Lutfi Al-Sharif,Enas AlOsta,Noor Abualhomos,Yazan Suhweil.  
The University of Jordan, Jordan

One of the sources of efficiency in the operation of double deck lifts is the simultaneous transfer of passengers into and out of the elevator cars, thus leading to a reduction in the value of the round trip time, and thus an increase in the handling capacity. However, due to the randomness of passenger destination selections, this reduction is not optimal. This paper presents this phenomenon as an efficiency coefficient, denoted as the Passenger Transfer Efficiency Coefficient (PTEC) and is representative of the time taken by passenger to alight from the double deck lift. PTEC is mainly applicable to passengers alighting, rather than passengers boarding. This is true in the case of a single pair of entrances. For the case of multiple pairs of entrances, the PTEC applies to both alighting and boarding operations. A set of equations are derived in order to calculate the PTEC. The results from the equations are verified using the Monte Carlo simulation method. The method of stepwise verification has been used in order to verify the equations.



Gina Barney.
Gina Barney Associates, UK.

This paper, relying on the first 100 years of lift traffic design, briefly relates the developments in lift traffic design since 1950. The paper will look at the contributions of, amongst others of: Alexandris, Barney, Closs, Dos Santos, Peters, Schroeder, Strakosch. These developments are of necessity intertwined with lift traffic control changes, including Hall Call Allocation, during the same period. A view ahead will be indicated.



Michael Bottomley.
MovveO Ltd, UK.

Hospitals, Universities and Research Laboratories often need to transport liquid Nitrogen and other hazardous substances in lifts. Passengers are at unacceptably high risk if they travel along with these substances and employers have a duty to avoid employees being put at risk. The paper examines the design features required for a lift, management arrangements and training requirements to establish a safe system of work for these situations. The paper concludes that a code of practice is required to set best practice for what is currently dealt with on an ad hoc basis.


A History of the Lift Safety Gear

David Cooper.

The safety gear is regarded as the last line of defence in the relatively safe world of lifts. Industry contemporaries recall Elisha Otis declaring “All safe” after cutting the ropes on a platform upon which he was standing and the safety gear preventing his uncontrolled descent. The design of safety gears has moved on significantly from an original proposal to place a bag of feathers in the lift pit to designs that now arrest uncontrolled movement in ascent. This paper will look at UK patents and standards and tracks the development of the safety gear from the embryonic days of lift installations to the present day.



Thomas Ehrl, Jonathan Adams, Stefan Kaczmarczyk and Benedikt Meier.
The University of Northampton, UK.

Urban “Open Teaching & Learning” in a University/ academic environment becomes more and more important and needs to be designed in the most efficient and effective way to ensure a balanced return-on-investment. This issue is of particular importance when it comes to complex learning areas. In this context the paper addresses challenges arising in a multi-disciplinary and multi-cultural environment and that can be solved using a range of problem solving strategies. The development and application of problem solving strategies become an outcome of a learning process to gain and to develop knowledge.

This paper presents an in-depth analysis of state-of-the-art learning methodologies (knowledge transfer process) to ensure a higher learning engagement of all employees, taking into consideration function, age, culture and technological abilities. The differences between an expert and a novice approaches to engineering problem solving are investigated and identified. The results show how important is to understand and implement the effective means of communication and the use of common science/ engineering language. The results arising from this paper will identify the pedagogic and business impact of an individualized application of problem solving strategy. Based on the current state of the art and literature on the subject, the paper concludes with a proposal of the optimal knowledge transfer strategy to be integrated into the existing pedagogic provisions to be implemented in a multi-disciplinary / multi-cultural R&D (learning) environment of a global PTS company and an academic environment to aid problem solving and engineering knowledge transfer.



Osamu Furuya, Satoshi Fujita, Naoki Fujiwara.
Tokyo Denki University, Japan

Various safety devices are provided to ensure the safety of the lift passengers. A number of safety systems are employed to prevent injury in case or uncontrolled movement. The car and counterweight buffers (shock absorber) play an important role. This paper considers appropriate performance of the car and counterweight buffers. Buffer performance is examined to satisfy a safe condition in the revised JIS A 4306.



Stefan Gerstenmeyer1,2, Richard Peters2,3, Rory Smith2,4.
1thyssenkrupp Elevator Innovation GmbH, Germany. 2The University of Northampton. UK, 3Peters-Research Ltd, UK. 4thyssenkrupp Elevator North America, USA.

There is a range of lift systems with more than one car or cabin per shaft. Double deck lifts have a car with two attached cabins, serving adjacent floors at the same time. Other systems enable two independent cars to share the same shaft. The next generation ropeless lifts will allow many cars to share the same shaft.

