{Collins} Re: A few thoughts on mains voltage



Bob:

Consider a couple of slight revisions to the explanation below.

In the power world, it is normal for sources to be in multiples of 120 
volts, and loads to be in multiples of 115 volts.  That's why industrial 
motors are typically rated at 460 volts 3 phase (for instance), while the 
MCC feeding the motor is rated at 480 volts 3 phase, as is the transformer 
feeding the MCC.  As well, house feeds are 240 volts single phase (120 volts 
either side of the neutral); in this case, a motor (single phase only, of 
course) would be either 230 volts or 115 volts.  Anything else is a 
specialty device.

Second, the voltage range for almost all typical electrical loads is 
typically considerably wider than +/-10%.  Whether it's good, bad, or makes 
no difference, depends on the device.  Induction motors run cooler at a 
higher voltage, for instance, so long as the voltage rating isn't terribly 
abused.  Tubes might or might not run hotter, depending on how they're 
utilized.  Finals would probably run cooler at a higher voltage, if the 
output power is held constant, for instance.  Obviously, a non-tuned tube (a 
6AU6, for instance) would produce more current flow at a higher plate 
voltage, which might or might not be bad.

There's more that could be said, but more would invite additional responses, 
I suspect.

Sound okay?


Kent W5TXV


----- Original Message ----- 
From: "Robert & Linda McGraw K4TAX" <RMcGraw@xxxxxxxxxxx>
To: <XE1YZY@xxxxxxx>; <Jim.Isbell@xxxxxxxxx>
Cc: <collins@xxxxxxxxxxxxx>
Sent: Tuesday, February 08, 2005 1:51 PM
Subject: {Collins} A few thoughts on mains voltage


>A few thoughts on mains voltage:
>
> Years ago in the US the normal residential mains voltage was stated to be
> 110 VAC and 220 VAC.  With the various distribution systems being used,
> delta, wye, single phase and 3 phase, it has become more economical to
> derive voltages in our homes from the more popular and demanded 3 phase
> system, be they delta distribution or wye distribution system.  Thus the
> nominal voltage became  115 and 230 and then later became 120 and 240.
> These of course are held to about +/- 10 percent tolerance or less.
> Additionally, in order to make up for loss in power distribution systems
> (among other reasons) around the country the power companies typically run
> the voltage on the high side. Thus we see values in the 125 to 128 range
> depending on load conditions on the system.  I've seen as high as 260 here
> at the house.  Lights are bright and the power amp really sings out some
> watts.
>
> Most of the Collins radio equipment and others for that matter, of 40+ 
> years
> ago, did consider that mains voltage would be a bit lower than it actually
> is today.  Usually in most cases today a 10% increase for ICAS usage 
> causes
> no concerns.  Thus equipment rated, as my 516F-2 at 115 VAC, has no 
> problem
> with today's 125 to 128 VAC mains.  Neither does my 1938 Western Electric
> broadcast transmitter on which the cover plate is printed:  "Mains voltage
> 220 VAC".
>
> Also consider this.  Since we buy electricity based on kilowatt hours of
> usage, more volts means more current thus more watts.  In reality, that
> translates to more dollars for the utility companies.
>
> As to standardization on frequency, the US probably has the best and most
> stable power grid in the world.  At least our clocks keep good time. 
> Since
> the sole broadcast of color TV exists, as B & W has gone away, the TV
> stations no longer rely on "line frequency" for synchronization.  Since we
> no longer play phonograph records on which player motors relied on line
> frequency for correct speed, and refrigerators don't really care if it's
> 59.5 or 60.5 Hz., stable frequency is basically for utilities swapping and
> selling power to one another.  Again another financial interest activity.
>
>
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- 
> From: <XE1YZY@xxxxxxx>
> To: <Jim.Isbell@xxxxxxxxx>
> Cc: <collins@xxxxxxxxxxxxx>
> Sent: Tuesday, February 08, 2005 10:39 AM
> Subject: {Collins} Re: 30L1 output Help! Now Fixed!
>
>
>>
>> En un mensaje con fecha 07/02/2005 07:57:25 p.m. Hora estándar de México,
>> jim.isbell@xxxxxxxxx escribe:
>> Have you  measured the AC voltage???  It is my understanding that 115,
>> 117, 120  and 125 are all used interchangeably and if you really want
>> to know the  voltage you have to measure it.  Mine is between 119 and
>> 121 most  times.  The voltage is not exact nor very closely regulated.
>> The load  is far too variable. The frequency is much more accurate, at
>> least in the  US.
>>
>>
>> On Mon, 07 Feb 2005 16:09:56 -0800 (PST), XE1YZY@xxxxxxx 
>> <XE1YZY@xxxxxxx>
>> wrote:
>>> Many thanks to all the people who help  me with my 30L1 problem, the
>>> amplifier its finally working very  good!
>>>
>>> The problem was the filament bifiliar choke,dont have  any short but
>>> leaks
>>> RF, also a fuse are blow , this fuse are made with  #30 wire conected 
>>> to
>> the
>>> central tap ground return, of the  filament winding on T1
>>> BE AWARE , THIS FUSE  DO NOT  APPEARS  IN THE  SCHEMATICS!! only shows a
>>> connection to ground!. The  tubes lights up, but the  amp dosent works.
>>>
>>> The 30L1 was  dessigned for 115V, not 125V, that makes the HV rise to
>>> 1990
>> to
>>>  2000V, and also the power dissipation to almost 278W, the maximun
>> disipation
>>> for the 811A are 180W
>>>
>>> Thanks a lot and  73's!
>>>
>>> Pedro XE1YZY
>>>
>>> Sponsored by the Collins  Collectors Association
>>> http://www.collinsradio.org
>>> Nets: Tues: 3.805  Mc-2000 Central / Thur: 3.875 Mc-2000 Central
>>> Fri: 3.895 Mc-2000  Pacific / Sun: 14.263 Mc-2000 UTC
>>> 1st Wed (of the month) AM Net 3.880  Mc-2000 local (ET, CT, MT, PT)
>>> Sun AM Net: 29.050 Mc-1200  Central
>>>
>>>
>>
>>
>>
>>
>>
>>
>> Back in 1960 line voltages were in the vicinity of 110V, all existing
>> transformers reflect the 115 Volts values, and that means, that the 
>> 811A's
>> in  the
>> filament and plate supply voltages frequently are higher than " Normal" 
>> in
>> todays usual higher voltages, this will result in high resting current 
>> and
>> quiescent plate dissipation.
>> The resting current in the 30L1 connected to more than 115V, will exceed
>> the
>> maximun plate dissipation of the 811A's.
>>
>> If you have a 30L1 and you AC supply have 119 to 121V, you are on the way
>> of
>> trouble, simply read the votage in the 30L1 meter, if you dont read 
>> 1800V,
>> your amp. is on risk.
>>
>> Hope you find this information handy
>>
>> Regards
>>
>> Pedro XE1YZY
>>
>> Sponsored by the Collins Collectors Association
>> http://www.collinsradio.org
>> Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
>> Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
>> 1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
>> Sun AM Net: 29.050 Mc-1200 Central
>>
>
>
> Sponsored by the Collins Collectors Association 
> http://www.collinsradio.org
> Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
> Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
> 1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
> Sun AM Net: 29.050 Mc-1200 Central
>
> 


Sponsored by the Collins Collectors Association http://www.collinsradio.org
Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
Sun AM Net: 29.050 Mc-1200 Central






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