If the hydraulic proportional valve receives a 4-20 mA current ...

[sc00by25]

If the hydraulic proportional valve receives a 4-20 mA current loop signal to control the hydraulic cylinder that extends or retracts to set the position of the blade pitch between 0 and 90 degrees, what is the value of the electrical signal needs to be sent to the proportional valve to set the cylinder rod to extend to 75 so the blade pitch is set at 67.5 degrees?
 
  What will be an ideal response?

Question 2

Why is constant rotational speed of the generator shaft important for many wind turbines?
 
  What will be an ideal response?

[jgranad15]

Answer to Question 1

The range of 4-20 mA is 16 mA.

16 mA/90 degrees = 0.178 mA/degree + 4 mA offset (0.178 mA x 67.5 degrees + 4 mA) = 16 mA.

Answer to Question 2

For ac generators, a constant rotor speed simplifies maintaining a constant frequency.

[sc00by25]

Thank you!

[jgranad15]

Always glad to help...