The electric load is connected across the terminals with protective fuses. Single-phase alternators are usually used in smaller systems (limited to 25kW or less) and produce AC power at utilization voltages. An alternator designed only for single-phase operation usually does not have coils in all of the armature slots because end coils contribute little to the output voltage and increase the coil impedance in the same proportion as any other coil. The power rating is reduced from that of the three-phase unit as limited by the amount of current carried by a coil. Since the lead is unused, it is not brought out to a terminal. Variations include three-phase alternators used as single-phase units by insulating and not using one phase lead. Industrial Electric Motors and Generators MenuĪlternators are single-phase or polyphase. AC Alternator Types Alernating Current Review
