Universal motors have high starting torque, can run at […]
Universal motors have high starting torque, can run at high speed, and are lightweight and compact in design.
The various applications of the Universal Motor are Portable drill machine, Used in hair dryers, grinders and table fans. A universal motor is also used in Handheld power tools, blowers, blenders, vacuum cleaners, polishers and kitchen appliances.
A universal motor is defined as a motor which may be operated either on direct or single phase AC supply at approximately the same speed and output. It is a commutated series-wound motor where the stator'sfield coils are connected in series with the rotor windings through a commutator. It is often referred to as an AC series motor. The universal motor is very similar to a DC series motor in construction, but is modified slightly to allow the motor to operate properly on AC power. This type of electric motor can operate well on AC because the current in both the field coils and the armature (and the resultant magnetic fields) will alternate (reverse polarity) synchronously with the supply. Hence the resulting mechanical force will occur in a consistent direction of rotation, independent of the direction of applied voltage, but determined by the commutator and polarity of the field coils.
If it is portable, it is either a permanent magnet brushed dc motor, or a brushless synchronous motor, also with permanent magnets. The permanent magnets minimise the use of energy wasted and space wasted in the electromagnetic field coils.
If the motor is a conventional mains operated one, then a series universal motor is used, where the field coils are in series with the armature. This is cheap and effective.