Read our FAQs to know more about SEM
- What is SEM?
SEM is an energy control, storage and recovery system.
- Is SEM an inverter?
SEM is also an inverter, indeed inside the electronic unit there is an inverter to control the elevator motor.
- What do you mean by for energy storage?
SEM is composed by an electronic control unit and an energy storage. This means that SEM stores energy into its own accumulator, to give it back to the elevator whenever it is necessary.
- What do you mean by energy recovery?
During its normal working operations, the elevator is where energy transformations happen, from kinetic to potential energy and vice versa. Usually this energy is dissipated as heat in the braking systems (braking resistance in the inverters, on valves group in the hydraulic elevator). On the other hand, SEM, instead of dissipating the energy, recovers the same energy in its own accumulator, using an electric motor as generator. So the descending and braking energy, usually lost in normal elevators, thanks to SEM system is always recovered and given back to the elevators, so it is actually restored.
- What do you mean by energy control?
The elevator flow is highly recurring and casual. SEM allows to reduce the instantaneous power absorption from the electricity grid (by controlling the power), supplying to the elevator the necessary power from the accumulator, charging the latest whenever the elevator is in pause. This enables a very lowered and much more continuous absorption (of power) from the electricity grid.
- On which kind of elevators is it possible to install SEM?
SEM can be installed on any elevator, both new and existing, either hydraulic and electric with or without transformer (elevators with highest power of 15kW or maximum energy 600kJ).
- What modifications on the electrical panel are necessary prior to SEM installation?
SEM is installed upstream than the electrical panel, between the network and the panel itself, so no modifications are required on the panel nor on the existing elevator plant. The power supply of the electrical panel must be connected to the auxiliary SEM inverter (optional component for the panel supply in case of Blackout), while the power supply of the motor must be connected to main SEM inverter. For a proper functioning, it is necessary to provide to SEM the information regarding rising and descending phases, speed etc. through clean contacts (usually these contacts are available on main contactors on the panel). If the motor is supplied by a Wye-Delta System, this should be removed and the motor must be connected into the delta configuration directly to SEM.
- If the motor has a power supply with a wye-delta configuration, how is connected to SEM?
If the motor connection is wye-delta, when using SEM we must remove the wye and delta-connect it directly to SEM.
- SEM power supply is single or three-phase?
SEM can be indifferently powered as single phase at 230 V or as three-phase at 400 V, 50-60 Hz. When powered in single phase the limit power is 3 kW, while in three-phase limit is 9 kW. This means that SEM will never absorb an higher power than the limit one. Anyways it is always possible to reduce the absorbed power with regards to the limit power by programming the configuration parameters. In other words, in single phase it is possible to set a power in between 1 kW and 3 kW, while in three-phase a power in between 2 kW and 9 kW.
- If SEM is powered in single phase is it possible to install it on elevators which are normally three-phase?
Sure it is. SEM power supply does not condition the inverter outputs characteristics, which are always three-phase 400 V. Indeed SEM provides an outgoing three-phase voltage stabilized at 400 V.
- SEM accumulator is made of batteries?
No, it is not. SEM does not use batteries to store energy. Batteries have different disadvantages, as low efficiency, short lifespan, high maintenance costs, high disposal costs, as well as the impossibility to restore energy. SEM uses a kinetic accumulator, with a very long lifespan, very high performance, low maintenance costs and totally regenerating.
- What is a kinetic accumulator?
The kinetic accumulator is a mechanical flywheel that has very high inertia, rotating at high speed. The stored energy is kinetic.
- How long does a kinetic accumulator last?
Theoretically the accumulator has a never ending lifespan. The only limit can be found in bearings lifespan, which is usually 8-10 years. After this period of time, it is necessary to replace the bearing to renovate completely the accumulator. This is part of a scheduled maintenance with very low costs. A new accumulator (inspected) is delivered, as replacement of the old one, that will be inspected at his turn. Total replacement time: less than an hour. The substituted accumulator is regenerated at 100%.
- How much can we save with SEM?
It depends a lot according to the elevator where SEM is installed. On electric elevators there is a 25% up to 50% saving, according to the elevator performance. For hydraulic elevators, if there are not regenerating, saving is not possible, while if it is regenerating you can save up to 30%, increasable if new generation control units are used, having a non-plunged motor, brushless motor, high efficiency valves group etc…
- If there is no energy advantage on existing or non-regenerating elevators, why installing SEM?
Mainly for a money reason. SEM allows to reduce the installed power of about 75-80%, this means from 15 kW to 3 kW, so there is an energy costs saving (bill) up to 50%.
- How can an hydraulic elevator become regenerating?
To make it regenerating, it is necessary to modify the valve group, so that the oil, during descending phase, can flow through the pump, enabling the motor to turn also for the descending control, so that energy can be recovered.
