Driven from a higher voltage, (and so delivering a higher torque the torque motors can also achieve fast-forward and rewind operation without requiring any additional mechanics such as gears or clutches.
A fractional-horsepower (FHP) motor poker supplies calgary either has a rating below about 1 horsepower (0.746 kW or is manufactured with a standard-frame size smaller than a standard 1 HP motor.
When the field is weakened, the back-emf reduces, so a larger current flows through the armature winding and this increases the speed."Early Three-Phase Power (History.Basic properties edit Define Eb, induced or counter EMF ( V ) Ia, armature current ( A ) kb, counter EMF equation constant kn, speed equation constant kT, torque equation constant n, armature frequency ( rpm ) Rm, motor resistance ( ) T, motor torque.Therefore, DC motor brush design entails a trade-off between output power, speed, and efficiency/wear.Archived from the original on Retrieved ubbell,.W.The back EMF is the reason that the motor when free-running does not appear to have the same low electrical resistance as the wire contained in its winding."Account of the Repetition.The shunt field windings of both DC machines are independently excited through variable resistors.The possibility of accidentally opening the field circuit is quite remote.
In the nonsalient-pole, or distributed field, or round-rotor, machine, the winding is distributed in pole face slots.
Speed control edit Generally, the rotational speed of a DC motor is proportional to the EMF in its coil ( the voltage applied to it minus voltage lost on its resistance and the torque is proportional to the current.
AC asynchronous motors AC polyphase squirrel-cage or wound-rotor induction motor (scim) or (wrim) Self-starting Low cost Robust Reliable Ratings to 1 MW Standardized types.Kirtley, James.,.Thyristor Phase-Controlled Converters and Cycloconverters party playing card games : Operation, Control, and Performance.Wound stators edit A, Shunt B, Series C, Compound f, Field coil The field coils have traditionally existed in four basic formats: separately excited (sepex series -wound, shunt -wound, and a combination of the latter two; compound-wound.It will hold the arm in position when the arm makes contact with the magnet."SRM Inverter Topologies: A Comparative Evaluation".

7 - Alternating-Current Generators and Motors.