Re: Soft transformer turn on without a variac

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

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?

I'm enjoying the strange waveforms of input current to unloaded
transformers, nice peaks you can shape with a resistive load or capacitors.

KEN


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, October 31, 2003 2:37 PM
Subject: Re: Soft transformer turn on without a variac


 > Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
 >
 > At 01:22 PM 10/31/2003, you wrote:
 > >I'm going to stick with zero crossing turn on is not a bad idea. I
started
 > >to rig up a test setup to try this. I'll switch on a large power
 > >transformer at various parts of the AC cycle and have the core magnetized
 > >with a DC current in another winding.
 > >KEN
 >
 > I am (will) use solid state zero crossing relays for my sync motor dwell
 > controller.
 >
 > http://www.pupman-dot-com/listarchives/2003/June/msg00253.html
 >
 > In the testing I did, it seemed to help the turn-on current spikes
greatly,
 > but I have a big cap in there too...  Seems when you turn on the thing at
 > maximum voltage, is where the problems occur.  Interesting to see what Ken
 > finds out here too...  Those solid state relays are great, but they cost
 > about $50.
 >
 > Cheers,
 >
 >          Terry
 >
 >
 >