[Amps] Solid State Relays Again

[TexasRF at aol.com]

Additionally, the step start R will alter the phase relationship as the  
load is primarily resistive when it is in the circuit.
 
So, perhaps the more critical scenario is at switch off?
 
73,
Gerald K5GW
 
 
 
In a message dated 2/10/2014 10:47:40 A.M. Pacific Standard Time,  
g8on at fsmail.net writes:

If you  switch at zero voltage, there is no EMF to drive a current through 
the load  impedance. A quarter cycle later, when there is EMF across the 
load, the  current will lead or lag by a factor depending on the phase angle 
and  magnitude of the impedance. So there's a difference between the transient 
 condition existing for the first part of the cycle - probably somewhere  
between 5 and 10 degrees -  and the stabilised condition. But the initial  
switch of zero volts must be with zero current.

73

Peter  G3RZP


========================================
Message Received:  Feb 10 2014, 06:24 PM
From: donroden at hiwaay.net
To:  amps at contesting.com
Cc: 
Subject: Re: [Amps] Solid State Relays  Again

Quoting Peter Voelpel <dj7ww at t-online.de>:

> I  guess with transformers the relay should switch in on the peak  
voltage.
> As current peaks 90 degree behind that should be the best  moment with 
least
> surge current.
>
> 73
>  Peter



But if you switch at zero voltage, the current is at zero  90 degrees 
later...

So you have at least 1/4 of a cycle where there is  minimum IxE  
supplied to the load.

Don  W4DNR

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