Having trouble with JLD-612

[Joe146]

I purchased 2 of the JLD-612 controllers. Have connected each to a DC Relay controlling current to a small 12 volt fan. I have a Type K thermocouple and it is working correctly. Both controllers are sending out a pulsating voltage of about 3 volts every 2 seconds all the time, below and above the target range. The fan should be running continuously up to the target temperature. I have set up test with the following setting:

Heating 0
Fahrenheit 1

Su = 80
AH1 = 90
AL1 = 88
AH2 = 70
AL1 = 72

The AL1 and AL2 lights are going on and off as they should. Everything is working fine but the SSR signal.

Please Help

[richiem]

You don't indicate your OutY setting, which matters a lot.

Just to be clear, you have two controllers, each running one relay and one fan? What are the specs on the coil voltages and currents of the relays?

[Joe146]

Yes, I am building 2 seperate controllers. Each one will have it's own replay and fan. Outy = 2

I just figured out that the relay I have is not the one I thought I was getting. The one I have is a DC60S5 which is 5 amps and I thought I was getting a DC60S3 which is 3 amps. Will this matter?

The relay power source is 3 to 32 VDC and the load power is 5 to 60 VDC. Here is a link to the relays

http://www.alliedelec.com/catalog/pf.aspx?FN=1167.pdf

This is the DC60S3 link: http://www.davis.com/catalog/product_vi ... ku=6847452

Do you recommend a different relay?

At the time I ordered the relay they only had one and I swapped it from one controller to the other. Waiting to resolve this before ordering another one.

thanks

[richiem]

OK, OutY = 2 is good. What does this system need to do? The running of a fan until a set temperature is reached and then held by turning the fan on and off is kind of a normal heating solution, except that normally some heating element is involved, and that is what is controlled -- a few details about what you're trying to do would help in general understanding....

I don't know what the fan looks like as a load on your relay & power supply, but I'm assuming the fan is a (relatively) low-voltage, low-current DC fan, perhaps like those used in computers, and not an AC powered fan; if the fan is actually an AC unit, then you have the wrong relay.

As long as the relay is rated to handle at least the voltage and current required by the fan, it doesn't matter if you use a larger relay with higher voltage/current rating.

The SSR output to the relay seems to be working. But I need to know your circuit details -- fan voltage and current rating, fan power source voltage and current rating.

Here's how a basic system is connected:
The PID controller sends a low-voltage control current to the SSR (relay) with the correct polarity of connection: + from controller to + control input on SSR, and - to -.

A DC power source appropriate for the fan is connected to the relay's controlled input, with correct polarity. The relay's controlled output connects to the fan, with the correct polarity. The fan's other connection returns to the DC power source.

Any mis-wiring or polarity reversal will make the system inoperable, except that the controller will still be trying to control the relay.

Hope this helps.

[Joe146]

Thank so much for helping me with this.

The fan is a computer fan with spec,
rated voteage 12VDC
rated current 0.16A
Power Input 1.92W

The fan is to blow air into the fire box of a BBQ Smoker until the target temp is reached in the cooking chamber where the type K TC is located and then maintain the target temp.

The wire is as you described: + from the controller to + on the relay (Pole 3). - to - on the other wire. On the other end of the relay the power source is a 12v power supply + on power supply to + on relay and the The wire leaving the relay goes to the fan and the return wire to the - on the power supply.

I don't understand why voltage from the controller to the relay is pulsating. And when it does the fan runs for about a half a second.

Again thanks for your help. I am sure I must be doing something wrong here.

[richiem]

As the controller (in PID mode, OutY = 2) senses the temperature approaching the set value, it begins to turn the SSR on and off in pulses, effectively pulse-width modulating the signal to the fan by changing the on-to-off duty cycle. In this mode, as the actual temp converges on the set temp, the duty cycle gets longer and longer and so the on time gets proportionally shorter and shorter for very fine control. For your application, given the vagaries of ambient temps and of fires, using a straight thermostat mode may work better.

