why we take 4 to 20 mA as out put of every instrument like
pressure transmittre ?why we cant take 0 to 20mA as output?
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Answer Posted / guhan
AS PER OHMS LAW V=IR...WE R USING THE SIGNAL IN DCS 1 TO 5 VOLTAGE DC..SO WE KNOW THE RESISTANCE VALUE 250 OHMS...OK
VOLTAGE=1,2,3,4,5,V DC..RESISTANCE S 250 OHMS...FIRST STEP S VOL=1 V, R= 250, SO V=IR, 1=I*250,I=1VDC/250 OHMS...SO 1000MA/250 = 4 MA..( HERE 1 V DC S = 1000MA) ...SAME LIKE 2V S 8 MA,3 VOLS S 12 MA, 4 VOL 16 MA, 5 VOL 20 MA....THAT S WHY WE USE 4 TO 20 MA...
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