We use 3 and 4 point starters in DC motors. What happens if a DC motor is started without a starter? Let's check it. Consider a dc motor at standstill. When a dc motor is at rest the speed of the motor is zero, therefore the back emf is zero. We know that Back Emf, Eb= V - IaRa Therefore, Ia = (V - Eb)/Ra Armature resistance Ra in a DC motor is very small. Now at rest … [Read more...] about Need of a Starter (3 & 4 Point) in DC Motors

# DC Motor

## Voltage and Power Equations of DC Motor | Condition of Maximum Power

In this post, we will look at the voltage and power equation of a dc motor and the condition for maximum power in a dc motor. Voltage Equation of a DC Motor The voltage V applied across the motor armature has to overcome the back emf Eb and supply the armature ohmic drop IaRa . This is known as voltage equation of a motor. Back EMF and Its Significance in DC … [Read more...] about Voltage and Power Equations of DC Motor | Condition of Maximum Power

## Characteristics of DC Series Motor

In this post we will look into the characteristics of a DC series motor. A DC series motor is one type of DC motor in which field winding is connected in series with armature winding. The performance of any motor can be judged from its characteristic curves known as motor characteristics. There are three characteristic curves that can be derived from the working of a DC … [Read more...] about Characteristics of DC Series Motor

## How to Build a DC Motor at Home?

Motors convert electrical energy (from a battery or voltage source) into mechanical energy (used to cause rotation). Are you thinking of making a DC motor yourself? Then you are lucky to be landed in this page. Here we discuss how to build a simple dc motor yourself at home. Components Needed Please make sure you have the following components before starting this … [Read more...] about How to Build a DC Motor at Home?

## Why Electric Motors are Rated in kW and not in kVA?

Unlike Generators and Transformers, Electric Motors are rated in kW instead of kVA. We have already discussed why electric transformers are rated in kVA. This article explains why electric motors are rated in kW.We Know that,kVA = Voltage×CurrentkW = Voltage×Current×Power Factor In the case of transformer and generator, the designer or manufacturer does … [Read more...] about Why Electric Motors are Rated in kW and not in kVA?