[Amps] SSR in amp PS not working as expected

[Ulf Tjerneld]

Oh… din’t know Paul was SK. I bought a few tuned input boards from him a few years ago. Great guy, great build. I’ll take a look in his gallery and see if there are any comments. I know he proposes SSR in his control board, but no reference to what types he uses.
K8RA also uses SSR:s in his handbook-build. But they are random fire. That might Work better…

< I don't like solid state relays for this reason and others in this 
application. I still use sealed 20 or 25 amp relays. Never had a failure 
yet.>

I’ll probably end up there too. Now I just want to dig to the bottom of the challenge and learn something on the way.


/ulf

Sent from Mail for Windows 10

From: Jim
Sent: den 9 januari 2019 02:29
To: amps at contesting.com
Subject: Re: [Amps] SSR in amp PS not working as expected

Hey Ulf....

The late Paul, WD7S, had issues with this too... Or was it was the late 
Jerry, K8RA... I don't remember. Both great guys!

One of them had the same issue where they had to add a resistor across 
the primary of the plate transformer to stop this exact thing.

Take a look at WD7S's site. It's till on line... You may find were has 
pictures of the resistor across the transformer primary and an 
explanation of why...

I don't like solid state relays for this reason and others in this 
application. I still use sealed 20 or 25 amp relays. Never had a failure 
yet.

Let us know.
73
Jim W7RY

Thanks
73
Jim W7RY

On 1/5/2019 4:59 AM, Ulf Tjerneld wrote:
> Hi All,
>
> I start with the question:
> Is there anything around SSR:s in general or anything in particular around the Crydom CSD2525P that I don’t’ understand when used as breakers and step -start in a HV PS?
>
> And the background:
> After a few years off the reflector and amp building I recently dusted off my big-ultimate-amp-project and took up the work again.
> This winter’s focus is the PS. I thought it could be nice to use SSR:s in the AC-circuit for breaking and step-start. I have never used SSR:s before, but I expected it to work as planned as I perceive them as pretty simple devices. Anyhow, I bought three surplus SSR:s off Ebay, Crydom CSD2525P rated at 25A, and built a standard breaking and step-start circuit around them.
> Everything was tested with a low voltage 230/12 Volt small transformer on the bench. It works as expected; the two SSR:S in the 230V line switches on and the third SSR shortens the inrush resistor after about a second of delay.
>
> But, when testing with the HV-transformer, it doesn’t work.
>
> The HV transformer is boxed in the chassis and disconnected from all secondary loads. The HV-output is isolated and off from anything in the circuit. I measure voltage on the 105 volt secondary winding. The only things outside of the box is the multimeter and the 12Volt DC control voltage. After applying control voltage the SSR:s in the AC line actuates and the transformer starts to hum, which it shouldn’t, and after a second the step-start SSR actuates and the transformer starts to hum loudly. The reading on the 105V secondary was close to zero.
>
> The transformer in itself is a custom made 2KVA toroid beast wound for me in Germany in 2013. With the breaking circuit out of the loop, the transformer is almost inaudible and delivers as expected in the 105V secondary,
>
> So, the question is: is there anything around SSR:s in general or anything in particular around the Crydom CSD2525P that I don’t’ understand? Please advise! 😊
>
> /73’s SM0NOR - Ulf
>
>
>
>
>
> Sent from Mail for Windows 10
>
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