Non Linear Loading Gen Sets [RE-wrenches]

[Kurt Albershardt]

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All of this depends on the particular charger design.  Power Factor Corrected (PFC) power supplies are becoming more common these days.

Good gensets are built with oversized alternator ends (a 90 kW genset we recently installed used a 125 kW continuous rated alternator.)  If you expect predominantly nonlinear loads you can actually have the alternator pitched to accommodate those (similar to specifying a K-factor transformer.)






--On Monday, June 30, 2008 5:12 PM -0700 daryl_solar at yahoo.com wrote:

>
> Hello
> I am sure you will get a more complete answer from others, but a very simple charger just clips the tops of the voltage wave and makes the current in increased amplitude spikes.  The winding heat by I^2 R the higher Current causes higher heating.  So for simple chargers he is correct, and the generator should not be loaded to full value.
>
> Many inverter chargers are not simple chargers Imax ripple current on an Outback has much lower peak current than a simple charger.  Perhaps Christopher could give us a ratio?
> Darryl
>
>
> --- On Mon, 6/30/08, Kurt Albershardt <info at es-ee.com> wrote:
>
>> From: Kurt Albershardt <info at es-ee.com>
>> Subject: Re: Non Linear Loading Gen Sets [RE-wrenches]
>> To: RE-wrenches at topica.com
>> Date: Monday, June 30, 2008, 5:04 PM
>> Is the genset wired for 3-phase?  If so, the nonlinear loads
>> issue is a big one (as in melted neutral conductor.)  In
>> single phase operation, nonlinear loads pose far less of an
>> issue, though power factor will play a part in useable
>> genset rating.
>>
>>
>>
>> --On Monday, June 30, 2008 2:53 PM -0400 Dan Brown
>> <Cvsolar2 at aol.com> wrote:
>> >
>> >
>> > Hi;
>> >        I just installed a good sized off grid system
>> that uses a 20k gen set
>> > as a Back up. Documentation for the Set was sparse, so
>> i called the gen set
>> > manufacturer for advice -- like break in issues and
>> the like. i got one of their
>> > tech. types that suggested i load their set right up
>> for break in. i
>> > suggested we could do that by bumping up the charge
>> rate on the inverters (yes the
>> > batteries can handle it). the tech. dude promptly
>> flipped out, and went into a
>> > rant about non linear loading gen sets caused by
>> chargers.   he said the problem
>> > is that chargers only use pieces of the wave form
>> causing the gen set
>> > windings to heat - up among other things. he said they
>> recommend a max. of only
>> > 15-20% nonlinear loading of their sets, and that i
>> should load up the balance with
>> > linear loads (like heating elements), to balance the
>> load on the windings.
>> > this is a new one on me folks. my gen. people suggest
>> the guy might be smoking
>> > oregano, and instructed me to set up the system to
>> operate just under the sets
>> > continuous duty rating. i.e. 80A,  (set is rated for
>> 83.3A continuous). another
>> > colleague suggests the tech dude might be thinking of
>> mod. sine wave inverter
>> > / chargers, and that good inverters don't chop up
>> the wave form. i scope'd
>> > out the wave form under load and it looked good to me.
>> seen worse. so the
>> > question is, has any one else ran into this issue?
>> could oregano be making a come
>> > back? thoughts? thanks db
>> >
>> > Dan Brown
>> > President
>> > Foxfire Energy Corp.
>> > Renewable Energy Systems
>> > (802)-483-2564
>> > www.Foxfire-Energy.com
>> > NABCEP #092907-44












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