Guys who have built PID controllers

[razor1115]

Hi guys,

I recently built a home brew PID controller modeled after Electric Brewery's control panel. I have a HERMS system.

I purchased 3 Inkbird PID controllers (ITC-100VH). My system is 240V, 5500W elements using PT100 RTDs. I have 40A SSRs.

I tried to calibrate the system in auto mode for the first commissioning of the controller. The RTD in the mashtun temp feeds the PID for the boil kettle to provide closed-loop control (as opposed to reading mash tun and HLT on their own, looking at the difference in temps, and open loop/manually setting my temp in my HLT to compensate for the system heat loss).

I set the SV = 64.4°C (148°F). The PV on the PID achieved the SV, and I would have expected some overshoot, then turning off the SSRs, allowing the temp to drop, then turn back on to zero in/ dampen the oscillations and understand the heat losses of the system.

The SSR never turned off, even when PV >>> SV. I let it keepp going up to 90°C, and the system never stopped powering the element. At this point, I set the Hi Alarm to a value (15°) below the current PV value of 85°C. The PID control went into alarm mode, shown on its screen. However, the NO relay in the PID did not trip the buzzer/lamp alarm. It appears the controller is faulty in not only controlling temp, but the relay NC alarm circuit also does not work.

Can anyone find any issues with my diagram?

I have attached an abbreviated schematic of the HLT circuit to ask for help.

 

[Ozarks Mountain Brewery]

Ive built many and have one going together now, I would use a contact relay to turn on the power to the element

in oder for the alarm to work you have to supply power to it

 

[dyqik]

For the SSR output, is the CtrL mode set to 1, 2 or 3 rather than 0?
You could try setting the CtrL mode to 0 for testing, as then the system should work as a simple thermostat.

I also take it that the "Run" light is off, and that the run parameter is set to 1, so that it's not in manual mode.

For the alarm, is the ALP setting set to 0 (so the alarm triggers the AL1 output)?

 

[razor1115]

On power up, following instructions of holding the << arrow more than 2sec never set PID into auto cal. I had to go into setting an write CtrL as &#8220;2&#8221; value, then it kicked into auto. After unsuccessful calibration, I set it back to 3.

Yes, run light was off (If I recall correctly - and it would have to be if it's not in manual , correct?), run = 2 automode

ALP = 0 as default from the factory

Here's the instructions:

http://ink-bird.com/asset/file/ITC-100_%20Manual_%20V1.0_6.30.pdf

 

[lschiavo]

Are terminals 9& 10 proper? If they got swapped, your alarm would not work. Test for voltage on terminal 11 during alarm.

 

[razor1115]

Ive built many and have one going together now, I would use a contact relay to turn on the power to the element

in oder for the alarm to work you have to supply power to it

I'm not sure if you reviewed the schematic or not I use a relay the turn on the power to the element. additionally I have power run to the alarm

 

[razor1115]

Are terminals 9& 10 proper? If they got swapped, your alarm would not work. Test for voltage on terminal 11 during alarm.

I'll triple check it but it's wired properly according to their diagram

 

[Ozarks Mountain Brewery]

yup didn't see that just saw the switches, Ill draw up my design soon, I don't have it on paper just my head, it works flawlessly

 

[razor1115]

Worked out the alarm circuit - it's resolved.

However, element always remains powered on one leg coming from the power bus, even w/ the PID not powering the SSR that controls the other leg of the 240V circuit. I found this by removing the 120V leg that goes directly to the relay that powers the element.

So, it looks like, even with the SSR not powering the other 120V leg of my element, I always have 120V continuously power my element from the non-SSR controlled half of my 240V circuit.

It's wired just like everyone else's, so not sure why element stays powered when SSR is off....

 

[Ozarks Mountain Brewery]

this is how mine is set up the purple is the Pid

 

[Ozarks Mountain Brewery]

if your ssr's heatsink is underrated it will stick on or off and sometime work

 

[orangehero]

Why does your element have a neutral wired to it? A 240V element should just get both hots connected to it, with one leg controlled by the SSR. The element should be grounded though, including the enclosure and metal vessel. Can you take a photo of your element and how it's wired?

 

[Ozarks Mountain Brewery]

its a ground not neutral, the ground connects to the pot through the box

 

[orangehero]

I'm trying to help the OP.

 

[Ozarks Mountain Brewery]

oh thought that was for me, carry on

 

[razor1115]

Sorry - drew that up at work away from brew system. Same answer, 2 hots go to element, and the Neutral is actually a ground, ensuring if something shorts, all kettles are grounded and will not be live and waiting to bite me...

 

[razor1115]

this is how mine is set up the purple is the Pid

Mine's wired the exact same way....

 

[razor1115]

Worked out the alarm circuit - it's resolved.