Set OutY = 3, Rd = 0, Hy = 0.3 (= 3 deg.) to give a 3-degree dead-band of hysteresis so that the fan doesn't hunt around the set value and upset things. Set your SV to your desired max temp. Now the system will not provide fine proportional control but will give accurate temperature control within the 3 degree hysteresis dead-band and within the response time of the fire to the effect of the fan.

The alarm settings don't do anything here and can be ignored, unless you want them to light a lamp or sound a buzzer if the fire gets too hot or too cool.

You could also not use the SSR at all and just hook the 12V power supply and fan to the J1 relay and set the OutY = 0, then set AL1 = to your high temp and set AH1 a couple of degrees lower -- this also results in a straight thermostat heating mode. But I like having the controller separate from the other stuff -- the SSR provides great isolation.

Hope this helps. Let us know how it turns out.

[Joe146]

I changed the Outy to 3 and if the fan is working fine now. After reaching the target temp it comes back on when the temp drops 3 degrees. If I change the Hy to .2 I am guessing if will change that to a 2 degree drop. I did connect 12V lights to the J1 and J2 output hoping they would come one as an alarm if the temp did get too high or low. But, they do not come on. I can make it without that, but it would be nice. Can that be done?

Thanks for your help.

[richiem]

Glad it's working!!

You can connect lamps to the alarm relays. Use your 12VDC power source and small 12V low-current indicator lamps, say 100mA or 200mA lamps -- auto parts stores or Radio Shack have what you need. The alarm outputs don't supply power, they only control mechanical relays inside the controller that switch the power to the lamps off and on. See the manual for the connections.

[Joe146]

Thanks for your help. Look like I need to get a couple more relays to have the Alarm lights.

The type K TC is a little off around 85 degrees. About 10 degrees to high. Based on 2 meat thermometers and another digital. The K will go up to around 2300. Do I need to get a TC with a less spread? I will operate it between 225 and 350 and the K my be fine in that range. It should never get hotter than 700 degrees.

[richiem]

You don't need more relays for the alarm lights -- the ones in the 612 will work fine, since the currents are low. As to the thermocouple, I think your K will do fine at the temps you're looking at; but it wouldn't hurt to have a spare if you don't already. Hard to say why there's so much error at 85, though -- shouldn't be off by more than a couple of degrees.

[Tech_Marco]

As the controller (in PID mode, OutY = 2) senses the temperature approaching the set value, it begins to turn the SSR on and off in pulses, effectively pulse-width modulating the signal to the fan by changing the on-to-off duty cycle. In this mode, as the actual temp converges on the set temp, the duty cycle gets longer and longer and so the on time gets proportionally shorter and shorter for very fine control. For your application, given the vagaries of ambient temps and of fires, using a straight thermostat mode may work better.

Set OutY = 3, Rd = 0, Hy = 0.3 (= 3 deg.) to give a 3-degree dead-band of hysteresis so that the fan doesn't hunt around the set value and upset things. Set your SV to your desired max temp. Now the system will not provide fine proportional control but will give accurate temperature control within the 3 degree hysteresis dead-band and within the response time of the fire to the effect of the fan.

The alarm settings don't do anything here and can be ignored, unless you want them to light a lamp or sound a buzzer if the fire gets too hot or too cool.

You could also not use the SSR at all and just hook the 12V power supply and fan to the J1 relay and set the OutY = 0, then set AL1 = to your high temp and set AH1 a couple of degrees lower -- this also results in a straight thermostat heating mode. But I like having the controller separate from the other stuff -- the SSR provides great isolation.

Hope this helps. Let us know how it turns out.

Rich:

I talked to the manufacturer about the 0.3 (3 degree) issue. The reply was that if the probe is PT100 and setting was PT10.0, then the 0.3 means really 0.3 degree. But if it's set to other probe type like the K, then the 03 = 3 degree. It shouldn't show the decimal point per manufacturer.


Marco

[richiem]

Thanks, Marco -- that's good to know!