Answer / maiatec

The main reason is that the current 4-20mA can reach long distances without loss of information. The current does not alter because it is a loop without derivations. Moreover, with the voltage of 0-10V can not reach long distances due to voltage drop on the resistance of the wire.

Answer / hari krishna

the signal are transmitted from the field to the
controlroom and vseversa through cables. for long
transmission the cable resistance increases.thus if 0-10v
are transmitted over this long distance,due to the
resistance of cable there will be drop in the voltage and
the signal received at the controlroom will not be
accurate. to overcome this difficulty 4-20ma signal is used
for transmission.

Answer / ribin

while transmitting current there is a less drop, while
transmitting as a voltage more drop occurs. so prefer 4-20mA

Answer / swagat pundpal

For detecting open loop we need non zero current ie "live zero".
For transmitters min 3mA current is needed to turn it ON.
so 3mA + safety factor (1mA) =4mA

Within 4-20mA range, get good linearity, also one more reason is if more than 25mA current flows through human heart hi dies so safety point of view 20mA.

Answer / shafqat khan

when 0-10 v will b use in the transmission line the out put
value will b not correct bcz of voltage drop due to resistance
and the 0 which is used win case 0f v signal can b effect
in case of input fault we can,t find the input fault as well
as the o/p value will b also effected.....

Answer / pooja

becoz in 0-10 v there is voltage drop due to increase in resistance ( due to increase in length) that us why signal obtained is not accurate

Answer / satishpatel

generally in a transister some amount of voltage is
required for turning it on. this voltage is the cutin
voltage. up to this voltage the exists a nonlinerity in its
charecteristics. beyond this cutin voltage the char. of
transister is linear. this nonlinear region lies between 0-
4ma,beyond 4ma it linear. this is why 4-20 ma range is used.

How servomotor controls throttle valve of TURBINE?

0 Answers  

how can we understand about dcs "bailey infi 90 dcs system" . how its work how signal come from field how it process and how o/p creative by controller. how its cards work.the bsic principle of working of dcs

1 Answers  

Why trim span ? How?

0 Answers  

GIVE THE TEMPERATURE RANGE OF PLATIUM RESISTANCE THERMOMETER.

7 Answers   DVC,

hi sir yhis is zahid ali i am preparing for the jspl at oct.4.please send me the recently updated sample paper.

0 Answers   Jindal,

what is sil (safety integrity level

0 Answers   Essar,

what is the input of digital counter during the the calibration time?

0 Answers  

we are having yokogawa centum cs3000 dcs in our power plant. i need some of the operator guides NOT to appear in HIS0163 AND HIS 0162 but it shoul appear in HIS0164 HOW TO DO IT?

0 Answers   Yokogawa,

I have a orifice installed in plant which is design for 0~100 inH2O for 0~80MMSCFD, now due to process change the maximum flow is change to 120 MMSCFD so for this new process value what will be the DP across orifice.

1 Answers  

what is the standard of determining opening/closing time of Motor Operated Valve?

1 Answers  

why we use 24v dc in instrument rahter than 230vac????

4 Answers  

what is the name of thermocople element cable from field to pannel end?

3 Answers