Elevator on generator

Status
Not open for further replies.
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
Occupation
Electrician
Stupid question here, but what happens if the power goes out while someone is in the elevator? How often are elevators provided with backup power? I have a three story building that I am providing with some optional standby power, and it just occurred to me that perhaps I should consider putting the elevator on it. We have lost power three times in as many weeks for about 5 hours due to a chronic problem with an underground POCO feeder. Disadvantage is of course the elevator chews through a decent chunk of the generator capacity, and starting could be an issue if the generator is already loaded up. I metered a max of about 80 amps 208 three phase for the elevator, out of 550A of standby capacity.
 
I know pretty much nothing about elevator codes but something tells me there probably has to be at least enough standby energy to allow the car to move to a position where it can open and let passengers out, possibly nearest available level at a minimum but not necessarily required to be the ground floor level.
 
hillbilly1 said:
It just reboots as if utility is lost and regained. It may have battery backup that takes it to the nearest floor down and open the doors.
Click to expand...
This is a hydraulic elevator, and I noticed it uses very little juice when going down as all it is doing is releasing the valve. I wonder if it has an option for a standby connection where it will just go to lowest floor and open the door? Is that a common thing? Perhaps I could get an elevator company to look and see if it has an option like that.
 
kwired said:
I know pretty much nothing about elevator codes but something tells me there probably has to be at least enough standby energy to allow the car to move to a position where it can open and let passengers out, possibly nearest available level at a minimum but not necessarily required to be the ground floor level.
Click to expand...
This is done with a battery backup unit. At least on one occasion for a job I worked on. Where it gets tricky is when you have a shunt trip involved. If you're not careful how you arrange things, the car continues to operate on battery once main power is cut.
 
gadfly56 said:
This is done with a battery backup unit. At least on one occasion for a job I worked on. Where it gets tricky is when you have a shunt trip involved. If you're not careful how you arrange things, the car continues to operate on battery once main power is cut.
Click to expand...
I admit I know next to nothing about elevators, but seems like in a perfect world, the manufacturer would just provide a set of terminals for a generator or back up unit that would lower the car and open the door and then cease any other operation until the main supply comes back on? Seems like just a few lines of code and a few bucks in terminals (in a perfect world). This elevator is early 80's I believe.
 
electrofelon said:
I admit I know next to nothing about elevators, but seems like in a perfect world, the manufacturer would just provide a set of terminals for a generator or back up unit that would lower the car and open the door and then cease any other operation until the main supply comes back on? Seems like just a few lines of code and a few bucks in terminals (in a perfect world). This elevator is early 80's I believe.
Click to expand...
I don't disagree, assuming the generator has sufficient capacity. You would need a voltage relay to tell the controller that main power has been lost. This would be very similar to Phase I elevator recall.

The elevator I mentioned was an hydraulic unit, so the battery provided enough power to operate the bleed valve that let the elevator down and maybe the interior lights. I don't think this scheme would work with a traction elevator.
 
electrofelon said:
Stupid question here, but what happens if the power goes out while someone is in the elevator? How often are elevators provided with backup power? I have a three story building that I am providing with some optional standby power, and it just occurred to me that perhaps I should consider putting the elevator on it. We have lost power three times in as many weeks for about 5 hours due to a chronic problem with an underground POCO feeder. Disadvantage is of course the elevator chews through a decent chunk of the generator capacity, and starting could be an issue if the generator is already loaded up. I metered a max of about 80 amps 208 three phase for the elevator, out of 550A of standby capacity.
Click to expand...
Typically on Hydraulic elevators if power fails there is enough energy stored in the hydraulic system to bring the elevator down. That has been my experience with Hydraulic elevators. If this is not happening I would talk to the elevator rep to see what can be done. On traction elevators driven by an electric motor, when power fails the motor will stop where ever the elevator is and the solution is to provide backup power whether with a generator or batteries. If the elevator is not part of the building evacuation system (this is determined by the architect during design while doing the life safety plan) then providing backup power to the elevators is not a Code requirement. Personally I don't agree with this and we have done a few projects where an optional standby generator has been added after the fact just to bring the elevators safely down.
For high-rise buildings providing generator backup power to the elevators is a Code requirement.
 
Most elevators today have what's called ARD's. (automatic rescue device) When power is lost, it will return to a nearby floor or the ground floor and the doors will open and remain out of service until power is restored. Very similar to what they do in case of fire.
 
Rick 0920 said:
Most elevators today have what's called ARD's. (automatic rescue device) When power is lost, it will return to a nearby floor or the ground floor and the doors will open and remain out of service until power is restored. Very similar to what they do in case of fire.
Click to expand...
I could try and get the owner to consult with an elevator guy for options. Perhaps a quick and dirty option would be to provide an interlocked ,small alternative supply that could just get the elevator down and the door open. Not sure how the elevator behaves after power is restored though, it could potentially continue with an in process up cycle.
 
