A distribution transformer is rated 11 kV/400 V (rms) and is considered ideal for…
PHYSICS · Multi-part · CBSE · Physics · Alternating Current · Alternating Current
Problem
A distribution transformer is rated 11 kV/400 V (rms) and is considered ideal for calculation purposes. Initially, a resistive load of 16 Ω is connected across the 400 V secondary.
(i) Calculate the rms current in the secondary and the corresponding rms current in the primary.
(ii) Compute the power delivered to the load and show that it equals the input power.
(iii) The 16 Ω load is replaced by a 25 Ω load while the primary voltage remains 11 kV. Recalculate the secondary and primary currents.
(iv) Determine the percentage decrease in the primary current when the load is changed from 16 Ω to 25 Ω.