In these systems the interaction between the cars and cabins affects the quality of service for passengers. Departure delays occur when passenger loading and unloading times or the sequence of stops required to serve passengers is not the same. The consequence is that cars and cabins delay each other’s departure. Departure delays can also occur in lift systems with a single car and cabin per shaft, for example as a consequence of destination calls which are registered at a significant distance from the lift lobby.

To include departure delay in an assessment of quality of service, a definition of passenger and cabin departure delays and a method to measure these delays is required. This paper describes the different types of departure delays and their causes. It proposes a way to measure these delays in both simulation and real systems. This provides a metric which can be applied in lift planning and dispatcher design.



Adrian Godwin.
MovveO Ltd, UK.

Multiple academic papers and articles point to vertical transportation quickly becoming the “roadblock” to the viable design of super tall and mega tall buildings, despite the development of light weight ropes, high speed drives and advanced control algorithms. The space take of traditional elevators with only one or two cars per shaft is onerous and the obvious solution is to develop a system in which multiple cars can safely travel within a single shaft. The technology required to undertake the construction and delivery of the first MMLS (Multi Mobile Lift Systems) is now around us and, given the overwhelming business case for such systems, is more than paid for by their space saving capabilities. It is now simply a question of when, not if, these systems become safety certified for public use. This paper overviews some of the new planning tools that have been developed to analyse such systems and reviews some of the practical aspects of how such systems might operate in the coming years.



Aleksey Gorilovsky, Dmitry Gorilovsky.
LiftEye Ltd, UK.

Lift cars used for years to be more like closed transportation boxes than an element of architectural experience. The limited visual stimulation experienced in a conventional lift typically became awkward interruption to the complex, enriching experience offered by the architecture of public buildings. The glazed car brings an ideal solution to overcome that interruption, but is not feasible in most cases and associated with high extra costs. As a result, the lift level indicator became the typical tool to inform passengers about current position, additionally featured in some advanced cases with cartoons. A realistic virtual elevator window system designed to transform the passenger’s experience was released four years ago and gradually occupies its segment of sophisticated lift features for upscale buildings. The technology based on precise calculation of every pixel is capable of providing a real-time picture of building surroundings as well as an augmented reality and environment. Modern trends of visualization, utilized in lift cars up to and including the virtual lift window, are compared in terms of actual environment reflection degree, adjustment to height position and time lag delay. In times ‘while architecture at its best is coming up with something that is pure fiction’, we see an architects’ tool which is already embedded in the vertical transport cab. There is a sound advertising potential, more humanized typology of lift design, and barely universal navigation tool for visitors of public buildings. Further prospects of employing that technology in forthcoming multidimensional elevators as well as in conventional elevators are shown in terms of technical feasibility, costs and outcome.


Lee Gray.
UNC Charlotte, USA.

A survey of recent literature on lift traffic analysis and planning reveals that only one pre-1950 source is referenced in this body of work: “The Probable Number of Stops Made by an Elevator,” Bassett Jones, General Electric Review, August 1923. While the number of works that include this article in their bibliography highlights its apparent significance, the fact that only one source is referenced from the period from 1900 to 1950 prompts the following questions – 1.) What was the intellectual context for Jones’ work? and 2.) Were there others who sought to establish a mathematical basis for determining lift traffic needs and parameters? This paper will examine the history of lift traffic analysis and planning from 1900 to 1950 and will chronicle the initial development and articulation of quantified criteria and mathematical formulas designed for determining the proper number of lifts, their operating speeds, and required traffic flow. The early history of this subject defines the foundation for contemporary work as well as serving as a reminder that, while many things have changed (often dramatically) since the first half of the 20th century, others appear (perhaps surprisingly) to have remained the same.



Roger Howkins.
Arup, UK.

This paper will consider if the published lift modernisation standard such as BS EN81-80 or guidance given in CIBSE Guide D goes into sufficient detail to allow for safe lift modernisations. It will ask the question if lift contractors have all the required skill sets to design and sign off the total complete lift installation as being safe and also if a lift modernisation is structurally, mechanically or electrically safe or do we need a professional engineer to sign off on the design?

The paper will use as a basis examples to highlight deficiencies in designs and where lift contractors should employ specialist consultants to check and sign off proposed designs which currently are not required by guidance or code. Also how much information should a lift modernisation contractor have before starting a complex lift modernisation? It will also investigate why because of price driven modernisation contracts lift contractors are not employing professional qualified engineers to advise on structural, electrical, mechanical and public health aspects which may possibly affect passenger safety and structural integrity of the lift shaft and the modernisation of lifts.

