Forum Electric: Electrical forum, Electrical engineering, electrician, power plant, energetics,wires

martin draper · Joined: 18 Apr 2007 Posts: 1

--------------------------------------------------------------------------------

hi people, i am new to this site so be gentle.
I did a experiment using a 12A resistive load at college with a 5kva 230/110 step down transformer the results i got are: 238v Up, 115v Us, 11.47A Is, 6.07A Ip.
What could i learn from this about efficiency and losses and hysterisis.
all help appreciated

WFO · Joined: 21 Jan 2007 Posts: 19

Let's see if I can remember from 30 years ago.

No load losses (hysteresis and eddy currents) can be detected by measuring the power requirements on the primary with the secondary open circuited.

Full load losses can be measured by applying sufficient voltage at the primary to cause rated secondary current to flow with the secondary short circuited. The percent of rated voltage applied is the percent impedance.

By using these values to calculate the impedance of the transformer, the efficiency of energy transfer from the transformer to the load will be when their impedances match, so if your transformer had a 12 ohm impedance, it was at optimum efficiency as far as load transfer was concerned.

Any critiques out there? My memory ain't what it used to be.

gabrielpacyna · Posted: 2007-10-12, 19:44

Sorry, these are only two measurements with four parameters.
To describe the most simply model of the transformator you have to measure six parameters :
three measurements current and voltage:
both the primary and secondary windings : current, votltage and angle between voltages and currents and the counting precisaly parameters of the transformer would be very complicated.
And of course the coeficient like unlinear all the process is not helping but complicate all.
Sorry I couid not say, this is all and I can surely say-I counted and that is the tru, I could mistake.