Ultra Fast Fuses - 35ET

[awemawson]

I'm working on some CNC equipment that uses 35ET fuses to protect semi-conductors - the current (sic) issue manifests by blowing these fuses that are about £25 each from legitimate sources with VAT and carriage

35ET | Eaton 35A Bolted Tag Fuse, 500 V dc, 690V ac, 63.5mm | RS

uk.rs-online.com

So I don't want to pop too many fault finding (It's a power supply card in a Siemens 610 AC servo system, buried in a rack with numerous cables connected that are needed when testing:

Pardon our interruption...

These fuses trip in about 2mSec whereas DC breakers take about 20 mSec so I can't substitute one of those temporarily.

There are several others by other manufacturers but they also command stupid high prices - LSCB35, 35FRB, GSGB35

Anyone have any line on cheaper sources ? - Amazon has loads from China for about £8 each but theses ones blow fast as they have ultra high purity silver as the conductor and any fakes with copper in would be hard to eliminate

 

[daleyd]

We use them for thyristor protection, they will typically blow in less than 1 mains cycle to protect the thyristor in the event of a complete short on the output side (you need other normal fuses or breakers for circuit protection as well, the high speed fuses are usually rated a fair bit higher than the standard circuit protection) - I don’t really know of any sources for cheap ones though, and I don’t have any kicking around either.

I can ask around in work for you.

 

[awemawson]

Thanks for your reply - one mains cycle is of course 20 mSec
(There was a batch of three s/h ones on eBay for about £20 but as soon as I added them to my watch list the seller ammended the listing to be for one only but three available - argh !)

 

[Martin-Sy]

Bit cheaper here:

https://www.kempstoncontrols.co.uk/35ET/Bussmann/sku/14805

Don't think I've ever bought anything from them so cannot comment on service level etc.

 

[Ross365]

Just yesterday, I blew the 10A fuse inside my Fluke DMM. Ugh, I thought that will be £2 or 3. Well, I've found fuses being sold for that ranging from about £6 to over £40, and so I'm just slightly suspicious that some of the items on offer might just not quite match the original spec . So, I too am on the look out for a reliable product at a reasonable price.

If we regard Farnell as a more reliable supplier, I noted they had some fuses fitting the bill for the Fluke and reasonably priced. I just had a look at Kempston- £23.42 in total.

Of course for £23, you could buy a reasonable brand new DMM.

 

[awemawson]

Bit cheaper here:

https://www.kempstoncontrols.co.uk/35ET/Bussmann/sku/14805

Don't think I've ever bought anything from them so cannot comment on service level etc.

That's looking better - thanks - I'd rejected them as a wide search brought Kemston up but with a very high shipping cost - but if I buy two it's free shipping - !

 

[Turbo]

Just yesterday, I blew the 10A fuse inside my Fluke DMM. Ugh, I thought that will be £2 or 3. Well, I've found fuses being sold for that ranging from about £6 to over £40, and so I'm just slightly suspicious that some of the items on offer might just not quite match the original spec . So, I too am on the look out for a reliable product at a reasonable price.

If we regard Farnell as a more reliable supplier, I noted they had some fuses fitting the bill for the Fluke and reasonably priced. I just had a look at Kempston- £23.42 in total.

Of course for £23, you could buy a reasonable brand new DMM.

2 bits of 5a fuse wire soldered to the outside of the old fuse will be a lot cheaper. Add some heat shrink if you want for protection.

 

[GaryS65]

Kempston controls. Never cheap but if they say they have stock they do

 

[GaryS65]

Carry lots of obsolete items. Always had good service from them.

 

[Erie Fred]

2 bits of 5a fuse wire soldered to the outside of the old fuse will be a lot cheaper. Add some heat shrink if you want for protection.

And this will be guaranteed to blow before taking out the electronics ?

 

[eddie49]

And this will be guaranteed to blow before taking out the electronics ?

I think that post about 5A wire should have been accompanied by the Wink emoji or the semicolon and close bracket emoticon.

 

[Ross365]

Re the Fluke fuse, I'm only a radio ham, but I knew that post#7 was tongue in cheek. However, I am a radio ham from darkest Yorkshire and so prefers that my money stays in the bank. I found some fast-blow 8A fuses (for very little money) - I wondered about wiring one of those in place of the original 11A. . The rationale is that the fast 8A will be as fast or faster than the superfast 11A ??? I don't think I need to the sort of physical protection afforded by the original fuse. Or I could just use my old Avo8 ?

 

[Seadog]

No, you're a radio amateur.

 

[Erie Fred]

No, you're a radio amateur.

Have you heard him on SSB ?
He's a ham alright.....

FWIW when I worked at the electronics supply house, I ran inventory every month (pre-computer days)
We sold BUSS fuses, and yes, we had the fast blow IIRC called "Rectifier Fuses" not that they
did any rectification, rather they could protect a diode or xsistor junction.

 

[Ross365]

No, you're a radio amateur.

Well, I passed the RAE back in 1968, had a lot of fun and made a lot of friends working on 2m for about three years, but 2m went in to sharp decline and I transferred my interests first to women and then to cars. So, truth be told, I'm not really a radio ham or a radio amateur any more (though I still have a licence, G4... and various rigs, just zero interest).

 

[Seadog]

Well, I passed the RAE back in 1968, had a lot of fun and made a lot of friends working on 2m for about three years, but 2m went in to sharp decline and I transferred my interests first to women and then to cars. So, truth be told, I'm not really a radio ham or a radio amateur any more (though I still have a licence, G4... and various rigs, just zero interest).

I think I passed in '68 and, like you spent a couple of years before getting bored with 2m.
I still have my G8 ticket.

 

[Ross365]

I'm sorry that we've taken awemawson's thread off topic, though I think he got the info he wanted.

You'd have to suspect that the 2m band could be lost given its lack of use. If I was going to get back on the air, it would be to join the "AM geezers" who get together daily on 80m (3.615MHz). I started to build a 10W 80m AM rig (4 valves) a couple of years ago, but progress is "slow" . I was initially licenced as G8, but in '73 the same call suffix came up on the G4 series and so I took the Morse test just to get that.

​

 

[Ross365]

I've just bought this disposable 10A multimeter (with battery tester thrown in) https://www.aliexpress.com/item/1005010018068975.html? spm=a2g0o.order_list.order_list_main.5.21ef1802LJwL46
£4.12, inc delivery . I suspect that it's time-on-test at 10A is no more than 15 seconds, but I'm (currently) only working at 5A and below (investigating how my CTEK smart charger works).

 

[Erie Fred]

I think that post about 5A wire should have been accompanied by the Wink emoji or the semicolon and close bracket emoticon.

CouldA....ShouldA.....WouldA.....if it ain't on the screen, I'm not filling in the blanks
for someone else's scribblings.