- How much power can we reduce by using SEM?
Achievable power reduction is in between 66% and 80%, depending on the operation cycle to which the elevator is subject. If the elevator has an high performance, we reach up to 90% reduction.
- Does the power reduction involve a reduction of elevator performances, like speed, loading, etc.?
No it does not. There is no performances reduction, otherwise with SEM it is possible to increase the elevator speed, if allowed by the safety components. For example, if the elevator works at 0,5 m/s and the safety components are suitable for 0,63 m/s (parachute), then the speed can be increased up to that limit, for example by setting the inverter control frequency to 60 Hz, without changing anything to the existing plant.
- Does SEM reduce the power as any other Inverter?
No, it does not. SEM allows a much higher power reduction.
Any other inverter enables only to reduce the pick power and, by reducing the speed, also the installed power against lower performances. Otherwise SEM allows a severe power reduction, having the kinetic accumulator as auxiliary energy source. Thanks to SEM it is also possible to increase the elevator speed up to elevator safety limits, without increasing the absorbed power.
- What does it happen in case of Black-out?
SEM guarantees to complete the race up to the programmed floor, without any continuity solution, both for electric and hydraulic elevators. For this operation the elevator panel must be powered by its own back-up unit or by SEM through an external inverter (optional component).
- How is the electrical panel powered during a Black-out?
SEM is provided with an auxiliary inverter (optional component) for the panel power supply, guaranteeing the operations continuity during a black-out.
- During a black-out, how many races does SEM allow?
During a clack-out, SEM does not accept new commands, but it finishes the existing race up to the chosen floor, without any continuity solution. This choice is dictated by safety reasons.
- By using SEM, is it possible to remove three-phase power source in the condominium?
SEM allows the elevator to have a normal single phase 230 V power supply. If there are any other three-phase loads in the condominium, such as watering pumps, autoclave, etc., then it is not possible to remove the three-phase power source. Otherwise it is possible.
- How long does it take to install SEM?
It takes about 2 hours to install SEM. It will take longer for those plants where cable passage is difficult, anyways not more than 4 hours.
- What operations are required for the functioning?
SEM is supplied as pre-set and it does not require any special programming operation. Only some elevator configuration information are needed (elevator type, electric or hydraulic elevator, regenerating or not, etc.).
- How does SEM programming work?
SEM is provided with a Wi-Fi device, so it can be connected to any PC, tablet or smartphone, with a Windows or Android operating system. In the same way it is possible to monitor SEM functioning to check the status and network absorption.
- After SEM installation is it necessary to have a new elevator certification?
No, any additional certification isn’t required, because SEM does not modify the electric panel nor gets into elevator safety. SEM is placed only in between the electricity grid and the panel and it controls only the power supply, guaranteeing power continuity and voltage stability.
- What kind of practices are needed to install SEM?
To install SEM there is no need for any practice. Otherwise to take advantage of power reduction it is necessary to go to its own network manager and inform them about installed power change.
- Is SEM noisy?
SEM is a dynamic machine so it has a light noise that in some application could be a problem. If the plant has its own dedicated engine room then the light noise is not a problem. But for those applications where there isn’t any engine room, SEM should be provided with soundproof protection, which removes completely the problem.
- Is SEM always functioning?
SEM is composed by a flywheel, which is a kinetic accumulator so it is charged when it’s rotating, therefore it is always functioning, while the electronic control works only during races and flywheel is charging. However SEM enables some alternative procedures in order to manage its own activity during low traffic hours, permitting a smarter use of energy.
- How much is SEM self-consumption?
SEM is an high performance energy control system. However during stand-by times it has an average absorption of 60-80 W, including the electronic part when it turns at highest speed.
During night hours value can be reduced to about half of it.
- What is the operation intensity or service cycle that SEM can tolerate?
SEM has undergone different typical operation cycles tests. The most extreme case was with cycles that lasted 2 months powered with 2kW absorbed (single phase) and 14kW absorbed from the elevator, around 2 races per minute, for a total of 1400 daily races.
- Are there any SEM systems installed on external plants?
Yes, there are. Different units have been installed in condominium plants since some months and up to today they are working perfectly.
- Can I have a saving immediately?
Saving obtained thanks to SEM is immediate, and it is equal to 45% of energy bill for a condominium elevator.
- How long do I need to get back on the investment?
It depends on plant characteristics, but usually payback time is around 3-5 years.
- Does SEM benefit of tax credits?
Yes, it does. By installing SEM you can have a tax credit of 50% in 10 years and VAT tax at 10%.
- What is the delivery time?
Currently delivery time is around 60 days. In the future it will possibly be reduced to maximum 30 days.
- What does it happen in case of SEM malfunction?
In case of SEM malfunction, the elevator stops and the technician will replace the non-working component within 24 hours.