also shown on the nameplate. ?Rated capacity (SN, kVA or MVA)?Rated voltage (UN, V or kV)?Rated current (IN, A )?Rated Frequency (fN, Hz)Р2.2 Analysis of a Single Phase Transformer in No-load conditionР2.2.1 Physical Situation of transformers in no-load conditionРThe primary winding is connected to an ac power source. The secondary winding is open-circuited. ?If the resistor of the primary winding is r1, the voltage drop will be . The open-circuit voltage of the secondary winding is , which is equal to emf.РAccording to Faraday’s law, the induced emfs in two windings can be expressed as:РThe only difference between e1 and e2 is brought about by the difference in the number of winding turns i.e. N1 and N2. If N1≠N2, then e1≠e2, which explains why transformers can change the voltage levels.
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