Any ideas on this? Most elevators i've seen all of the power for the control elements is derived from the 3-phase main power feed to the controller/machine drive, usually tapped inside the controller's terminal block, or tapped at the isolation transformer. So I'm not sure why a second 480V feed is brought to the controller?

All elevators I have seen were supplied via a 3 phase bus for each lift, and the group controller. Separate supplies were required so that if there was an issue with the group, each lift could still run on independent or what we used to call MA ( when say the group was out), which sent each lift to set floors all the time.

Interesting. What I do know about Otis systems though is most of the modern controllers like the 411 and 401 I noted use a ring style communication loop and each car controller has an ocss board (operation control sub system). My understanding is that All OCSS boards have the abity to become the group dispatcher. So it still isn't clear to me why there exists a separate feed to the group unless one of the car controllers was set as a master for the group and the others cannot assume any dispatching responsibility. What I'm trying to understand is when another 480V power feed for the group is required to be installed.

Well is there a separate group controller in the machine room? There is no reason a group dispatcher would need 3 phase 480. That is why most dispatchers are just powered off a circuit that is hot as long as any 1 car is on. Is the breaker huge? Maybe it's a main that feeds the individual car's breakers.

Its only a 30A 3-pole fused switch, never saw the sizes of the fuses. No separate group controller that I could see, just the (4) main controller cabinets. Each controller has a 100A, 3-pole feeder. There are also the car lights 120V disconencts, but those are different.

What is strange is that the single service car also has another separate disconnect which is labeled as "#5 group' Well the one and only service car is #5, so yeah, that's that. And that service elevator also has a 100A 3-pole feeder and 120v car lights circuit just like the other 4 cars.. It seems like they must be powering the controller logic boards separate from the machine DC drives. Its strange, I'll have to see if I can look at the prints when I go out there again.

You can try pulling the switch and see what happens. However if everything is running good, it may be best to keep on wondering. Wondering never hurts. If it ain't broke, don't fix it.

401's will always have a separate group disconnect, they have a separate group controller. Some of the earlier 411HS units, specifically Mod versions, had a separate disconnect that fed a 3 phase transformer, this in turn fed the hall button power supply.

Yeah our stuff nearly always had a separate group control supply, and didn't rely on parallel feeds coming from all lift to keep them active.

Would the group controller for the 401's be typically installed in a separate cabinet, or did they just install the group boards and transformer in one of the controllers in the group?

Indeed, the 411 I was referring to was a modernization job (411M). Similar question to above, one of the controllers contains the hall button power supply transformer then?

Thanks for the feedback.

Guys,

I went back to the job which has the 411M HS and yes, the group power supply fed directly to the lead controller, so I think I agree with the response for providing common power for the group fixtures in the halls. I think I understand it a little better at this point, turns out some controllers can have a DC supply with blocking diodes so that all controllers are able to provide a source of power for the group control boards. In that sense, as long as one controller is online, it can power the group control board and hall fixtures. Seems like each manufacturer handles this a bit differently.

Thanks for the responses/feedback.