However, element always remains powered on one leg coming from the power bus, even w/ the PID not powering the SSR that controls the other leg of the 240V circuit. I found this by removing the 120V leg that goes directly to the relay that powers the element.

So, it looks like, even with the SSR not powering the other 120V leg of my element, I always have 120V continuously power my element from the non-SSR controlled half of my 240V circuit.

It's wired just like everyone else's, so not sure why element stays powered when SSR is off....

 

[lschiavo]

If I'm understanding correctly, if your main switch is on, one side of the element will be hot straight from the contactor. You are only switching the other leg for control of the element.

Also, you will measure voltage through the SSR even when off. There will be a small leakage current but nowhere near enough to heat the element.

 

[razor1115]

Got the chance to troubleshoot today - both SSRs are faulty and remain constantly on even with 12VDC signal wires disconnected. I have 120VAC on both terminals at all times, therefore the heating element was always 100% on.

 

[razor1115]

Got the chance to troubleshoot today - both SSRs are faulty and remain constantly on even with 12VDC signal wires disconnected. I have 120VAC on both terminals at all times, therefore the heating element was always 100% on.

 

[lschiavo]

Got the chance to troubleshoot today - both SSRs are faulty and remain constantly on even with 12VDC signal wires disconnected. I have 120VAC on both terminals at all times, therefore the heating element was always 100% on.

Just so we are on the same page, you WILL measure voltage on the load side of the SSR even when off. This is normal and very misleading when testing with a voltmeter. The SSR stops CURRENT flow like a switch but unlike a switch, it is solid state and will allow a small leakage current. Also, the output terminal of the SSR is not physically disconnected from the supply terminal and will give you a voltage reading at the output.

If your element is actually firing with the control leads to the SSR disconnected, you have a faulty device. If you are only measuring voltage at the SSR output, it is likely that the device is fine. You need to test this with a load like the actual element or a light bulb to be sure.

 

[Bobby_M]

It's very rare to have two faulty SSRs. If you don't have a load on the SSR, it will leak voltage and that's most likely why you are reading voltage there.

 

[razor1115]

Just so we are on the same page, you WILL measure voltage on the load side of the SSR even when off. This is normal and very misleading when testing with a voltmeter. The SSR stops CURRENT flow like a switch but unlike a switch, it is solid state and will allow a small leakage current. Also, the output terminal of the SSR is not physically disconnected from the supply terminal and will give you a voltage reading at the output.

If your element is actually firing with the control leads to the SSR disconnected, you have a faulty device. If you are only measuring voltage at the SSR output, it is likely that the device is fine. You need to test this with a load like the actual element or a light bulb to be sure.

Great post. All leadS to ssr disconnected and element still fires.

 

[razor1115]

It's very rare to have two faulty SSRs. If you don't have a load on the SSR, it will leak voltage and that's most likely why you are reading voltage there.

Good post and info. Both + - ssr control leads disconnected and ssr still fires element

 

[Ozarks Mountain Brewery]

sound like a bad ssr, defiantly get a bigger heat sink and use thermal paste, bolt the ssr directly to the heat sink tight, put a fan on it if you have too, also use a better grade ssr, like http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=30

 

[razor1115]

sound like a bad ssr, defiantly get a bigger heat sink and use thermal paste, bolt the ssr directly to the heat sink tight, put a fan on it if you have too, also use a better grade ssr, like http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=30

Good tips - I have a huge heat sink designed to dissipate 10X the power i draw and used thermal paste.

 

[WScottCross]

They wouldn't happen to be Fotek SSR's would they? There have been many counterfeit Fotek SSR's that are actually lower rated devices that have been relabeled as higher current devices. Lots of discussions on those over the past couple of years. I also got bit by one of those.

I would crack the SSR open and research the TRIAC part number inside. That's the part mounted to the heatsink plate. I wouldn't be surprised if it's a part rated for 20A or under.

 

[razor1115]

They wouldn't happen to be Fotek SSR's would they? There have been many counterfeit Fotek SSR's that are actually lower rated devices that have been relabeled as higher current devices. Lots of discussions on those over the past couple of years. I also got bit by one of those.

I would crack the SSR open and research the TRIAC part number inside. That's the part mounted to the heatsink plate. I wouldn't be surprised if it's a part rated for 20A or under.

EXACTLY the brand - I will crack one open...

 

[WScottCross]

EXACTLY the brand - I will crack one open...

It's sad because Fotek actually makes good product. It's just that some idiots are relabeling them as higher amperage units and reselling them just to make a buck.

Here is an UL warning about these and how to recognize the fakes: http://canada.ul.com/safetyalerts/ul-warns-of-solid-state-relay-with-counterfeit-ul-recognition-mark-release-13pn-52/