Mains Power Supply for Testing - Page 1
Forum section: electronics / beginners

author: grogantech
author_rank: Contributor
timestamp: December 31, 2016, 09:23:40 pm
content: Hi,I'm quite new to electronics however I have been working with a couple of projects which require a quick link up to the mains (I am in the UK so it will be 240V). However it is a pain to rewire a plug for a quick test. Another problem I have is that if there is a short circuit in the device I am running, it often trips the main circuit breaker in the house which is hassle. I could build something myself with a couple of MCB's but I was interested if anyone has done this or if there is something available on the market. I have done a few Google searches with no results.In effect I would like a bench mounted device that will trip a MCB if short circuited and has easy-connect terminals for quick linkup.I hope I have made my question clear.Thanks,James Grogan

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 01, 2017, 12:01:57 am
content: What exactly are you looking for?What outputvoltage? AC or DC?What sort of projects are you working on?An adjustable DC powersupply could be an option.You would not need to worry about the mains side and you can set it up for whatever you're working on.

author: tautech
author_rank: Super Contributor
timestamp: January 01, 2017, 12:09:36 am
content: Quote from: grogantech on December 31, 2016, 09:23:40 pmWelcome to the forum.A Dim Bulb Tester can be invaluable for faultfinding, very easy to knock up like my roughy.Further comment on use in this old thread:https://www.eevblog.com/forum/repair/suggested-for-a-sticky-part-one-comments-or-additions-please/msg470686/#msg470686

author: jkf1000
author_rank: Regular Contributor
timestamp: January 01, 2017, 12:31:01 am
content: Have a look at this as an alternative to fitting a plug each time,http://www.ebay.co.uk/itm/Quicktest-Electrical-quick-bare-wire-connection-device-Make-safe-temporary-box-/390528210146?hash=item5aed4b94e2:g:ZpkAAOSwiwVWRIFH

author: grogantech
author_rank: Contributor
timestamp: January 01, 2017, 12:42:11 am
content: Hi Guys thanks for the help.However what I really want is something with resettable trip fuses (MCB's) so I can flip it back if there is a short circuit and not have to worry about tripping the entire mains circuitry.This doesn't have to be adjustable just an extension of the mains ring circuit so 240V @13AThanks again,James

author: julian1
author_rank: Frequent Contributor
timestamp: January 01, 2017, 12:42:29 am
content: Quote from: jkf1000 on January 01, 2017, 12:31:01 amI have the same unit and would recommend it.Big Clive also does a good review here,

author: grogantech
author_rank: Contributor
timestamp: January 01, 2017, 12:46:42 am
content: I have already seen these but they don't come with resettable fuses like this:https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwjQzdya3J_RAhVCfhoKHcE7Dp8QjRwIBw&url=http%3A%2F%2Fwww.schneider-electric.co.in%2Fen%2Fproduct-range%2F2586-neobreak-mcb%2F&psig=AFQjCNEZ0Lh80fHcnP_X-waBvwRn71hMLw&ust=1483317934668108

author: tautech
author_rank: Super Contributor
timestamp: January 01, 2017, 12:48:18 am
content: Quote from: grogantech on January 01, 2017, 12:42:11 amGet some safety glasses while you're at it, blindly supplying full power mains to a known faulty DUT is NOT SAFE. Period.If it won't power up, blows/trips fuses then it's got a major fault, probably a shorted device and a Dim Bulb tester or Variac are the appropriate tools for the job.

author: grogantech
author_rank: Contributor
timestamp: January 01, 2017, 12:51:51 am
content: Thanks tautechI will keep the advice in mind. But I was hoping there might be a device that would automatically trip a fuse if short circuited, damaged etc. So this saves me from killing all the power in the house.

author: amirm
author_rank: Regular Contributor
timestamp: January 01, 2017, 12:56:14 am
content: Quote from: grogantech on January 01, 2017, 12:42:11 amThe light bulb does that it doesn't need resetting. If your device pulls too much current/is a short, it will light up heavily limiting the current to the device.It can however have nuisance tripping if the device has a very high inrush current but is working otherwise.

author: grogantech
author_rank: Contributor
timestamp: January 01, 2017, 01:02:50 am
content: Sorry I misinterpreted that as being a device for checking for faulty bulbs.Do You have any recommendations for these on the market as I don't have the time to build my own at the moment?Thanks for your help.James

author: tautech
author_rank: Super Contributor
timestamp: January 01, 2017, 01:09:55 am
content: Quote from: grogantech on January 01, 2017, 01:02:50 amIt's just a incandescent bulb in series with the mains supply to the DUT to limit the current that can be drawn.. Takes a minute to hobble something safe together.Read the link provided above.Google it.

author: karoru
author_rank: Regular Contributor
timestamp: January 02, 2017, 02:23:37 pm
content: If you don't want to rewire the plug every single time and find hard to justify the expense of QuickTest just go to your nearest electric equipment store and buy few Wago connectors and mains cable. With them it takes 10 seconds to connect your mains cable with plug to any wiring you need.

author: Richard Head
author_rank: Frequent Contributor
timestamp: January 02, 2017, 02:58:35 pm
content: Don't immediately poo-poo the series light bulb setup as crude. It is simple but because of the highly non-linear nature of the filament resistance it actually works really well for many mains loads. You can use different power rating globes or parallel combinations to suit your particular load.