CN209417136U - A circuit for measuring transient voltage - Google Patents

Abstract

The utility model discloses a transient voltage measurement circuit, which comprises a proportional voltage divider circuit, a voltage holding circuit and an output display module. The proportional voltage divider circuit receives a transient voltage signal and generates a plurality of output voltage, the voltage holding circuit receives multiple output voltages, the voltage holding circuit generates a display signal based on the multiple output voltages, and the voltage holding circuit outputs the display signal to the output display module. The measurement circuit of the utility model adopts the principle of simple resistance-capacitance proportional voltage division and capacitor energy storage, which better solves the problem of measuring the transient voltage of field equipment and ensures the accuracy and operability of the intelligent analysis system for breakdown fuses. .

Description

A circuit for measuring transient voltage

【Technical field】

The utility model relates to the technical field of electric power testing, in particular to a circuit for measuring transient voltages.

【Background technique】

At present, in many power testing equipment, it is necessary to accurately measure the transient voltage. For example, the intelligent analysis of the breakdown fuse requires accurate testing of important parameters such as the breakdown discharge voltage and breakdown current of the fuse. .

However, the usual transient voltage measurement devices either use oscilloscope equipment for interpretation, which is intuitive but complex and inconvenient to operate, or use professional high-speed sampling chip circuits for measurement, but also have the disadvantages of complicated circuits, high cost, and long test time.

【Content of utility model】

In order to overcome the deficiencies of the prior art, the purpose of this utility model is to provide a transient voltage measurement circuit, which adopts the principle of simple resistor-capacitor proportional voltage division and capacitor energy storage, which better solves the transient voltage of field equipment. The measurement problem ensures the accuracy and operability of the breakdown insurance intelligent analysis system.

In order to solve the above problems, the technical scheme adopted in the utility model is as follows:

A transient voltage measurement circuit, which includes a proportional voltage divider circuit, a voltage holding circuit, and an output display module, the proportional voltage divider circuit receives a transient voltage signal, and generates multiple outputs based on the received transient voltage signal voltage, the voltage holding circuit receives a plurality of the output voltages, the voltage holding circuit generates a display signal based on the multiple output voltages, and the voltage holding circuit outputs the display signal to the output display module; The proportional voltage divider circuit includes a first resistor, a second resistor, a third resistor, and a fourth resistor connected in series in sequence, and the proportional voltage divider circuit also includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor connected in series in sequence. capacitor, the first resistor is connected in parallel with the first capacitor, the second resistor is connected in parallel with the second capacitor, the third resistor is connected in parallel with the third capacitor, and the fourth resistor is connected in parallel with the first Four capacitors are connected in parallel.

A further solution is that the voltage holding circuit includes a voltage input terminal, a sample-and-hold device and a voltage comparator, the non-inverting input terminal of the voltage comparator, the third pin of the sample-and-hold device are respectively connected to the voltage input terminal Electrically connected, the eighth pin of the sample-and-hold is electrically connected to the output of the voltage comparator, the inverting input of the voltage comparator, the fifth pin of the sample-and-hold are respectively connected to the The input terminal of the output display module is electrically connected.

A further solution is that the voltage holding circuit further includes a pull-up resistor and a switch tube, the first end of the pull-up resistor is electrically connected to the output terminal of the voltage comparator, and the collector of the switch tube is connected to the output terminal of the voltage comparator. The sixth pin of the sample-and-hold device is electrically connected, and the emitter of the switch tube is electrically connected to the output terminal of the voltage comparator.

A further solution is that the resistance values of the first resistor, the second resistor, the third resistor and the fourth resistor are 20M, 10M, 1M and 500K respectively.

A further solution is that the capacitance values of the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are 100PF, 1000PF, 0.1uF and 1uF respectively.

A further solution is that the first resistor, the second resistor, the third resistor, and the fourth resistor all use high-power metal film resistors; the first capacitor, the second capacitor, and the Both the third capacitor and the fourth capacitor are high-voltage ceramic capacitors.

Compared with the prior art, the beneficial effects of the utility model are:

When the transient high voltage is applied to the RC network composed of resistors and capacitors, the capacitors and resistors are divided according to the step ratio. The principle is that the capacitors with greater energy storage effects are connected in parallel with smaller resistance values, so that when the peak transient voltage passes, Its value is proportionally distributed among the four capacitors and stored, and according to the rule that the shorter the transient time, the smaller the capacitor will store more, the longer the transient time, the larger the capacitor will store more, through the voltage The holding circuit records the voltage across the capacitor respectively, and obtains the highest transient voltage. Of course, when the measurement is over, the resistor can also play a role in helping the capacitor discharge for re-measurement.

