Lake Shore expert: I am using a Lake Shore 335 temperature controller to keep cryogenics experiment system at a fix temperature at 15K, or 2.8K. When experiment finished, we need to heat up to room temperature. If I set point to 298 at 15K, heat ranger set to “high", the power show 100% may damage the heater. I need to heat up with constant power. I learnt from manual that both WARMUP(needed voltage mode) and MOUT command can to set a fix heating power. But we always use current mode, I don not know whether heat up with voltage mode have anything different. Can I use WARMUP command with voltage mod to heat to room temperature? or use MOUT?
Last Edit: Apr 5, 2018 3:42:57 GMT -5 by akafootman
Thanks for your reply. I look up in user's manual. Is there any way to limit the output power while ramping to protect heater and instruments if my ramping rate setting is not proper after ramping to a higher temperature? Or I must set different rate for different temperature zone?
Post by Lake Shore Ogi on Apr 6, 2018 13:09:29 GMT -5
Another way to do this is to set the manual output to a low percentage, which will give you a constant power output as you initially asked. The only CAUTION I have with this is that the instrument will be outputting a constant power and won't stop after you reach your setpoint. You would absolutely have to make sure that you enter a maximum temperature limit in your sensor input settings to protect your system in case you or someone leaves the experiment while you're warming up your system. If a set temperature maximum limit is reached, the controller shuts all heaters off to prevent an overheating scenario.
Post by Lake Shore Ogi on Apr 11, 2018 7:48:52 GMT -5
You're very welcome. Yes, this will work but please highly consider setting a maximum temperature limit (if you haven't done so already) in order to protect your system. Open loop can be dangerous in certain situations because there's no feedback and the controller will keep outputting power indefinitely (or until something is damaged due to overheating).