The way scr's and diodes are rated...
Quantum Singularity, Tue Aug 29 2006, 01:36PMThis is probably a basic question but wanted to confirm this. I have been looking for some higher rated diodes for various EMP projects I am starting on. Most of the ones I see cheap second hand are dual diode packs, and I have only really ever used just individual diodes before. So when the datasheet indicates V and I ratings that is for each individual one correct? Same goes for a scr/diode pack... both the scr and diode have the same V and I ratings?
And similarly take for example a 3 phase bridge rectifier that is rated for say 1000V and 100A and is comprised of 6 diodes. Used as a single diode (just hooking up the - and + terminals) should have a 300A rating? But are the individual diodes only rated at half the nominal rating so that 2 in series would then match the actual rating, or would it be double?
Just wanted a clarification since the datasheets dont really indicate individual parts of a 'pack'.
Re: The way scr's and diodes are rated...
Part Scavenger, Tue Aug 29 2006, 02:49PM
Well, I can help you with the second question. In a normal Bridge Rectifier, all the diodes are rated the same. In effect, a 600V, 20A recifier has 600V, 20A individual diodes. I would expect the three phase to be the same.
BTW, you stole my really cool avatar idea and made it look better! Shame!!! That's ok, I've been working on a new one anyway. Looks great.
Part Scavenger, Tue Aug 29 2006, 02:49PM
Well, I can help you with the second question. In a normal Bridge Rectifier, all the diodes are rated the same. In effect, a 600V, 20A recifier has 600V, 20A individual diodes. I would expect the three phase to be the same.
BTW, you stole my really cool avatar idea and made it look better! Shame!!! That's ok, I've been working on a new one anyway. Looks great.
Re: The way scr's and diodes are rated...
Sulaiman, Tue Aug 29 2006, 06:34PM
It is normal for power rectifiers to be specified in dc amps,
because that's usually the desired quantity,
so a Dual OR Bridge rectifier rated for say 600V 10A means
for 60 Hz sinewave input (sometimes 50 Hz) the 'rated' output current is 10 Adc.
(subject to temperature etc.)
This means that each diode has a peak current rating MUCH higher than 10A
(due to the expected 'pulses' of current)
Ifsm is usually quoted, maximum surge current
Sulaiman, Tue Aug 29 2006, 06:34PM
It is normal for power rectifiers to be specified in dc amps,
because that's usually the desired quantity,
so a Dual OR Bridge rectifier rated for say 600V 10A means
for 60 Hz sinewave input (sometimes 50 Hz) the 'rated' output current is 10 Adc.
(subject to temperature etc.)
This means that each diode has a peak current rating MUCH higher than 10A
(due to the expected 'pulses' of current)
Ifsm is usually quoted, maximum surge current
Re: The way scr's and diodes are rated...
Quantum Singularity, Wed Aug 30 2006, 12:17AM
Part Scavenger, thanks for the compliment. I occasionally rotate through avatars, this one actually isnt new, and originally designed about 5 yrs ago (check out my other 3d designs at
). Yours looks just as good! Back to the topic...
So then just to confirm take a common bridge rect rated at 100V 100A if you used it as one big diode by going across the + and - terminals you would in affect have a 200V 200A diode correct? And a 3 phase module with 6 diodes with the above rating would be 200V 300A correct?
But what about something like this
Were you have a module that consists of 2 diodes (in different arangements determined by the 2 letter code in the part number). Is the ratings given for the entire 'module' or each individual diode inside? The actuall rating like rms, dc amps, Ifsm, are all given in the datasheets I am not confused with that, but wether those ratings apply to the whole module or each individual part inside. I am always a little cautious when trying to pulse thousands of amps and try to make sure of the details ahead of time lol!
Quantum Singularity, Wed Aug 30 2006, 12:17AM
Part Scavenger, thanks for the compliment. I occasionally rotate through avatars, this one actually isnt new, and originally designed about 5 yrs ago (check out my other 3d designs at
). Yours looks just as good! Back to the topic...So then just to confirm take a common bridge rect rated at 100V 100A if you used it as one big diode by going across the + and - terminals you would in affect have a 200V 200A diode correct? And a 3 phase module with 6 diodes with the above rating would be 200V 300A correct?
But what about something like this
Were you have a module that consists of 2 diodes (in different arangements determined by the 2 letter code in the part number). Is the ratings given for the entire 'module' or each individual diode inside? The actuall rating like rms, dc amps, Ifsm, are all given in the datasheets I am not confused with that, but wether those ratings apply to the whole module or each individual part inside. I am always a little cautious when trying to pulse thousands of amps and try to make sure of the details ahead of time lol!
Print this page