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6kw Pure Sine Wave Inverter? Is it possible?

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blackwoolf511

Fri Jun 01 2012, 01:21AM

Registered Member #4278 Joined: Tue Dec 20 2011, 09:03PM
Location:
Posts: 17

Hello!
My appology if i made a mistake on where to post this thread!

My question is this:
If i have an AVR generator(19% distortion of the waveform)
how can i clean this signal and take down the distortion to 2-3%?

Would it be better if at the generator V_out i put a rectifier that converts the AC/DC and then connect it to an DC/AC power inverter and have a pure sine wave, or is there any other way to filter the signal directly?
I saw on various websites that AVR generators aren't suitable for electronics as pc,tv and ...

The generator 3-phase with 230/380v ac exits, has an cop of 0.80, 7.2kva -> 6kw output
the DC/AC inverter has cop of 0.87 8kw -> ~5.4kw final output of the system
(if i connect AVR generator ~ rectifier ~ DC/AC power inverter(1-phase)

Any advise would be of a great help!
Thanks.

brandon3055

Fri Jun 01 2012, 04:39AM

Registered Member #4548 Joined: Mon Apr 23 2012, 03:52AM
Location: tasmania
Posts: 271

What is an AVR generator? All I could find on Google was automotive voltage regulator

Sulaiman

Fri Jun 01 2012, 05:12AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

The problem with some AVR generators may be voltage regulation more than waveform distortion, what equipment do you want to power from the generator?

Steve Conner

Fri Jun 01 2012, 06:32AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

19% distortion is awful. Either the generator is faulty, or really cheap and nasty.

A 6kW sine wave inverter would be pretty expensive. I would spend the money on a better generator instead.

AVR is automatic voltage regulator. An electronic gadget that controls the field excitation on a generator to regulate the output voltage. I don't see how an AVR is associated with waveform distortion. If anything it should be the opposite, because only bigger, more expensive generators have AVRs.

blackwoolf511

Fri Jun 01 2012, 12:10PM

Registered Member #4278 Joined: Tue Dec 20 2011, 09:03PM
Location:
Posts: 17

my replacement generator motor is a :

7.2kva/6kw 3-phase 230/400 AC
Voltage regulation. â‰¤ Â± 2% static, dynamic -18% ~ +25%.
What does it mean?

What % of wave distortion must an AVR (automatic voltage regulator) have ,
to be suitable for home electronics like hd tv, notebook, ...?

I saw online that AVR has this 19% of distortion, so it isn't suitable for electronics.
The most suitable are the PWM inverter generators.

Please let me know!

Steve Conner

Fri Jun 01 2012, 12:28PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

In that article, the voltage distortion is not caused by the AVR. It's the fault of the heavy non-linear loads, combined with the high output impedance of a small generator. You get the same problem on oil platforms and ships with electric propulsion.

Most home electronics should either be light loads, or should have PFC, so the problem shouldn't arise in the first place.

"AVR generator" seems to be some sort of jargon term from the film industry. It doesn't mean anything in power engineering.

Ash Small

Fri Jun 01 2012, 12:50PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I'm aware that you can't drive a heavy inductive load from a small generator (I tried running a ~5kW buzz-box welder from a ~5kW generator).

I assume you could encounter similar problems when running large capacitative loads too (pfc capacitors, etc?)

The only solution I'm aware of (in my situation) was to use an inverter type welder. or add an additional resistive load in parallel with the inductive load (eg edison light bulbs).

blackwoolf511

Fri Jun 01 2012, 01:23PM

Registered Member #4278 Joined: Tue Dec 20 2011, 09:03PM
Location:
Posts: 17

So, aparently, if i switch on a 3500w induction cooker, and a 1200w water boiler and my pc ,
the load wouldn't effect the wave distortion so
there will not be any problem of overheating or burning of electronic circuits(pc, hd tv...)
on the long run.
Am i right?

Steve Conner

Fri Jun 01 2012, 01:31PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

That would depend on whether your induction cooker has PFC or not, I guess. Look at the nameplate, it should list a current as well as a wattage. If the current is a great deal more than (power divided by voltage) then there is probably no PFC.

You may also have problems because your generator is 3 phase but your appliances are single phase. If the generator is rated 6kW at 3x400V, then each 230V leg can only supply 2kW, but your cooker is 3.5kW.

A 400V to 230V step-down transformer might help by distributing the load between two phases.

blackwoolf511

Fri Jun 01 2012, 03:31PM

Registered Member #4278 Joined: Tue Dec 20 2011, 09:03PM
Location:
Posts: 17

the generator has 3 internal positive ac legs + 1 ground and has 2 plugs 230ac 1-phase and 360-400ac 3-phase. does this mean that at single phase i have a 4kw gain and on the 3-phase only i have 6kw?
what is the "PFC"?

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