24 volt dc

guest119 · Jan 30, 2013

Seen an ammended control panel today sporting a bs 60898 DP type C 2 amp mcb controlling 24v dc.

Usually weidmuller etc din rail fuseblocks and links.

Something I am missing?

Boydy

Knobhead · Jan 30, 2013

And the problem is?

dan86 · Jan 30, 2013

Boydy said:
Something I am missing?

I think there's something We're missing here!

ian.settle1 · Jan 30, 2013

Hang about Tel will be along soon with his crystal ball again.

dan86 · Jan 30, 2013

he'll have had too many broons by now!

chrish_1977 · Jan 30, 2013

I've consulted the magic 8 ball and it says more info please

dan86 · Jan 30, 2013

mine says cannot predict now

Knobhead · Jan 30, 2013

No, still can't see it.

guest119 · Jan 30, 2013

Aye, youre a cruel lot.
Searched this one and found the dc voltage rating shown by manufacturers to be 60v upwards.
Multi 9 System UL 489 Miniature Circuit Breakers - Schneider Electric Schneider Electric

Boydy

Knobhead · Jan 30, 2013

What size is the supply transformer feeding the rectifier?

Engineer54 · Jan 31, 2013

Boydy said:
Seen an ammended control panel today sporting a bs 60898 DP type C 2 amp mcb controlling 24v dc.

Usually weidmuller etc din rail fuseblocks and links.

Something I am missing?

Boydy

I can't see what your problem is or what your missing?? lol!! MCB's protecting DC circuits is perfectly acceptable, when they are designated suitable for DC protection by the manufacturer!!
BTW, the Schneider web page you linked too, is from they're USA site...

Guest111 · Jan 31, 2013

Engineer54 said:
I can't see what your problem is or what your missing?? lol!! MCB's protecting DC circuits is perfectly acceptable, when they are designated suitable for DC protection by the manufacturer!!
BTW, the Schneider web page you linked too, is from they're USA site...

An understanding of the functioning of mcb's perhaps?

Darkwood · Jan 31, 2013

C60HB, C60HC and C60HD are suitable for 24v DC .....

The number of poles required on your DC breaker is determined by the type of DC system you have:-

1- one polarity of dc supply is earthed
2- center point of the dc supply is earthed
3- insulated systems

As already mentioned you linked to a mcb designed to comply to UL requirements as areas including USA have differing regulations from us and the mcb's we use would not comply in their control systems..hence you have a differing dc rating and you have got yourself confused.

SheffSimon · Jan 31, 2013

I generally spec slow blow fuses for protecting 24Vdc circuits, for cost and panel space reasons.

Clive P · Jan 31, 2013

Hi,

Schneider MCB's are acceptable for DC provided you follow their guidance, they generally have to be down rated though. In their catalogue they have a page on 'DC operation of Miniature Circuit Breakers'.

Regards.

Knobhead · Jan 31, 2013

Apart from Phil can none of you realise the significance of my asking what size of the transformer feeding the rectifier was? Hint PFC!

Because DC doesn’t go through a neutral transition 100 times per second it is harder to break. To sustain an arc requires energy. You are not going to get that energy in a control panel due to the impedance of the control transformer feeding the rectifier! The energy let through is going to be minuscule!