amplifying circuit 5. Specifically, the rectifying and filtering circuit includes diodes D1 and D2, capacitors C2 and C3, and zener diodes D3 and D4. The positive electrode of the diode D1 is connected with the other end of the common point of the voltage-reducing capacitor C1 and the bleeder resistor R1, the negative electrode of the diode D1 is connected with the positive electrode of the capacitor C2 and the negative electrode of the voltage-stabilizing diode D3 to form charging voltage stabilization of +9V, and the charging voltage stabilization is provided for 8 pins (namely positive input ends of power supplies) of the first operational amplifier and the second operational amplifier; the negative electrode of the capacitor C2 and the positive electrode of the zener diode D3 are grounded. The negative electrode of the diode D2 is connected with the other end of the common point of the voltage-reducing capacitor C1 and the discharging resistor R1, the positive electrode of the diode D2 is connected with the negative electrode of the capacitor C3 and the positive electrode of the voltage-stabilizing diode D4 to form charging voltage stabilization of-9V, and the charging voltage stabilization is provided for the pins 4 (namely the power negative input end) of the first operational amplifier and the second operational amplifier; the anode of the capacitor C3 and the cathode of the zener diode D4 are grounded.
In this embodiment, the second dc power supply circuit 2 is also taken from the power frequency 11, and forms a power supply voltage of ±5v, and the voltage stabilizing reference circuit 3 forms a reference voltage of 2.5V for display. The second direct current power supply circuit 2 comprises a voltage-reducing capacitor C8, a bleeder resistor R16, a rectifying and filtering circuit, the voltage-reducing capacitor C8 and the bleeder resistor R16 which are connected in parallel, one end of the voltage-reducing capacitor C8 is connected with a live wire of 220V alternating current through a plug P3, the other end of the voltage-reducing capacitor C is connected with the input end of the rectifying and filtering circuit, the positive voltage output end of the rectifying and filtering circuit is connected with the positive power input end of the signal display 8, and the negative voltage output end of the rectifying and filtering circuit is connected with the negative voltage input end of the signal display 8; the voltage input end of the voltage stabilizing reference circuit 3 is connected with the voltage positive output end of the rectifying and filtering circuit. Specifically, the rectifying and filtering circuit of the second dc power supply circuit 2 includes diodes D7 and D8, capacitors C9 and C10, and zener diodes D9 and D10. The positive electrode of the diode D8 is connected with the other end of the common point of the voltage-reducing capacitor C8 and the bleeder resistor R16, the negative electrode of the diode D8 is connected with the positive electrode of the capacitor C9 and the negative electrode of the voltage-stabilizing diode D9 to form +5V charge voltage stabilization, and the charge voltage stabilization is provided for the positive electrode of the signal display 8; the negative electrode of the capacitor C9 and the positive electrode of the zener diode D9 are grounded. The negative electrode of the diode D7 is connected with the other end of the common point of the voltage-reducing capacitor C8 and the bleeder resistor R16, the positive electrode of the diode D7 is connected with the negative electrode of the capacitor C10 and the positive electrode of the voltage-stabilizing diode D10 to form charging voltage-stabilizing of-5V, and the charging voltage-stabilizing is provided for the negative electrode of the signal display 8; the anode of the capacitor C10 and the cathode of the zener diode D10 are grounded. The voltage stabilizing reference circuit 3 comprises a resistor R17 and a voltage stabilizing diode D3, one end of the resistor R17 is connected with the cathode of the voltage stabilizing diode D9, and the other end of the resistor R17 is connected with the cathode of the voltage stabilizing diode D3 so as to provide 2.5V reference voltage for the display of the signal display 8.
