Is current measured in Watts or kW?

[JosephF]

Homework Statement

I'm using the following equation:

Is Vs = Ip Vp

Is the current measured in Watts or kW?

Homework Equations

n/a

The Attempt at a Solution

n/a

 

[RoryP]

well power is measured in Watts, not current.

 

[JosephF]

Ok. I'll show you the question and hopefully I've gone in the right direction.

Homework Statement

A power line supplies electrical energy to a transformer in a manufacturing plant.
The input voltage to the transformer is 11,000V. The transformer changes this to 415V for use in the manufacturing plant. The power input to the transformer is 800kW.

i. Calculate the current in the secondary coil of the transformer, stating any assumptions you have made about the transformer.

Homework Equations

$$I_p V_p = I_s V_s$$

The Attempt at a Solution

Assuming 100% efficency in the transformer.

x / 415 = 800,000 / 11,000

x = 30.181 (3dp) kW

I think I'm using the right equation but have I got my units mixed up?

Thanks,

 

[RoryP]

you are using the right equation except that you have substituted the power as the current!
you need to get the primary current using P=IV
then you can use that equation =]

 

[RoryP]

i get 1927.7 Amps, is this correct?

 

[JosephF]

I also got 1927.7108...

Thanks for your help Rory :)

 

[RoryP]

Excellent!
No worries JospephF =]