The reading of the electromagnetic flowmeter fluctuates significantly
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The control power supply for the water pump and the frequency converter for the fan are located in the same control box. When the frequency of the frequency converter is adjusted to below 20 Hz, the readings of the electromagnetic flow meter used to measure the water pump’s flow rate fluctuate significantly, reaching 100%; under normal conditions, these fluctuations are around 5%； Another water pump control power supply is installed separately, and the readings of the electromagnetic flowmeter used to measure its flow rate show little variation, within 1%. What could be the reasons for the larger fluctuations in the flowmeter readings?
This is quite normal; the problem lies with the inverter, as there is interference. I propose a few options; if they exist in practice, it’s best to try making changes. Solution: 1. Supply the electromagnetic flowmeter with power from a main power circuit that is separate from that of the frequency converter. 2. Grounding of the electromagnetic flowmeter. 3. The cable of the electromagnetic flowmeter and the cable of the frequency converter should be laid separately.
Electromagnetic flowmeters have sensitive outputs; even the slightest interference can have an impact. First, ensure proper grounding; second, check for any electromagnetic interference at the site. Vibrations at the site should also have an impact.
In short, the possibility of interference is high. The pump circuit has a significant impact on the electromagnetic flowmeter. Check the shield wire and grounding system!