# Efficiency of Transformer

Discussion in 'Electronic Basics' started by [email protected], Feb 28, 2005.

1. ### Guest

I am currently attempting a project on the efficiency of a transformer.
As I am using low voltage and current inputs I am recieving low
efficiency level eg. below 15% I am wondering if this is normal and
possible solutions to the problem. Any good website's on transformers
and their efficiency.

Cheers

2. ### Andrew HolmeGuest

How are you measuring efficiency?

3. ### John PopelishGuest

What frequency and power level are we talking about? Very different
problems at 60 Hz than at 10 MHz.

4. ### JamieGuest

thats a wind open area.
the first problem to be concerned about is the
DC resistance in the primary and secondary windings.
the primary winding dc resistance can be scaled to the
secondary windings in the same manner as the voltage
is scaled.
for example, if you had lets say 30 ohms of DC resistance
on the primary and the ratio was 10:1, for a rough guess
you could assume that you will have an effective resistor
drop in the secondary load circuit of 3 ohms.
then talking into account the Dc resistance in the
secondary winding compounds the problem.
then you have the saturation problem of the transformer
that also plays a roll in the efficiency along with the way
its would on each other, capacitance built up, core type etc.

if you need a nice PDF to look at here you go.
http://www.midcom-inc.com/pdf/TN69.pdf

http://eccentrix.com/members/jfcole/water_transformer.htm

5. ### Guest

I think charles is using a 12 volt ac signal, with a current of 10mA i
dont know the frequency he is using

roy

6. ### roy davidsonGuest

I think charles is using a 12 volt ac signal, with a current of 10mA i
dont know the frequency he is using

roy

7. ### Guest

Hi I am using a 12v supply and a frequecy of 5KHz

I am using formula current*voltage*cosÎ¸/2 for power at input

Using P=IV at output

Cheers

8. ### JamieGuest

i don't remember dividing the angle by 2?

P= I*V*cos(PhaseAngle);

or am i missing something here?