Motors

[L Plate]

Can anyone please show me the calculation on this ... I'm confused , not really sure if it is 203 exam as well...

1.A current taken by the load of an 8kw motor with a power factor of 0.9 when connected across a 400V supply would be..

a) 2.02A

b)200A

c)20A

d) 22.2A

2. The phase Voltage of a three phase star connected system with a line voltage of 660V would be.

a. 760 v

b. 190 v

c. 230 v

d. 380 V

thanks a lot

 

[Mikeymike]

Can anyone please show me the calculation on this ... I'm confused , not really sure if it is 203 exam as well...1.A current taken by the load of an 8kw motor with a power factor of 0.9 when connected across a 400V supply would be..

a) 2.02A

b)200A

c)20A

d) 22.2A

Formula: V x P.F 400v x 0.9 = 360v

KW/V = I 8KW/360 = 22.2A

2. The phase Voltage of a three phase star connected system with a line voltage of 660V would be.

a. 760 v

b. 190 v

c. 230 v

d. 380 V

Star: Il = Ip Vp you Devide / by root of 3 & Vl you Times * by root of 3

Delta: Vl = Vp Ip you Devide / by root of 3 & Il you Times * by root of 3

660v / root of 3. = 380v

thanks a lot

Thats how I learned it at college. But everyone has there own ways of doing there formulas or methods

 

[L Plate]

Thats how I learned it at college. But everyone has there own ways of doing there formulas or methods

thanks a lot mate, I manage to figure out the question no.2 .. and in question 1. the answer on my calculator was 0.0222222222222 , headbang I forgot to press ENG key..

thanks again bro ..