On 16.05.19 21:18, Nicklas Karlsson wrote: > > ... > > I'd put the battery bank in an outbuilding. If something shorts out and > > the battery bank melts down, the little building may burn but my house > > won't. > > There certainly is a lot of power from a byttery and it could be a > little bit hard to turn off. You put a fuse at battery cable?
If local regulations do not require a HRC (High Rupture Capacity) fuse between the battery bank and any connection to it, then it's an invitation to disaster. A dc arc is much more difficult to extinguish, because there are no zero crossings, and molten metal can end up flowing on the floor. Small HRC fuses are generally in ceramic tubes, and are sand-filled, to quench the arc when the element fuses. The one I have on the desk beside me is a 100 A with a 100 kA (100,000 A) arc rupture capacity, but it's 27x44x49 mm, and is overkill. Just 10 times AH rating seems to be normal, i.e. 2000 A rupture capacity for a 200 AH bank. (The fault current will be limited by battery internal resistance.) > I also think DC relays have to be a little bit different than AC > relays, used an ordinary AC relay for a few few days connected to a DC > voltage and even though two switches is connected in series it > sometimes make a buzzing sound then turned off. Most relays and switches are marked with both AC and DC current ratings. The DC rating is always much lower, due to the difficulty of rupturing a DC arc. Rather than bother with maintenance/replacement due to contact deterioration after many switching cycles, I prefer to switch DC loads with MOSFETs - they're easy to parallel, as the inherently share. Erik _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
