thyristors/diodes 1

[majuba]

Hi

How do I test a thyristor/diodes?

Can anybody suggest a maintenance interval/strategy for a thyristor operated device?

I am interested in a generic output waveform expected from a thyristor. Can somebody please explain the concept of the firing angle and how it affects the operation of a thyristor?

Thanks in advance

 

[fangas]

Good Morning,

That's a lot of explanation. I would suggest that you get a book on SCR theory. GE's SCR Handbook ( if it's still published) is excellent. Even an out of date one. Mine is from '63 but, I still find occassion to use it.

A quick explanation. By varying the phase angle at which the SCR conducts, you change the effective voltage.

Good luck

 

[mvcjr]

Briefly, if you fire at 0 degrees your voltage wave output (for a half-wave rectifier) will be a full half-cycle of a sine wave voltage. At 90 deg firing angle you'll get only half of the half-cycle of the sine wave voltage.

God bless!

 

[Skogsgurra]

The best maintenace strategy has very little to do with waveforms. What you have to do is to check the temperature now and then and change ventilators every 15 000 or 20 000 hours, depending on what the manufacturer says. If the environment is dirty, then it is important that the filters are changed when they get clogged (or rather before that happens). Also, if the heat sinks get hot (without overload and working fans), you may have to clean them between the fins (a dirty but necessary work).

Thyristors need no maintenance, but it is very good if you know something about their operation. There are many tutorials available on the web. Do a google search for SCR, thyristor, DC drive and such things. The previous posts have told you some of the fundamentals and the rest is out there.

Good luck

 

[jbartos]

Suggestion: Visit

http://www.divdev.fsnet.co.uk/datab.htm

for: GE SCR Handbook