The universal AC motor is the most commonly used type. When the universal motor is powered by alternating current, the variation of the current direction causes variation in the field of both the rotor and the stator. In this way, the conjugate will continue to rotate in the same starting direction, without reversing the normal direction of rotation. Only by changing the brush connections can the direction of rotation of this type of motor be reversed.
Universal electric motors feature a high starting torque and a tendency to fire, but they allow you to vary the speed by changing the supply voltage value. Both can run on DC and AC. The constructive details influence the operation of this type of engine, https://www.mrosupply.com/lighting/lighting-fixtures/led-lighting-fixtures/5871806_seal4-50d10_rab-lighting/ which could throw many sparks causing it to burn. Under full load, they can reach more than 10,000 rpm (revolutions per minute), however, without danger of the engine starting if it is connected directly to the load. The universal motor is the single-phase motor whose stator coils are electrically connected to the rotor by means of two sliding contacts (the brushes). These two contacts, in turn, serially connect the stator to the rotor.