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Alternator Fuse?
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Alternator Fuse?
On Wed, 29 Apr 2009 08:39:55 -0500, Richard Casady
wrote: On Wed, 6 Nov 2002 11:02:15 -0500 (EST), (Ron Thornton) wrote: Whenever I have shorted out an alternator, the diodes blow in about 2 nanoseconds. If the alternator output to the battery shorts, the source for power becomes the battery. So it you are going to fuse it, fuse it at the battery end cause the other end (diodes) opens up real quick. A fuse can go anywhere in a wire, it makes no difference, the current is the same everywhere along the length of it. And I will just bet the diodes would protect any fuse by blowing faster. Putting a fuse in the output of an alternator is not a good idea and contrary to normal practice. If the fuse blows the alternator will be running with no load which will increase the voltage level and exceed the PIV rating of the diodes. The output of the alternator should go directly to the engine starting battery. Any other connection such as a house bank can be fused however. |
Alternator Fuse?
On Wed, 29 Apr 2009 11:22:32 -0400, Wayne.B
wrote: On Wed, 29 Apr 2009 08:39:55 -0500, Richard Casady wrote: On Wed, 6 Nov 2002 11:02:15 -0500 (EST), (Ron Thornton) wrote: Whenever I have shorted out an alternator, the diodes blow in about 2 nanoseconds. If the alternator output to the battery shorts, the source for power becomes the battery. So it you are going to fuse it, fuse it at the battery end cause the other end (diodes) opens up real quick. A fuse can go anywhere in a wire, it makes no difference, the current is the same everywhere along the length of it. And I will just bet the diodes would protect any fuse by blowing faster. Putting a fuse in the output of an alternator is not a good idea and contrary to normal practice. If the fuse blows the alternator will be running with no load which will increase the voltage level and exceed the PIV rating of the diodes. The output of the alternator should go directly to the engine starting battery. Any other connection such as a house bank can be fused however. If the alternator is producing electricity and you open the connection to the load it probably will blow the diodes. In fact West Marine, among others sells a diode to wire across the output terminal to ground to dissipate the IV. Cheers, Bruce in Bangkok (bruceinbangkokatgmaildotcom) |
Alternator Fuse?
Richard Casady wrote in
: On Wed, 6 Nov 2002 11:02:15 -0500 (EST), (Ron Thornton) wrote: Whenever I have shorted out an alternator, the diodes blow in about 2 nanoseconds. If the alternator output to the battery shorts, the source for power becomes the battery. So it you are going to fuse it, fuse it at the battery end cause the other end (diodes) opens up real quick. A fuse can go anywhere in a wire, it makes no difference, the current is the same everywhere along the length of it. And I will just bet the diodes would protect any fuse by blowing faster. Casady Apart from the arguments against fusing the output of the alternator, I believe that ABYC requires the fuse to be placed within 3 feet (I'm going on memory here) from the source of the power output. I assume that they require this to keep you from having long, unfused runs of power lines that aren't protected. Placing a fuse at the end of the run would protect the device in case of overload, but wouldn't protect the line from a short. -- Geoff www.GeoffSchultz.org |
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