SSR relay problem solution

marconi · Jul 2, 2022

mdkmdk said:
In the input of the relay and at the output of the rectifier bridge the measured direct current is 22.6 volts. When the heating process is on, the DC current measured at the SSR input is 22.3-22.4v instead when the heating process is off, it is approximately 22.6-22.8v.

So to be clear - the voltage across the ssr terminals 3 and 4 is always in the range 22.3 - 22.8 V? It never drops to zero Volts even when the heating process is Off? This is surprising and not what one would expect.

Why will you not connect the SSR to the controller's SSR output? This output is designed to switch the SSR on and off.

Could you draw a diagram of how items are connected please?

mdkmdk · Jul 2, 2022

marconi said:
So to be clear - the voltage across the ssr terminals 3 and 4 is always in the range 22.3 - 22.8 V? It never drops to zero Volts even when the heating process is Off? This is surprising and not what one would expect.

Why will you not connect the SSR to the controller's SSR output? This output is designed to switch the SSR on and off.

Could you draw a diagram of how items are connected please?

Yes, it is always in that range even when the heating is not on.
I can't fully understand how the oven works.

mdkmdk · Jul 2, 2022

marconi said:
So to be clear - the voltage across the ssr terminals 3 and 4 is always in the range 22.3 - 22.8 V? It never drops to zero Volts even when the heating process is Off? This is surprising and not what one would expect.

Why will you not connect the SSR to the controller's SSR output? This output is designed to switch the SSR on and off.

Could you draw a diagram of how items are connected please?

What if I directly connected the SSR relay to the thermoregulator using terminals 11 and 12 (currently not used since the SSR is driven by the thermoregulator through the internal relay function of the thermoregulator) of the thermoregulator?

If I disconnect all the wires of the input and output of the SSR and to the input of the SSR 3+ and 4, I connect some wires that I am going to connect to terminal 11 and 12 of the thermoregulator, while in the output of the SSR I connect directly only the wires of the resistance? It might work?

I measured the direct current at the output of terminals 11 and 12 of the thermoregulator, it corresponds to 11.9 volts. Could it be fine for the relay as there is currently 22.6 volt current in use?

DPG · Jul 2, 2022

I still say you are beyond your abilities here. No shame in that.

Without a wiring diagram I feel we shall get nowhere.

marconi · Jul 2, 2022

mdkmdk said:
What if I directly connected the SSR relay to the thermoregulator using terminals 11 and 12 (currently not used since the SSR is driven by the thermoregulator through the internal relay function of the thermoregulator) of the thermoregulator?

If I disconnect all the wires of the input and output of the SSR and to the input of the SSR 3+ and 4, I connect some wires that I am going to connect to terminal 11 and 12 of the thermoregulator, while in the output of the SSR I connect directly only the wires of the resistance? It might work?

I measured the direct current at the output of terminals 11 and 12 of the thermoregulator, it corresponds to 11.9 volts. Could it be fine for the relay as there is currently 22.6 volt current in use?

Yes. Ensure correct polarity, The minimum voltage is 3V and across 11 and 12 there is 12V. ssr input has to be greater than 3 and no more than 32V.

marconi · Jul 4, 2022

I have attached a picture showing you how to connect the ssr to the controller. MAke sure the SSR and controller are connected with + to + and - to -.

mdkmdk · Jul 4, 2022

marconi said:
I have attached a picture showing you how to connect the ssr to the controller. MAke sure the SSR and controller are connected with + to + and - to -.

I solved the problem by directly connecting the thermoregulator to the SSR relay as you told me, now it works fine. Perhaps it was the rectifier bridge transformer circuit that failed, by directly connecting SSR and thermoregulator the transformer was bypassed. What do you think caused the failure? Before doing all this I also disconnected the thermoregulator from feeding the transformer through terminal 4, although the problem persisted, this shows that the thermoregulator works well. I also put some terminals on the connectors that I no longer use and I wrote the corresponding number on them, in case of a possible future use by fixing the transformer problem. The only thing is that it gets to 790 degrees in 2 hours and 20 minutes. I would need it to get to that temperature in 2 hours. If I put a fan on top of the SSR would I be able to reduce the time? When the oven was open and reached 500 degrees, the relay by touching it above had a temperature slightly above that of the environment. Then I had to close the panel and turn the oven to test it up to 790 degrees.

