At 09:46 AM 6/12/2001 +1200, Barry Kirkwood wrote:
>I am no guru on transformers, but would be surprised if 50-60 Hz shift
>needed anything like 30% more iron for equal performance.
>Is there someone on the reflector who has transformer design tables/software
>that has primary supply frequency as a variable and can give us an answer?
>73
I've designed and built a few Barry. Text e-mail doesn't lend itself to
presenting the equations in a readable form. But it really isn't needed in
this case. The iron difference is simply the ratio of the frequencies :
60/50 in this case. Therefore a 50 Hz transformer need 20% more iron than a
60 Hz transformer, if the flux density, magnetizing current and number of
turns are to be kept constant between the two designs. This statement is
good for two frequencies that are as close as 50 & 60 Hz. There are other
complications when the frequency spread increases, and when the frequency
itself is considerably higher. So, if you build a transformer for 50 Hz,
it's automatically good for 60 Hz.
Phil
>end
>Barry Kirkwood PhD ZL1DD
>Signal Hill Homestay
>66 Cory Road
>Palm Beach
>Waiheke Island 1240
>NEW ZEALAND
>www.waiheke.co.nz/signal.htm
>----- Original Message -----
>From: Barry Kirkwood <bjk@ihug.co.nz>
>To: Paul Christensen <paulc@mediaone.net>
>Cc: <amps@contesting.com>
>Sent: Monday, 04 June, 2001 8:35 AM
>Subject: Re: [AMPS] 50~ vs 60~ ???
>
>
> > Hi Paul et al:
> > We have been down this track on this reflector before.
> > 50Hz at 230 or thereabout volts is the common mains supply in the UK,
> > Australia, New Zealand and quite a lot of other places.
> > It is very rare to have significant problems with transformers rated for
> > 60Hz and rated less then 2kVA or so when used on 50Hz.
> > To my knowledge Henry 2Ks, SB220s etc perforrm on 50Hz with the greatest
>of
> > ease. The Drake L series power supplies get hot, but I believe they do so
>on
> > 60Hz, too, being a pathetic design and out of character with the Drake
> > tradition.
> > Stuff about needing 30% more iron is not based on fact.
> > If one has equipment where there is a key component eg a tuned choke which
> > is specific to 60Hz then of course there will be problems unless the
>system
> > is retuned.
> > To run a tuned choke supply on a different frequency means that the power
> > supply voltage will soar and regulation will be lost.
> > Operating the amp at the then available max will quite likely result in
> > overload of the entire system and the weakest link will probably fail.
> > In the case cited the part that failed was the power transformer, but the
> > fault was not the 50hz supply but the high vacuum between the ears of the
> > appliance operator who just plugged it in and blasted away without
>checking
> > to see what the plate voltage was doing.
> > We all make mistakes, but the serious mistakes are the ones we do not
>learn
> > from.
> > 73
> >
> > end
> > Barry Kirkwood PhD ZL1DD
> > Signal Hill Homestay
> > 66 Cory Road
> > Palm Beach
> > Waiheke Island 1240
> > NEW ZEALAND
> > www.waiheke.co.nz/signal.htm
> > ----- Original Message -----
> > From: Paul Christensen <paulc@mediaone.net>
> > To: Barry Kirkwood <bjk@ihug.co.nz>
> > Sent: Monday, 04 June, 2001 7:46 AM
> > Subject: Re: [AMPS] 50~ vs 60~ ???
> >
> >
> > > I agree Barry. I believe someone on this refelctor indicated that an
> > > approximately 33% increase in iron was required for for an equal VA
>rating
> > > from 60 ro 50 Hz. I wonder if Hypersil steel tape designs require the
> > same
> > > degree of added mass as does the traditional E-I core design?
>Neverthess,
> > > it would seem that the prudent amplifier manufacturer would foresee the
>50
> > > Hz condition and factor it into his power supply calculations and
> > > design...if for no other reason than to establish a bit more reserve at
>60
> > > Hz.
> > >
> > > 73,
> > >
> > > -Paul, W9AC
> > >
> > > ----- Original Message -----
> > > From: "Barry Kirkwood" <bjk@ihug.co.nz>
> > > To: "Vic Rosenthal" <rakefet@rakefet.com>
> > > Cc: <amps@contesting.com>
> > > Sent: Sunday, June 03, 2001 3:36 PM
> > > Subject: Re: [AMPS] 50~ vs 60~ ???
> > >
> > >
> > > >
> > > > It is most unusual for transformers of a size commonly used in the
> > amateur
> > > > service and rated 60Hz to "burn up" when used on 50Hz.
> > > > Worst case is usually poor regulation. If the 60Hz device "burns up"
>on
> > > 50hz
> > > > it was proably a very poor transfromer when used at 60Hz.
> > > > BTW if there are problems, they are usually with tiny transformers in
> > > > accessories, not linear amp power supplies.
> > > > 73
> > > > end
> > > > Barry Kirkwood PhD ZL1DD
> > > > Signal Hill Homestay
> > > > 66 Cory Road
> > > > Palm Beach
> > > > Waiheke Island 1240
> > > > NEW ZEALAND
> > > > www.waiheke.co.nz/signal.htm
> > > > ----- Original Message -----
> > > > From: Vic Rosenthal <rakefet@rakefet.com>
> > > > To: AMPS REFLECTOR <amps@contesting.com>
> > > > Sent: Sunday, 03 June, 2001 4:56 AM
> > > > Subject: Re: [AMPS] 50~ vs 60~ ???
> > > >
> > > >
> > > > >
> > > > > "A.AIMETTE" wrote:
> > > > > >
> > > > > > What happens when you operate a USA 60~ hi power amp on 50~? Does
> > the
> > > > > > filament voltage change? B+ voltage changes?
> > > > >
> > > > > It depends. Some transformers in US-made equipment are rated for
> > 50/60
> > > Hz
> > > > and
> > > > > others are not. I used an SB-200 in Israel with no problems.
> > However,
> > > if
> > > > the
> > > > > transformer is not explicitly rated for 50 Hz., it can definitely
>burn
> > > up.
> > > > I
> > > > > recommend checking with the equipment manufacturer.
> > > > >
> > > > > 73,
> > > > > Vic, K2VCO
> > > > > Fresno CA
> > > > >
> > > > > --
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> > > > >
> > > >
> > > >
> > > >
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> > > > Submissions: amps@contesting.com
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> > >
> > >
> >
> >
>
>
>
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