Rotor angular position

The field phasor is a continuously rotating phasor in the space, whose angular position keeps changing with the position of the rotor with respect to the stationary stator. Let the rotor field displacement under the stationary condition with respect to the stator be denoted by angle /3as shown in Figure 6.11, This displacement will continue to change and will rotate the rotor (field frame). All the phasor quantities of the stator arc now expressed in terms ol the field frame. Figure 6.11 shows these two equivalent stator side phasors transformed to the rotor frame. 

Pulse encoder-To feed back actual speed ol the motor and the angular position of the rotor with respect to the stator at a particular instant. 

Locked-rotor (static) torque, starting, or breakaway The minimum torque that a motor will develop at rest for all angular positions of the rotor, with rated voltage applied at rated frequency. 

In an optical encoder, a linear pattern or rotor disk is provided with adjacent transparent and opaque sections, allowing pulses of light to reach the detectors as the move progresses. These light pulses produce the electrical output pulses that indicate the linear or angular position change and direction. 

The common feature of these pump types is that, unlike the products described above, they are two-stage pumps. This structure makes these pumps more expensive to produce than conventional vacuum pumps. The rotors are made so that the gap between the rotors and between the rotors and the housing is the same, whatever the angular position of the rotors. 

Nonexcited Hysteresis. Hysteresis motors have no physical pole arrangement on then-rotors but develop fixed magnetic poles in some random angular position as they reach synchronous speed (Fig. 5.112). 

---