Therefore, the measurement circuit is simple, reliable, passive, and easy to connect with various voltage measurement equipment test terminals; it can measure both transient transient voltage and accumulated transient voltage, ensuring breakdown The accuracy and operability of the insurance intelligent analysis system; the high impedance characteristic does not affect the output characteristics of the high voltage generator, ensuring the integrity of the high voltage test value and waveform; the circuit has the characteristics of being able to automatically maintain the high voltage to be tested, which is convenient for testing and analysis .

【Description of drawings】

Fig. 1 is a schematic circuit diagram of an embodiment of a transient voltage measurement circuit of the present invention.

Fig. 2 is a schematic circuit diagram of a voltage holding circuit in an embodiment of a transient voltage measuring circuit of the present invention.

【Detailed ways】

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not limited to the utility model.

Referring to Fig. 1, a kind of measuring transient voltage circuit of the present utility model comprises proportional voltage divider circuit 10, voltage holding circuit 20, output display module 30, proportional voltage divider circuit 10 receives the transient voltage signal of electric power test equipment 1, and based on The received transient voltage signal generates multiple output voltages. The voltage hold circuit 20 receives the multiple output voltages. The voltage hold circuit 20 generates a display signal based on the multiple output voltages. The voltage hold circuit 20 outputs the display signal to the output display module 30 .

Specifically, the proportional voltage divider circuit 10 includes a resistor R1, a resistor R2, a resistor R3, and a resistor R4 connected in series in sequence, and the proportional voltage divider circuit further includes a capacitor C1, a capacitor C2, a capacitor C3, and a capacitor C4 connected in series in sequence, and the resistor R1 and the capacitor C1 connected in parallel, and resistor R1 is connected in parallel with capacitor C1 and then connected in series between power testing equipment 1 and breakdown fuse 2, resistor R2 is connected in parallel with capacitor C2, resistor R3 is connected in parallel with capacitor C3, and resistor R4 is connected in parallel with capacitor C4. The voltage across capacitor C1 is voltage V1 , the voltage across capacitor C2 is voltage V2 , the voltage across capacitor C3 is voltage V3 , and the voltage across capacitor C4 is voltage V4 .

Referring to Fig. 2, the voltage holding circuit 20 includes a voltage input terminal, a sample holder U1 and a voltage comparator IC1, the non-inverting input terminal of the voltage comparator IC1, and the third pin of the sample holder U1 are respectively electrically connected to the voltage input terminal, and the sampling The eighth pin of the holder U1 is electrically connected to the output terminal of the voltage comparator IC1 , the inverting input terminal of the voltage comparator IC1 , and the fifth pin of the sample holder U1 are electrically connected to the input terminal of the output display module 30 . Preferably, the sample-and-hold unit U1 is a sample-and-hold chip LF398, and the voltage comparator IC1 is a voltage comparator LM311.

In this embodiment, the voltage holding circuit 20 further includes a pull-up resistor R5, a switch tube Q1, and a sampling capacitor C5. The first end of the pull-up resistor R5 is electrically connected to the output terminal of the voltage comparator IC1, and the collector of the switch tube Q1 It is electrically connected to the sixth pin of the sample-and-hold device U1, and the emitter of the switch tube Q1 is electrically connected to the output terminal of the voltage comparator IC1.

Specifically, the voltage hold circuit 20 is composed of a sample-and-hold chip LF398 and a voltage comparator LM311. The output voltage of the sample-and-hold chip LF398 is compared with the input voltage by the voltage comparator LM311. When the input voltage V1, voltage V2, voltage When V3 and voltage V4 are greater than the output voltage, the voltage comparator LM311 outputs a high level and transmits it to the logic control terminal of the sample-and-hold chip LF398, that is, the eighth pin, so that the sample-and-hold chip LF398 is in the sampling state; when the output voltage When it reaches the peak value and falls, the voltage V1, voltage V2, voltage V3, and voltage V4 are less than the output voltage, the voltage comparator LM311 outputs a low level, and the logic control terminal of the sample-and-hold chip LF398 is set to be low-level, so that the sample-and-hold chip LF398 is on hold.

Since the voltage comparator LM311 uses an open-collector output, it needs to be connected with a pull-up resistor R5; because the pulse sent from the output terminal of the sample-and-hold chip LF398 controls the conduction of the switch tube Q1, and the sampling capacitor C5 discharges when there is no power, Otherwise, the sampling capacitor C5 has been tracking the change of the peak value.

