Normally closed SSR's?

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You need to be more specific. What are you switching and what is your input.

Fair enough.

I want to run an HLT (115v 2kw) and a RIMS Tube (220v 3.5kw) from the same 115v 20A outlet. I want the PID controlling the RIMS tube to run 2 SSR's: the first closing, powering the RIMS heater on, and the other opening, to cut power to the HLT element.

So, the input would need to be PID driven. On the controlled side, it could be 115V 20A, or it could be low voltage DC, either way.
 
Search for MOSFET form B SS relays, made by many manufacturers.
MOSFET's are DC devices, also available for AC switching.


Cheers,
ClaudiusB

I've always heard of MOSFET's, but don't know what they are. I guess I know what I'm going to be reading about tonight.
 
That's plan B, but I was hoping to keep the control solid state.

Problem with solid state is that you need some sort of energized circuit to do anything. I second the relay idea, there are mechanical relays designed for billions of operations, very reliable.
 
I'm planning on doing the same for the HLT and BK. Was going to use a relay but thought there must be an easier way.

My design will have an on/off switch for each of the elements, the NC contact is used in series with the other switch making it impossible to power both at the same time.
 
Why not get a 120 volt reed relay and install it across the RIMS SSRs in parallel with the element.

Then you hook the normally closed side of the relay to the trigger signal for the HLT SSR.

So this way, when the RIMS fires it triggers the relay, opening the normally closed switch, breaking the trigger for the HLT SSR.
 
Pretty much all relays I've seen on ebay for example.

I'm using these:
1
http://cgi.ebay.com/Solid-State-Relay-SSR-24-480-VAC-40A-Heat-Sink-/150508876837?pt=LH_DefaultDomain_0&hash=item230b073425


That is a normally open relay.

Think of closed/open as a wire connection instead of like a door or faucet.
When it is closed, it allows current to flow, when it is open, current is stopped.
 
Pretty much all relays I've seen on ebay for example.
hrafnkell sorry for answering so late, but I am recovering from my second Oktoberfest and I was in charge this time.
Sawdustguy helped me out and gave you the answer.
Edit: Fixed link
Here is the picture showing your MGR-1 SSR NO output, click to enlarge
http://cgi.ebay.com.sg/Lot-1-Solid-State-Relay-SSR-24-480V-AC-40A-/160471380891
hrafnkell using a NC SSR to control temp with most temperature controllers could be a disaster. The controllers output logic requires NO devices (positive logic) unless the logic can be inverted.

Cheers,
ClaudiusB
 
...Why not get a 120 volt reed relay....

Because, judging from the responses here, I've drastically underestimated the life expectancy of the reed relays.

Am I correct in thinking that there's no reason I couldn't do the same thing with an 8v dc relay on the signal side?
 
chuckjaxfl,
did you find a suitable nc relay? I'm in the same position, looking to ensure both elements can't be on together. Since it's fed from and controlling and SSR signal, the relay only has to take 12V and a few milliamps.

I found plenty of reed relays, but all DIL/SIL. Ideally I'd like something that I can mount on the panel backplane.

what did you end up using?
 
chuckjaxfl,
did you find a suitable nc relay? I'm in the same position, looking to ensure both elements can't be on together. Since it's fed from and controlling and SSR signal, the relay only has to take 12V and a few milliamps.

I found plenty of reed relays, but all DIL/SIL. Ideally I'd like something that I can mount on the panel backplane.

what did you end up using?

Just discussed this the other day.
https://www.homebrewtalk.com/f170/element-switching-relays-218950/
 

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