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.

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.

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.

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.

what is the best method to measuring level in high pressure and temperture thank?

4 Answers  

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What is Positive Calibration and Negative Calibration?

0 Answers   SA Kent,

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How to convert mmWc(mili meter water colam) to tph(ton per hour)?

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how u meassure room temp?is it possible 2 meassure room temp by rtd or thermocouple?between rtd n thrmocouple which is more regard?3 meassure diff. between rtd n thermocouple?

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Can someone give a detailed chart on the temperature ranges which can be measured by various temperature sensors.

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why orfice is not used for main steam flow calculation

0 Answers   OEG,

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Square root calculation for dp flow transmitter?

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How Control valve sizing is done?

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What is safety barrier and how it is work

2 Answers   IOCL,

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If the on Of the DO module is off in the System cabinet, then what is the Procedure to check weather the Module is working or not.

2 Answers   Honeywell,

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capillary type tranmitter using remote seals and capillary tubes filled with liquid of known of known density so if you wanna callibrate it just close block valve just before capilary @ high side & connect druck apply it's calibrated range pressure as normal calibration ensure low side block valve must be closed & if you asking commissioning so this is not a DP type pressure tx so simple if you wanna put in servie this tx just open high side block valve & than low side block same way i do it but still transmitter showing -13 ma.just tell me what i want to do ?

1 Answers   Gasco,

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

3 Answers  

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