EMRFD Message Archive 12779
Message Date From Subject 12779 2016-05-02 23:25:01 Ashhar Farhan wire rating for RF how does one rate the maximum RF current that a wire can carry? Given a particular wire (let's say 36 swg) what is the maximum current that it can carry when wound over a toroid or an air core?is there any standard table that one can pick this data from?- farhan 12780 2016-05-02 23:37:18 Sandeep Lohia Re: wire rating for RF I use multistan wire that isolated from each other by varnish or
Teflon coat, can be reused from discarded mobile headphone, followed
by high gain ECM...
Please encourage recycling, reuse or repairing of E-waste.
░7░3░ ░d░e░ ░V░U░3░S░X░T░
12781 2016-05-03 01:52:01 Russell Shaw Re: wire rating for RF 12782 2016-05-03 01:54:34 Russell Shaw Re: wire rating for RF 12786 2016-05-03 21:33:28 Brooke Clarke Re: wire rating for RF Hi Farhan:
In general wire is rated based on some problem such as the insulation failing thus allowing a short. This is a thermal
issue and so the thermal characteristics of the insulation and surroundings are part of the solution.
The "ampacity" of wire: https://en.wikipedia.org/wiki/Ampacity can be found on line in tables. Here are tables for
solid magnet wire and corrections for stranded wire:
When RF is part of the consideration Skin Effect comes into play reducing the DC cross section.
So, in order to use the ampacity you would first need to reduce the physical cross section of the wire by using skin
effect then look in the tables.
The effect of the torodial core will have a small thermal effect, but not much as it will heat up. In some cases
heating of the core becomes a problem of it's own.
The lesser of evils is still evil.
2a. wire rating for RF Posted by: "Ashhar Farhan" firstname.lastname@example.org ashhar_farhan Date: Mon May 2, 2016 11:25 pm
((PDT)) how does one rate the maximum RF current that a wire can carry? Given a particular wire (let's say 36 swg) what
is the maximum current that it can carry when wound over a toroid or an air core? is there any standard table that one
can pick this data from? - farhan
12788 2016-05-04 13:12:57 Sandeep Lohia Re: wire rating for RF 12789 2016-05-04 14:50:46 Nigel Maund Re: wire rating for RF The wickipedia info says Litz wire is rarely used above 2 MHz. So I don't think this meets the design objectives.
12791 2016-05-04 16:04:43 w3lpl2000 Re: wire rating for RF I'd hate to think what a few feet of Litz wire designed for use at2 to 3 MHz would cost! 3 MHz is the practical upper frequencylimit for Litz wire, at higher frequencies Litz wire has little or nobenefit.As frequency increases, its necessary to fabricate Litz wire outof smaller and smaller wire. Litz wire with equivalent DCresistance to 18 AWG magnet wire is fabricated from one thousandone hundred strands (!) of 48 AWG (0.032 mm diameter) insulatedwire.2 -3 MHz Litz wire is certainly not very practical except for themost demanding military and industrial applications where moneyis no object...73FrankW3LPL 12792 2016-05-04 17:56:03 Russell Shaw Re: wire rating for RF 12793 2016-05-04 22:14:13 Ashhar Farhan Re: wire rating for RF thanks all for the most informative discussion. i will do some tests now with an aircore coil using 36 swg to see if it can take that current.- f