Separately Excited DC Motor
In this we will discuss about separately excited DC motor . Direct current (DC) motors converts electrical energy into mechanical energy and they works on dc supply.
Type of DC motors
1) Permanent magnet type dc motor
2) Separately excited dc motor
3) DC series wound motors
4) Shunt wound DC motor
5) Compound DC motor.
In this component we will separately talk about in regards to the excited motor that is dc. These engines provide both rotor and stator like other DC motors. Stator defines the component that is static of, including the industry windings. And so the rotor could be the armature that is contains which can be going windings or coils.
Individually motor that is excited is dc field coils just like that of shunt wound dc motor. The construction is preferred by the true title regarding the type of engine. Usually, in other DC machines, the field coil as well as the armature coil both are energized from the supply that is solitary. The industry of them doesn't have any excitation that is split.
But, in separately excited DC motor, split supply
In a separately excited motor, armature and field windings are excited form two different dc supply voltages. In this motor,
Armature current Ia = Line current = IL = I
Back emf developed , Eb = V â€“ I Ra
where V is the supply voltage and Ra is the armature resistance.
Power drawn from main supply , P = VI
Mechanical power developed , Pm = Power input to armature â€“ power loss in armature = VI â€“ I2 Ra = I ( V â€“ IR a) = Eb I
Both in shunt wound dc motor and separately excited dc motor field is supplied from constant voltage so that the field current is constant. Therefore these two motors have similar speed -armature current and torque â€“ armature current characteristics. In this type of motor flux is assumed to be constant.
Speed â€“ armature current (N â€“ Ia) traits: we understand that speed of dc motor is proportional to back emf / flux or in other words Eb / Ï† . Whenever load is increased Eb that is back emf and flux decrease because of armature resistance fall and armature response correspondingly .However right back decreases that are emf more than Ï† to make certain the rate with this engine notably decreases with load.
Torque â€“ armature current ( Ï„ Ia that is : Here torque is proportional towards the armature and flux current . Neglecting armature reaction, flux Ï† is constant and torque is proportional to your armature present Ia . Ï„ â€“ Ia characteristics is a lien that is directly through the foundation. Through the curve we're able to see that current that is huge had a need to begin loads that are hefty. And this variety of engine will not starts on hefty lots.
Independently dc that is excited have actually applications which are industrial. These are typically generally used as actuators. This kind of motors can be used in trains as well as for automatic traction purposes.