SCR versus MG Drivegreenspun.com : LUSENET : Elevator Problem Discussion : One Thread
Some elevator companies have been claiming that the beneits of adding SCR drives during the modernization of elevators with DC drive motors was overstated. They claim, thereore, that building owners are usually better off retaing the existing MG sets. Any opinions?
My second question, a new VVVF geared elevator, 350 fpm, has about a 1.5 second delay beore it moves once the doors have closed. The installer says that this is normal for variable frequency AC drive motors. Any comments?
-- Ted Arnon (firstname.lastname@example.org), September 03, 1998
Hopefully, both of the responses that you refer to aren't coming from the same elevator company. If they are,.... you should run like hell to the nearest reputable installer. (Bad advice in both cases,... cliche?... Lie to me once, shame on you,... twice, shame on me.
-- RAGman (email@example.com), September 03, 1998.
We(Johns Perry Lifts) were doing mods using a computer generated pattern in a simple '70s style thyristor amp going to the generator fields.It has proved to be much quieter than SCRs(no hum) and no problems.This was until we were sold out to Otis a couple of years ago.I don't know if Otis has any intention of continuing the idea.They were still selling our SCR lifts last year because they're heaps cheaper to make than 411s.
-- Jarrod Emery (firstname.lastname@example.org), October 02, 1998.