(1) The 3% harmonic current requirement is realistic and needed. The need to control harmonic currents to some limit is consistent with what industry is finding both in this country and in Europe. It is a problem that power supply subsystem designers cannot ignore but will have to solve.
(2) The only solution generally available to most Navy contractors at this time is multipulse rectification. If this solution is chosen for each individual power supply, the advantages in size and weight of off-line switching-mode power supplies is largely negated since a 60 Hz transformer must be a part of each design.
(3) Applying the multipulse rectification solution at the combat system or higher level can solve the 3% harmonic current problem at minimum cost in size and weight to the combined overall ship and combat systems. This is because with present technology, the 440 V ship service power is almost always stepped down to 115 V before being processed by the final power conditioners. The transformer needed to accomplish this can be combined with a multipulse rectifier to solve the harmonic current problem and provide DC to the final power conditioners. This requires the specification of DC input power for use at the system and subsystem level.
(4) Electronic solutions are possible and may be practical and even superior to multipulse rectification at the system level. For general use by Navy contractors, they must be in the public domain or developed on government contracts with the proper contracting clauses. When developed by an individual contractor, they may give a significant competitive advantage. For this reason there is considerable private R&D in this area. This may solve the problem on one contract, but is not a Navy-wide solution. If the Navy wants one or more Navy-owned designs which solve the problem and can be used by any Navy contractor, the Navy R&D efforts and funding in this area will have to be increased considerably.
(5) Establishing a DC ship service power and providing it to combat system and similar electronic loads eliminates the harmonic current problem.