A (50/60 Hz) Transformer. Which one will give more Output? (When operates on 50 or 60 Hz frequency)Posted by: Electrical Technology 04/26/2013in AC Fundamentals, Alternating Current, Basic Electrical Fundamentals, MCQs ( With Explanatory Answers), Questions/Answers (Electrical), Single Phase AC Circuits, Three Phase AC Circuits2 CommentsA Transformer is designed to be operated on both 50 & 60 Hz frequency.For the Same rating, which one will give more out put; when,1. Operates on 50 Hz 2. Operates on 60 Hz

Obviously! It will give more out put when we operate a transformer (of same rating) on 50 Hz instead of 60 Hz.Because in previous posts, we proved that, in inductive circuit, when frequency increases, the circuit power factor decreases. Consequently, the transformer out put decreases.Lets consider the following example.Suppose,When Transformer operates on 50 Hz FrequencyTransformer = 100kVA, R=700, L=1.2 H, f= 50 Hz.XL = 2fL = 2 x 3.1415 x 50 x 1.2 = 377 Impedance Z = (R2+XL2) = (7002+ 3772) = 795 Power factor Cos = R/Z = 700/795 =0.88 Transformer Output (Real Power)kVA x Cos 100kVA x 0.8888000 W = 88kWNow,When Transformer operates on 60 Hz FrequencyTransformer =100kVA, R=700, L=1.2 H, f= 60 Hz.XL = 2fL = 2 x 3.1415 x 60 x1.2 = 452.4 Impedance Z = (R2+XL2) = (7002+ 452.4 2) = 833.5 Power factor = Cos = R/Z = 700/833.5 =0.839 Transformer Output (Real Power)kVA x Cos 100kVA x 0.839 =83900W = 83.9kW OutputNow see the difference (real power i.e., in Watts)88kW- 83.9kW = 4100 W = 4.1kWIf we do the same (As above) for the power transformer i.e, for 500kVA Transformer, the result may be huge, as below.(Suppose everything is same, without frequency) Power Transformer Output (When operates on 50 Hz)500kVA x 0.88 = 44000 = 440kWPower Transformer Output (When operates on 60 Hz)500kVA x 0.839 = 419500 = 419.5kWDifference in Real power i.e. in Watts440kW 419.5kW = 20500 = 20kVA