Interested to Buy Any Domain ? << Click Here >> for more details...
In instrumentation standard we use 4 to 20ma for transmission , why cant we use 3 to 19ma ?
- 1 Answers
- 3255 Views
- NSH, I also Faced
- E-Mail Answers
Answer Posted / naveen
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 ? | 2 Yes | 0 No |
Post New Answer View All Answers
CONTROL VALVE OPERATING IN MANUAL BUT NOT IN MANUAL. WHAT SHOULD BE THE PROBLEM ?
Calculate the maximum pressure drop that can be allowed to occur across a control valve, so that we can prevent cavitation / flashing from occurring. Use the following formula: Δ P allow = Km (P1 – PvapourA) where, Δ P allow - the maximum allowable differential pressure for sizing purposes, or terminal pressure drop; Km- the valve recovery coefficient from the manufacturer’s catalogue; P1 - absolute inlet fluid pressure; PvapourA - absolute fluid vapour pressure at the inlet temperature; Use Atmospheric pressure = 101.3 kPa, P1 = 1200 kPa(g), PvapourA = 4 kPa, KM = 0.72
model question paper of instrumentation for Jindal GET 2010.plz reply sudhanshukumar08@yahoo.com
what does the ratio 800-400-300-200/1-1-1-1-1 in the specification of current transformer indicates?
TEMPERATURE VARIATION FOR FREQUENTLY.
What are the type of bonnets in the control valves?
Can anyone convert a 5/2 way or 3/2 way valve into an ISO valve?
i want formula for flow control.am doing project in flow control using orifice . i know value of the flow level(Q) . upstream(p1) pressure, orifice diameter(Do) , pipe diameter(Di) and oil viscosity(Vi) how can i calculate downstream pressure
Senior engineer's please help me, what is Loop Checking and Loop test? and write difference also? soon urgent
what step is taken for ESD ( emergency shut down) in DCS REPLY to hashimka20009@gmail.com
what is different between 2,3&4 wire rtd and how much maximum distance using plc to field.
what is span value and zero ? and how set ?
Explain the mechanism behind the turbine meter.
key phaser where is use and work
kindly sent some demo question and answer
