[Amps] Step start resistors

[Marcinio Afonso Stabile]

Hi Peter!

I am using thermistors as inrush current limiters, for a variable frequency
AC drives, in a pre-charge system, to limit the charging current on the DC
bus capacitors. More information at Ametherm web site:

http://www.ametherm.com/Inrush_Current/welcome.html

I hope it could be a usefull idea. Here in Brazil, PY2WM (De Marco) tested
this solution on the rebuilt of your Delta 1000 linear amplifier (4 x 811A)
with sucess, using a thermistor removed from a surplus PC power supply. See
the description (in portuguese only, sorry!) at:

http://geocities.yahoo.com.br/jkdemarco/Delta1000/Delta1000.htm

73!

Marcinio Afonso Stabile - ZZ2TWT
Jaboticabal - SP - Brazil
http://www.stabile.eng.br/tubes

----- Original Message ----- 
From: <peter.chadwick at Zarlink.Com>
To: <amps at contesting.com>; <amps-bounces at contesting.com>
Sent: Monday, January 05, 2004 8:41 AM
Subject: [Amps] Step start resistors


>
> Any ideas on what values to use for step start resistors? In the past,
I've
> tended to choose a value from the available stock - something like 50
ohms,
> 100 watts, which limits the surge current to just over 4 amps. I expect
> that a value such that the current won't exceed the full load primary
> current of the transformer is probably best, but any suggestions?
>
> (I'll probably still use what's available in my stock of vitreous
enamelled
> wirewound resistors about 10 inches long and an 1 inch in diameter,
> though!)
>
> 73
>
> Peter G3RZP
>
>