Another Generator Question

[ValiantOne]

PinkE's question on Generators reminded me of a question I always wanted to ask. I know you guys can answer.

When you start a generator, and you are not drawing any power from it, what happens to the electricity it is making? Or does it somehow not generate until a load is put on it?

Thanks for any insight! 

[ValiantOne]

Really? no one yet? I figured Clark and Chad would be all over this question. Well, maybe they are actually working today

[PinkE]

I think it builds up....

[satellite65]

Barak Obamas campain fund? 

[PinkE]

It's got a clutch in it...It doesn't put out till you plug something in, then it engages....

[68_Val_Sedan]

Yea ...some of us have to put pants on and go to work ... not sit in our undies and play computer network genius all day .... 


To answer you question ... a generator needs power to make power.  It is basically a big as alternator .... it will just spin and nothing ill happen until  you put a small current across the field terminals, then it starts to to generate power.   the only difference between a generator and an alternator, welll besides waht drives it, is that a generator does not use diodes to change the power created to DC like in your car ....

[NYrr496]

It's exactly like an outlet.  You stick a meter in it and there's voltage.  Plug something in and it will draw current. The power in your home is made by huge generators, so it's the same exact idea.

Watch the governor/ throttle linkage when you first start it up.  It will be at a very low throttle opening with no load on the engine.  Now, every time you plug something in and increase the load, the governor gives the engine more fuel to maintain the engine's rated speed.  In the case of most portables, 3600 RPM.  While the governor is controlling the engine's speed, the voltage regulator is keeping the generator's voltage output to the specified level. 
  So... The best way to start a generator is with the main output breaker open, let it build up stable voltage and frequency and then close the breaker and start loading it up. 

[ValiantOne]

Yea ...some of us have to put pants on and go to work ... not sit in our undies and play computer network genius all day .... 

HEY! I resemble that remark  And I really like working in my sweat pants, waass wrong wiv dat?? 


But I am still confused on the generator thing. So if it is like a car, the more draw the voltage regulator senses at the battery (outlets in a genny), the more power it sends to the alternator (generator), the higher the output, right?

Then of course as Clark mentioned the engine will throttle up to support the load put on the alternator.

Am I getting it now? 'cause it is kinda making sense in my head 

[NYrr496]

 A generator makes electricity like this:  The stator spins inside the windings.  As the stator spins, it creates a magnetic field.  This magnetic field forces the negative ions from the windings, leaving only positive ions.  The windings all come together at the phase leads.  The more demand that is placed on the leads, the more magnetic field has to be built up to keep it positive. 
  Generators have a little generator on the back. It's the exciter.  It generates the DC charge that creates the magnetic field on the stator.  Older ones had brushes and slip rings. I sure do NOT miss servicing those.  Newer ones are brushless. It's like having an extra alternator on the back of the gen.

[ValiantOne]

Ok, thought I was catching on

So is the exciter (love that term btw ) responsible for making and controling the level of power going into the main generator?

Please bear with me here

[NYrr496]

The exciter creates the magnetic field.  Without regulation, the voltage would climb way beyond a useful level.  Old style voltage regulators actually had a small contactor that opened and closed to control the power created by the excitation field to control the voltage created by the gen.  New ones are solid state.