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Will standard mcbs work on 12v AC?

hertzal123
The customer is using a 300va 12v tx to supply 5 no 60w takeaway heated food bags

and is having problems with the 5 no 10A ceramic fuse holders overheating on their spade terminals.

I wondered if B10 mcb,s would solve the problem,or would they be too slow to protect the tx on a short

cct on one output?

                         Regards,

                                    Hz
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    The MCBs will be fine - the whole ppoint is the that they are a series element that does not drop much voltage.


    They do come unstuck on DC however, or rather they don't - without the zero crossing of the AC waveform , they can weld - not an issue at 12V, but certainly a problem by you reach arc welding sort of voltages (50-80) .

    Some designs do not work at anything far from 50Hz, so the 'electronic transformers' that are really a switching supply at a supersonic frequency, as used to generate "12V AC"  for some light fittings, can cause them to trip at the wring setting.


    I'd be tempted to look at the wiring to the fuse holders first - this is almost automotive quality

    regards Mike.

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  • 0
    The MCBs will be fine - the whole ppoint is the that they are a series element that does not drop much voltage.


    They do come unstuck on DC however, or rather they don't - without the zero crossing of the AC waveform , they can weld - not an issue at 12V, but certainly a problem by you reach arc welding sort of voltages (50-80) .

    Some designs do not work at anything far from 50Hz, so the 'electronic transformers' that are really a switching supply at a supersonic frequency, as used to generate "12V AC"  for some light fittings, can cause them to trip at the wring setting.


    I'd be tempted to look at the wiring to the fuse holders first - this is almost automotive quality

    regards Mike.

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