Transformer performances

[Eden Lights]

I would like to perform a test, but I don't have all the transformers right now: A test of several of the top transformers: Acme, MDL, and Unique. Transformers loaded with equal wattage, equal wire size and length, and controled input voltage. The results would be a voltage drop comparision. Any guesses???

[sitelights]

Transformer performance can be quantified using the method outlined in the post "transfomer regulation". A simple comparison can be made by replacing an existing transformer in a system of known performance with a "competing" transformer. This has the advantage of real world comparison; you only change the transformer; everything else remains the same. The voltage at the lamp pins is the critical measurement; if you record the voltage at the first, middle and last lamp by backing out the lamp to a point where you can place the meter leads against the lamp pins (with the lamp still energized) you will get a very accurate assessment of the transfomer performance under the existing load. The only fair assessment of transformer performance is made when everything is identical except the transformer itself. This means that the taps must be the same and the input (line) voltage must be the same. If you test a transformer on the bench at 122v input but your on site input is 117v the test is invalid. A field test changing only the transformer is the best indicator of performance. Test results on a multi-tap transfomer should also be equalized; what is to be compared is "apples" to "apples". This makes it difficult to compare non UL1838 (above 15v output) with compliant 12v to 15v output 25 amp max units. One way to test the performance of a 12v -22v transformer would be to record the output (secondary) voltage unloaded and then loaded. Since the most accurate evaluation of transformer regulation is determined by comparison of the secondary output under load at the transformer to the actual voltage at the lamp most distant from the transformer, actual voltage readings rule. Too many claims of performance are based on rigging the test procedures or nomenclature. When you change only one thing in a test you have a real world evaluation of the difference.

[ricavers]

Not quite "everyting else remains the same". Necessarily the connection (and resulting Impedence or Resistance at the contact point) changes with the reconnection.

[sitelights]

Not measurable by my very basic test equipment and inconsequential to the subject at hand but technically correct.