James · Jul 4, 2022

have you done the PID tuning?

marconi · Jul 5, 2022

Installing a fan will not help. Why do you have to reach 800C in 2 hours? What difference does 20 minutes more have?

mdkmdk · Jul 5, 2022

marconi said:
Installing a fan will not help. Why do you have to reach 800C in 2 hours? What difference does 20 minutes more have?

For a matter of saving time in the long cooking process of the flasks and the goldsmith casting. There are heat losses from the opening door and the hole where the oven exhaust pipe is, perhaps trying to contain them using ceramic fiber or other heat resistant materials I could reduce the time.

Avo Mk8 · Jul 5, 2022

mdkmdk said:
For a matter of saving time in the long cooking process of the flasks and the goldsmith casting. There are heat losses from the opening door and the hole where the oven exhaust pipe is, perhaps trying to contain them using ceramic fiber or other heat resistant materials I could reduce the time.

Please don't ignore the PID tuning advice.
You need to find out if the longer heating time is due to the controller "slowing down" the heating as set temp approaches.
or it may be that it's just the time it takes because of the thermal mass of the oven and the power of the heating element.

The controller has to be set to balance power "= speed of heating" vs overshoot. If you don't want to exceed 800 deg, it will take longer to heat the oven than if it doesn't matter about overshoot. See illustration below. Have you looked into these settings?
There's plenty on the web about this if you haven't investigated it already.

marconi · Jul 5, 2022

Here is a youtube clip which explains how to set up the controller initially and then to select auto tune (AT) to optimise how the oven heats up and then regulates its temperature. It is the same controller as the one you have although it has a different name.

Here is leaflet on your controller but I recommend you use the YouTube clip first.

https://images-na.ssl-images-amazon.com/images/I/91cH5fgtECL.pdf

mdkmdk · Jul 5, 2022

I did as specified in the manual but the AT light always blink endlessly without ever stopping.

marconi · Jul 5, 2022

Look at 4 mins 18seconds onwards. Have you turned the derivative function on?

James · Jul 5, 2022

Also, remember it could take 2 to 3 hours to tune if your set point is really high.

marconi · Jul 5, 2022

The computer inside the controller is making small changes to the P, I and D values and then seeing how the oven performs in terms of oven temperature PV and its error when compared with the desired or set temperature SV all over time. Iteratively it will be homing in on the P, I and D values which give the best oven temperature PV time performance. When it has arrived at these values any changes away from them will make the performance worse each time which is how the controller knows when to stop auto tune.

marconi · Jul 5, 2022

I should have said that in order for the auto tune to work you will need to cycle your oven from cold to hot to cold, a number of times for the AT function to work and the light to stop flashing, before you use the oven for business.

I also need you to confirm you have turned the derivative or d function on.

marconi · Jul 6, 2022

mdkmdk - Would you mind letting us know your progress please?

mdkmdk · Jul 9, 2022

marconi said:
mdkmdk - Would you mind letting us know your progress please?

Sorry for the delay in answering, I did get it to 800 degrees centigrade but the auto tuning light was still flashing. I saw the video at minute 4.18, should I set the AL1 value, if so why?

marconi · Jul 9, 2022

Good you have been looking at the controller's settings. Would you go through the steps as in the youtube video and report to me the settings you find? I can then tell you what to change or keep the same.

More immediately please me tell if you have set up 'InP' value as 'k' ( see at 5m57s) to tell the device you are using a thermocouple - and then tell me if the 'd' function is set to on or off (see at 6m57s).

Share this page

-

Attachments

-

-

-

Attachments

Attachments

-

-

-

-

Attachments

-

-

-

-

-

-

Share this page

Similar Threads

OFFICIAL SPONSORS

Electrical Forum

Tags