#1 SSDG was operating in parallel with #2 SSDG in supplying the 480 VAC main bus while sharing the electrical load evenly. As a result of a problem, if #1 SSDG begins to motorize, but the generator has not yet tripped out by the action of the reverse power relay, what would be the indication of this?

Question

#1 SSDG was operating in parallel with #2 SSDG in supplying the 480 VAC main bus while sharing the electrical load evenly.  As a result of a problem, if #1 SSDG begins to motorize, but the generator has not yet tripped out by the action of the reverse power relay, what would be the indication of this?

Accepted Answer

Option A: The kilowatt meter of #1 SSDG would indicate a negative wattage (a reversed reading).. Motoring occurs when a paralleled generator's prime mover fails, causing the machine to draw power from the bus and act as a motor. The kilowatt meter reflects this reverse power condition by indicating negative wattage, necessitating immediate reverse power relay tripping per 46 CFR requirements.