Dear friends;
I am new in this Forum.
I have an Automatic voltage stabilizer 5KVA 220V +/- 3% with 24VDC servomotor control for fans in a school. I have been facing a problem for one year that two power transistors D401 and B546 installed on its PCB break down frequently. I replace but after one or two months, one of them or both break down. For me, when ever local power supply shut down and then again comes and all the fans were already switched on, the failure of transistor(s) then appear. May be I am completely wrong as I could not find the real cause.
This is a local designed stab which worked perfectly one years after purchasing. I have replaced its servo motor but fault did not remove. Replacing the trans again and again also damaged the PCB. Now I have been thinking to replace the both transistors with doubled capacity. Any tip from anyone? Can anyone help me out which transistors would be better for replacing the old?
I am new in this Forum.
I have an Automatic voltage stabilizer 5KVA 220V +/- 3% with 24VDC servomotor control for fans in a school. I have been facing a problem for one year that two power transistors D401 and B546 installed on its PCB break down frequently. I replace but after one or two months, one of them or both break down. For me, when ever local power supply shut down and then again comes and all the fans were already switched on, the failure of transistor(s) then appear. May be I am completely wrong as I could not find the real cause.
This is a local designed stab which worked perfectly one years after purchasing. I have replaced its servo motor but fault did not remove. Replacing the trans again and again also damaged the PCB. Now I have been thinking to replace the both transistors with doubled capacity. Any tip from anyone? Can anyone help me out which transistors would be better for replacing the old?