Help! Capacitor burnt out on a halogen transformer

[Aulus]

what to do? I have a 600vA transformer running a 12v halogen dimmable lighting system in my surgery. After many years, today the lights grew dim & went out.

The small capacitor on the mains neutral side of the transfomer has burnt away & I cannot identify its pF.

Can anyone recommend what to get, or should I just by pass it?

The earliest I can get a proper electrician in is next Tuesday!!


All help greatly appreciated!!!

 

[Yarn]

Being more of an elecrtonics person than an electrician, i can not think how or what this would be doing.

The fact that the bulb wont light implies that the capacitor was in series with the bulb. I cant see why a capacitor on an AC supply would be in series with a bulb.

You can get 'resetable fuses' that look like capacitors.

The usual application of capacitors accross transformers (in parallel) is to act as a supresser, but if this went open circuit, it should not stop the bulb working.


Have you tried replacing the bulb ?

Where is the capacitor connected, you only mention one circuit point. Capacitor has 2 legs!

 

[Aulus]

Weird huh? It was on the 240v side in series with the N wire (!!!). Specifically, the mains N runs into a connector block, & this thing bridged from that terminal into the one next to it, which had the N wire to the tranny.

Now I dont know if it was a capacitor! It's a 1cm disc, wire on either side, coated in ceramic.

It's been 30 years since I dabbled in electronics so I'm only going what what I thought it looked like!

 

[Adam_151]

Look like this then? http://www.rapidonline.com/producti...r4=Polyswitch+resettable+fuses&moduleno=64686

 

[bernardgreen]

Weird huh? It was on the 240v side in series with the N wire (!!!). Specifically, the mains N runs into a connector block, & this thing bridged from that terminal into the one next to it, which had the N wire to the tranny.

Now I dont know if it was a capacitor! It's a 1cm disc, wire on either side, coated in ceramic.

It's been 30 years since I dabbled in electronics so I'm only going what what I thought it looked like!

Could be a PolySwitch self re-seting fuse.

 

[Aulus]

Thats it! That's it!! It;s the third one along. Thank you all!!

Now how do I decide what rating? 600vA tranny, output load is currently 520W

 

[bernardgreen]

600 / 230 = 2.6 so a 3 amp Polyswitch will do.

But if the temperature around the fuse is higher that 25 deg C then the fude rating needs to be a bit higher as heat affects them.

 

[Spark123]

The other side of the coin is the fuse might have blown for a reason, the transformer could be faulty?? Is it an electronic transformer or a nice wire wound one?

 

[Aulus]

In summer it can get up to about 34 degrees C, so 4A or 5A be OK?

 

[breezer]

might be chaepaer to get new transformer

try the tlc site

 

[Aulus]

It's a nice wire square one in a metal cage & ten fused outputs, been in use almost every day for 14 years, I think it just had enough.

One of the bulbs failed recently, & its replacement did the same last week.

But 50p & 5 minutes is better than £200 & hours of fun rewiring so I'll get a 4A & keep a 5A in reserve!


Thanks for all your help!