Question { Sabic, 53462 }

Why we use 250 ohm resistor in series with HART protocol
communication?

Answer

this is the hart requirment hart need minimum 250ohmes it
need to communication between hart and transmiter in dcs
and singel loop already have this resistence but bench
calibration need to comunication with hart

Question { 13248 }

which type of rtd is good for any system,2wire,3wire or 4
wire

Answer

3 wire rtd is good bcz thired wire is used to compensate
wire resistence it is a wheet stone bridge

Question { 16763 }

why the discharge pressure of ID fan showing negative at fan
running condition.(boiler operating condition.)

Answer

bcz this fan is inducing draft fan this is suctioning the
draft

Question { 6290 }

Functions of electropneumatic valve positioner:

Answer

i/p recive the signel 4 to 20 ma and calibration time when
we give 4 ma it gives penumatic out put valves position
that time is moniterd by by positioner it is 0% or 100% and
when we give 12ma valves stem position that time 50% on
12ma positioner will recive the current sigenel and campare
it with valve stem if the valve stem position is not same
it will produse penumatic out put on same 12 ma more till
it will not match with the position of valve stem when the
on 12ma valve position is 50% then this will close the
penumatic out put and close the nozel with fleper and block
the air till current signel changes(.... it compare the
current signal with valve position through valve stem it
genrate penumatic out put till differenc between current
signel and valve position.....)