What is DC Motor? It is an electrical device that converts direct electrical energy into mechanical energy. DC Motor is usually powered from direct current (DC), such as batteries, DC power supplies or an AC-to-DC power converter. When a DC voltage is supplied to its input terminals, the voltage pushes electric currents to flow through the motor windings, hence creating a magnetic field. Due to the interaction of these magnetic fields, electromagnetic torque acts on the rotors and the rotors rotate. This way, the given electrical energy gets converted into mechanical energy. There are 2 types of DC motors; Separately Excited and Self Excited. A separately excited DC motor is rarely used because they require 2 different power sources while self-excited DC motors only need a single source to run, making it a more commonly used type of DC motors used in many applications. Armature and field winding can be connected to a single DC source in 3 ways; Parallel or Shunt, Series and Compound. When armature and field winding are connected in parallel, it is called Shunt DC motor. Due to the same voltage applied to armature and field winding, the field winding must have a higher resistance than an armature. Else, maximum current will flow to the field winding and armature will produce less torque. For higher resistance, field winding must have a large number of turns of the wire. The other type of DC Motors is the DC Series Motor. When armature and field winding are connected in series, then it is called a DC Series Motor. Due to the same current passing through armature and field winding, the field winding must have lower resistance or else current through armature will decrease and will result in lower value of torque. To have lower resistance of field winding, it has to contain thicker wire and a lesser number of turns. DC Series Motor also has a special characteristic. Its static torque is extremely high and that’s why it is well suited for traction application, whereas its output torque decreases considerably with the increase in speed. The 3rd type of DC motor is the Compound Motor. Good speed regulation property of the DC Shunt Motor and high torque of DC Series Motor can be achieved in a single motor. For this type of DC motor, the field winding is divided into 2 parts; in Shunt and Series. The Shunt winding must have 10 wires with more number of turns while Series winding must have thick wires with a fewer number of turns. The DC Compound Motor is best suited for rolling mills and load that require large momentary torque. For more information on DC Motor, please contact us at +65 6457 7159.
