What happens to a lift system installed in an area where there is a widespread and prolonged power outage? To the lifts themselves, nothing: they stop without suffering any damage. Most systems will return to normal service when the power supply is restored, although some may need to be reset by the maintenance company. Not all systems will stop during a blackout. Some types will remain in operation. In particular: • Most hydraulic lifts are equipped with an automatic return device to the floor in the event of a power failure. They should only travel to the designated exit floor of the building, usually the lowest floor, allowing people to exit the car. The lifts then remain stationary until the power failure is over. It is understood that if the car doors (and possibly also the floor doors) are automatic, the system must also power the operator motor to allow people to exit the car; otherwise, once at the floor, the doors can also be opened manually. • Some electric lifts are equipped with a DC motor powered by batteries. These systems can also make more than one trip, depending on the battery charge and the energy consumption determined by the trips, if more than one. • All types of lifts for fire brigades (i.e. compliant with EN 81-72) and for evacuation (compliant with EN 81-76), which must have an emergency power supply. These include those that are defined as “fire lifts” in Italy. • Potentially, all types of lifts that comply with standard EN 8177, and therefore suitable for operation in the event of seismic events, or those compliant with standard EN 81-73, which regulates the behaviour of lifts in the event of fire, provided that the sensor or switch that puts them into emergency operation is configured to activate even in the event of a blackout and not only in the event of a seismic event or fire. In the case of electric lifts, this is only possible if there is an emergency power supply. • In principle, other electric lifts that have an emergency power supply. All other lifts will stop in the event of a power failure, trapping people in the car, if there are any. Lifts put into service after the entry into force of the Lifts Directive (1999 in Italy), or adequately modernised even if installed previously, must have a two-way voice communication system. This system allows trapped people to call for assistance by pressing the alarm button for a few seconds. The request is forwarded to a rescue centre, which in turn activates the maintenance company. The system must have an emergency battery power supply to ensure that it continues to function even during a power failure. Lifts that are not yet compliant, i.e. without a two-way voice communication system, may in some cases be connected to a concierge desk via an intercom. In any case, pressing the alarm button in the lift car will activate an audible alarm signal in the building. It is assumed that anyone in the building will hear the alarm and call the maintenance company by telephone. It goes without saying that most people today carry a mobile phone with them, which they can use to call the emergency services, provided that the maintenance company’s telephone number is displayed in the car,, that the telephone network is active, and that it covers the lift shaft, which is not always the case. The assumption that the telephone network is still active must still be verified even if there is a two-way voice communicator. Today, in fact, diallers mostly use a mobile network rather than a fixed network, which would probably be more reliable. The EN 81-28 standard, which regulates the operation of the rescue system in the event of entrapment in the car, obviously assumes that the network is functioning. Another important detail is that, in Italy, the current Presidential Decree 162/1999 WHAT HAPPENS TO LIFTS DURING A PROLONGED POWER OUTAGE? THIS ARTICLE EXAMINES THE TECHNICAL EFFECTS, EMERGENCY SYSTEMS, CURRENT MAINTENANCE LIMITATIONS, AND OPERATIONAL ISSUES IN THE EVENT OF A PROLONGED POWER OUTAGE Power outages and lifts: MANAGEMENT AND OPERATIONAL ISSUES 32 DI GIUSEPPE IOTTI* BLACKOUT
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