What is the value of these bridge rectifiers?

[gary350]

I can not find a datasheet of any of these bridge rectifiers. I did find information that said MDA 952-5 is 400v 200a but I find it hard to believe this tiny thing is rated 80KW

Part numbers are.

MDA 990-4 bridge rectifier

MDA 962-5 bridge rectifier

MDA 952-5 bridge rectifier

 

[ronsimpson]

MDA952 is 6A.

 

[ronsimpson]

MDA962 is 10 amp

 

[AnalogKid]

There is some variability among manuracturers and cross-reference tables. Here are representative numbers. For all cevices, the -5 suffix indicates a 400 V PIV rating.

MDA962 = 10 A continuous, 300 A 1-cycle surge.

MDA952 = 6 A continuous, 125 A single-cycle surge.

MDA90 = 30 A continuous, 300 A single-cycle surge.

ak

 

[ronsimpson]

The 300A is for one cycle then you must stop and let it cool off. At 300A the diode will die in 20mS

 

[gary350]

What is voltage rating?

We are 1/2 way there.

 

[ronsimpson]

 

[unclejed613]

but I find it hard to believe this tiny thing is rated 80KW

the voltage spec is for inverse (i.e. when the diode is not conducting) and the current is the maximum current in the forward direction. with forward conduction, the drop across the diode is only 0.7V, so, for instance the MDA-962 at 10A would only dissipate 7 watts (actually 14 watts, since you have two forward biased diodes at a time in a bridge rectifier.

 

[AnalogKid]

with forward conduction, the drop across the diode is only 0.7V, so, for instance the MDA-962 at 10A would only dissipate 7 watts (actually 14 watts, since you have two forward biased diodes at a time in a bridge rectifier.

The forward voltage is listed as 1.2 V at 12.5 A, 71% greater than 0.7 V. The full-wave power dissipation at 10 A would be close to 24 W.

ak

 

[unclejed613]

The full-wave power dissipation at 10 A would be close to 24 W.

that's still a manageable amount of heat.... nowhere near 80kW