[Amps] Soft Start

[TexasRF@aol.com]

An interesting characteristic of an AC relay is that it buzzes like crazy  as 
the voltage ramps up to the value it needs to fully operate. I assume that  
the relay contacts are doing that as well which probably doesn't hurt  anything.
 
If the tube has a directly heated cathode, the filament typically has about  
1/10 resistance cold vs. hot. The limiting resistor would be a big help in  
reducing the filament current at turn on and that is a good thing.
 
Solid state timers are available from Grainger for about $20, and are  
adjustable over a wide range of times. They simply connect between one of the  relay 
coil terminals and the AC supply voltage; could not be easier to install  and 
work perfectly.
 
73/K5GW
 
 
In a message dated 8/12/2005 12:21:11 P.M. Central Standard Time,  
theo.bellamy at spirittelecom.com writes:

silly me  .... that works with a B+ supply, but probably not with a filament
xmfr.  Sorry ....

Theo

-----Original Message-----
From:  amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
Behalf  Of Theo Bellamy
Sent: Friday, August 12, 2005 1:00 PM
To:  amps at contesting.com
Subject: Re: [Amps] Soft Start


Why not just  put the soft start relay coil across the primary. Since there
will be a big  voltage drop across the step start resistors - leaving very
low voltage  across the transformer primary until the filters charge - the
relay will be  timed "naturally". This will also protect against an open step
start  resistor since the relay won't ever fire in that case.

Theo  K4MO



-----Original Message-----
From:  amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
Behalf  Of Rich
Sent: Friday, August 12, 2005 12:21 PM
To: Amps
Subject:  [Amps] Soft Start


OK guys I made the subject soft start , but that  about the only thing
right this time.  The resistor should be big  enough , 50ohms 100w. It
all worked one part at a time but when I hooked it  all up together my 60
main power relay chatters , I am going to rewire and  not run the coil
supply for the 60 amp through all the relays. I have the  120- control
voltage daisy changed the coils and I think I am getting VD.  That aint
good.
I am able to adjust the delay as required from .15 sec  to 180  with the
Dayton relays so ignore my original statement about  10sec delay on HV, I
will adjust it.
More when I know  more.

Rich ,  kd0zz
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