Winding Terminologies

a). Conductor : It is the actual armature conductor which is under the influence of the magnetic field, placed in the armature slot. b). Turn : The two conductors placed in different slots when connected together, forms a turn. While describing armature winding the number of turns may be specified from which, the number of … Continue reading Winding Terminologies

Types of Armature Winding

According to the way of connecting the conductors, armature winding has basically two types namely, (i). Lap winding and (ii). Wave winding Lap winding : In this case, if connection is started from conductor in slot 1 then connections overlap each other as winding proceeds, till starting point is reached again. Developed view of part … Continue reading Types of Armature Winding

Construction of DC Machine

Whether a machine is d.c. generator or a motor the construction basically remains the same as shown in the figure. DC machine consists of the following parts : Yoke : a). Functions : It serves the purpose of outermost cover of the d.c. machine. So that the insulating materials gets protected from harmful atmospheric elements … Continue reading Construction of DC Machine

Types of DC generator

Methods of Excitation The magnetic field required for the operation of a d.c. generator is produced by an electromagnet. This electromagnet carries a field winding which produces required magnetic flux when current is passed through it. Thus supplying current to the field winding is called excitation and the way of supplying the exciting current is … Continue reading Types of DC generator

Four Point Starter

The basic difference between three point and four point starter is the connection of NVC. In three point, NVC is in series with the field winding while in four point starter NVC is connected independently across the supply through the fourth terminal called 'N' in addition to the 'L', 'F' and 'A'. Hence any change … Continue reading Four Point Starter

Action of Commutator

It is seen that, the emf induced in the conductors is always sinusoidal converts this sinusoidal emf to unidirectional emf. For simplicity of understanding the commutator action, consider commutator in its simplest form. Commutator is divided into number of copper segments is insulated from each other. Commutator is divided into number of copper segments insulated … Continue reading Action of Commutator

Three point starter

The starter is basically a variable resistance, divided into number of sections. The contact points of these sections are called studs and brought out separately shown as OFF, 1,2, .... up to RUN. There are three main parts of this starter : 'L' → Line terminal to be connected to positive of supply. 'A' → … Continue reading Three point starter

Necessity of Starter

All the d.c. motors are basically self starting motors. Whenever the armature and the field winding of a d.c. motor receives supply, motoring action takes place. So d.c. motors do not require any additional device to start it. The device to be used as a starter conveys a wrong meaning. So starter is not required … Continue reading Necessity of Starter

Characteristics of dc motors

Torque and Speed Equations For a d.c. motor >> Torque is directly proportional to the product of Armature current and main flux. $latex \displaystyle T_a = \phi I_a \biggl ( \frac {PZ}{2\pi A} \biggr ) &s=3 &bg=ffffff$ $latex \displaystyle T \propto \phi I_a &s=3 &bg=ffffff$ Now $latex \displaystyle \phi &s=2 &bg=ffffff$ is the flux produced by the … Continue reading Characteristics of dc motors

Types of D.C. Motors

The d.c. motors are classified depending upon the way of connecting the field winding with the armature winding. The different types of d.c. motors are shunt motors, series motors and compound motors. The compound motors are further classified as short shunt compound and long shunt compound motors. DC Shunt Motor In this type, the field … Continue reading Types of D.C. Motors