How to connect a temperature PID controller with an external relay

Where did the relay come from? Can you give us a link, or a scan/photo of the data which came with it?

Where did you find the picture of the relay connections? Can you post the pic on its own? Can't resolve any of the writing as it is.

Dear JohnDG, Thanks for your questions.

1. The relay was a suggestion from the electronics store, was purchases as a spare part, without technical data info.

2. the wiring diagram shown in the picture is a picture in the CAL controler, please see below:

Dear WoodyGB,

Thanks for your support. Your picture is very small, so I have copied it in a bigger size, please review below. are right my connections?

There we go ...a bigger pic of the relay connections.

Dear Woodygb,

thanks for your support. I apolgyze for my ignorance, so in the next scheme, where the 0 is the pin, with identified with a number.

(1) 0 (2) 0

(3) 0 (4) 0

(5) 0

- what means the arrows in (1) and (2) ?

. there is an spiral between (3) and (4) ?

- what kind of connection is required between (5) and (2)?

I hope that I am not bothering you with my answers!

thanks!

(1) 0 (2) 0 Connect 1 to your Peltier

(3) 0 (4) 0 5v Relay coil

(5) 0 Connect this to your Peltier voltage supply LIVE.

- what means the arrows in (1) and (2) ? They are contacts of the internal switch
The line from connection 5 that initially rests on contact 2 indicates a mechanical arm that will flip over to contact 1 when 3 and 4 have 5v applied to them.

. there is an spiral between (3) and (4) ? That is a 5v coil ...applying 5v to this coil operates the relay....Turns it ON.

- what kind of connection is required between (5) and (2)? NONE
In the OFF position 5 and 2 are connected internally ..energizing the relay ...ON...causes the connection to swap over to pin 1 ...thus 5 and 1 are connected internally when the relay is energized.

Thanks.

Correct me if I'm wrong, but I think you're supplying the Peltier device with 5Vdc. estebanoliveros states his Peltier device is rated at 12V, so he'd need a separate supply for it, yes? If the relay datasheet were available, we could work out the value for a resistor to be put in series with the relay coil, so the whole thing would run from 12V. I'd guess at something like 500R for the resistor, but without the datasheet, who knows?

estebanoliveros, if this is the correct diagram for the relay, it's not very likely that it's a solid state relay. Where did you get that information? SS relays with changeover contacts are not very common.

"Correct me if I'm wrong, but I think you're supplying the Peltier device with 5Vdc. estebanoliveros states his Peltier device is rated at 12V, so he'd need a separate supply for it, yes?"

Whoops!...My bad ...You are correct John.

What little data I could find on the RH-005C is here.
http://www.techman-usa.com/info/118.pdf

The Cal3300 has a 5v SSR driver rated @ 15mA and may be able to drive the small relay.... in which case the RH-005C could be connected directly to 3 and 4 on the CAL3300.

I've altered my first erroneous pic.

That's more like it!

If estebanoliveros can measure the resistance of the relay coil, he could save adding a 5V supply.

If the resistance is R_coil, then the current i (at 5V) is 5/R_coil. If i ≤ 0.015 (i.e. 15mA) he may get away with using the SSR drive from the controller (tho' he'd have to set up the dead band wide enough to stop chatter - sometimes SSR drive outputs are used in a more-or-less PWM mode, and switch on & off quite often).

Alternatively (whatever the value of i) he could use the 12V supply throughout, with a padding resistor (R_pad) in series with the coil and the controller relay contacts.

R_pad = R_coil x (12-5)/5 = 1.4R_coil

Dear WoodyGb, thanks for your support.

Here goes some pictures, so please be patient, I am not an expert, but I am sure that with your support I will reach the success.

this is the wiring diagram that I want, the relay is not included here. The peltier is 100W, 12 V

and that is the suggestion in the CAL3300 user manual, as you can see, the relay (SSR) shown have four connectors,

so the relay that I have (recommended by the dealer) have 5 pins!

So I hope that I am not bothering you, I can cooperate giving you all the information that you want!.

Seems to me that the best way to help me should be a wiring diagram and a list of required components.

thanks in adavance!,

Esteban.

The relay you have (whatever the dealer said) is NOT a solid state relay. It's a conventional single pole changeover relay with a 5Vdc coil.

Also, you'll need 12V DC for your Peltier device - the diagram you've reproduced (with the SSR & a transformer) will supply AC, which is fine for a heater. Most Peltier devices driven with AC may heat up (both sides), but it won't pump heat anywhere (so can't be used for cooling). Can you post any more details of your Peltier device?

Dear WoodyGb,

Thanks for your support!. You are right, the CAL3300 have an internal 'mechanism' (15mA, 5Vdc, as printed in the label of the controller) to drive an external SSR, in the connectors 3 and 4. So, if you agree with this, why in your scheme the wires are from ports 5 and 6?.

Seems to me that we are close to resolve this, so please, a new scheme will help me to solve this!

thanks for your patience!

Hi estebanoliveros

As John pointed out the relay you have is NOT an SSR... you have a 5v mechanical relay and unfortunately the 15mA SSR output will not be suitable to drive your mechanical relay.

I merely attempted to use the other pair of contacts to drive your relay.

Easiest option is to purchase a DC DC SSR

Dear WoodyGb and JohnDG,

Thanks for your valuable support. Sorry for my mistake, you are right about the relay that I have. I have discarded it and I am searching for a real SSR

I have checked in the electronic store here, and they have the model P240D4, shown in http://www.opto22.com/site/pr_details.aspx?item=P240D4&qs=100610141053,,,5,6&

(3-32VDC, 4A)

I can use a smaller peltier, with 65W max when cooling. I have no datasheets, but the peltier can freeze up to -15ºC (at 18ºC ambient temperature)seems to me that at this point is the max consumption of 65W (65/12=5.4A at -20ºC).

The Peltier will be used to freeze only to 12ºC (at 24ºC ambient temperature), so I am sure that it will not comsume the 65W max. The max current that supports the SSR P240D4 is 4A, more information in the manufacturer's link http://www.opto22.com/site/pr_details.aspx?item=P240D4&qs=100610141053,,,5,6&

could I use that SSR?, I wait for your suggestions!

Esteban.

Hi Esteban.

If your load is DC then you MUST have a DC - DC Solid State Relay.

The SSR you've linked to appears to be an AC load type.
P 240 D4
P Model, 240 VAC, 4 Amp, DC Control Solid State Relay (SSR)

I could however be wrong.

Hopefully John will jump in ...he has more knowlegde of electrickery than I .

Alan (Woody)

Dead right, Woody. The nearest these folks seem to get to something suitable is the DC60P, which is only rated up to 3A.

DC output SSRs with a decent current rating tend to be expensive.

estebanoliveros, there's nothing wrong with the relay you have - it will drive your Peltier device admirably -but you'll need either a separate 5Vdc supply, or you'll have to find the coil resistance & use a series resistor (as I've already suggested).

Your easiest way out would be to go back to your dealer, & exchange your RH-005C for an RH-012C (same thing but with a 12V coil), or an equivalent, then use Woody's circuit from #2, but with 12Vdc instead of the 5V shown.

Tsk ....I got sidetracked from this obvious solution by the original question concerning the 5v relay....simply switch the AC going to the DC power supply.

This should work using the SSR P240D4.

Dear Friends,

I have solved the problem and my process is running very good at setpoint!.

The solution was to connect an AC SSR before the 12Vpower source, so the CAL3300 controler swicth on/off the current before the power source.

Thanks a lot for your support and for all the time!