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TOPIC: Thermal limits

Thermal limits 6 years, 8 months ago #44

All motors WILL trip on thermal limit at 85Deg.C. They will not reset until cooling back down below 80Deg.C SmartMotors should be operated between 0 and 85Deg.C non-condensating. In other words, reaching dew-point can cause moisture to condense on the encoder disk causing loss of integrity of position feedback. SmartMotors should not be started up cold below zero Deg. C.

Re: Thermal limits 4 years, 7 months ago #415

Please elaborate on cold start condensation, specifically to smart motors sealed in water-tight, and partially air-tight housings. Even in a nitrogen purged enclosure, there will still be moisture in the air, even within the elecetronics PCBs, rubber components, and potential ingress of outside air in limited quantity from leaky seams. The Alaskan pipeline case study touts operation below -40C, which my application desires as well.

You explain condensation may deposite on the encoder wheel and disrupt position feedback, but this is not permanent damage. Is there any permanent damage potential from condensation on the motor electronics or motor coils?

Can the motor boot up, check it's temp first, and pause in an MTB wait state for the coils and PCB to self heat and burn off the moisture? If no power should be delivered to the motor until an attached heater warms up the motor, it will add additional user or host processor monitoring, as well as a power efficiency loss to actuate a lossy relay or MOSFET on the power line.

For the upper limit, is 85C the ambient temperature, or internal thermister? What ambient temperature range can be expected to overheat the NEMA 17 and NEMA 23 motors running intermittantly?

Re: Thermal limits 4 years, 7 months ago #416

  • csearcy
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The 85C limit is determined by an internal thermistor. It's hard to say if the motor would run for long in an 80C ambient environment. Even intermittant operation can generate alot of heat, if the motor is heavily loaded.
The specification is 0-85C internal, though some applications have been done outside that temperature range.
We recommend external heating if the specification is below 0C, and cooling in high temperature environments.

As far as condensation. You should use our IP motors for your application. I would recommend adding the IP67 option.

www.animatics.com/smartmotor/ip-motors.html
Last Edit: 4 years, 7 months ago by csearcy.

Re: Thermal limits 3 years, 8 months ago #787

  • Zac
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Is there a way to set a Series 4 motor to trip at 85C? Right now, I have one that keeps tripping at 70C and I just need a couple of degrees of wiggle room. Thank you!

Re: Thermal limits 3 years, 8 months ago #788

  • csearcy
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Some Class4 motors had components that worked up to 85C. If your default limit is 70C, then you do not have these components. An external fan blowing on the motor may help you shave a few degrees off.
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