In this embodiment, the power frequency ac amplifying circuit 5 includes a first operational amplifier U1A and a second operational amplifier U1B, which are respectively powered by the first dc power supply circuit 1, so that ac is symmetrically amplified, and the resistances of the feedback resistors R5 and R8 of the two are respectively 10mΩ. The input end of the first operational amplifier U1A forms the input end of the power frequency alternating current amplifying circuit 5, the output end of the first operational amplifier U1A is connected with the input end of the second operational amplifier U1B, and the output end of the second operational amplifier U1B forms the output end of the power frequency alternating current amplifying circuit 5. The signal of the sampling resistor R2 enters the first operational amplifier U1A through the 3 pin of the first operational amplifier U1A for amplification, the obtained value is fed back to the 2 pin of the first operational amplifier U1A through the feedback resistor R5, the amplification factor of the first operational amplifier U1A is determined, and the intermediate signal is grounded through the resistor R0. The amplified signal of the first operational amplifier U1A is supplied to the second operational amplifier U1B through a pin 1 and a resistor R6 to be amplified in the second stage, the amplified intermediate value is output in an electric degree and phase through a pin 7 of the second operational amplifier U1B, and is fed back to a pin 6 (namely an inverted input end) of the second operational amplifier U1B through a feedback resistor R8, and the intermediate signal is grounded through a pin R7, so that the whole amplification is finished.
The detection circuit 6 comprises capacitors C11, C6 and C5, diodes D5 and D6 and resistors R12, R13 and R10, and the calibration circuit 7 comprises resistors R11, R14 and R15, a potentiometer RP4 and a capacitor C7. The pin 7 of the second operational amplifier U1B is connected with one end of a capacitor C11, the other end of the capacitor C11 is connected with the cathode of a diode D5 and the anode of a diode D6, after the diodes D5 and D6 are respectively rectified, the diode D6 stores potential for a resistor R10 and the capacitor C5 which are connected in parallel, the potential is further filtered through the resistor R11 and the capacitor C7 which are connected together, and then the potential is provided for a potentiometer RP4 through a resistor R14, and a tap in the middle of the potential is used as a potential signal of current to provide display output. The other end of the potentiometer RP4 is also connected with one end of a resistor R15, and the other end of the resistor R15 is grounded. The positive electrode of the diode D5 is connected with one end of a resistor R12 and a capacitor C6 which are connected in parallel, the other ends of the resistor R12 and the capacitor C6 are connected with a resistor R10 and a capacitor C5 which are connected in parallel, and are connected with a resistor R13, and are connected with the ground through the resistor R13. The second operational amplifier U1B further comprises a resistor R9 and a capacitor C4, one end of the resistor R9 is connected with one end of the resistor R10 and one end of the capacitor C5, and the other end of the resistor R9 is connected with the capacitor C4 and is provided for 6 pins of the second operational amplifier U1B. The capacitor C4 is used for filtering, so that the output voltage jump becomes more gentle.
In this embodiment, the small transformer 10 is formed by winding a copper wire with a diameter of 0.5mm on a ring-shaped body of a magnetic core or film alloy with an outer diameter of 2.3cm, an inner diameter of 1cm and a height of 1.2cm for more than one hundred turns, and then wrapping and fixing the copper wire. The signal display 8 comprises a nixie tube driving circuit and a multi-bit nixie tube display module matched with the nixie tube driving circuit, and is powered by +/-5V, so that the power consumption is low, and the display is accurate.
At the time of actual current and electrical measurement, 20A of alternating current was measured and COS phi was shown with a red copper wire of phi 2.4mm and a length of 4cm as a sampling wire R2. After amplification and detection, the display value is 1400, (this is the value adjusted by the potentiometer RP 4). If the resistance of the sampling wire R2 is calculated, it is the resistivity/(square of wire radius. Pi.) the wire length, i.e. 1.851×10 -8 /(0.0012 2 *3.140)*0.04The resistance of the section of sampling wire is 0.0001637473 omega, and the digital display value can be increased to 1.637473 after ten thousand times of amplification.
The sampling lead R2 is used as a sampling element and a 1-nano-volt measuring mode, so that on one hand, no extra power consumption is generated, and on the other hand, no auxiliary part outside the on-line lead is needed for sampling, and the current measuring range is very large (infinite); meanwhile, the mode of directly using the online lead does not need to consider the problems of measuring range and specification of auxiliary components, because the measurement is only carried out by sampling, the limit parameter of the conductor of the sampling element is limited, the device has very stable and reliable performance, the consistency is easy to ensure, and the measurement cost is low. In addition, the mode of directly using the online wire has no auxiliary components, such as a mutual inductance coil, a high-resistance resistor and the like, so that the potential safety hazard of the auxiliary components is avoided, and the safety is good.
