Re: Soft transformer turn on without a variac

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Robert Jones" <alwynj48-at-earthlink-dot-net> 

 > Original poster: "Crow Leader" <tesla-at-lists.symmetric-dot-net>
 >
 > I found this fun link about transformers and inrush current:
 >
 > http://www.allaboutcircuits-dot-com/vol_2/chpt_9/12.html
 >
 > which supports Gary. It turns out my solid state relays are "zero
crossing"
 > on the spec sheet, not phase (like I though) control so that screws up my
 > project. It does seem interesting you don't see any solid state relays
that
 > are 90 degrees off zero crossing or maybe "full voltage crossing"  for
 > transformers, or are there any?


Try this link http://relays.tycoelectronics-dot-com/app_pdfs/13c3206.pdf

It explains the transient x2 thing and with saturation the x2 and beyond
thing.  Its also mentions residual magnitisim which may perpetuate the view
that that has something to do with the surge.  In fact normal transformer
materials are selected to have low hysterisis ie the residual flux is low
compared with the induced flux hence the effects of residual flux on the
size of the surge will be small compared to the surge size without
saturation.


Bob