2009-03-03

Primary and Secondary Current in Transformers

Although we can make the secondary voltage greater than the primary voltage in a transformer, this does not mean energy is created. Energy is still conserved.

In an ideal transformer, there is no loss of energy. Hence,

Power supplied to the primary coil = Power used in the secondary coil

That is,

VpIp = VsIs

Vp = Primary voltage , Ip = Primary current

Vs = Secondary voltage, Is = Secondary current

(Remember, Power, P = IV)

Which brings us to the ratio of current which is

Is / Ip = Vp / Vs

This means that if the voltage is stepped-up, the current in the secondary coil is stepped-down by the same ratio.

Comparing the transformer equation.

Vs / Vp = Ns / Np

We ultimately get

Is / Ip = Np / Ns

(Ns = number of coils in secondary coil)

(Np = number of coils in primary coil)

5 comments:

Lokesh Raju said...

i need clarity over ohm's law and the relation posted in this topic

Lokesh Raju said...

I need clarity over ohm's law and the relation existing in your post over voltage-current relationship

muralidharan041 said...

Hi Lokesh, why u confuse this formula with ohms law. ohms law involved with resistance. Transformers involved with No. Of coil turns

Mubassir Mk said...

it is good

Anonymous said...

Transformer ratings are in KVA so no impedance