Flat, laminated “stick” RTDs fit in slots between stator windings to monitor temperature rise and prevent overheating. The National Electrical Manufacturers Association (NEMA) recognizes embedded detectors as a standard protection for motor and generator insulation. 
Unlike on-off devices, RTDs provide continuous sensing for earlier warning without unnecessary tripouts. The sensing elements of stator RTDs extend through most of the body length to provide an average temperature reading. This eliminates the danger of a point-type sensor missing a localized hot spot. Six sensors are recommended for each motor, two per phase. Locate sensors near the hottest point of the windings for best performance. Manstronics® stator RTDs meet the specifications of ANSI C50.10-1990, general requirements for synchronous motors.