An amplidyne is an electromechanical amplifier with the characteristics of a rotating machine. It was invented prior to the second world war by Ernst Alexanderson. An amplidyne is a special-purpose DC generator. It comprises an electric motor that turns a generator on the same shaft. It supplies large currents, precisely controlled, to the large motors used to drive heavy … [Read more...] about Amplidyne – Working and Application

# DC Motor

## Need of a Starter (3 & 4 Point) in DC Motors

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

## 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

## How Star Delta Starter Works?

Star-Delta starting is frequently referred to as “Soft-starting” a motor. But what is soft about his starting method? Why is it used? What are the advantages? What are the disadvantages? Let’s first analyse what Star Delta starting is! It will be explained by using an example motor. What is Star Delta starting? Star Delta starting is when the motor is connected (normally … [Read more...] about How Star Delta Starter Works?

## 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 the 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