The new face of power

摘要

Variable-speed gensets are lighter, leaner, and burn half the fuel. They're also kind to engines. Pity the poor genset. Solemnly hammering away below decks, it might he asked only to power the galley lights through the night. In the morning, the crew plugs in the coffee, and it gives up a few more watts. Then, with the flick of a switch, the chief throws a compressor or circ pump online. The load skyrockets, and the genset is expected to deliver. Not only do marine gensets suffer wildly differing current demands, they've also got to produce "clean power," in the parlance of electrical engineers, or pure sine-wave 60 Hz AC electricity. When the cycles bounce all over the place, you've got dirty power. That creates all sorts of problems: lights brown and flicker, stereos hiss and pop, and anything with printed circuitry goes haywire. You can't even run a microwave. To both generate clean AC power and meet load demands, a genset's engine has to be run at a consistent 1,800 rpm or even 3,600 to maintain the constant 60 cycles, depending on the unit. That burns an insufferable amount of fuel, about half of it unnecessarily. It also forces boats to put artificial loads on their gensets, since a roaring engine without enough load on it smokes and foulsitself. Even tied up in port, crabbers blaze away with their sodium lights so their genset engines don't sieze themselves with unhurried fuel.