Answer / senthil

1.During commissioning, we ll do loop checks.it means from
field instrument( PT,TT,FT,LT or switches) the signal is
checked with the DCS.
for example : consider a PT,we ll simulate 4 to 20 mA in the
instrument and the same value should be shown in the DCS also.

2.there are two loops
open loop and closed loop
closed loop for controllers to control the process.for
example, antisurge control in Gas Compressor,Three element
control in Boiler

Answer / g.venkat

There are two loops
1. open loop
2.close loop


open loop using for monitoring and recording purpose

close loop using for controlling the fianal control element

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