# Transformer analysis

1. Apr 14, 2012

### greg997

I am asked to compare analytical values of the loaded transformer with measeured values of the transformer. I have got no clue how to do that. The transformer is singl ephase 230/115V with rated secondary current 0.43 A.
According to open circuit test the Rcore = 15.9kOhm, Xcore = 10.5kOhm. From SC test Req= 80 Ohm,
Xeq = 33.8 Ohm, Zeq = 86.8 Ohm

I have values of load test as follows. The load is connected to secondary R= 150k Ohm,
Vp = 211V, Ip= 24 mA, Pp = 3.2W, Vs = 115.1, Is=0.75 mA.

I am not sure what to do with that data. I also dont know how to find actual efficiency of the transformer. What is the power output of that transformer?
Thank you

2. Apr 14, 2012

### rude man

What exactly is "Rcore" and "Xcore"? Also your "ewq" parameters. How exactly were they measured?

What you should have measured id

3. Apr 14, 2012

### earlofwessex

have you been introduced to an equivalent circuit model? I would guess that you have to compare your results from the 150k loaded experiment, to the results from the open and short circuit experiments.

4. Apr 14, 2012

### rude man

What exactly are "Rcore" and "Xcore"? Also your "eq" parameters. How exactly were they measured?

What you need is:

with no other connections to the transformer:
primary inductance L11
primary resistance R1
secondary inductance L22
secondary resistance R2

with primary excited:
secondary voltage, open-circuit secondary: V2(oc)
secondary voltage, loaded secondary: V2(150K)

You might also determine the reverse voltage gain, i.e. V1(oc) and V1(150K) with V2 excited, although that should be redundant.

EDITED:
Not sure what the intent here is. Looks like you are to do just the unexcited measurements (the first four) and then assume a fully coupled transformer (k = 1.0) and compare the caculated output voltage with the measured one. But I'm just guessing.

Last edited: Apr 14, 2012
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