[Amps] soft start, how to determine if needed?

[Felipe Ceglia - PY1NB]

Folks,

Thank you for your replies.

Is there a way to calculate what R values and relay contact Amp rate 
should I need?

Also, if the primary is feed with 110+110 volts, I should use one R on 
each primary leg winding, right?

73 tu,

Felipe - PY1NB




Edward Swynar wrote:
> Hi Guys,
>
> FWIW, I had to re-build my rectifier stack at least twice before I finally
> incorporated a soft-start / step-start scheme in the primary of my B+
> transformer...
>
> The p.s. is a full-wave rectifier job, applying 2.5 KV to a pair of 813s.
>
> Since incorporating the scheme, I have had no further troubles in this
> regard.
>
> As someone said before me, it's "...cheap insurance", and not all that
> daunting a task to add-in, even after the fact.."
>
> ~73~ de Eddy VE3CUI - VE3XZ
>
>
> *******************************
>
> ----- Original Message -----
> From: "Alex Eban" <alexeban at gmail.com>
> To: <felipe at dxwatch.com>; <Amps at contesting.com>
> Sent: Wednesday, February 24, 2010 3:39 AM
> Subject: Re: [Amps] soft start, how to determine if needed?
>
>
>   
>> As far as possible, USE ONE!!!!!
>> First, the cold resistance of a tube's filament is as low as one tenth of
>> the warm filament, so inrush currents can reach 10 times the operating
>> value.
>> Second, inrush current of a HV power supply can reach a hundred amperes,
>> measured with a Tektronix current probe. If nothing else, that current can
>> weld the switch contacts!
>> I don't have to tell you that the stresses on the rectifiers don't do any
>> good and the capacitors are also badly stressed.
>> Today, almost all integrated circuits intended for power supply control
>> incorporate some form of soft start circuitry, precisely for reducing
>>     
> these
>   
>> stresses.
>> Use step start or soft start, it's very cheap insurance.
>> Alex 4Z5KS
>>
>> -----Original Message-----
>> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
>> Behalf Of Felipe Ceglia - PY1NB
>> Sent: Tuesday, February 23, 2010 3:34 PM
>> To: Amps at contesting.com
>> Subject: [Amps] soft start, how to determine if needed?
>>
>> Hi folks,
>>
>> Regarding this recurring topic about soft starting...
>>
>> How can one determine if it is needed or not?
>>
>> Should HV be soft-started as well?
>>
>> What would be the best math to determine the soft-start dumping resistors?
>>
>> 73,
>>
>> Felipe - PY1NB
>>
>> --
>> Felipe Ceglia - PY1NB
>> --------------------------------------------------------------------------
>>     
> --
>   
>> ---------
>> PR1T team member /// Rio DX Group member /// Araucaria DX Group member
>> http://www.dxwatch.com /// http://reversebeacon.net ///
>> http://riodxgroup.dxwatch.com
>>
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>>     
>
>
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>   

-- 
Felipe Ceglia - PY1NB
-------------------------------------------------------------------------------------
PR1T team member /// Rio DX Group member /// Araucaria DX Group member
http://www.dxwatch.com /// http://reversebeacon.net /// http://riodxgroup.dxwatch.com