Magnum PT-100 faults during sub zero temps

[Greendream]

We've had a cold snap come through this week. Got down to -10F and -5F the past two nights. I woke up to check the equipment in the shed and saw the PT-100 had F02 fault on cold night 1, and last night was F08 fault. Both times it recovered by following the instructions in the manual to reset the PT-100.

I tried to understand the fault codes and expected if anything, I would have had the same fault both nights. Odd its different.

F02
FAULT LED ON
Internal Power Supply Fault - the PT controller turned off because the voltage from the auxiliary power supply in the controller has dropped to a low level.

This can be caused by a load from the power circuit on the PT NETWORK or STACK port. This happens if an accessory cable that is plugged into the PT controller has shorted, or an accessory—that should be powered externally—is plugged into the PT and is attempting to be powered from one of the ports on the PT controller.

Remedy: Remove any cable plugged into the NETWORK (or STACK) port and also check these two ports for debris; then, clear the fault by pressing the RESET pushbutton for one second. If the fault continues—after removing all cables, checking the ports for cleanliness, and pressing the RESET button— then the controller will require service.

F08
FAULT LED ON
Internal Overload Fault - the PT controller turned off to help protect itself because the current to an internal sensor has exceeded the controller’s protection limits.

Remedy: Press the RESET pushbutton for one second which should clear the fault and turn the controller on. If the fault cannot be cleared, their may be damaged/faulty components inside the controller and it will require
repair

Any thoughts on these faults only occuring at night when temps are sub zero?

Thanks!

EDIT;

I should have checked the spec sheet. This may explain it to a point.

Environmental Specifications
Operating Temperature -20°C to +60°C (-4°F to 140°F)
Non-operating Temperature -40°C to +70°C (-40°F to 158°F)
Operating Humidity 0 to 95% RH non-condensing

FWIW the Magnum MS4448PAE is inverting below -4F just fine. Perhaps the temps in the inverter are warmer than ambient temps whereas the PT-100 is idle at night and not generating any heat.

 

[BurOakSOLAR]

We are having this issue on a few sites where the PT100s are installed in an unheated space. So the problem is that the device (not every one of them, but quite a few) faults out and then requires a reset intervention. Magnum tech support immediately pointed to the temperature so they must be aware of this issue. So Non-Operating for them must mean powered down. We also need a solution or Magnum just can't be used in Canada unless it is in a heated space. In your case are you using the "Network" port?

We are testing a solution where we place a 240V DC 13W cabinet heater between the PV in +&- with a series thermal switch that is on below -15c. But I am not sure if this would correct the issue since I think it happens at night (and I think this should be considered "Non-Operational), if it happens as it is waking up, hopefully the heater would have the opportunity to warm it enough to allow a fault free power up.

Have you tried anything or got any feedback from Magnum? I think this is a bit of a design flaw for a big part of North America.