Advantage of DC door operatorgreenspun.com : LUSENET : Elevator Problem Discussion : One Thread
Can anyone please tell me the advantage of using DC door operator than that of a VFD controlled door operator.
-- S.Sivakumar (firstname.lastname@example.org), December 04, 2004
There is no real advantage, especially given that variable frequency creates little in the way of excess heat, the control is smoother,and there is current monitoring which acts if there is an obsruction not seen by the safety edge, giving extra safety for the passengers. The only consideration that I could think of would be energy saving if the D.C. motor was a permanent magnet instead of an energised field, but this saving would vary from site to site depending upon door sizes ,weights, etc.etc. but the savings would be so small. VFD seems like the way to go for door gear operators Sounds like you have a specification to deal with from a consultant who has not kept up, or just found an old specification and used that without giving it too much thought!!
-- geoff judge (email@example.com), December 06, 2004.
Perhaps they are looking for simplicity, and abilty to repair circuitry in the field (assumin non- solid state control).
-- Dan (firstname.lastname@example.org), December 06, 2004.
The main reason in general nowdays for AC door motor is that it is a cheaper motor than DC and the VFD controls it and also gives you a closed loop operation that the consultants specify in their specs. You cant get good door control using a ac motor without a drive but you could with a dc motor and just some resistors and relays. There are many old DC door operators still running that are 50 years old or more. I dont think a ac door motor with a solid drive can make the same claim.
-- Jim (email@example.com), December 06, 2004.
"There are many old DC door operators still running that are 50 years old or more. I dont think a ac door motor with a solid drive can make the same claim."
Give it some time Jim, they've only been out for less then 10 years of so.
-- mike lardner (firstname.lastname@example.org), December 28, 2004.
yes, there are a lot of dc operators out there still running, and for what i have seen, i would put my money on them, very reliable, easy to work on and reasonably priced replacement parts. i have some closed loop operators on my route, spec'd by some goverment consultants that are junk. hard to adjust, difficult to troubleshoot, and expensive to replace. GAL has the only closed loop system i would consider.
-- big joe (email@example.com), February 12, 2005.