The invention uses a two-stage amplification form, which firstly enables the alternating current from the sampling end to obtain high-magnification amplification, has short amplification diameter and ensures the signal amplification precision; on the other hand, the amplification factor in the detection circuit 6 is set to a variable-magnification form controllable by the calibration circuit 7 so that the signal stability of the first stage is not excessively affected at the time of calibration, and therefore, the stability and accuracy thereof are high.
The invention adopts a low-resistance mode to detect the alternating current on line, so the invention is easy to expand into a plurality of schemes of detection devices and methods, such as low-resistance measuring instruments, electric meters, universal meters, alternating current nanovolt measurement, power meters, phase meters, safety switches, fuses, overcurrent switches, high-voltage transformers and the like; meanwhile, the advantages of ultra-low energy consumption, high reliability and the like are maintained.
fixedly connecting two sampling points to a section of sampling lead along the length direction, and enabling the sampling lead and the sampling points to be positioned in a tested alternating current loop;
amplifying the voltage difference of the two sampling points through the power frequency alternating current amplifying circuit 5, and sequentially connecting the output of the power frequency alternating current amplifying circuit 5 with the input end of the signal display 8 through the detection circuit 6 and the calibration circuit 7, wherein the signal display 8 displays the measured value of alternating current between the sampling points; the power frequency alternating current amplifying circuit 5 has a power supply voltage larger than that of the signal display 8;
measuring the alternating current between two sampling points by using a standard instrument (such as a clamp meter) to obtain a reference value;
comparing the measured value with a reference value and adjusting the calibration circuit 6 (i.e. adjusting the potentiometer RP4 of the calibration circuit 6) until the measured value coincides with the reference value;
the electromagnetic conversion COS phi amplifying sampling measuring circuit is used for measuring the electric power and phase signals of alternating current between sampling points: the electromagnetic conversion COS phi amplifying sampling measuring circuit comprises a small transformer and a phase meter, wherein one end of a coil of the small transformer is grounded, when the output end of a sampling voltage signal of a sampling wire is disconnected with the input end of the power frequency alternating current amplifying circuit, the other end of the coil of the small transformer is connected with the input end of the power frequency alternating current amplifying circuit, the sampling wire penetrates into the coil of the small transformer, and the input end of the phase meter is connected with the output end of the power frequency alternating current amplifying circuit, so that the phase meter obtains electric power and phase signals.
Because the resistance value of the sampling wire can be determined, and the amplification value and the total amplification factor of the power frequency alternating current amplification circuit can be determined uniquely, the current value flowing through the sampling wire can be determined as an estimated value according to the data by using ohm's law. In consideration of practical situations, such as ohmic contact at two ends of a sampling wire, errors of an amplifying circuit, material and composition changes of the wire, etc., an estimated value and a true value are usually slightly different. Therefore, the measured value is corrected by adjusting the calibration circuit to be matched with the true value (reference value), so that the actual current flowing through the two ends of the sampling resistor can be reflected. After being calibrated by the calibration circuit, the calibration circuit does not need to be regulated when the alternating current dynamic detection device is adopted for carrying out alternating current dynamic detection next time.
In this embodiment, the resistance value is calculated by the resistivity of the sampling wire R2 and the geometric feature between the sampling points, so that the resistance value and the temperature/humidity characteristics of the sampling wire R2 are easy to control, and mass production consistency is easy to realize; moreover, the whole scheme is not influenced by ohmic contact of the sampling wire R2 and a loop in which the sampling wire R2 is positioned, and the connection and the unloading are very convenient.
The micro-potential sampling circuit 4 of the alternating current dynamic detection device is connected with a protected load in series, the output end of the calibration circuit 7 is connected with one input end of the voltage comparison circuit 16, the output end of the voltage stabilizing reference circuit 3 is connected with the other input end of the voltage comparison circuit, the output end of the voltage comparison circuit is connected with a driving mechanism, and the locking piece is matched with the side face of the crimping piece 30 and is connected with the driving mechanism so as to be driven by the driving mechanism to lock or release the pressed crimping piece 30.
