What is cascade control in process instrumentation?
Answers were Sorted based on User's Feedback
Answer / himanshu bhardwaj
In CASCADE control output of one system works as the set
point for the next system , this is called cascading and
hence the system is said to be cascade control system.
Is This Answer Correct ? | 31 Yes | 5 No |
Answer / abhishek vyas srf limited
Best example of cascade control is level control of a
tank. first taking care of it's actual level( getting
signal from level transmitter) then controlling it's flow.
so only controlling element is flow and level singnal will
work as a setpoint for flow controlling.
There are two controller used one for level whose
controller o/p will work as a set point for flow controller
then final control signal from flow controller will actuate
the control valve. Thus actual level will achived.
Is This Answer Correct ? | 25 Yes | 3 No |
Answer / sanjay kumar it-bhu
Cascade Control uses the output of the primary controller
to manipulate the setpoint of the secondary controller as
if it were the final control element.
Reasons for cascade control:
Allow faster secondary controller to handle disturbances in
the secondary loop.
Allow secondary controller to handle non-linear valve and
other final control element problems.
Allow operator to directly control secondary loop during
certain modes of operation (such as startup).
Requirements for cascade control:
Secondary loop process dynamics must be at least four times
as fast as primary loop process dynamics.
Secondary loop must have influence over the primary loop.
Secondary loop must be measured and controllable.
Reasons not to use cascade:
Cost of measurement of secondary variable (assuming it is
not measured for other reasons).
Additional complexity.
Examples of cascade control:
Control of heat exchanger outlet temperature using steam
flow as secondary loop.
Is This Answer Correct ? | 24 Yes | 3 No |
Answer / swarndeep signh
Cascade Control system in process instrumentation is
defined as a system whose gain is dependent of other
control controlled variable vice versa.For Example: Four
conveyor running process if the speed of any one drive is
changed other will also vary acording to its defined gain.
Is This Answer Correct ? | 13 Yes | 10 No |
What are the most frequent problem faces with Vortex flow meter?
i have used level transmitter in starch cooking preparation tank. tank total height 2mtr.sometime LT display shows some error value when tank is fully empty and diaphragm side i already checked okay no problem in diaphragm area. field cable checked 24volt and mA shows correct value while tank empty mA is 4mA. 4mA i needed that 0% but display showing 10% or 15% percentage values are varying continously please give any good solution for me.....
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