"There is no such thing as a generator". The electrical people normally gets highly pissed of with me when I ask them this question since it is a bit confusing I think.

All electrical power is generated by a alternator and supply AC, right? Ok so what is a generator? That is also a alternator and the rectification to DC takes place inside the housing of the machine so that it will supply DC as a output instead of AC. So DC cannot be generated by itself like AC and have to be derived from AC so a DC generator as such does not exist.

Can DC be generated in any other way I might be unaware of?

Some opinions on this and maybe some information I might be unaware of about electrical power generation will be appreciated.

 

Sam,
What you are saying is correct.. The DC generator or the AC generator both work on the principle of electromagnetic induction. The emf produced in both of them is time varying. The voltage in AC generator changes direction during each cycle (that is where from the name alternator comes) where as the voltage output from DC generator does not change direction.

DC generation, can be achieved by electro-chemical methods as in the batteries.

 

> Can DC be generated in any other way I might be unaware of?

Look up "homopolar generator".
http://en.wikipedia.org/wiki/Homopolar_generator

 

> Can DC be generated in any other way I might be unaware of? <

None may be commercially viable with or without government subsidies :'), but these are sources of DC electrical power:

1) electrochemical: cell, multiple cell batteries, fuel cells

2) thermoelectric Seebeck effect: dissimilar metals generate potential over a thermal gradient\

3) photovoltaic: solar power

4) static discharge: lightning

 

Hi Guys,

My English dictionary says "Generator, machine for converting mechanical energy into electrical energy". So now we have a master grouping.

My dictionary says "Alternator, electric GENERATOR for producing alternating current."

Seems clear to me a generator makes something, final output is a secondary issue.

Cheers Jaon.

 

Just remember, you asked for opinions.

My opinion is that AC flows in the armature of any electric machine. A machine considered to be an AC machine does nothing to or with the AC flowing in the armature.

A machine considered to be a DC machine uses a commutator to reverse the direction of current flowing in the loop connected to the commutator bars as they rotate under/past the brushes.

A generator is a device for converting torque into amps, be they AC amps or DC amps.

A motor is a device for converting amps into torque, but they AC amps or DC amps.

An electric machine considered to be an AC generator is more rightly called an 'alternator'.

An electric machine considered to be a DC generator is more rightly called a 'dynamo'.

The only real difference between a generator and a motor is whether or not the device is converting torque into amps, or converting amps into torque. The world is filled with examples of electric machines that operate as both motors and generators, though they typically operate primarily as motors or generators.

There are very large electric machines that are used in pumped hydro storage facilities. During the day when electric demand is high, they operate as generators as the water flows "down the hill". During the night when electric demand is low, they operate as motors pumping the water back "up the hill", for use the next day to drive the electric machine as a generator. And so on.

If you want to consider that there are only AC machines, and no such things as DC machines (because AC is what's flowing in the armature of the DC machine), that's your prerogative. The rest of, thank you very much, will consider DC machines to be DC machines, and AC machines to be AC machines. (Oh, and by the way, there are even machines that can run on either AC or DC!)

But, if you "asked" me "There's no such thing as a generator," I'd be pretty confused at first. Because that's not even a question, even without the question mark for punctuation. It's more of a statement of your belief that AC is flowing in any electric machine so therefore there's no such thing as DC machines. Never mind the generator part.

And pretty soon, if you kept "asking" me the same thing, I'd begin to get highly pissed as well. Because if the discussion you're having with the electrical people (and we don't what kind of person you are) is remotely like what you've tried to describe, then you don't know your generators from your motors from your AC from your DC. And having a conversation with you would quickly try my patience after a very short while.

Look up 'DC commutator theory' or 'DC dynamo' or
'synchronous generator' or 'armature' using your favorite Internet search engine. It's all there! And there are some great animations these days on the Internet to do all the explaining. Cause I'm with the electrical people on this one.

That's my opinion.

<b>And you asked for it.</b>

 

Actually It is Initially

ENGINE FITTED ALTERNATOR

which later become

ENGINATOR

which simplifies to

GENERATOR

 

Following is the definition provided in the ELECTRICAL APPARATUS SERVICE ASSOCIATION's (EASA) May 2010 Publication, by Tom Bishop, EASA Senior Technical Support Specialist

"We will begin this article by clarifying the terms “alternator” and “generator.” Both terms refer to a machine that converts mechanical to electrical power.

An alternator is a synchronous machine that converts mechanical to AC electrical power.

A generator is a more general term and is a machine that converts mechanical to electrical power, either AC or DC.

An alternator is always a generator, but not vice-versa."

Phil Corso

 

Phil Corso,

That's the best, most concise, most appropriate response you've ever given.

And, you didn't use a single exclamation point.

 

Erm, I think you will find that "alternator" is an abbreviation of ALTERNating current generATOR. Which is consistent with the definition of "Generator" as a device for generating something and "alternator" being specifically for generating alternating current.