What is the maximum length of the 24-volt power supply circuit for the instrument?
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There is a mass flow meter of Dongfeng Electric at the site, and the manufacturer suspects that the power supply is insufficient. The distance from the control room to the site is around 300 meters; all other meters are working properly, but only this one does not function correctly. I would like to ask whether such a long distance has any impact on voltage and power
24V minus the voltage drop in the circuit should meet the minimum power supply voltage required by the instrument.
It has an impact; first, one needs to know the minimum operating voltage of the mass flow meter, then subtract this minimum voltage from 24V to obtain the voltage loss in the circuit. By dividing this voltage loss by the current, the resistance of the circuit can be determined, and finally, the transmission distance can be calculated.
Experience tells us that there should be no power supply issues at 300 meters. One more question: is the power supply at your site 24VDC or 220VAC? If it must be powered by 24VDC, then use a better multimeter to power the flow meter directly and see if the problem still persists!
There must be a connection; what is the cross-sectional area of your cable? A 300-meter pressure drop is significant
300 meters is acceptable; try connecting a power switch on-site
Everything else is fine; only this one doesn’t work. Use the replacement method to determine whether the issue lies with the gauge, the 24V power supply, or the wiring.
Mass flow meters consume more power than other instruments; as a result, their operating current is also higher. With a higher current, the voltage drop across a cable of the same length is greater. I’ve encountered this situation: when testing on-site, the supply voltage of 24V was normal, but once power was supplied to the mass flow meter, the screen flashed. The voltage at the connection terminals was insufficient; in fact, even the handheld controller couldn’t provide enough power for the setup, as the required power level wasn’t met. You can take the flow meter near the power supply and see if the display works properly!
The measured voltage is more or less the same, but it becomes unstable when a load is connected
The mass flow meter has no output connection; it functions normally when displayed on-site, with only a slight flickering of the screen. Once an output signal is connected, the screen remains on the startup interface and it’s not possible to access the self-check page. I suspect that the output board may be damaged