Transformer causing mcbs to trip

[Quantum dan]

Hi. Could someone confirm weather you think I'm right or not. Today I installed a ceiling mounted suspension wire lighting track in a domestic kitchen. It's fed via a fairly chunky wire wound transformer (I don't know the kva of hand). The mcb supplying the circuit is a type b 6 amp rcbo. Pretty much most of the time I flick the switch to turn it on and also when I turn it off it trips the mcb.

im thinking I need to change the mcb to a type c to manage what appears to be an inductive load caused by the wire wound tranny. Would you guys agree or suspect something else?

thanks in advance..

 

[telectrix]

you are on the right lines. for e.g. a 3kva 240V/110V site transformer will only pull 13A@ full load, but even unloaded, will trip a 16A MCB on start-up. a type C MCB is advised.

 

[Octopus]

Don't forget to check the Zs of the circuit before changing to the 6A type C

What size cable is it? You could try a 10A type B

 

[Jamzie]

Fitted some suspension lamps in a kitchen a few years back. Tranny was massive and hummed like bu$gery. Changed it for an electronic transformer. Worked a treat, plus it can be dimmed. You won't get any inrush current issues with one either

 

[Guest77]

Agree with Tel (this once :biggrin I have had the same problem myself and changed the MCB to a C type, it held when a B wouldn't.

 

[Knobhead]

Once a week I used to switch a 2000KVA transformer on. It even frightened me when it shot of scale 200A+ @11KV.

Have a look on Google for "transformer inrush and magnetizing currents" if you want to understand why it happens, otherwise just stick a C or D MCB in.

 

[Quantum dan]

Thanks guys. I think I'll try a type c and see how I get on..

 

[davesparks]

Thanks guys. I think I'll try a type c and see how I get on..

Only after confirming that the Zs is suitable for a type C, you cant just go swapping types to see what happens!

 

[ImpededLoop]

Don't forget to check the Zs of the circuit before changing to the 6A type C

What size cable is it? You could try a 10A type B

As Murdoch says, check the Zs first to ensure you'll comply with disconnection times if you change the breaker.

 

[Knobhead]

He's shafted if it doesn't

 

[Quantum dan]

Zs was fine and so was the type c. Instant cure!

 

[telectrix]

ta for posting the result. what was the Zs, btw?