Newport 3040 temperature controller. - Page 1
Forum section: electronics / testgear

author: jchw4
author_rank: Regular Contributor
timestamp: July 05, 2023, 07:47:31 am
content: I got a Newport 3040 temperature controller and I have trouble setting it up.I am trying to make it work with a cheap car thermoelectric cooler, which I rewired directly to the controller.The issue is that it does not stabilize. And I don't have experience with thermoelectric controllers. I need some help understanding whether it works as intended or something is broken.I found user manual here:http://www.iproweb.fr/test/0%20-%20MATOS%20GUILLAUME/NEWPORT%20-%203040/DOC%20US.PDFQuoteThe in Principles of operation on page 32-33 (42-43 in PDF) they say:QuoteSo my guess is that it is actually a digitally controlled fully analog device.I.e. once the mode is set, the rest is done on the analog side. Digital side at this stageonly does monitoring.I set up a script to try all the 16 modes for 5 minutes each.Room temperature is about 25C, target temperature 30C.Temperature and TE current values are from the controller.I just checked that it measures current correctly. So the values seem to be real.Here is what I got:What surprised me is that it continues to drive the TE at nearly the full current until after target temperature is reached and then tries to go in the opposite direction at full power. Here is the central part of the graph above:The “10” mode is interesting because it offers both “slow” and “fast” integrator modes. So we can compare them:Actually I can see that there was one case, "60 Slow" which has decreasing amplitude. But I don't feel that the stabilization time is usable:So my question is whether this device is working. And if not, what could be wrong with it?Upd: I had to re-upload all the images to make img tags work.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 05, 2023, 08:36:11 am
content: The curves look like a poorly adjusted regulator that oscillates or is very close to oscillation. To me this looks like the instrument itself works, but the system used for testing may be not suitable for this regulator. The settings seem to be limited to a small number of settings and as it looks as PI only (so no PID).A significant point is how fast the temperature sensor reacts to power changes. The larger the delay, the more difficult to regulate is the system. One may still be able to use the controller with the temperature sensor paced closer the peltier element, so that it reacts faster.

author: jchw4
author_rank: Regular Contributor
timestamp: July 05, 2023, 09:49:59 am
content: Quote from: Kleinstein on July 05, 2023, 08:36:11 amThe sensor is attached to the screw holding the element:But the issue is that the temperature values are read from the controller itself. So this is how it sees the temperature. If I attach the sensor even closer the controller reaction delay will still be the same.Let's look at the default mode "30 Fast" that is suggested as a starting point in the manual:The zoomed-in version:So you can see that it continues heating or cooling at full speed even when it already knows that the sensor has reached the target temperature.

author: ch_scr
author_rank: Frequent Contributor
timestamp: July 05, 2023, 10:48:08 am
content: You could try lowering the gain of the system by setting a lower max current for the TEC. Since the control loop is analog, with digitally controlled switched elements (R, C), one would have modify the hardware to make it work.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 05, 2023, 11:06:47 am
content: Quote from: jchw4 on July 05, 2023, 09:49:59 amThe behavior is normal. The time the heater is still on after reaching the set point is actually relatively short. This suggests that there is some anti-windup active. This is common with a digital regulator and a bit rare with an analog regulator. So chances are the regulator is digital.The position of the sensor aready looks not that bad, though the liquid in direct contact to the sensor will slow the response. It would not be ideal for an accurate control, but some isulation around the actual sensor could help.

author: jchw4
author_rank: Regular Contributor
timestamp: July 05, 2023, 11:36:51 am
content: Quote from: ch_scr on July 05, 2023, 10:48:08 amI tried this manually (so that I don't have any data) but I think that it did not help.I'll repeat my experiment with lower current limits in a few days.

author: jchw4
author_rank: Regular Contributor
timestamp: July 05, 2023, 11:40:00 am
content: Quote from: Kleinstein on July 05, 2023, 11:06:47 amI feel that adding more thermal mass to the target side of the TE could help. But still, looking at the device specification:I don't understahd how short term stability of 0.0005C is expected to work.