With the gradual improvement of industrial production automation technology and the gradual increase of frequency converter application scope, electromagnetic interference caused by higher harmonic of frequency converter is becoming more and more serious.
Especially in high-precision instruments and microelectronic control systems, electromagnetic interference is particularly prominent.
If the fault that the ultrasonic flowmeter does not display instantaneous flow is caused by the electromagnetic wave of the frequency converter interfering with the signal intensity transmitted by the signal line of the flowmeter,
In order to reduce the influence of frequency converter on signal strength to a greater extent, the following measures should be taken:
1. Reasonable layout. Reasonable layout shall be made during installation. Flowmeter and data transmission line shall be as far away from frequency converter as possible.
The control line should be as far away from the frequency converter as possible in space. If not, it should cross the input and output lines of the frequency converter as far as possible, preferably vertically.
2. Weakening interference sources. When economic conditions permit, the frequency converter is connected with a filter, but for some low-power frequency converters, the cost is relatively high, so a low-cost electromagnetic interference suppression method can be adopted.
3. Shielding the line. The flowmeter and signal transmission line close to the frequency converter shall be installed in the metal box or penetrated into the metal box for shielding as far as possible.
4, accurate grounding. Inverter grounding wire should be as thick as possible, the ground point should be as close as possible to the inverter;
Grounding wire shall be as far away as possible from power line and signal line of ultrasonic flowmeter. Grounding wire used for frequency converter must be separated from the grounding wire of ultrasonic flowmeter.
It must be absolutely avoided to connect the grounding wires of all equipment before grounding. The grounding terminal of the frequency converter cannot be connected with the 'zero line' of the power supply of the ultrasonic flowmeter;
Although electromagnetic interference cannot be seen or touched, it can still be followed by certain rules to deepen the understanding of electromagnetic interference.
As well as the understanding of the methods and means to combat electromagnetic interference, improve the ability to combat electromagnetic interference, and gradually eliminate the harm caused by electromagnetic interference.