A DIY & home improvement forum. DIYbanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » DIYbanter forum » Do - it - Yourself » UK diy
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions.

Low Voltage Lighting transformer problem



 
 
LinkBack Thread Tools Display Modes
  #1  
Old April 26th 06, 03:33 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Low Voltage Lighting transformer problem

Hi

I've installed some 12V halogen lights in some shelves, such that I have
to mount the transformer remotely. I used 3m of normal 1.5mm^2 lighting
cable to connect the transformer to the lights, having calculated a
300mV drop across the cable (30mV/A/m x 3.3A x 3m)

However in practise I'm losing around 6V in the cable, and have
discovered that the transformer output is 125kHz, not 50Hz, explaining
the bad attenuation in the cable

So my question is - do all compact dimmable 12V transformers have high
frequency outputs?

I don't have space for an old-fashioned 50Hz transformer

Cheers
--
Ben Mack
Watchfront Electronics - Bespoke R&D - http://www.watchfront.co.uk/
Watchfront Internet - ADSL, Colo - http://www.watchfront.net/
Are you bricking it? - Firewalls - http://www.firebrick.co.uk/
Ads
  #2  
Old April 26th 06, 04:12 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Low Voltage Lighting transformer problem

In article , Ben Mack
writes
Hi

I've installed some 12V halogen lights in some shelves, such that I have
to mount the transformer remotely. I used 3m of normal 1.5mm^2 lighting
cable to connect the transformer to the lights, having calculated a
300mV drop across the cable (30mV/A/m x 3.3A x 3m)

However in practise I'm losing around 6V in the cable, and have
discovered that the transformer output is 125kHz, not 50Hz, explaining
the bad attenuation in the cable

Look for another cause to the problem, 100pF/m for the T/E over 3m still
gives 4k impedance at 125kHz so unlikely to be causing your 6V problem.
Look at minimum load, maximum load, wiring faults & faulty transformer.
--
fred
Plusnet - I hope you like vanilla
  #3  
Old April 26th 06, 05:26 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Low Voltage Lighting transformer problem

In article ,
Ben Mack wrote:
I've installed some 12V halogen lights in some shelves, such that I have
to mount the transformer remotely. I used 3m of normal 1.5mm^2 lighting
cable to connect the transformer to the lights, having calculated a
300mV drop across the cable (30mV/A/m x 3.3A x 3m)


However in practise I'm losing around 6V in the cable, and have
discovered that the transformer output is 125kHz, not 50Hz, explaining
the bad attenuation in the cable


So my question is - do all compact dimmable 12V transformers have high
frequency outputs?


I don't have space for an old-fashioned 50Hz transformer


TLC have a cable calculator for LV lamps. Dunno if it will help with your
problem.

http://www.tlc-direct.co.uk/Technica...ltageDrop.html

--
*You sound reasonable......time to up my medication

Dave Plowman London SW
To e-mail, change noise into sound.
  #4  
Old April 26th 06, 05:46 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Low Voltage Lighting transformer problem

fred wrote:
In article , Ben Mack
writes
Hi

I've installed some 12V halogen lights in some shelves, such that I have
to mount the transformer remotely. I used 3m of normal 1.5mm^2 lighting
cable to connect the transformer to the lights, having calculated a
300mV drop across the cable (30mV/A/m x 3.3A x 3m)

However in practise I'm losing around 6V in the cable, and have
discovered that the transformer output is 125kHz, not 50Hz, explaining
the bad attenuation in the cable

Look for another cause to the problem, 100pF/m for the T/E over 3m still
gives 4k impedance at 125kHz so unlikely to be causing your 6V problem.
Look at minimum load, maximum load, wiring faults & faulty transformer.


http://en.wikipedia.com/wiki/skin%20effect
  #5  
Old April 26th 06, 06:07 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Low Voltage Lighting transformer problem

Ben Mack wrote:

Hi

I've installed some 12V halogen lights in some shelves, such that I have
to mount the transformer remotely. I used 3m of normal 1.5mm^2 lighting
cable to connect the transformer to the lights, having calculated a
300mV drop across the cable (30mV/A/m x 3.3A x 3m)

However in practise I'm losing around 6V in the cable, and have
discovered that the transformer output is 125kHz, not 50Hz, explaining
the bad attenuation in the cable


it doesnt at all. Look for a bad connection or too many bulb watts for
the transformer. Bear in mind multimeters may read the 12v wrong if its
not sine wave.


So my question is - do all compact dimmable 12V transformers have high
frequency outputs?

I don't have space for an old-fashioned 50Hz transformer


tronic TFs are high frequency, toroidals are 50Hz.


NT

  #8  
Old April 26th 06, 07:20 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Low Voltage Lighting transformer problem

In article , Ian
Stirling writes
fred wrote:
In article , Ben Mack
writes
Hi

I've installed some 12V halogen lights in some shelves, such that I have
to mount the transformer remotely. I used 3m of normal 1.5mm^2 lighting
cable to connect the transformer to the lights, having calculated a
300mV drop across the cable (30mV/A/m x 3.3A x 3m)

However in practise I'm losing around 6V in the cable, and have
discovered that the transformer output is 125kHz, not 50Hz, explaining
the bad attenuation in the cable

Look for another cause to the problem, 100pF/m for the T/E over 3m still
gives 4k impedance at 125kHz so unlikely to be causing your 6V problem.
Look at minimum load, maximum load, wiring faults & faulty transformer.


http://en.wikipedia.com/wiki/skin%20effect


Only 5% increase in impedance on 1.5mm2 @ 125k
--
fred
Plusnet - I hope you like vanilla
  #10  
Old April 26th 06, 07:34 PM posted to uk.d-i-y
external usenet poster
 
Posts: n/a
Default Low Voltage Lighting transformer problem

fred wrote:

Only 5% increase in impedance on 1.5mm2 @ 125k


Only 5% increase in *resistance* due to skin effect, perhaps, but a huge
increase in *impedance* due to the inductive reactance...

--
Andy
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Low Voltage Lighting (MoonRays) + Swimming Pool? Bob Home Repair 0 April 21st 06 05:37 PM
Toshiba high voltage problem Bobby Villamor Electronics Repair 4 November 23rd 04 12:40 AM
Which is the advantage of low voltage lighting? Faustino Dina Home Repair 12 January 31st 04 10:18 PM
12 volt lighting transformer tips Paul Furman Home Repair 8 December 8th 03 10:56 PM
Low Voltage Lighting MLB Home Repair 0 July 3rd 03 10:34 PM


All times are GMT +1. The time now is 09:57 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.SEO by vBSEO ©2010, Crawlability, Inc.
Copyright 2004-2014 DIYbanter.
The comments are property of their posters.