New Posts New Posts RSS Feed - PSU1 is 13 amp fuse ok?
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Welcome to the Graham Slee Audio Products Owners Club

 

Open to all owners plus those contemplating the purchase of a Graham Slee audio product wishing to use our loaner program: join here
Subscribe to our newsletter here (Rules on posting can be found here)


PSU1 is 13 amp fuse ok?

 Post Reply Post Reply Page  <12
Author
John C View Drop Down
Admin Group
Admin Group

gspaudio moderator

Joined: 13 Jan 2008
Location: Sheffield
Status: Offline
Points: 110
Post Options Post Options   Thanks (0) Thanks(0)   Quote John C Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 10:20am
UK plug fuses are only there to protect the cable, not the equipment. Most appliances will have some form of protection internally. I worked in electrical inspection and test for 7 years so this was often a question that came up.

The PSU1 has either thermal protection in the current (sorry) model and fuse in the older models. This is made clear on the rating plate.
Back to Top
Aussie Mick View Drop Down
Senior Member
Senior Member


Joined: 21 Feb 2014
Location: Bendigo Aust.
Status: Offline
Points: 699
Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Mick Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 2:08pm
Don’t be sorry, John. Excellent work with far more subtlety than the current (sorry) spate of 20/20 vision puns. 
Mick.
Rega RP8/Ortofon 2M Black/Rega Apheta 2 - Reflex M/Elevator EXP - C.E.C. TL5 CD Transport - MacBook Pro/Roon - Majestic DAC - Solo ULDE (Focal Elear) - Proprius - PMC Twenty5.22
Back to Top
BackinBlack View Drop Down
Senior Member
Senior Member
Avatar

Joined: 05 Feb 2012
Location: Hinton, N'hants
Status: Online
Points: 1386
Post Options Post Options   Thanks (0) Thanks(0)   Quote BackinBlack Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 2:35pm
£15 for a fuse?? I'd rather add another piece of vinyl to my collection. Not that I'm sceptical. Wink
Just listen, if it sounds good to you, enjoy it.
Back to Top
CageyH View Drop Down
Senior Member
Senior Member
Avatar

Joined: 30 Apr 2012
Location: Toulouse
Status: Offline
Points: 620
Post Options Post Options   Thanks (0) Thanks(0)   Quote CageyH Quote  Post ReplyReply Direct Link To This Post Posted: 10 Jan 2020 at 5:07pm
Originally posted by John C John C wrote:

UK plug fuses are only there to protect the cable, not the equipment. Most appliances will have some form of protection internally. I worked in electrical inspection and test for 7 years so this was often a question that came up.

The PSU1 has either thermal protection in the current (sorry) model and fuse in the older models. This is made clear on the rating plate.

Are those alternate (sorry) methods of protection?
Kevin

European loan coordinator
Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Telling it as it is

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 8980
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2020 at 4:18pm
The mains fuse protects the cable, not the product being powered, and a fuse can only be fitted to a British appliance plug.

To meet IEC/CSA/ISO/BS 60950 - the standard in force when the PSU1 was tested - requires the product to fail safe, and the smallest mains fuse (3 amps) will not do that.

The 230V version used a 63mA internal fuse; the 115V version had a 125mA fuse. Later models have a winding fuse built-into the transformer. It is not a "one shot" and will reset after disconnection from the mains, after it cools.

If not for such protection the power supply used in a fault condition could cause fire or electric shock, and to receive its KEMA Quality certification (CB certificate) had to undergo considerable testing, as well as on-test development.

The required development was done by me on the advice of KEMA labs in Holland, following the requirements of the standard at all times.

It was identified that during short circuited operation that although the output shutdown prevented damage to the power supply, the heat generated by the transformer was in excess of the case plastic rating. As such, the PSU1 had to be de-rated such that a fuse value (as stated above) would open before the transformer reached that temperature.

On-load temperatures had to be measured by the "resistance method" which was compared with thermocouple measured results to substantiate the "resistance method". Each test lasted 72 hours at an ambient temperature of 25c (required by the standard), which took some doing as it was during the winter months in a draughty workshop.

The case plastic material (ABS) proved to be a major problem, and the transformer had to be isolated from the base with an FR4 glass-fibre panel. Internal wiring also had to be temperature rated using wire with approved insulation, and carrying the required markings, and from an approved manufacturer. It also had to be proved that output wiring could never come into contact with mains-side wiring.

All this and a lot more went into the design of the PSU1 to ensure it met with every application of the standards.
Not simple enough for Google-Bot to understand...
Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Telling it as it is

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 8980
Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 11 Jan 2020 at 4:40pm
Now, in addition to the above

1. The standard dictates an instant method of disconnection from the mains must be used. This must be on the product itself. Therefore a plug and socket arrangement had to be used. Captive wiring is not allowed.

Consider that mains power therefore passes two contacts, the live and the neutral of the plug-socket. The plug-socket arrangement must also comply with the standard. These are nickel plated and conduct quite nicely and any corrosion is flashed away by disconnecting and reconnecting the live power cable.

So much then for gold plated mains fuses!

They simply reduce the chance of corrosion between the fuse clips of the plug, and the fuse caps; but what about where the pins make contact in the mains socket?

The fuses themselves are ceramic bodied bought-in fuses which are "boob printed" with a logo, and are then immersion or brush gold plated in electro less jewellery plating solution. There is no way this can be electro-plated unless done one end at a time. The gold plating is jewellery flash plated which is for decorative purposes and is soft high carat gold and a very thin deposit. It will soon wear off if changed over a few times.

2. Audiophile aftermarket cables will not meet the standard unless they are CB certificated and display the required standard markings (CE is insufficient). If used and they result in danger, the manufacturer of the power supply could be unfairly blamed through no fault of his own!

These are two reasons why I don’t join in enthusiastically with these conversations.
Not simple enough for Google-Bot to understand...
Back to Top
Aussie Mick View Drop Down
Senior Member
Senior Member


Joined: 21 Feb 2014
Location: Bendigo Aust.
Status: Offline
Points: 699
Post Options Post Options   Thanks (0) Thanks(0)   Quote Aussie Mick Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2020 at 12:11pm
Thanks for the explanation, Graham. I’m glad you think about that stuff, and just plug things into the wall and listen.
Mick.
Rega RP8/Ortofon 2M Black/Rega Apheta 2 - Reflex M/Elevator EXP - C.E.C. TL5 CD Transport - MacBook Pro/Roon - Majestic DAC - Solo ULDE (Focal Elear) - Proprius - PMC Twenty5.22
Back to Top
 Post Reply Post Reply Page  <12
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.063 seconds.