[Amps] Zero Crossing circuit

[R.Measures]

On Nov 17, 2004, at 5:03 PM, jeff millar wrote:

> Ed...
>
> I've used zero voltage switched solid state relays twice in 2KW 
> amplifiers, one at 432 and one at 144 MHz.  The 432 amp included the 
> normal step start circuit, but once I noticed that the zero voltage 
> switching feature, I tried it without a step start in the 144 amp.  
> The circuit switched on with very little drama, the lights blinked 
> about the same amount as when transmitting at full power.
>
> One design note on high voltage power supplies suggested that 
> extremely high surge currents can damage electrolytic capacitors.  
> These surge current maximizes when the turn on relay or switch happens 
> to make contact at the peak of the line cycle.  The zero voltage 
> switching function reduces the surge currents to approximately the 
> same amount as what it takes to recharge the caps at the peak of the 
> line cycle.

Free, unsolicited advice:  Measure the peak mains-I in both situations 
with an oscilloscope before assuming that  this statement as valid.

> ...
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org