Copyright Goodheart-Willcox Co., Inc. Chapter 13 Electric Motors 257 2 2 N S – + L1 N L2 Centrifugal switch Start winding (blue lines) reaches peak current and maximum magnetic pole strength Run winding (red lines) is a zero current and no magnetic field Second Half Cycle of Sine Wave S Goodheart-Willcox Publisher Figure 13-9. The second half sine wave cycle begins and the start winding poles change polarity. 2 2 N S – + L1 S N L2 Centrifugal switch Run winding (red lines) reaches peak current and maximum magnetic field strength Start winding (blue lines) at zero current and no magnetic field Inertia causes continued rotation to complete 180° in a half cycle Rotor completes 360° rotation in one sine wave cycle Second Half Cycle of Sine Wave Goodheart-Willcox Publisher Figure 13-10. The run winding current peaks while the start winding current decreases. The rotor develops enough inertia to complete a 360° rotation.