Subject and UNIT: Electrical Machines: Unit III: a. D.C. Motors
• It is seen that the turning or twisting force about an axis is called torque. Consider a wheel of radius R metres acted upon by a circumferential force F newtons as shown in the Fig. 4.6.1.
Condition for Maximum Power
Subject and UNIT: Electrical Machines: Unit III: a. D.C. Motors
The voltage equation of a d.c. motor is given by, V = Eb + la Ra Multiplying both sides of the above equation by Ia we get, V Ia = Eb la + Ia2 Ra This equation is called power equation of a d.c. motor.
DC Motors
Subject and UNIT: Electrical Machines: Unit III: a. D.C. Motors
It is seen in the generating action, that when a conductor cuts the lines of flux, e.m.f. gets induced in the conductor. The question is obvious that in a d.c. motor, after a motoring action, armature starts rotating and armature conductors cut the main flux. So is there a generating action existing in a motor? The answer to this question is 'Yes'.
Fleming's Left Hand Rule | D.C. Motors
Subject and UNIT: Electrical Machines: Unit III: a. D.C. Motors
The direction of such force i.e. the direction of rotation of a motor can be determined by Fleming's left hand rule. So Fleming's right hand rule is to determine direction of induced e.m.f. i.e. for generating action while Fleming's left hand rule is to determine direction of force experienced i.e. for motoring action.
Subject and UNIT: Electrical Machines: Unit III: a. D.C. Motors
In a practical d.c. motor, field winding produces a required magnetic field while armature conductors play a role of a current carrying conductors and hence armature conductors experience a force.
D.C. Motors
Subject and UNIT: Electrical Machines: Unit III: a. D.C. Motors
A motor is a device which converts an electrical energy into the mechanical energy.
Electrical Machines
Subject and UNIT: Electrical Machines: Unit III: a. D.C. Motors
Electrical Machines: Unit III: D.C. Motors : Syllabus, Contents
D.C. Generators | Electrical Machines
Subject and UNIT: Electrical Machines: Unit II: D.C. Generators
Electrical Machines: Unit II: D.C. Generators : Two Marks Questions with Answers
DC Generators
Subject and UNIT: Electrical Machines: Unit II: D.C. Generators
The generating stations either of d.c. type or of a.c. type, normally consist of number of smaller generators operating in parallel instead of large single unit capable of supplying the maximum load demand. These smaller units can run in single or in various parallel combinations to supply actual load for following different reasons :
Subject and UNIT: Electrical Machines: Unit II: D.C. Generators
Consider the magnetisation characteristics of a d.c. shunt generator shown in the Fig. 3.29.1.
Subject and UNIT: Electrical Machines: Unit II: D.C. Generators
Separately excited generators: As a separate supply is required to excite field, the use is restricted to some special applications like electro-plating, electro-refining of materials etc.
Subject and UNIT: Electrical Machines: Unit II: D.C. Generators
If drop in Vt, due to increasing IL is more dominating than increase in Vt due to increase in flux then generator is called under compounded and its characteristics is dropping in nature, as shown in the Fig. 3.27.1.