WP6-Brochure-E4 brochure - ELA European Lift Association.

• Car electronics
• Light curtains / door detectors
Due to the extension of the waiting times – the rebooting sequence can take up to 30 seconds
– this second stand‐by mode would only be suitable for long periods of low passenger
demand.
Another cause for losses is that the lift shaft can facilitate thermal losses from the building.
Some lift shafts are required to have vents in order to dissipate smoke in case of fire, but also,
in high‐speed lifts, to reduce wind noise and transient pressure changes caused by the car
movement. They also help dissipating excess heat from the lift motor. Through leaky or open
basements, outside air flows into the shaft, is heated in the pit walls and rises ‐ as a result of
chimney effect. This flow also draws in warm air from the heated space opposite the lift doors,
which leads to comfort problems (drafts). The heated air flows outwards through the air vents
at the top of the shaft.
Correct insulation around the entire heated volume should be ensured to avoid such losses.
The lift shaft and machine room should be well insulated and flaps in the air vents should also
be airtight. Another option is to locate the lift shaft entirely on the outside of the heated
volume, the lift doors leading to unheated spaces or to the outside (this solution is not always
possible, for example in cold climate regions).
Another cause for inefficiencies are the guide rails and shoes that ensure travel in a uniform
vertical direction. Correct maintenance (e.g. alignment, lubrication) should be guaranteed to
minimise the losses in these components. Furthermore, when correctly maintained, the use of
roller guides is preferred to the use of sliding guides. Tests show an effective coefficient of
friction for roller guides of 0,03. With sliding guides, this friction can easily be 10 times as
much, especially if the lubrication is not well maintained. Sliding guides can easily cause over
100 kg (1000 N) of frictional losses in the system if it is not well balanced, or if the 4 guides and
rails are not perfectly co‐planar. Even with perfect balance, loads can be placed in the car off
centre, causing frictional losses at the guides. In roller guides, unbalances can also cause flat
spots, creating noise and reducing ride quality.
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