From what I have experienced working around hydraulic powered elevators is that during a PF the hydraulic valves open (thru battery backup controls) and gravity brings the cars down to the next landing and doors open to let out people. Also with this type of elevator design, it is not critical that the cars are moving when the powering ATS transfers to generator. Maybe an elevator mechanic or design engineer can join in and elaborate more on hydraulic elevator operation.
In high-rise buildings employing traction motor/ cable elevators (which I am more familiar) it is a whole different ball game. With the newer solid-state elevator controllers it is critical that signals are sent by the ATS to the elevator controllers to prepare for the load switching and also indicate that power will be fed from generators (switching the controller logic to a different mode of operation.) The traction motor discussion may be a little off topic but I think is important enough to note here and maybe help others in solving other types of problems when elevators are powered by generators. I have attached some files for reference. I may be able to send more files later.
 

Attachments

  • Elevator Presignal Theory_TKE.pdf
    350.6 KB · Views: 25
  • Elev Pre Sig spec_Shindler_0941.pdf
    1.3 MB · Views: 25
I don't know what kind of building you're working in, but it would really suck to have that elevator return to a lower floor and leave somebody in a wheelchair stranded two floors up
 
James L said:
I don't know what kind of building you're working in, but it would really suck to have that elevator return to a lower floor and leave somebody in a wheelchair stranded two floors up
Click to expand...
Well better than being stuck in the elevator! So there actually is a foot and ankle care place in there and I do see lots of wheelchairs.....but that tenant will be out when there lease is up, end of the year I think.....
 
ATSman said:
From what I have experienced working around hydraulic powered elevators is that during a PF the hydraulic valves open (thru battery backup controls) and gravity brings the cars down to the next landing and doors open to let out people. Also with this type of elevator design, it is not critical that the cars are moving when the powering ATS transfers to generator. Maybe an elevator mechanic or design engineer can join in and elaborate more on hydraulic elevator operation.
In high-rise buildings employing traction motor/ cable elevators (which I am more familiar) it is a whole different ball game. With the newer solid-state elevator controllers it is critical that signals are sent by the ATS to the elevator controllers to prepare for the load switching and also indicate that power will be fed from generators (switching the controller logic to a different mode of operation.) The traction motor discussion may be a little off topic but I think is important enough to note here and maybe help others in solving other types of problems when elevators are powered by generators. I have attached some files for reference. I may be able to send more files later.
Click to expand...
Cool thanks. I have been in the elevator control room and didn't see any batteries, but I wasn't specifically looking. It's of course easy enough to throw the disconnect and see what happens, I won't be back there for a few weeks but I'll check it out when I do.
 
electrofelon said:
Cool thanks. I have been in the elevator control room and didn't see any batteries, but I wasn't specifically looking. It's of course easy enough to throw the disconnect and see what happens, I won't be back there for a few weeks but I'll check it out when I do.
Click to expand...
If this is a low-rise building with an hydraulic elevator, they may be just a couple of 12V-7A-hr batteries stuck inside the controller cabinet. IIRC, that's how it was with the one I worked with.
 
electrofelon said:
Stupid question here, but what happens if the power goes out while someone is in the elevator? How often are elevators provided with backup power? I have a three story building that I am providing with some optional standby power, and it just occurred to me that perhaps I should consider putting the elevator on it. We have lost power three times in as many weeks for about 5 hours due to a chronic problem with an underground POCO feeder. Disadvantage is of course the elevator chews through a decent chunk of the generator capacity, and starting could be an issue if the generator is already loaded up. I metered a max of about 80 amps 208 three phase for the elevator, out of 550A of standby capacity.
Click to expand...

Talk to the engineer and AHJ. For low rise three story there maybe local codes. Also still low rise IBC or some other codes also might apply.

Some elevators do have enough battery backup to bring it down to X floor and open doors and thats it and some dont.

Be careful if this elevator is part of egress or its part of fire elevator then the battery backup internal would Not be enough and backup power would be needed as elevator would need more trips up and down Not just one down.

Of course depends also where u install elevator other than above scenario more important question u should ask is more than one trip necessary life safety issues, in case of fire etc? If yes then put the gen backup.

Also do u want people in elevator without lights hvac? Elevator cab lights and hvac would go in backup life safety perhaps

Of course i only see this sitting at my desk reviewing plans

Talk to designer and AHJ.
 
Last edited:
James L said:
I don't know what kind of building you're working in, but it would really suck to have that elevator return to a lower floor and leave somebody in a wheelchair stranded two floors up
Click to expand...
The kind of buildings we work in are major hospitals, high rises, data centers, telcos., etc. I suggest you stick with your residential/ commercial customers and stuff you are knowledgeable about unless you are willing to educate yourself and grow. This is the big boy's arena and all of what we do are based on sound principles backed up by 51 years of field experiences, industry standards and all of the electrical institutions: IEEE, NEMA, NEC etc,, etc.
Sorry but this comment really ticked me off ................along with the extra glass of red vino! lol
don't forget your daily amount of anti-oxidants (Resveratrol) and other Meditrenian foods to fight the Covid!
Pls feel free to comment as I always love a challenge.
 
This is a continuation of the attachments for post #11
 

Attachments

  • ATS Elev Pre Signal explained_MH pdf.pdf
    5.6 KB · Views: 20
Status
Not open for further replies.
Top