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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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20th Oct 2018, 11:34 am | #41 | |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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Re: Separate current transformer?
Quote:
Al. |
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20th Oct 2018, 1:14 pm | #42 | |
Octode
Join Date: Nov 2004
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 1,885
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Re: Separate current transformer?
Quote:
As a youngster I once got "stuck" to a live feed and it was not pleasant. I'd have liked an RCD then but as a first line defence I'd rather avoid getting the belt in the first place. With a klutz like me a live chassis is just asking for trouble. |
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20th Oct 2018, 4:29 pm | #43 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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Re: Separate current transformer?
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20th Oct 2018, 5:11 pm | #44 | ||
Nonode
Join Date: Mar 2010
Location: Sunderland, Tyne and Wear, UK.
Posts: 2,476
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Re: Separate current transformer?
Quote:
It is the speed of operation (disconnection speed) that is the potential life saver, ie, within 300ms @ Idn X1 (30mA) and within 40ms for Idn X5 (150ms) for a 30mA RCD/RCBO to BSEN 61008 and BSEN 61009 non-time delay types. It is possible even probable to briefly experience the full fault current available in the finite time it takes until the device trips. Edit: it is possible to get a current limiting of sorts if the device happens to trip within the time taken to reach the peak of a half cycle of the AC waveform, but as these are by nature an electro-mechanical device the current versus trip time is far from linear, and even then you hit the time limit it takes to mechanically disconnect regardless of the magnitude of current.
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I don't suffer from Insanity. I enjoy every minute of it. Last edited by Red to black; 20th Oct 2018 at 5:28 pm. Reason: addition |
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21st Oct 2018, 2:07 pm | #45 |
Heptode
Join Date: Jul 2012
Location: Daylesford, Victoria, Australia
Posts: 675
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Re: Separate current transformer?
The Daylesford repair café went well, and we had at least ten people wanting electrical appliances looked at. Much to my surprise, I fixed a PlayStation that had been jammed by a sticky DVD label. Nothing else, though; the big problem at the moment is all the different types of security screws found on modern equipment. I don't have the drivers to get inside half the stuff that was brought in. There's Torx, and the central pin version of that, I can find those, but what are the three-blade and the forked-screwdriver types called?
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21st Oct 2018, 2:46 pm | #46 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,215
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Re: Separate current transformer?
Security screws are a right pain and they turn up where you least expect them.
As well as security Torx (with the central pin), there's also a similar version of the Allen Hex screw. The 3-bladed version of Phillips/Pozidriv is TriWing I think. I know the forked ones, but I can't remember what they are called. Then there's Torq, a sort-of off-set Phillips. I have this set from Wera : http://products.wera.de/en/kraftform..._62_kk_62.html which I found on my father's bench after he passed away. I am still using it of course. There are also 5-point versions of the Torx, known as TS, for example : https://www.machinemart.co.uk/p/clar...r-set-ts-star/ And then there's System Zero, which I believe was designed to be almost impossible to remove without the right tool, such as : https://uk.rs-online.com/web/c/tools...=system%20zero |
21st Oct 2018, 2:52 pm | #47 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,195
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Re: Separate current transformer?
Hi Sue, I call the 3 bladed ones Isle of Man types.
I found some good sets of screwdrivers on the web, they were for mobile phone repair and I think Jay-car have something similar for not too much. I'll probably call in when I'm over there next year. Ed |
22nd Oct 2018, 1:59 am | #48 |
Heptode
Join Date: Jul 2012
Location: Daylesford, Victoria, Australia
Posts: 675
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Re: Separate current transformer?
They're listed as TriWing, I'll ask the organisers to look for those as well as Security Torx. Apparently the Americans call the forked driver system "snake-eyes". Sometimes you can get these moving with circlip pliers if the screw's not deep set.
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22nd Oct 2018, 2:16 am | #49 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Separate current transformer?
I just ground an old flat blade screwdriver to make the forked tool and have been using it for ages.
When I go for a bit of modern kit I sometimes end up with a number of power tools with different tips in them to avoid wasting time changing them all the time. |
22nd Oct 2018, 10:21 am | #50 |
Nonode
Join Date: Oct 2010
Location: Tintinara, South Australia, Australia
Posts: 2,340
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Re: Separate current transformer?
Surprisingly, I got a screwdriver set (interchangeable bits) with just about every type of security screw head in Bunnings a few years ago and not expensive either.
Don't know if they still have them. Otherwise, try Jaycar or Altronics. Make sure you get a set with long shafts for the deeply set screws. |
22nd Oct 2018, 11:12 am | #51 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Separate current transformer?
Our local flea market has loads of sets and they cost so little that each likely work place gets a kit bunged into its tool box.
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22nd Oct 2018, 11:38 am | #52 |
Retired Dormant Member
Join Date: Dec 2007
Location: Shropshire, UK.
Posts: 3,051
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Re: Separate current transformer?
Yes, I too have a couple of sets of interchangeable hex-fit bits which cover all the larger security screws I've come across, plus a precision miniature driver set, which again has a range of bits to meet most eventualities.
I'm not sure how much use 'security' fastners really are when the appropriate bits are so readily available! Only those whose heads snap off intentionally when torqued-up seem anything like secure. |
22nd Oct 2018, 1:20 pm | #53 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Separate current transformer?
Back in the 1970s I spotted some wood screws with the flats to tighten them but ramped so that they could not be removed.
You would have had to drill them out and remove the remains with grips. |
23rd Oct 2018, 2:29 am | #54 |
Heptode
Join Date: Jul 2012
Location: Daylesford, Victoria, Australia
Posts: 675
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Re: Separate current transformer?
I've seen those around. Fortunately they're not common!
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23rd Oct 2018, 2:40 am | #55 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Separate current transformer?
Drills are common enough to sort them out so perhaps that is why I have not seen them since the 1970s.
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23rd Oct 2018, 7:49 am | #56 |
Hexode
Join Date: Oct 2010
Location: Box End, Beds. UK.
Posts: 271
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Re: Separate current transformer?
The problem with the sets of "security" bits is that sometimes they are not long enough; the "security" screw(s) is at the bottom of a hole may be 2" deep or more and little larger than the diameter of the screw head
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