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A power transformers are used in substations to
Change frequency
Step up or step down the voltage
Improve the power factor
Convert AC to DC
Step up or step down the voltage
Power transformers are static electromagnetic devices used in substations to step up or step down AC voltages for efficient power transmission and distribution. They operate on the principle of electromagnetic induction while maintaining a constant frequency.
Power transformers are static electromagnetic devices used in substations to step up or step down AC voltages for efficient power transmission and distribution. They operate on the principle of electromagnetic induction while maintaining a constant frequency.
V2тАЛV1тАЛтАЛ=N2тАЛN1тАЛтАЛ=I1тАЛI2тАЛтАЛ тАФ Voltage, turns, and current relationship
P=VIcos╧Х тАФ Apparent power conversion maintaining constant VA rating
A power transformer consists of two inductively coupled coils, the primary and secondary, wound on a common magnetic core. When an alternating current flows through the primary winding, a time-varying magnetic flux is produced in the core, which links with the secondary winding to induce an electromotive force (EMF) via Faraday's Law of Induction. The magnitude of the induced voltage depends on the turns ratio N2тАЛ/N1тАЛ between the two windings.
Transformers operate on AC supply only; they cannot step up or down DC voltage.
Frequency remains constant from primary to secondary side.
Power transformers are designed for high efficiency at or near full load.
They facilitate long-distance power transmission by reducing I2R losses through voltage stepping.
Enables high voltage transmission to minimize line losses
High operating efficiency (often > 98%)
Maintenance of electrical isolation between circuits
Requires significant cooling and oil-based insulation systems
Incapable of changing frequency or converting AC to DC
Heavy and bulky construction requiring specialized civil works
Step-up at generating stations to match grid voltage
Step-down at distribution substations for consumer use
Interconnection of power grids at different voltage levels
Option A is incorrect because transformers do not alter the input frequency.
Option C is incorrect because power factor is managed by capacitor banks or synchronous condensers, not transformers.
Option D is incorrect because AC to DC conversion requires power electronic converters like rectifiers.
B is correct тАФ Power transformers are essential for stepping up voltage to reduce transmission losses and stepping down voltage for safe utilization.
Always remember that transformers maintain the Power (VA) rating constant; thus, stepping up voltage inversely reduces the current.