In this embodiment, the driving mechanism includes a reset elastic member (defined as a second reset elastic member 70), a photoelectric switch, and a magnet 80, where the locking member is an electromagnet, a positive input end of the photoelectric switch is connected to an output end of the voltage comparison circuit, a negative input end of the photoelectric switch is grounded, two output ends of the photoelectric switch, a coil of the electromagnet, and a power supply voltage are connected in series, specifically, one output end of the photoelectric switch is grounded, another output end of the photoelectric switch is connected to one end of a coil 60 of the electromagnet, another end of the coil 60 of the electromagnet is connected to a power supply, and the power supply voltage is specifically 220V. The iron core 50 of the electromagnet is positioned between the pressing member 30 and the magnet 80, and when the iron core 50 is magnetized, the iron core 50 is attracted to the magnet 80 and releases the pressed pressing member 30, and when the iron core 50 is demagnetized, the iron core is reset by the second reset elastic member 70.
In this embodiment, a first wedge 31 is disposed on a side surface of the press-fit member 30, a second wedge 51 is disposed at an end of the core 50, and the first wedge 31 and the second wedge 51 are correspondingly engaged.
In this embodiment, as shown in fig. 3, the voltage comparison circuit 16 includes a dual operational amplifier U1 with a chip model LM358 and a peripheral circuit, where the peripheral circuit includes resistors R18-R23, the output end of the power frequency ac amplification circuit 5 is connected to the positive input end of the dual operational amplifier U1 sequentially through the detection circuit 6, the calibration circuit 7, and the resistor R21, and the output end of the voltage stabilizing reference circuit 3 is connected to the negative input end of the dual operational amplifier U1 through the resistor R23; the resistors R18 and R20 are connected in parallel between the positive input end of the double operational amplifier U1 and the ground; resistors R19, R22 are connected in parallel between the negative input of the dual op amp U1 and ground. The photoelectric switch is an optical isolation triac driver U2, the chip type of the photoelectric switch is MOC3021M, the positive input end of the photoelectric switch is connected with the output end of the double operational amplifier U1, and the negative input end of the photoelectric switch is grounded.
The working process of the safety device of the invention is as follows:
when the pressing member 30 is pressed down, the first reset elastic member 40 is compressed, and the first wedge 31 at the side surface of the pressing member 30 pushes the second wedge 51 on the iron core 50, so that the second wedge moves along with the iron core 50 in a direction away from the pressing member 30, and compresses the second reset elastic member 70; the bottom end of the crimping piece 30 drives the power-off switch 90 to be closed, so that a circuit where a protected load is located is conducted, the iron core 50 is reset, the second wedge block 51 is blocked on the upper side of the first wedge block 31, and therefore the crimping piece 30 is locked, and the crimping piece 30 is limited to reset.
When the protected load fails and the current rises instantaneously, the voltage at the positive input end of the dual operational amplifier U1 is greater than the reference voltage of 2.5V, the photoelectric switch is turned on, the coil 60 of the electromagnet is electrified and magnetizes the iron core 50, the iron core 50 is attracted by the magnet 80 to release the pressed crimping piece 30, the crimping piece 30 resets upward, the power-off switch 90 is turned off, and the load loop is turned off.
When the load loop is disconnected, the voltage of the positive input end of the double operational amplifier U1 is smaller than the reference voltage, the photoelectric switch is reset, the coil 60 of the electromagnet is powered off, and the iron core 50 is demagnetized and reset. After the cause of the overcurrent is detected and the fault is removed, the crimp 30 can be re-depressed.
