Torque Equation of DC Motor

Torque equation of DC Motor gives the amount and nature of electrical torque Te developed whenever it is taken into service. Basically the performance of DC machine centers around two equations. One is EMF equation and another is Torque Equation. Therefore, understanding of torque equation is a must for performance analysis. These equations equally apply … Read more

Factors Affecting Lead Acid Battery Life

A storage battery can have a relatively long life. Some lead acid batteries may operate efficiently for around 20 years or more, provided all conditions of operation are ideal. Such conditions are not usually obtainable. The end of battery life may result from either loss of active material, lack of contact of active material with … Read more

Sulphation and Buckling in Lead Acid Battery

What is Sulphation? Sulphation in Lead Acid Battery refers to the formation of Lead Sulphate (PbSO4) on the plates of battery. For better understanding of Sulphation, let us first consider the chemical reaction taking place in the lead acid battery. In lead acid battery, lead dioxide (PbO2) acts as a positive plate and lead (Pb) … Read more

Brake Test of DC Machine

DC Machines can be tested by three different methods namely Direct Method, Indirect Method and Regenerative Method. Direct Method of testing of DC Machine, also known as Brake Test (if carried out for a DC Motor) will be discussed in this post. Direct method is suitable for small DC machines. In Direct Method, the DC … Read more

Why DC Series Motor has High Starting Torque?

DC Series Motors are widely used for the purposes requiring high starting torque like in Hoist, Crane, Electric Traction etc. In this post we will discuss the reason behind the high starting torque of DC Series Motor. For any DC motor, torque is directly proportional to the flux and armature current i.e. Ƭ = KaØIa  … Read more

Detrimental Effects of Armature Reaction

As discussed in earlier post, Purpose of Interpole in DC Machine, there are two types of effect of armature mmf on the main field flux: 1)      Distortion in Main Field Flux 2)      Net reduction of Main Field Flux Due to the above two effects of armature mmf, there are many detrimental effects on the Electrical … Read more

Advantage and Disadvantage of DC Series Motor

Advantages of DC Series Motor: The series motor has the highest starting torque for a given power rating. When the motor is overloaded, the speed drops and the torque increases. While delivering high torque during an overload, the series motor draws less current and power from the source compared to a shunt or compound DC … Read more

Purpose of Interpole in DC Machine

 For understanding the role of Interpoles, we need to understand the effect of armature reaction in the DC Machine. The effect of armature mmf on the main field flux is to distort the main field flux and to reduce the net main field flux. The figure below, shows the effect of armature mmf on the … Read more