Re: [tesla] Soft transformer turn on without a variac

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jwhitmor-at-muscanet-dot-com>

I have used Negative Temperature Coefficient Thermistors in power supplies 
before.
They are very simple inexpensive series devices, but they do need to be 
properly
sized for the average current draw. Check them out at:

http://www.ametherm-dot-com/Inrush_Surge_Limiters.htm

Other companies also sell NTC limiters. I bought mine from the "Digi-Key" 
catalog.


On 23 Jul 2003 at 18:53, Tesla list wrote:

 > Original poster: "Peter Terren by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <pterren-at-iinet-dot-net.au>
 >
 > Hi all.
 > For my 5 kW museum
 > coil,
 > 
<http://members.iinet-dot-net.au/~pterren/Scitech.htm>http://members.iinet-dot-net.au/~pterren/Scitech.htm 

 > ,   I need to have a single switch for turn on preferably without a variac
 > to keep things simple for the staff.  The present system has solid state
 > relays but is complicated and unreliable. I need to turn on the motor first
 > then a couple of seconds later soft turn on the power to the transformer.
 > Even switching  on power to a normal variac gives a spike that will trip my
 > lower current breakers. The whole system will have to be electrically
 > quiet.  Does anyone have experience with inrush limiters or have other
 > suggestions?
 >
 > Cheers
 > Peter (Tesla Downunder)
 >
 >
 >
 >
 >
 >