Embodiment 4, please refer to fig. 4 and 5, a current display device of the present invention is used for measuring the current of a high-voltage ac, and is implemented based on the design concept of an ac dynamic detection device of embodiment 1, and specifically includes a first dc power supply circuit 1, a second dc power supply circuit 2 with a lower power supply voltage than the first dc power supply circuit 1, a voltage stabilizing reference circuit 3, a power frequency ac amplifying circuit 5 for performing at least two-stage amplification, a detection circuit 6, a calibration circuit 7, a signal display 8, and a high-voltage transformer 14; the voltage output end of the first direct current power supply circuit 1 is connected with the power input end of the power frequency alternating current amplifying circuit 5, the voltage output end of the second direct current power supply circuit 2 is connected with the power input end of the signal display 8, the voltage input end of the voltage stabilizing reference circuit 3 is connected with the second direct current power supply circuit 2, and the voltage output end of the voltage stabilizing reference circuit 3 is connected with the reference voltage input end of the signal display 8; the output end of the power frequency alternating current amplifying circuit 5 is connected with the input end of the signal display 8 through the detection circuit 6 and the calibration circuit 7 in sequence;
the diameter of the high-voltage transformer 14 is 40cm, and the high-voltage transformer comprises an insulating bracket 141, a silicon steel wire 142 wound on the periphery of the insulating bracket 141, and a coil 143 penetrating through the inside of the insulating bracket 141 and crossing the silicon steel wire 142, wherein one end of the coil 143 is grounded, the other end of the coil is connected with the input end of the power frequency alternating current amplification circuit 5, and the measured high-voltage load wire 13 penetrates into a central hole 144 of the insulating bracket 141. The first dc power supply circuit 1 and the second dc power supply circuit 2 are derived from the power frequency power 11, and besides, the first dc power supply circuit and the second dc power supply circuit may directly use dc power or a battery, respectively.
The above embodiments are only used for further illustrating an ac dynamic detection device and method according to the present invention, but the present invention is not limited to the embodiments, and any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention falls within the scope of the technical solution of the present invention.
Claims (14)
1. An alternating current dynamic detection device is characterized in that: the device comprises a first direct current power supply circuit, a second direct current power supply circuit with the power supply voltage lower than that of the first direct current power supply circuit, a voltage stabilizing reference circuit, a micropotential sampling circuit, a power frequency alternating current amplifying circuit for at least two-stage amplification, a detection circuit, a calibration circuit and a signal display; the voltage output end of the first direct current power supply circuit is connected with the power input end of the power frequency alternating current amplifying circuit, the voltage output end of the second direct current power supply circuit is connected with the power input end of the signal display, the voltage input end of the voltage stabilizing reference circuit is connected with the second direct current power supply circuit, and the voltage output end of the voltage stabilizing reference circuit is connected with the reference voltage input end of the signal display; the micro-potential sampling circuit is connected with the tested alternating current, the output end of a sampling voltage signal of the micro-potential sampling circuit is connected with the input end of the power frequency alternating current amplifying circuit, and the output end of the power frequency alternating current amplifying circuit is connected with the input end of the signal display through the detection circuit and the calibration circuit in sequence;
the system also comprises an electromagnetic conversion COS phi amplifying and sampling measuring circuit, which is used for measuring the electric degree and phase signals of the alternating current flowing through the micro-potential sampling circuit, and is connected with the power frequency alternating current amplifying circuit when the micro-potential sampling circuit is not connected or disconnected with the power frequency alternating current amplifying circuit;
the power frequency alternating current amplifying circuit comprises a first operational amplifier and a second operational amplifier, wherein the input end of the first operational amplifier forms the input end of the power frequency alternating current amplifying circuit, the output end of the first operational amplifier is connected with the input end of the second operational amplifier, and the output end of the second operational amplifier forms the output end of the power frequency alternating current amplifying circuit;
the micropotential sampling circuit includes a section of sampling wire.
2. The alternating current dynamic detection device according to claim 1, wherein: the electromagnetic conversion COS phi amplifying and sampling measurement circuit comprises a phase meter and a small transformer, one end of a coil of the small transformer is grounded, and when the sampling voltage signal output end of a sampling wire is not connected or disconnected with the input end of the power frequency alternating current amplifying circuit, the other end of the coil of the small transformer is connected with the input end of the power frequency alternating current amplifying circuit, and the sampling wire penetrates into the coil of the small transformer; the input end of the phase meter is connected with the output end of the power frequency alternating current amplifying circuit.
3. The alternating current dynamic detection device according to claim 1, wherein: the first direct current power supply circuit is taken from power frequency electricity and comprises a voltage reduction capacitor C1, a bleeder resistor R1 and a rectifying and filtering circuit, wherein the voltage reduction capacitor C1 and the bleeder resistor R1 are connected in parallel, one end of the voltage reduction capacitor C1 is connected with a live wire of 220V alternating current through a plug, the other end of the voltage reduction capacitor C1 is connected with the input end of the rectifying and filtering circuit, the positive voltage output end of the rectifying and filtering circuit is connected with the positive power input end of the power frequency alternating current amplifying circuit, and the negative voltage output end of the rectifying and filtering circuit is connected with the negative power input end of the power frequency alternating current amplifying circuit.
