Transformers Single Phase

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An electrician is not expected to know how to construct or repair a transformer. Our job is to install what we are told to install. Usually the specifics about a transformer are provided on a blueprint. An electrician may be expected to evaluate an issue with a transformer. So some familiarity with terminology and calculations is helpful.

Here are terms associate with transformers:

Line Side - Input - Primary - L1 L2 L3 - Supply Side

Load Side - Output - Secondary - T1 T2 T3 - Use Side

P primary (p) wattage of line side
P secondary (s) wattage of load side
E primary (p) voltage of line side
E secondary (s) voltage of load side
I primary (p) current of the line side
I secondary (s) current of the secondary
N primary (p) number of turns in the primary
N secondary (s) number of turns in the load side
eff efficiency of a transformer
pf power factor of a transformer
ratio comparison of primary to secondary voltages


To insure that you understand the calculator technique for these formulas, here is a check values chart which you can use to practice with a calculator. Use the values given in the chart to find other values given in the chart. If after making the calculation, you get a different answer than in the chart, redo the calculation until your answer matches the check values. HERE

Find practice problems HERE. There are several pages available for this topic.

Find audio support HERE.

Many electrician workbooks and practice exams are now available 
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Click HERE to see what is available.

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