[ARC5] Vibrator Power Supplies

[Geoff]

The standard in the USA is 122-123 and heading to125. Variations can put it 
at 130 in many locales when the loads are light. I have heard of some 
rebellion in the utilities that are actually reducing voltage voluntarily.

A lot of the old gear transformers are already starting saturation at 123 
and are toast at 130. The use of bucking transformers to get down to 110-113 
is very popular and the heat reduction is dramatic.


----- Original Message ----- 
From: "Brian Clarke" <brianclarke01 at optusnet.com.au>
To: "Robert Eleazer" <releazer at earthlink.net>; <arc5 at mailman.qth.net>
Sent: Friday, December 07, 2012 7:33 PM
Subject: Re: [ARC5] Vibrator Power Supplies


> Hello Wayne,
>
> Transformers up till about 1960 had rather poorer steels than we have 
> nowadays. So, the hysteresis curve was much fatter; this meant that more 
> energy went into heating the core, particularly if the Voltage rose. So, 
> to handle mains surges and dissipate the heat, manufacturers in those days 
> designed bigger transformers. Nowadays, accountants have become 
> transformer designers and so, transformers are flatter to reduce the 
> magnetic path length, and run the copper at over 3000 A / sq in. So, 
> modern transformers run hotter and burn out sooner.
>
> Generally, you can select an input Voltage almost directly proportional to 
> the operating frequency. So, in Australia where the mains is 50 Hz, an 
> American piece of equipment cannot be fed more than 5/6 x 115 = 95 Vac, 
> which then has a direct effect on the available secondary Voltages. I find 
> it strange that Americans 'on loan' over here bring all their heavy white 
> goods and connect them to simple Voltage converting transformers and then 
> wonder why stuff burns out. Perhaps the US embassy doesn't give out such 
> advice.
>
> We face a related problem in Australia. Our new (since 2000) standard 
> mains Voltage is 230 V. But for the last century, it was 240 V. So, the 
> standard has been re-written to have a higher plus tolerance to cater for 
> when you are at the end of a distribution line. Then, of an evening when 
> all the cookers get turned off, and before the distribution transformer 
> tap changers take effect, the Voltage rises to 265 - 275 V. The Europeans 
> that have 50 Hz mains have 220 V as their standard. European goods 
> imported into Australia will invariably burn out their transformers, 
> unless the importer changes the transformer before sale - but that negates 
> the benefit of importing cheaply from Europe, so, it doesn't happen. The 
> customer pays ... and pays.
>
> 73 de Brian.
>
> ----- Original Message ----- 
> From: "Robert Eleazer" <releazer at earthlink.net>
> To: <arc5 at mailman.qth.net>
> Sent: Saturday, December 08, 2012 10:51 AM
> Subject: [ARC5] Vibrator Power Supplies
>
>
>>I have a 1945 Aviation Magazine that has a full page color ad touting a 
>>new innovation: vibrator power supplies.
>>
>> Also note that the lower iron in higher frequency transformers affects 
>> what voltage the transformer can handle at lower frequencies.  Lower 
>> frequencies, then lower voltage is allowed.  I am using those 
>> transformers at what I assume is 1/2 their normal operating voltage in 
>> their secondaries: 125VAC rather than the 250V I assume was the norm.
>>
>> And they are big heavy beasts.
>>
>> Wayne
>
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