4. The alternating current dynamic detection device according to claim 1, wherein: the second direct current power supply circuit is taken from power frequency electricity and comprises a voltage-reducing capacitor C8, a discharging resistor R16, a rectifying and filtering circuit, the voltage-reducing capacitor C8 and the discharging resistor R16 are connected in parallel, one end of the second direct current power supply circuit is connected with a live wire of 220V alternating current through a plug, the other end of the second direct current power supply circuit is connected with an input end of the rectifying and filtering circuit, a positive voltage output end of the rectifying and filtering circuit is connected with a positive power supply input end of the signal display, and a negative voltage output end of the rectifying and filtering circuit is connected with a negative voltage input end of the signal display; the voltage input end of the voltage stabilizing reference circuit is connected with the voltage positive output end of the rectifying and filtering circuit.
5. An alternating current dynamic detection apparatus according to claim 1 or 3, wherein: the first operational amplifier and the second operational amplifier are respectively powered by the first direct current power supply circuit, and the feedback resistance of the first operational amplifier and the second operational amplifier is respectively 10MΩ.
6. An alternating current dynamic detection apparatus according to claim 1 or 3, wherein: the power supply voltage of the first direct current power supply circuit is +/-9V, the power supply voltage of the second direct current power supply circuit is +/-5V, and the power supply voltage of the voltage stabilizing reference circuit is 2.5V.
7. The alternating current dynamic detection device according to claim 2, wherein: the small transformer uses a magnetic core or a thin film alloy ring body with the outer diameter of 2.3cm, the inner diameter of 1cm and the height of 1.2cm, and after one hundred circles of red copper wires with the diameter of 0.5mm are scratched on the ring body, the small transformer is well insulated and fixed; and/or the device also comprises a single-pole double-throw switch, wherein the sampling voltage signal output end of the sampling lead and the other end of the coil of the small transformer are connected with the input end of the power frequency alternating current amplifying circuit through the single-pole double-throw switch.
8. An alternating current dynamic detection method based on the alternating current dynamic detection device according to any one of claims 1 to 7, characterized by: the method comprises the following steps:
fixedly connecting two sampling points to a section of sampling lead along the length direction, and enabling the sampling lead and the sampling points to be positioned in a tested alternating current loop;
the voltage difference of the two sampling points is amplified at least in two stages through a power frequency alternating current amplifying circuit, the output of the power frequency alternating current amplifying circuit is connected with the input end of a signal display through a detection circuit and a calibration circuit in sequence, and the signal display displays the measured value of alternating current between the sampling points; the power supply voltage of the power frequency alternating current amplifying circuit is larger than that of the signal display;
measuring the alternating current between two sampling points by using a standard instrument to obtain a reference value;
comparing the measured value with a reference value, and adjusting a calibration circuit until the measured value is matched with the reference value in value;
the electromagnetic conversion COS phi amplifies the sampling measuring circuit to measure the electric degree and phase signal of the alternating current between the sampling points.
9. The alternating current dynamic detection method according to claim 8, wherein: the electromagnetic conversion COS phi amplifying sampling measuring circuit comprises a small transformer and a phase meter, wherein one end of a coil of the small transformer is grounded, when the output end of a sampling voltage signal of a sampling wire is disconnected with the input end of the power frequency alternating current amplifying circuit, the other end of the coil of the small transformer is connected with the input end of the power frequency alternating current amplifying circuit, the sampling wire penetrates into the coil of the small transformer, and the input end of the phase meter is connected with the output end of the power frequency alternating current amplifying circuit, so that the phase meter obtains electric power and phase signals.
