Just realized older elevators with DC motors run way smoother than newer VVVF models

I was doing a service call on a 1983 Otis in a downtown Seattle building last month and when it ran I barely felt it level at all. Compared it to a 2019 Schindler I worked on the day before that jolts every time it stops. I think the older gearless DC setups just had better speed control built in, even if they chew through brushes like crazy. Has anyone else noticed vintage DC drives ride nicer than the modern variable frequency setups?

3 comments

3 Comments

derek9392d ago

You’re romanticizing old brush gear, johnson.lee - those DC drives had huge lag in their speed loops and would overshoot on leveling if the pots drifted even a little. New VVVF setups can ride just as smooth if the building pays for proper tuning instead of the cheapest install package.

river18225d ago

My 1985 Otis in the building I manage levels smoother than my 2019 neighbor's Kone that sounds like it's slamming into a brick wall every floor. Guess we traded ride quality for energy efficiency.

johnson.lee25d ago

It's funny how that works, we optimize for efficiency and end up losing the little comforts that made old stuff feel solid (like a good car door thud vs a tinny new one).