Methods of frequency measurement in power system

kuopinger

Methods of frequency measurement in power system [Copy link]

I want to use analog comparison method to measure frequency. Please help me design a circuit. Thank you.

kuopinger

The chip is 89c52. I hope an expert can give me some advice. Thank you.

automation

What frequency should I measure? There was a previous post that suggested making a DIY frequency meter. You can refer to it. Otherwise, you can search online.

kuopinger

To measure the voltage frequency, a voltage transformer, a low-pass filter, and a voltage comparator are needed. Finally, the 89c52 microcontroller is used for measurement, but the circuit diagram cannot be drawn.

automation

Look for that post, there are circuit diagrams on it.

kuopinger

I looked for it but couldn't find it. Could you please give me a link? Thanks.

kuopinger

I need a circuit diagram urgently. I hope an expert can give me some advice.

njdyp

Looking at your five posts, you did not clearly define the test object and test requirements. Unclear requirements are a taboo for any design. The conventional test methods (techniques) for different frequencies are different. If the power supply is 50Hz, then some key requirements must be clear before the specific ones can be truly carried out: such as key parameters such as accuracy and test stability. The difference in design results for different requirements is also quite large, and even completely different design structures are used. Assuming that it is a high-precision frequency test of a low-frequency signal, it is usually obtained by testing the signal period and then calculating the frequency. The role of the microcontroller is concentrated on test control and test calculation display, which is very important but not the core of the problem. There are two links to pay attention to here. One is the conversion of the measured signal, such as using the zero-crossing circuit to shape it to obtain a testable object; the second is the time (frequency) reference source, such as a crystal oscillator, or even a highly stable and high-precision crystal oscillator. If it is a low-precision test, then other methods such as the design based on the MCU can be used directly.

quanzx

Use a step-down transformer to connect the primary side to the grid, and half-wave rectify the secondary side (low-voltage winding) to let the pulsating current pass through the differential circuit MCU to test the count value within the time period.

tf393

This unit (www.time-freq.com) has an industrial frequency frequency meter. You can refer to it.

mikelode

I searched a lot on the Internet and got some information and summarized it myself.