What relay for temperature controller?

Do you have the manual ? or can get a pdf off a web ?

It might mean 2 amp 'electro-motive' relay or else. You need to find out if it is a dry or wet output - e.g does it supply voltage and if so - what voltage. If dry, the contacts are thrown - you supply supply and the relay coil and sink. This is often done when the relay is far away.

Remember surge currents - currents of 10x value can occur when the windings are cool.

Martin

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Alex wrote:

Here is the link, model CN3001:

is this one dry or wet?

Thanks, Alex

Mart> Do you have the manual ? or can get a pdf off a web ?

For a heat treating oven you want to use a solid state relay (ssr) . When your oven reaches its setpoint the controler cuts on and off every few seconds to maintain the temp.If you use a contactor you will hear it clicking on and off hundreds of times an hour ,its just not made for your setup . Here is a picture of the controler and ssr relay I use on my homemade heatreating oven.

Tim,

do you mind telling me what exactly control and relay you used?

Thanks, Alex

tim wrote:

Hello Alex here are some links for the stuff you will need for cotroling your oven. Fuzzy logic controler with pluse output to control for solid state relay type K thomocouple solid state relay This is the same setup I have and it will hold the temp. within 2 deg. What kind of heating element ar you going to use? If you have more questions just ask. Tim Kallam

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It looks like you found your solution - I'd do the SSR - from Omega or another - and it drives another power module SSR outside of the box. The outside one is the high current one that matches the load and voltages needed...

The one inside protects the expensive box.

for the mechanical relays - look at this pdf - they relay contacts sets for form A and C...

And they look like dry contacts - e.g. nothing applied to either.

Martin Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Alex wrote:

You mean mechanical relay will be connected directly to Omega controller and this mechanical relay will drive SSR that actually turn on/off power to the heating coil?

Thanks, Alex

Mart> It looks like you found your solution - I'd do the SSR - from Omega or > another -

I don't know about element yet. Can you recommend me one? My oven will be 4"x4"x16" on inside. Temperature up to 2200F. Powered by 220V.

Thanks, Alex

tim wrote:

Correct me if I am wrong: mechanical relay is already INSIDE controller. I just connect EXTERNAL SSR to that mechanical relay output.

Alex

Alex wrote:

No No.

It could if you want - but the guys here say click click... The pdf file shows you what you asked - the A form of relays and C type. In the doc - it says it has 4 slots for option output boards - up to 4 at a time. And they mentioned the type of relay contacts the boards had.

The SSR rely takes a voltage to drive it. The internal board that is optional has a small SSR that is isolated and can drive (silent is nice) the otter BIG one that handles 10 or 50 or 100 amp load.... from the small controlled signal it does with a pull up to a voltage on one contact - that feeds (when controlled ) to the other that drives the input of the BIG one and the other terminal of the BIG one goes to ground (of the pull up voltage supply). (e.g. a battery or a supply.).

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Alex wrote:

Read the doc - it says you have to order 1-4 output boards. One could be mechanical relay another their opto isolated SSR. Then they have voltage source - (that could do it easily - program the voltage needed on the output power SSR and forget other output boards) and ....

Not knowing what your outside SSR needs - likely 5-12v that is for a TRUE - ? then the voltage source is zero or 7v for off and on. If a new BIG one is needed and it was a low voltage input - new values could be done...

Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder

Alex wrote:

What Martin said. Get the ssr output board. A mechanical relay has a life rated in number of contact closures, maybe a couple hundred thousand. With the controller in time proportional mode, with a time interval of 2 seconds (for instance), a mechanical relay would hit

200,000 cycles in 4.6 days. The ssr will run indefinitely. By the way, for the big external ssr, I'd get it rated for at least 2-3X your load. The higher rating usually won't cost any more, and is likely to last much longer. Also, ssr's are now available which fail open, much to be preferred. In addition, when I'm using ssr's on 230V resistance heaters, I use two and break both legs. This prevents continued heating if the heater develops a partial ground.

I also put a mechanical relay in front of the power side of the control relay and control it with another high temp alarm controller with separate temperature measuring device, or failing that, an alarm relay (sometimes already there, sometimes an option) in the main temperature controller. The separate high temp controller is required where I work. It can be a much cheaper simple on-off controller. I usually series an on-off switch with the high temp controller output to the mechanical relay. The on-off switch must be switched on to enable the heater and allow the mechanical relay to pull in.

Good luck. Let us know how it turns out.

Pete Keillor

That sounds like electrical life at full load. Mechanical life at low current, which would be the case driving an SSR, is typically in the tens of millions of cycles. For example, IDEC RH series cube relays are rated for 50 million mechanical cycles. That'd be about 14000 hours with a 2 sec cycle.

Definitely a good idea. I'm furnace-less right now because the cheesy controller on my little Thermolyne furnace failed and burned out the elements.

To the OP - If you end up scrounging a controller that has a relay output, I have a bunch of SSRs that have a self powered input, so wouldn't require a controller with SSR output or a separate power supply. The downside is that they're only rated 15A @ 120VAC. But you're welcome to one if you think it'll work for you.

Ned Simmons