Question about transformer.

Thread Starter

RIKRIK

Joined Oct 11, 2019
93
Hi .
I recently acquired a 250vac 240v to 24v transformer. Which i am going to use for a project.

Just want to confirm my numbers are right. 3 things.
1)That @24v the maxium i can draw is 10a.
2) 24×10= 240watts. Would a 1a fuse on the 240v side do as suitable protection.
3) As i have a earth wire free. Should i ground the case of the transformer.

Any insite would be highly appreciated.
Kind regards,
Rick
 

dendad

Joined Feb 20, 2016
3,597
10A will be max current, bit it may heat up some at that rating. Best run it lower for constant loads.
1A fuse will pop on startup I reckon. Go a bit higher, and use a SLOW blow type. Or even a mains rated Polyswitch.
Yes, earth the frame, and the chassis of the case if you use one.
:EDIT> fixed it ;)
 
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Thread Starter

RIKRIK

Joined Oct 11, 2019
93
Okay thankyou . The max i will be taking it up too is 8a. Is there any other extra safty measure i could put in place apart from fusing and grounding. I will have a look at the mains polyswitch.
 

AlbertHall

Joined Jun 4, 2014
10,256
As this is presumably not a safety isolating transformer, it would be a good idea to earth one end of the secondary or one of the bridge rectifier outputs if using one,
 

MrChips

Joined Oct 2, 2009
21,687
Make sure that you wire the fuse and On/Off power switch correctly.

Some folks find it convenient to install one item on one supply line and the other on the other line. This is incorrect. Nothing goes on the NEUTRAL side.

The first item the LINE wire encounters is the fuse. The next item is the power switch, in that order.
(UK plugs have the fuse installed in the plug.)
 

dendad

Joined Feb 20, 2016
3,597
The first item the LINE wire encounters is the fuse. The next item is the power switch, in that order.
Yes!
I have seen switches that fail internally with a short between sides. Not common, but if the fuse is first, it protects against this.
 

dendad

Joined Feb 20, 2016
3,597
Just so you know,
Yep! Fixed the typo!
That comment was a bit of a "Low Blow",
Now I gotta go! ;)
(My poetry leaves a bit to be desired!)
 
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Thread Starter

RIKRIK

Joined Oct 11, 2019
93
Just so you know,
Yep! Fixed the typo!
That comment was a bit of a "Low Blow",
Now I gotta go! ;)
(My poetry leaves a bit to be desired!)
just noticed my typo , Yes VA volt amps :). well here the basic idea, the image isnt very sophisticated, More of a basic guide for me to follow, And yup its isolated, i a almost went down the road of a "variac" as they where quite cheap. Then researched auto transformers and saw it wasn't isolated. il also post a pic.
ACMACHINE.png

IMG_20200701_200618770.jpg
 

Thread Starter

RIKRIK

Joined Oct 11, 2019
93
Saying that i should have really made the breaker 8a instead of 10a. Would of made things safer. Well iv ordered the 10a from a uk supplier, il order the 8a from china as its alot cheaper but isnt needed straight away.

Brought a box to put it in. Decided on a kettle lead as i have aload hanging about in the shed. The kettle lead will have a standard 13a fuse in too.
 
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