Single phase a.c. motor

A cage rotor is used on single-phase a.c. motors, the turning force being produced in the way described previously for three-phase induction motors and shown in Fig. 2.49. Because both windings carry currents which are out of phase with each other, the motor is known as a split-phase motor. The phase... 

This part deals w ith three- and single-phase a.c. machines, and their protective switchgears. However, reference is inade to and comparisons drawn of a d.c, motor with an a.c. motor, to assist a user to inake a proper choice of machine. 

A single-phase a.c. supply produces a pulsating magnetic field, not the rotating magnetic field produced by a three-phase supply. All a.c. motors... 

With a view to achieve yet more standardization in motor design, NEMA Standard MG-1 has also recommended the maximum locked rotor current of single-speed three-phase motors for the various rotor designs A, B, C, and D, for various recommended torque values. These have been derived for a 415 V a.c. system and are shown in Table 2.2. 

Overload devices in current use are typically thermal overload relays to BS 4941, motor starters for voltages up to and including 1000 V A.C. and 1200 V D.C. or BS 142 electrical protection relays. Relays to BS 4941 generally provide overload and single-phasing protection. Those complying with BS 142 are also frequently fitted with instantaneous earth fault and over-current trips. 

Single-phase motors may be started (a) by incorporating a commutator, (6) by hand and (c) by operating them as polyphase motors, a phase splitter being used to throw two or more circuits out of phase with each other. ... 

Other motors do not fall under the EPAct regulations, for example, footless designs, other horsepower ranges, 900 rpm and slower speeds, two-speed versions, 50 Hz, 200/400 and 500 V, NEMA design C and D types, U frame, single-phase motors, frame sizes 56 and smaller, and motors designed for inverter use only covered motors may be used with inverters and still fall under the provisions of the EPAct. Underwriters Laboratory listed motors may be handled on a case-by-case basis. 

Motor 110-volt, single-phase, 60-cycle, a-c, General Electric right-angle... 

Motor 3- -hp, 110-volt, single-phase, 60-cycle, a-c, General Electric right-angle gearhead open motor, 56 rpm Available from Milton Roy Company, Philadelphia, Pa. 

Fig. 12.1. Manipulation of molecular motors and step movement of myosin 11. (a) Manipulation of a single-myosin molecule with a microneedle. A myosin molecule captured at a tip of the microneedle is allowed to interact with an actin filament placed on a glass surface, (b) Manipulation of an actin filament by a laser trap. Two beads attached at both ends of an actin filament are trapped by a laser. The actin filament is manipulated to interact with myosin molecules on the filament placed on a glass surface, (c) Nonprocessive movement of myosin 11. (Top) The displacement of the microneedle attached to single myosin 11 head (SI) was measured as a function of time and the binding of myosin to actin was measured by stiffness calculated from the displacement record (bottom), (d) Expansion of the rising phase of the displacement record above...

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