Help required!!

[2oldtocrowdsurf]

Hi all! im just on my 3rd yr on the 2330 , im struggling with 5 questions??

1- an inductive coil connected into a 230V 50hz circuit has a resistance of 40Ohms and a inductive reactance of 30ohms calculate the power factor of the coil??

2-state the turns ratio of a transformer whose primary voltage is 230 v50hz and its secondary output is 1380v 50 hz

3- express the efficiency of a machine in terms of output energy or power and input energy or power.

4- also a motor with an output of 10kw draws 25A from a 500v d.c supply determine the efficiency of the motor?

5- if a circuit current through a resistor of 500ohms is 4A cvalculate the energy dissipated in two minutes?

id appreciate any help at all?

 

[m4tty]

Number 2 is 1:6 as

230 : 1380

1 : 6

230 x 6 is 1380

If you can work ratios out it should be easy mate

hth

 

[2oldtocrowdsurf]

thanks for that Mat!! i need to get my head in some books i think!!! lol

 

[meerkat]

Hi 2Old,

formula

 

[2oldtocrowdsurf]

Thanks mate, is there any usefull books that are available with these formulea in if so what are they??

 

[m4tty]

Look for a book called Electrical Installation Calculations (Advanced) mate published by Watkins & Kitcher if your doing level 3. It helped me through mine but is very in depth.

Maybe you can get it through Amazon (through the forum link) and help the forum out.

Hope this helps

Matt