# Explain about brush and brushless alternators ?

#### kidash.zaki

• Sep 21st, 2011

Brushless alternators

A brushless alternator is composed of two alternators built end-to-end on one shaft. Smaller brushless alternators may look like one unit but the two parts are readily identifiable on the large versions. The larger of the two sections is the main alternator and the smaller one is the exciter. The exciter has stationary field coils and a rotating armature (power coils).

The main alternator uses the opposite configuration with a rotating field and stationary armature. A bridge rectifier, called the rotating rectifier assembly, is mounted on a plate attached to the rotor. Neither brushes nor slip rings are used, which reduces the number of wearing parts. The main alternator has a rotating field as described above and a stationary armature (power generation windings).

also in brush less altr. there the permanent magnet(or excitation) is use at rotor and
the output taken from stator.

brush alternator

in these the brush used for take the output. cause winding are placed on rotor and excitation winding are placed at stator.

#### bittu123 Profile Answers by bittu123 Questions by bittu123

• Nov 7th, 2011

@kidash.zaki,
You are right while explaining brush less alternator is used as exciter of large alternator since large excitation current cant be supplied by using moving contacts (or mechanical commutator, it may lead sparking).But you can't generalized this only as brush less alternator.
Actually brush less alternator is one, which supplies DC without using commutator and brushes..... shocked!!!!! How come one can supply dc without commutator??????? Yes, In Fact this is impossible...... So, let may be more precise, It can generate DC without using "mechanical" commutator. Actually it uses "electronic commutator". As you explained above it uses "bridge rectifier assembly " to convert them in dc.
Ohh, its too much...... So, lemme take it short........
Brush less alternator is basically synchronous alternator(supposed to give AC but) which gives DC without using any moving contacts such as brushes and commutator and uses permanent magnet as field winding on rotor.

#### Sourabh Jaiswal Profile Answers by Sourabh Jaiswal

• Nov 18th, 2011

To excite the rotor (salient type or non salient type pole) a dc supply is required to rotor which is done by small d.c shunt generator in brush alternators.

A brush less alternators are those which rotor exciter is self a small alternator. The exciter alternator has armature as rotor and pole as stator. So, the supply is given to rotor of main alternator by rectifying directly from rotor of exciter.

#### shashank

• Jan 19th, 2013

I want to ask one thing in brushless alternators commutator is present or not?

#### gauravpunj

• Feb 17th, 2013

Brush are used in low rating alternators to prevent huge sparking in high rating alternators the armature winding is fixed on stator.

#### shravan kumar

• Mar 5th, 2013

no..commutator is not present in brushless exciter..

#### Udhayakumar

• Jul 1st, 2014

NO

#### rathod abhishek

• Jul 5th, 2014

brush is used for collecting current for commutator and send to rotor and rotor rotate . in brush less alternator there is no need of brush....

#### djay

• Feb 24th, 2016

What is the function of carbon brush and slip rings present at the end behind exciter?

#### Shan

• Aug 24th, 2016

Is there a exciting stator in brushed generator? If not what is the reason?

#### A.Rajasekharreddy

• Sep 13th, 2016

Brush less alternator is nothing but stationary armature, Brush alternator is a rotating armature.