Fuses AC and DC

Fuse characteristic is guided by Isquare t characteristic. hence ac, dc is not a criteria.

The I²t may determine the breaking current & time, but the current breaking capacity is lower for DC. No time to look it up now - will try later.

Sparkstation

You have elaborated the answer. Thank you.

Helpful info. Thanks

Ashok Toshniwal, Bangalore - India

The answer is probably, yes.

Current capacity is equal for both AC or DC, however, The voltage ratings of a fuse is the highest voltage that the gap opened by the blown fuse, will still withstand without arcing. As DC tends to arc when the line is open the gap distance must be taken into account. For that reason under DC circuit conditions, some de-rating must be calculated. In your case the margin is over 100% which will be ok even in the case of slow acting fuses, so I would say it's safe enough.

Hope it helps

Wangito.

While the answer is probably yes, if apsauginis fits a fuse which is not approved for purpose by his local regulating authority (UL etc.), and something goes wrong, he could be in serious hot water.

Fundamental fact AC current rises and falls, and drops to ZERO (0) 120 times a second. This cessation in current flow makes it much easier for an ionized flow path (arc) to be extinguished and the current permanently interrupted. We use a convention in terminology with AC. Remember 120VAC means the voltage and resulting current is such that it has the same resistance heating of 120 VDC. The true peak voltage and current flow is 1.4 times the Root Mean Square (DC equivalent) value.

With DC voltage, the current does not ever drop and ionized current flow path (ARC) is much more difficult to extinguish. Wider gap and/or arc quenching materials/features are required.

Check with the manufacturer of your specific device to ascertain its suitability for the intended purpose.

Warning, never use AC fuses in place of DC fuses unless the fuses are rated to do so. If you look at a fuse, circuit breaker, relay, etc generally they give the manufacturers ratings. The problem with DC is the arc or lack of resistance in the air with DC.

As a rule AC collapses on it self, hence the term "alternating", while DC once an arc is created, it will not stop until the current does or the oxygen is depleted sufficiently.

If I am wrong please correct me. Teaching photovoltaics I preach never to use AC rated breakers or fuses unless they are specifically rated for that application. Up to this point only Square D has a DC rating. Bussman and other fuse manufaturers list the ratings of their fuses also.

be careful DC KILLS, but leaves a nice charcoal smell.

Regards.

Large Fuses now have some special design features:

1. Silica-sand of very small Grain-size is filled in the Tube / Shell to provide "Quenching" for ARC.

2. Fuse Elements have multi-Fusing Points & 2 or more elements are used in parallel; each separated by

Silica-sand fill.

3. Most of styles are Air-Tight.

Normally are used on AC & DC; of course AC has an advantage over DC of "Zero-Crossing" twice the Power Frequency.