Thread: VFD cable article
-
03-10-2019 #11
-
04-10-2019 #12
I have to say I'm unconvinced that's worth the expense. Coming from a communications background, to avoid significant radiation of noise I'd want each winding fed with it's own balanced, twisted pair. Telephones have been doing it this way since Alexander Graham Bell was in charge, twisted pairs minimise both radiation and reception of noise, and Ethernet cables are done the same way. I don't know if these VD cables are constructed as three twisted pairs but for minimal noise radiation they would need to be.
While we're on about it, using a twisted pair rather than loose wires for connecting limit switches etc. to your BOB might help reject noise pickup even for non-balanced inputs.
KitLast edited by Kitwn; 04-10-2019 at 02:17 AM.
An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.
-
04-10-2019 #13
Here in Oz some people ( mostly poms and other northern hemisphere ex-pats I suspect) celebrate 'Christmas in July' because that's when it's cold here and is the best time of year for enjoying huge roast dinners, mulled wine and other such traditional fare.
Kit
PS How come there's no smiley wearing a Santa hat? What's Lee playing at?An optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.
-
05-10-2019 #14
From what I read it's more of 2 interleaved twisted triplets - a bit like 1.5x the starquad cable the BBC OB guys I worked with were so fond of in high noise situations. You might be right in that at 3x twisted pair would work better as far as EMI goes, it would all depend on the switching points of the VFD. However it would make the cable even more bulky and/or increase copper losses, so that's probably why it's not been done. It would be nice to investigate this further, but as no-one makes a 1mm2 such cable and it probably won't matter much on a 2.5m run, I have more important things to concentrate on.
While we're on about it, using a twisted pair rather than loose wires for connecting limit switches etc. to your BOB might help reject noise pickup even for non-balanced inputs.
KitLast edited by Voicecoil; 05-10-2019 at 06:26 AM.
-
05-10-2019 #15
-
05-10-2019 #16
Ha! Owning up to an Auntie connection now! I haven't heard about star quad since my earliest days as a trainee back at Wood Norton back when Noel Edmonds was a lad.
I'm sure the cable manufacturers are brainy enough to construct their products in a suitably 3-phase field-cancelling way.
KitAn optimist says the glass is half full, a pessimist says the glass is half empty, an engineer says you're using the wrong sized glass.
-
05-10-2019 #17
Back in the day I worked for a company supplying audio equipment to the Beeb, mostly for OB trucks, got to know one or two of their engineers quite well during the acceptance testing. I got to see some of the syllabus from the training courses at Wood Norton, very good stuff: when it got watered down/shut down/hived off it was a great loss to the industry IMHO.
Thread Information
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
Similar Threads
-
Vfd cable
By D-man in forum Spindles & Drive MotorsReplies: 2Last Post: 29-06-2016, 01:23 PM -
Extending CY cable?
By Dwayne Dibbley in forum General ElectronicsReplies: 8Last Post: 11-03-2015, 08:33 PM -
cable prices
By deannos in forum Marketplace DiscussionReplies: 15Last Post: 10-12-2012, 10:25 PM -
Interesting Article "Makers unite - the revolution will be home-made"
By Fivetide in forum General DiscussionReplies: 4Last Post: 28-09-2012, 12:06 PM -
FOR SALE: Cable Glands...
By Jimmybristol in forum Items For SaleReplies: 0Last Post: 07-02-2011, 07:33 PM
Bookmarks