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| m3vuv:
hi all i have a diode bridge rated at 50 amp,if i use one diode from the bridge as a blocking diode for a charging system,would it handle 50a or 1/4 as its only one diode,ie 12.5a?,cheers m3vuv. |
| floobydust:
I think you can pass rated 50A out of any one diode. The current rating is the "maximum average forward output rectified current" below 60 ̊C temperature. Heat is the limiting factor, used as an AC rectifier a pair of diodes is on 1/2 the time. At 50A and 1.2Vf that's 60W of heat to dissipate in a single diode. Taitron MB5005 50A bridge datasheet pdf You could parallel two and use that out of the bridge for less stress on the part. But still 60W. At those currents, MOSFETS might be more attractive due to their much lower losses and heat generation. 60W requires a huge heatsink. |
| m3vuv:
its for the train regulator ive built,it needs a 100 amp blockind diode,they are expensive,im trying to find a way of doing it cheap. |
| digsys:
As been pointed out - there is no free meal ! :-) Any Si diode will incur a 0.8-1.0V drop at that current and temp rise (if it is well heatsinked). You may find lower Vf ones, but they will cost more. The "proper" 100+A blocks WILL cost a lot more. An ideal diode ie IC and FET pair will likely be cheaper with a LOT less heat, but still cost several $s If you want "real cheap", just wire 100x 1A diodes in parallel ? A few cents ea. Might look ugly, but it'd work. |
| bob91343:
You can parallel two or even four diodes. Trouble is, diode voltage drop goes down as it warms so unbalance gets worse with higher currents. You could select the diodes and put them in a series parallel arrangement with a high and a low in each side. Anyway, 100 A at maybe 1 Volt is a lot of power to dissipate. You could raise the rating a bit by bolting it to a heat plate and force some air over it. As has been said, there is no free ride. |
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