142 Shipboard Electrical Power Systems
6.3 SELECTION OF KVA RATING
The transformer size (kVA rating) for a given load prole is determined based on the
following factors:
• The peak load it would supply, taking into account the NEC load factors if
numerous small loads with intermittent use are connected to it. Large loads
are accounted for their individual on and off timing.
• For transformers supplying harmonic-rich power electronics loads, the
additional harmonics heating is accounted for by selecting correct K-rating
(discussed latter).
• About 30% margin is then added for the future growth, which will make
the transformer operate at about 1/1.3 = 0.77 or 77% of the rated capacity
until the load grows to full capacity. This indirectly makes ...