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

Figure 3‐36. Active power of an escalator in different operation modes (source: ISR‐UC).
Simpler solutions are also available, but are not as attractive due to the lower travel comfort
and limited energy savings:
• use of two‐speed‐motors
• switch the motor to star operation and supply it with lower voltage when there is low
escalator traffic the motor. When several passengers enter the escalator the motor is
switched back to delta operation.
Escalators can also be equipped with regenerative capability. Under ideal conditions, the
energy needed to move the escalator in the upward direction would equal the energy
provided by passengers travelling in the downward direction. Since losses are involved (friction
losses, motor losses, drive losses, etc.) this is not the case. Nevertheless, regeneration in
escalators can save up to 60% of the energy used by non‐regenerative systems in very high
traffic demand installations. It should be noted that regeneration capability is inherent to
induction motors connected directly to the power network, although the regeneration
performance can be improved by the use of inverters.
3.10 Low Friction Bearings
Losses in bearings result from several types of friction (rolling friction loss, sliding friction loss,
sealing friction loss and drag or lubricant shearing loss). A new generation of bearings is
appearing in the market that can reduce these losses by 30% to 50% while extending the
service life by a factor of two.
50