Section 1 - D.C. Motors & Controllers
Series Motors
Series motors are the simplist and most common of the direct current motors. In a series motor the electric current flows through the electromagnetic poles of the stater and then into the electromagnetic poles of the armerture. The common series motor has four stationary electromagnetic poles that make up the stater and these are usually fixed to the inside of the motor case. Two carbon brushes carry the current to the armerture through a section of the armerture known as the commutater.
A series motor varis in speed according to the current flowing through it, that is according to its load. At light loads it will run fast with little torque, and at heavy loads it will run slow with high torque. The highest effeceincy and lowest torque is near 95% of maximum motor speed. Below is an example of a typical series motor's performance chart.
Shunt Motors
Shunt wound motors are identical to series motors except that the field or stator windings are a parrallel circuit with the armature and may be controled seperately. In most cases the current through the field amounts to five percent or less of the total motor current. In shunt motors, because of the decreased excitation fields of the stator, the voltage decreases considerably as the load increases. If supplied with constant voltage, a shunt motor runs close to constant speed at all loads. By varing either the field current or armature current the speed of these motors can be regulated. Shunt motors have little starting torque.
Compound Motors
Permanent Magnet Motors
Switch Controllers