[Amps] Plate transformer current unknown

[Will Matney]

One thing I ought to mention here for winding a heater supply transformer. Generally, since the voltage is low, having a higher current, with a single layer winding (usually), plus being the winding on the outside, you can skimp some here. This meaning using something around 500 to 750 circular mils per ampere. The reason being is the heat can escape easier being on the outside and being of pretty large wire. The primary though, should be wound with 1000 to 1200 cir. mil. per ampere because it runs at a 100% duty cycle. Another trick here is there's enough window room, you can add some spacer sticks around the circumference of the primary and between it and the secondary. These are maybe 1/8" to 3/16" thick. They allow air to come up through the winding and cool it off plus keep the secondaries heat from being transmitted into the primary. This is done a lot on large transformers, either air, or oil cooled.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 4/30/05 at 10:50 PM W1GOR wrote:

>American Wire Gauge - AWG - and circular mils
>American Wire Gauge (AWG) is a U.S. standard set of wire conductor sizes. 
>The "gauge" is related to the diameter of the wire.
>
>The AWG standard includes copper, aluminum and other wire materials.
>Typical 
>household copper wiring is AWG number 12 or 14. Telephone wire is usually 
>22, 24, or 26. The higher the gauge number, the smaller the diameter and
>the 
>thinner the wire.
>
>The Circular Mil - CM - is a unit of area used especially when denoting
>the 
>cross-sectional size of a wire or cable.
>
>      American Wire Gauge
>      (AWG) Diameter Mil  Circular Mil
>      (CM)
>      0000 460 211,592
>      000 410 167,800
>      00 365 133,072
>      0 325 105,531
>      1 289 83,690
>      2 258 66,369
>      3 229 52,633
>      4 204 41,740
>      5 182 33,101
>      6  162 26,251
>      7  144  20,818
>      8  128 16,509
>      9  114 13,092
>      10  102 10,383
>      11 90.7  8,234
>      12  80.8  6,530
>      13  72.0 5,178
>      14  64.1 4,107
>      15  57.1  3,257
>      16  50.8 2,583
>      17  45.3 2,048
>      20  32.0  1,022
>      21  28.5 810.1
>      22  25.3  642.4
>      23  22.6 509.5
>      24  20.1  404.0
>      25 17.9  320.4
>
>
>----- Original Message ----- 
>From: "Will Matney" <craxd1 at ezwv.com>
>To: <amps at contesting.com>
>Sent: Saturday, April 30, 2005 11:40 PM
>Subject: Re: [Amps] Plate transformer current unknown
>> Dunno, but it's a bitch to keep typing or writing out, even abbreviating 
>> it! Probably one of those scientists who like using the longest words 
>> possible to describe somthing short, I wont say another word...........
>> Best,
>> Will
>> *********** REPLY SEPARATOR  ***********
>> On 4/30/05 at 7:45 AM Ian White GM3SEK wrote:
>>>Will Matney wrote:
>>>>anywhere from 700 to 900 circular mils per ampere
>>>Was the "circular mil" invented by someone who couldn't spell "pi"?
>>>73 from Ian GM3SEK         'In Practice' columnist for RadCom (RSGB)
>>>http://www.ifwtech.co.uk/g3sek