Answer / senthil ramanujam mohan

I can give you simple example:-

Consider a temperature controller(on/off valve),
setpoint - 100deg
Offset - (-4)
dead band - 2
ERROR - SETPOINT - ACTUAL VALUE

If temperature raises from 90deg>>>>94>>at >96degrees the
valve closes.this is becoz we have an OFFSET of (-4
degrees)(setpoint - offset value)
So,now the valve is closed.temperature drops down from
96degrees<<95<< at 94degrees the valve starts open.this is
becoz we have a DEADBAND of 2degrees.

Error(contrl valve):-
setpoint - 100degree and actual value - 90degrees.
temp range - ( 0 to 200)for error scaling(becoz
controller works from 0 to 100%)
error scaling = 100/200 - 0.2 which is multiplying
factor for error to the controller
Finally,
ERROR = [ SETPOINT - ACTUAL VALUE ] X ERROR SCALING.
[ 100 - 90 ] X 0.2
[ 10 ] X 0.2
2.

hope you guys understand.

dear sir we have insatlled positioner model no.sipart PS2 make Siemens at our control valves . now problem is if we want to increase the response of valve opening speedy /fast. what parameters do we change for positioner ? any idea. please guide us.

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