162 Shipboard Electrical Power Systems
Problem 6.12: A 1-ph, 100 kVA, 460/120 V transformer with 3% R and 6% X
is powering a 3-kW heater. Determine the total continuous circuit imped-
ance in ohms looking from the source side, and the current drawn from
the source.
Problems 6.13: Determine a 3-phase 480 V/208Y-120 V transformer kVA
rating if the daily variations in the secondary load current are 150 A for
5 h, 170 A for 1 h, and 130 A for 18 h, taking into account the service fac-
tor of 1.15 for 2 hours. Allow 30% margin for future growth.
QUESTIONS
Question 6.1 Explain the difference between power transformer, voltage
(potential) transformer, and current transformer.
Question 6.2 Why doesn’t the 3-phase transformer need the 4th core ...