10. A safety device, characterized in that: comprising a crimping mechanism, a locking member, a driving mechanism, a voltage comparison circuit, and an alternating current dynamic detection device according to any one of claims 1-7, wherein the crimping mechanism is provided with a crimping member which can be depressed and reset, and when the crimping member is depressed, the crimping member drives a power-off switch connected in a protected load circuit to be closed;
the micro-potential sampling circuit is connected with a protected load in series, the output end of the calibration circuit is connected with one input end of the voltage comparison circuit, the output end of the voltage stabilizing reference circuit is connected with the other input end of the voltage comparison circuit, the output end of the voltage comparison circuit is connected with the driving mechanism, and the locking piece is connected with the driving mechanism so as to be driven by the driving mechanism to lock or release the pressed compression joint piece.
11. The safety device of claim 10, wherein: the driving mechanism comprises a reset elastic piece, a photoelectric switch and a magnet, the locking piece is an electromagnet, the positive input end of the photoelectric switch is connected with the output end of the voltage comparison circuit, the negative input end of the photoelectric switch is grounded, and the two output ends of the photoelectric switch are connected with a coil of the electromagnet and a power supply in series; the iron core of the electromagnet is positioned between the crimping piece and the magnet, and when the iron core is magnetized, the iron core is attracted with the magnet and releases the pressed crimping piece, and when the iron core is demagnetized, the iron core is reset through the reset elastic piece.
12. The safety device of claim 11, wherein: the side of the crimping piece is provided with a first wedge block, the end part of the iron core is provided with a second wedge block, and the first wedge block is correspondingly matched with the second wedge block.
13. The safety device of claim 11, wherein: the voltage comparison circuit comprises a double operational amplifier and a peripheral circuit; the optoelectronic switch is an optically isolated triac driver.
14. A current display device for displaying a current of a high-voltage alternating current, characterized by: the power frequency alternating current amplifying circuit is characterized by comprising a first direct current power supply circuit, a second direct current power supply circuit with a power supply voltage lower than that of the first direct current power supply circuit, a voltage stabilizing reference circuit, a power frequency alternating current amplifying circuit for performing at least two-stage amplification, a detection circuit, a calibration circuit, a signal display and a high-voltage transformer; the voltage output end of the first direct current power supply circuit is connected with the power input end of the power frequency alternating current amplifying circuit, the voltage output end of the second direct current power supply circuit is connected with the power input end of the signal display, the voltage input end of the voltage stabilizing reference circuit is connected with the second direct current power supply circuit, and the voltage output end of the voltage stabilizing reference circuit is connected with the reference voltage input end of the signal display; the output end of the power frequency alternating current amplifying circuit is connected with the input end of the signal display through the detection circuit and the calibration circuit in sequence;
the high-voltage transformer comprises an insulating bracket, a silicon steel wire wound on the periphery of the insulating bracket, and a coil penetrating through the inside of the insulating bracket and crossing the silicon steel wire, wherein one end of the coil is grounded, the other end of the coil is connected with the input end of the power frequency alternating current amplifying circuit, and a high-voltage load wire to be tested penetrates into the center of the insulating bracket;
the power frequency alternating current amplifying circuit comprises a first operational amplifier and a second operational amplifier, wherein the input end of the first operational amplifier forms the input end of the power frequency alternating current amplifying circuit, the output end of the first operational amplifier is connected with the input end of the second operational amplifier, and the output end of the second operational amplifier forms the output end of the power frequency alternating current amplifying circuit.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201611071048.7A CN106443140A (en) | 2016-11-29 | 2016-11-29 | Device and method for dynamically detecting alternating current |
| CN2016110710487 | 2016-11-29 |
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| CN201710308925.6A Active CN107064592B (en) | 2016-11-29 | 2017-05-04 | AC dynamic detection device and method, safety device and current display device |
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| CN107462791A (en) * | 2017-07-27 | 2017-12-12 | 许文远 | A kind of alternating current intelligent detection device for power network distribution |
| CN107656135A (en) * | 2017-10-24 | 2018-02-02 | 尤宣来 | The measurement apparatus and measuring method of high-voltage conducting wires electric current |
| CN108037341B (en) * | 2017-12-21 | 2024-05-10 | 中国原子能科学研究院 | Low leakage current reset device for capacitance integral weak current measurement circuit |
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| AU2017101558A4 (en) | 2017-12-07 |
| CN106443140A (en) | 2017-02-22 |
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