Section 14.3: The Synchronous Speed cont.
The synchronous speeds (given f = 60 Hz.) are determined by the number of poles by way of: ns = 120f/p = 120´60/p = 7200/p (in RPM)
The smallest number of (magnetic) poles is 2 (magnetic poles always appear in N-S pairs) and yields the highest speed (3600 RPM)
The next three highest speeds are 1800-, 1200- and 900-RPM for p = 4, 6 and 8 respectively
List the four highest possible synchronous speeds for a 60 Hz. synchronous generator