Instrument power calculation issue
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There is a project that requires calculating the power of a meter, and for this purpose magnetic flap level gauges, pressure transmitters, and vortex flow meters are being used – all of them are two-wire systems. The selection guide does not provide any information regarding power calculation. If I want to calculate the power, should I simply multiply the DC 24V voltage by the 20mA current? Would that give me 0.48W as the result? Are there any other calculation formulas? Thank you
I personally think it is calculated in this way as well; a certain margin can be allowed – for example, if the value is 0.48W, a 1A power supply can be chosen.
No system; use 100 milliamps
It’s not calculated in that way. If you don’t have any specifications available, make an estimate: for magnetic flap level gauges that lack an on-site display, assume a power consumption of 1 W; for pressure transmitters, vortex flow meters, and similar devices that come with on-site LCD displays, assume a power consumption of 5 W. Once you’ve calculated the total power consumption, add some extra margin to it for proper power distribution.
The power consumption of the instruments is all estimated. No matter how accurate the calculation, a margin of safety should be reserved. The simple way is to count the fuses after completing the cabinet design. Generally, each two-wire instrument draws 0.5A ； For four-wire systems: 1A at 24V, 0.25A at 220V per unit ； Each solenoid valve requires 2A at 24V supply, and 0.5A at 220V supply ； Large cabinets or equipment, gas detectors, analyzers – power consumption can generally be determined for these.