Why we are measuring 4-20ma? Why we are not taking 0-20ma? Plz answer this
Answer Posted / mariyappan
Because of dead zero and live zero concept.
Dead Zero: this is basically derived from ohm's law
V=IxR. In electronics circuit minimum 250 ohm resistance is using. so V=Ix 250. Substitute I=0,1,2,3,4 after substitute 0 u will get V=0 ohm,(1;V=250 ohm,2;V=500 ohm,3;V=750 ohm,4;4=1000 ohm or 1 V) so when 4 ma is coming u will get 1 V,8 ma=2v,12 ma=3 V,16 ma=4v,etc..... u will get linearity .thats why 4 ma is choosing in all analogue value.
Live Zero: if tx is failure that time also zero value is coming.thats why 0 is not choosing
Is This Answer Correct ? | 10 Yes | 0 No |
Post New Answer View All Answers
NPN transistor, SCR, Zener diode, LED, Varactor diode, Vortex meter, RTD, Resistor, Crystal
Hi i m B.E. In elect. & comm. I m workin in bio mass plant from 6 mnths as inst. Engg. but now i m in dept. Of operation as shift engg...which is best operation or inst. 4 me? M confusd..plz help and reply me..
how to calculate orifice sizing? and tell me if pipe size bet 50mm t0 200mm then we can use pipe flange??? and above 250mm pipe size should i use D & D/2 Flange? is it right or wrong?
what is KV and XV valve
What care will you take in the installation of control valves,SCADA,DCS and FOC in Oil and Gas Project?
how pressure transmitter work, what is its principal to measure and how its generate signal. for pressure transmitterinstallation which precautions must be taken ??
Definition of reverse and acting controllers:
How can i copy program (parameter) from mm440 (V.F.D.) by using BOP?
how many types of preheaters are in cement industry & what r they can any body explain?
Explain an adaptive / self-tuning controller’s major draw card.
how to do dynolab wind speed sensor loop test, how to simulate value,i have simulate mA 4-20mA but not responding in DCS faceplate, please kindly advice me any one.
Turbidity analyzer working principle ?
what is the difference between attemperator and desuperheater ?
what is controlling card in dcs? how u measure dcs memory?what is bus in dcs?how u know dcs speed n ehternet speed?
what is Best Among SINK Or SOURCE Type Design In Digital Signal, Either Iput Or Output? WHY?Can any one..