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Looking For Cheap Ssr S (solid State Relays)

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BrissyBrew

MashMaster
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I am in the process of building control boxes for the PIDs I picked up off ebay and I need to by some SSRs

I am located in Brisbane

I need some sold state relays to switch my heating elements. I was thinking of going for overkill say 30A or 40A so I can always use my control box later on if I expand my system.

The other thing I was thinking about should I be using bi pole SSRs?
Can I set it up so one relay trips two other relays as I can see it being a handy thing to have.

Anybody with experience with this kind of thing is more than welcome to provide feedback and suggestions
 

Gulf Brewery

Microbrewed beer at it's best
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BrissyBrew said:
I need some sold state relays to switch my heating elements.
[post="64970"][/post]​
Hi BrrisyBrew

I bought a couple of SSR's from futurlec for my HERMS system. I haven't used them yet (another long story). The full specs of the SSR's are on their US site.

You can setup a relay to trip 2 more, but you would use a standard relay to drive the control lines of the SSR's. Hope that makes sense.


Cheers
Peter
 

Jye

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Hey BB,

I used this relay when making a thermostat for my fridge, jaycar also has a few other large ampage relays.

Hope this helps.
Jye
 

MAH

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BrissyBrew said:
I am in the process of building control boxes for the PIDs I picked up off ebay and I need to by some SSRs...............................I need some sold state relays to switch my heating elements. I was thinking of going for overkill say 30A or 40A so I can always use my control box later on if I expand my system.
[post="64970"][/post]​
In the application your suggesting 30A is unlikely to be overkill. When using a SSR for driving a heater load and the load is cycled on and off in a continuous manner eg in a temperature control, it can cause thermal fatigue in the thyristor chip at the point where the chip bonds to the lead frame. Consider operating any SSR at 75% rated current for cycling heater loads to ensure complete reliability. Therefore a 10A SSR should only be used for 7.5A or an 1800w element. The next step up are usually 25A or 30A SSRs, so one of these would the minimum for a 2400w element. If you were thinking of latter using 4800w, the 30A wouldn't be enough.


BrissyBrew said:
Can I set it up so one relay trips two other relays as I can see it being a handy thing to have.
[post="64970"][/post]​
No (if you mean running them in parallel). There is no way to guarantee that two or more relays will turn on simultaneously when operated in parallel. Each relay requires a minimum voltage across the output terminals to function; because of the optical isolation feature, the contact part of the SSR is actually powered by the line it switches. One relay turning on before the other will cause the second relay to lose its turn-on voltage, and it wont ever turn on, or at least not until the first relay fails from carrying too much current.

Cheers
MAH
 

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