Basic electrical engineering_alternators

BASIC ELECTRICAL ENGINEERING

ALTERNATORS

Course seminar on;

IMAGINE ,THE INTRODUCTION

….What you've just experienced is an example of an alternator breathing its last breath.

Your first thought might have been the battery is dying. In a sense, you would be right because the battery and the alternator are related, but the battery tends to get all the press.

This presentation aims to explain the mechanics of alternators, how you can diagnose problems and what you can do if you have a bad alternator.

You will come to now to some background information about alternators and the war of the currents.

An automotive charging system is made up of three major components: the battery, the voltage regulator and an alternator.

The alternator works with the battery to generate power for the electrical components of a vehicle, like the interior and exterior lights, and the instrument panel. An alternator gets its name from the term alternating current (AC)

WHAT IS AN ALTERNATOR?

SIMPLE WORKING PRINCIPLE

Alternators produce AC power through electromagnetism formed through the stator and rotor

The electricity is channeled into the battery, providing voltage to run the various electrical systems.

Most cars today have a serpentine belt, or one belt that drives all components that rely on crankshaft power. Most alternators are mounted using brackets that bolt to a specific point on the engine. One of the brackets is usually a fixed point, while the other is adjustable to tighten the drive belt.

Alternators are typically found near the front of the engine and are driven by the crankshaft, which converts the pistons' up-and-down movement into circular movement.

WHERE IT IS FOUND?

IG

ALTERNATOR COMPONENTS

On the back side of the alternator you'll find several terminals (or connecting points in an electrical circuit). Let's take a look at those:

S terminal - Senses battery voltageIG terminal - Ignition switch that turns the

voltage regulator onL terminal - Closes the circuit to the warning

lampB terminal - Main alternator output terminal

(connected to the battery)F terminal - Full-field bypass for regulator

Cooling is essential to an alternator's efficiency.

ALTERNATOR COMPONENTS

As we start to disassemble the alternator, we find :

1. The diode rectifier: The regulator distributes the power the alternator creates, and it controls the output of power to the battery

2. The voltage regulator: The rectifier bridge converts the power

3 .Slip rings

both help to conduct current to the rotor field winding,

4. Brushes:

5. The alternator reveals a large cylinder with triangular finger poles around the circumference. This is the rotor

•The rotor spins inside the stator.

• The rotor assembly fits inside the stator with tolerance between the two, so the rotor can spin at high speeds without striking the stator wall.

•On each end of the shaft sits a brush and a slip ring.

HOW ALTERNATORS PRODUCE POWER?

In the early days, cars used generators rather than alternators to power the vehicle's electrical system and charge the battery

Generators produce direct current, which travels in one direction, as opposed to the alternating current for the electricity in our houses, which periodically reverses directions.

Alternating current became more attractive as it generates higher voltage more efficiently, But car batteries can't use AC power since they produce DC power.

As a result, the alternator's power output is fed through diodes, which convert the AC power to DC power.

The rotor and the stator are the two components that generate power.

As the engine rotates the alternator pulley, This is referred to as a three-phase current.

This AC current is fed through stator leads into a connecting set of diodes. Two diodes connect to each stator lead to regulate the current.

The diodes are used to essentially block and direct the current.

Since batteries need DC current, the diodes become a one-way valve that will only allow current to pass in the same direction.

THE TWO BASIC STATOR WINDING DESIGNS

DELTA WOUND WYE STYLE

Delta wound are easily identifiable by their shape, as they're triangular

These windings allow for a high current flow at lower RPM

Wye windings resemble the flux capacitor

These windings are ideal for diesel engines, as they produce higher voltage than delta stators at even lower RPM.

AFTER THE AC TO DC CONVERSION,

The resulting voltage is ready to use in the battery. Too much or too little voltage can damage the battery, as well as other electrical components

To ensure the correct amount, a voltage regulator determines when and how much voltage is needed in the battery.

One of two types of regulators are found in most alternators: The grounded regulator works by controlling the amount of negative or battery ground going into the winding in the rotor, while a grounded field type works vice versa

THE LIFE AND DEATH OF AN ALTERNATOR

Bearing failure: The needle bearings that allow the rotor to spin freely inside the stator can break down from dirt and heat

When the bearings fail, the rotor will not spin efficiently and can eventually seize.

Usually an alternator with bearings failure makes a loud grinding noise

Stator windings : Test whether your car had an issue with one of its stator windings, you'd need to use a voltmeter to check the voltage . This is called a load test

If you have a failing alternator, the voltage will be well below 14 volts. If so, it's time to replace the alternator.

Serpentine belt : If the belt is worn or loose, the alternator won't function properly. A bad belt is easy to replace

Voltmeterbearings

Serpentine belt

Alternator stator

ALTERNATOR S ,THE POWER SUPPLIER

Alternators are less expensive than say, a power steering pump or air conditioner compressor

Batteries can only be recharged so many times before they'll lose their ability to hold a charge

A bad alternator will ruin a good battery if you don't address it quickly.

High-output alternators have become popular with custom car shops and in high-performance cars.

Some custom shops are even installing dual-alternator systems to handle the additional electrical loads seen in custom vehicles.

Thank you

Presented by,

Vedavyas P. Burli