OftenBaffled 0 Posted July 24, 2011 Chaps, I have a 30 Amp (Max.), 20 channel, regulated CCTV power supply with each channel being overload protected by a PTC 'fuse' rated at 1.5 Amp. Is it OK to utilize 3 channels simultaneously, wired in parallel, to power my multiplexer which pulls 4 Amps max? Apologies for what seem like a daft question, I'm pretty sure that it is OK but thought it best to check before proceeding. Thanks in advance, OB Share this post Link to post Share on other sites
mike_va 0 Posted July 24, 2011 Chaps, I have a 30 Amp (Max.), 20 channel, regulated CCTV power supply with each channel being overload protected by a PTC 'fuse' rated at 1.5 Amp. Is it OK to utilize 3 channels simultaneously, wired in parallel, to power my multiplexer which pulls 4 Amps max? The one subtlety is due to the variation in resistance of the PTC's you may not end up with good current sharing between them (the resistance of the PTC's will likely dominate current sharing since you'd be tying together at the PS). I just took a quick look at some PTC's on digikey. Looking at a very worst case scenario you may have two carrying 1.5A, one at 1A. You might want to consider using 4 outputs (to end up potentially with 3x 1.25 and one at 0.75A potentially for example). No telling what you'll get until you try it. Like the other post said, SHOULD work. Note: in space applications we used "matched" fuses if they are not available in a large enough rating. I can't remember all the details as to why right now, I need my morning coffee. If I were doing this I'd also consider just adding the right size fuse. Share this post Link to post Share on other sites
OftenBaffled 0 Posted July 24, 2011 Many thanks for the speedy and informative replies. I have plenty of spare channels so I'll give it a go using four of 'em. All the best, OB Share this post Link to post Share on other sites