Preferably, the resistance values of resistor R1, resistor R2, resistor R3 and resistor R4 are respectively 20M, 10M, 1M and 500K, and the capacitance values of capacitor C1, capacitor C2, capacitor C3 and capacitor C4 are respectively 100PF, 1000PF, 0.1uF and 1uF. Among them, resistor R1, resistor R2, resistor R3, and resistor R4 all use high-power metal film resistors, and capacitor C1, capacitor C2, capacitor C3, and capacitor C4 all use high-voltage ceramic capacitors.

Of course, as an optimization, you can also change the value and withstand voltage of the capacitor and resistor to adapt to a wider range of transient voltage measurement range; as an optimization, the RC network can use more than four steps to adapt to a wider range of transient voltage. State time measurement range; as an optimization, the voltage hold circuit can also add a summation circuit to realize automatic calculation of the highest transient voltage.

It can be seen that when the transient high voltage is applied to the RC network composed of resistors and capacitors, the capacitors and resistors will divide the voltage according to the step ratio. After the state voltage has passed, its value is distributed among the four capacitors in proportion and stored, and according to the shorter the transient time, the smaller the capacitor (high capacitive reactance) will store more, the longer the transient time, the larger the capacitor (Low capacitive reactance) the more rules are stored, the voltage at both ends of the capacitor is recorded respectively through the voltage holding circuit 20, and the highest transient voltage is obtained. Of course, when the measurement is over, the resistor can also play a role in helping the capacitor discharge for re-measurement.

Therefore, the measurement circuit is simple, reliable, passive, and easy to connect with various voltage measurement equipment test terminals; it can measure both transient transient voltage and accumulated transient voltage, ensuring breakdown The accuracy and operability of the fuse 2 intelligent analysis system; the high impedance characteristic does not affect the output characteristics of the high-voltage generating device, ensuring the integrity of the high-voltage test value and waveform; features.

It should be noted that the above are only preferred embodiments of the utility model, but the design concept of the utility model is not limited thereto, and any insubstantial modifications made to the utility model by using this concept also fall into the scope of the utility model. within the scope of protection.

Claims (6)

1. A measuring transient voltage circuit, characterized in that, comprising: A proportional voltage divider circuit, a voltage holding circuit, and an output display module, the proportional voltage divider circuit receives a transient voltage signal, and generates multiple output voltages based on the received transient voltage signal, and the voltage hold circuit receives multiple For the output voltage, the voltage holding circuit generates a display signal based on a plurality of the output voltages, and the voltage holding circuit outputs the display signal to the output display module; The proportional voltage divider circuit includes a first resistor, a second resistor, a third resistor, and a fourth resistor connected in series in sequence, and the proportional voltage divider circuit also includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor connected in series in sequence. Four capacitors, the first resistor is connected in parallel with the first capacitor, the second resistor is connected in parallel with the second capacitor, the third resistor is connected in parallel with the third capacitor, and the fourth resistor is connected in parallel with the The fourth capacitor is connected in parallel. 2. A kind of measuring transient voltage circuit according to claim 1, characterized in that: The voltage hold circuit includes a voltage input terminal, a sample holder and a voltage comparator, the non-inverting input terminal of the voltage comparator and the third pin of the sample holder are respectively electrically connected to the voltage input terminal, and the The eighth pin of the sample-and-hold is electrically connected to the output terminal of the voltage comparator, the inverting input of the voltage comparator, the fifth pin of the sample-and-hold are respectively connected to the input of the output display module electrical connection. 3. A kind of measuring transient voltage circuit according to claim 2, characterized in that: The voltage holding circuit also includes a pull-up resistor and a switch tube, the first end of the pull-up resistor is electrically connected to the output terminal of the voltage comparator, and the collector of the switch tube is connected to the first end of the sample holder. The six pins are electrically connected, and the emitter of the switch tube is electrically connected with the output terminal of the voltage comparator. 4. A transient voltage measurement circuit according to any one of claims 1 to 3, characterized in that: The resistance values of the first resistor, the second resistor, the third resistor and the fourth resistor are 20M, 10M, 1M and 500K respectively. 5. A kind of measuring transient voltage circuit according to claim 4, is characterized in that: The capacitance values of the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are 100PF, 1000PF, 0.1uF and 1uF respectively. 6. A kind of measuring transient voltage circuit according to claim 5, characterized in that: The first resistor, the second resistor, the third resistor, and the fourth resistor all use high-power metal film resistors; the first capacitor, the second capacitor, the third capacitor, and the The above-mentioned fourth capacitors are high-voltage ceramic capacitors.