Answer / vasu

VFD are used to make the motor to run in desired speed. By
variying the input supply frequency we can vary the speed of
the motor. some other types are VVFD - Variable voltage and
frequency drive, Vector drive.

Answer / rawjaw

We know a relation speed
say,N=120f/p,speed directly
proportional to freq.In some
applications large motors
used to drive a heavy load,we
start such motors from 0 rpm
& provides initial torque(say
160%) in order to achieve
energy efficient.ok..

Answer / hitesh kareliya

VFD Means Variable Frequency Drive,So that means we
controll the Pump's RPM via VFD in desired frequency.

Answer / amit shetkar

see firstly vfd is basically used mainly for 2 purpose i.e to
protect electrical motors & for speed control.
& now about that star delta arrangement it used before motor
in that star connection is used to give smooth start to motor
& when motor achieve it's speed so to maintain that speed
delta connection is used

Answer / vinay singh

When the elements are connected in neither series nor parallel
to reduce network star delta arrangement is used.

what is skin thermocouple?

3 Answers  

Where are use of pressure,level,flow switches?and what is input and output

3 Answers  

types of transformer.. 1ph 3ph or core shell?

1 Answers  

Hi friends, from Aug 4th onwards iam getting spikes for analog inputs in our DCS for a period of 800ms. I throughly checked every thing, finally i found that the DI, DO's from MCC panels shields are terminated in the Signal Earth where Analog Input signals shields are terminated. Is there any problem with this type of termination?. i checked the induction voltage from MCC and getting around 25VAC, please suggest me in this concern. Our plant is 8months old only. DCS is Siemens Make Simatic PCS7, and the transmitters are Yokogawa make.

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Can we use a 10000 Lph Flow Transmitter in 100 LPH flow line to get 20mA O/P by adjusting SPAN ?

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Vibration probe working principle?

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What is the difference between rich gas and lean gas?

3 Answers  

Draw a simple circuit for a well head control panel used to protect the well against fire, leak, blockage, ESD, & controls the operation of one downhole & one surface safety valve. Explain the operation and controls

0 Answers  

What is PDS and PDMS ?

0 Answers  

I need control valve ISA hand book. Is there any site to download that big book containing all the pages. Written by Paul Friedmann

0 Answers  

Why 1-5 vdc a standard?

1 Answers   Process Control Technologies,