×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

DC or AC drive for extreme temperature

DC or AC drive for extreme temperature

DC or AC drive for extreme temperature

(OP)
Hello,
I am looking for a motor speed control device to run a 1.5 Hp motor, could be AC or DC. I need to position a gate up and down, so the motor of course must be reversible. The speed (currently) is a constant 1750 rpm, and so the positioning is done by pulsing the motor on/off with a timer. I would like to replace this using a DC drive and a PI controller. The problem is that the environment is extremely cold, as low as -30 to -40F. A VFD wouldn't live very long in such temperatures. The power is not reliable, and so having a heater on site is also unreliable.

Any ideas on drives that can handle such low temperatures?

thanks
EE

RE: DC or AC drive for extreme temperature

Maybe a silly question, but if if power is unreliable, how would ANY motor open the gate reliably, VFD or not?

Can you remote-mount the drive in a warmer location and run wire / conduit to your motor location? At that temp, I'd be looking carefully at the motor as well. Very well might have to utilize low-temp bearing grease, etc... I'd also have similar concerns about the gearbox, and anything else with moving parts.



SceneryDriver

RE: DC or AC drive for extreme temperature

(OP)
The gate would not move if there was no power. Nothing can be done about that short of a generator.

RE: DC or AC drive for extreme temperature

The drive is not necessarily the problem, it's the capacitors in the rectifier that is. If you had a DC power source, i.e. batteries, you could conceivably solve both problems with a DC-DC drive, something like what is used on DC powered vehicles, they would not have an on-board rectifier with electrolytic caps.

But what's going to charge the batteries in that kind of cold? You may have to have a custom solution fabricated for you. I did one a long time ago where I had an input contactor for the AC that was tied to a a thermostat that stays open until the temperature rises above 10C. That way the power was kept off of the capacitors until the ambient was above freezing for long enough to ensure they were OK. The end user hated having to wait, bypassed it and blew the caps the first time he used it after that. But it worked fine up to that point.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)

For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies

RE: DC or AC drive for extreme temperature

(OP)
Thank you. That is an excellent idea.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources