DC Motors DC MOTOR THEORYThis increase in speed will then proportionately increase the CEMF. The speed and CEMF willcontinue to increase until the armature current and torque are reduced to values just large enoughto supply the load at a new constant speed.SummaryDC motor theory is summarized below.DC Motor Theory SummaryThere are two conditions necessary to produce a force on a conductor:- The conductor must be carrying current.- The conductor must be within a magnetic field.The right-hand rule for motors states that when the forefinger is pointed in thedirection of the magnetic field lines, and the center finger is pointed in thedirection of current flow, the thumb will point in the direction of motion.The function of torque in a DC motor is to provide the mechanical output todrive the piece of equipment that the DC motor is attached to.Torque is developed in a DC motor by the armature (current-carrying conductor)being present in the motor field (magnetic field).CEMF is developed in a DC motor by the armature (conductor) rotating (relativemotion) in the field of the motor (magnetic field).The function of the voltage that is developed in a DC motor (CEMF) opposes theapplied voltage and results in the lowering of armature current.The speed of a DC motor may be changed by using resistors to vary the fieldcurrent and, therefore, the field strength.Rev. 0 Page 7 ES-06
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