Universal Motor Wiring Diagram.
A universal motor is designed to operate on either alternating current or direct current (AC/DC). It is a series wound motor. It is provided with a field winding on the stator which is connected in series with a commutating winding on the rotor. Commonly manufactured in fractional horse-power sizes. Full load speeds generally range from 5000 to 10,000 RPM’s with no-load speeds from 12,000 to 18,000 RPM’s.
Typical uses are in portable tools, office appliances, electric cleaners, kitchen appliances, sewing machines, etc. The speed of universal motors can be adjusted by connecting a resistance of proper value in series with the motor. This makes it suitable for such applications such as sewing machines that operate over a range of speeds. Universal motors may be either compensated or uncompensated, the latter type being used for the higher speeds and lower ratings only.
Reversal of this motor is accomplished by an interchange of the brush holder leads, with the armature connected off neutral. In the split-series, three-wire reversible type universal motor, one stator coil is used to obtain one direction and the other stator coil to obtain the other direction with only one stator coil being in the circuit at a time. The armature connections must be on neutral in order to obtain satisfactory operation in both directions of rotation.