It will discuss important aspects which are sometimes overlooked such as; will the lift equipment being replaced in the lift motor room have new heat outputs which will require modification or does a redesign of the lift motor room heating and ventilation system need to be carried out to make sure it will be suitable for the new equipment provided. The paper will ask several fundamental questions, do lift modernisation contractors provide sufficient due diligence to the building occupiers and the end user client? Or do we accept without question the lift has worked without problem for the last “x” years and should possibly provide service for another “x” years without issue? How much design consideration is given to possible new load paths, structural alterations, adequacy of power supplies and carrying out “cloud surveys” of existing lift shafts? It will discuss important aspects which are sometimes overlooked such as; will the lift equipment being replaced in the lift motor room have new heat outputs which will require modification or does a redesign of the lift motor room heating and ventilation system need to be carried out to make sure it will be suitable for the new equipment provided.



Asami Ishii, Satoshi Fujita.
Tokyo Denki University, Japan.

The escalator is one of most important vertical transportation measures to connect each every one of storey-layers in buildings. During severe earthquakes, escalators are not only shaken by themselves, but withstand lateral relative deflexions induced in the structures or buildings installing them. Therefore, escalators are usually installed in the buildings with one side of them in fixed connection and the other side in free condition or utilized both sides in the non-fixed style in order to mitigate undesirable excessive deflexions induced in the truss-like structures of escalators. However, in the Great East Japan Earthquake, fall accidents of four escalators occurred in the three locations. Escalator truss might come off from the beam of the building, because excessive lateral deformations were induced in the storey-layers with more than assumption where the accidents happened. During these accidents, it was also considered that a non-fixed part might collide with the beam of building by larger deflexions than expected occurred in the sliding parts; this collision might cause excessive compressive force and residual displacement in the escalator truss might be caused. It is necessary to clarify the seismic behavior of the escalator to prevent such an accident. From the above-mentioned background, the object of this research is to construct an analytical model to clarify the seismic response behavior using the non-linear restoring force characteristics of the escalator truss model. In this paper, the restoring force characteristics model was build, which was similar from the load-displacement curve obtained from the full-scale escalator truss compression experiment. The seismic response analysis of an escalator installed in the building was performed using the restoring force characteristics and the Bi linear model. As a result, it is thought that the displacement to occur to the escalator is more likely to depend on the forced displacement to receive from a building. .



Stefan Kaczmarczyk.
The University of Northampton, UK.

Lift systems are susceptible to damage when building is subjected to strong earthquake motions. The counterweight - guide rail and car guide rail systems suffer from earthquake-induced vibrations. The most common mode of failure is the counterweight derailment. This paper reviews the dynamic phenomena and presents a robust model to study, to predict and to mitigate the effects of the seismic responses of guide rail – counterweight/ car – suspension systems. A Tuned Mass Damper (TMD) technology is a convenient method to reduce the guide rail-counterweight/ car response and to control the system operating under seismic conditions. In the TMD arrangement vibrations of the counterweight/ car can be suppressed and the stresses in the guide rails reduced by the application of an auxiliary spring – damper - mass system attached to the main structure. In the counterweight system a part of the counterweight mass can be used as the auxiliary mass. The performance of the TMD is improved by the application of an actuator force determined by a suitable feedback control algorithm. Both passive and active modes are examined in the paper and a computer simulation case study is presented to demonstrate the performance of the tuned mass damper system for a range of lift system parameters.



Dennis Major.
Wittur Ltd, UK.

The current EN 81-1 Norm is going to be replaced by EN 81-20 / 50: 2014 on August 31st, 2017. This paper covers some topics to be considered in the implementation of the new standard. In addition, innovative approaches for alternative suspension system and safety devices can also be taken by means of risk analysis, according to the Lift Directive 2014/33 / EU: the introduction of mechatronic systems opens up entirely new ways to dispense with conventional speed limiters in the near future. To implement such systems, fails-safe electromechanical brakes must also be developed. This is part of a trend in the lift business to reduce the number of required components and integrate them to optimise the use of available shaft space. The challenges to master this technology in the context of a complete lifts, and how to cope with the increasing complexity for installation, testing and maintenance by developing complete 3D models for each project are also discussed in this article.



Keisuke Minagawa1, Satoshi Fujita2 .
1Saitama Insititute of Technology, Japan. 2Tokyo Denki University, Japan.

Rupture of wire ropes is one of severe accidents in lift systems. Before rupture by aging degradation, diameter of wire ropes decreases and surface of wire ropes is rusted. Thus diameters and red rust of wire ropes should be checked in periodic inspections of lift systems in Japan. The diameters are usually measured by using vernier calipers or scales, and red rust is checked with eyes, so there are errors and difference among inspectors. Therefore development of a new monitoring system for the diameters and red rust is required in order to maintain qualities of the inspection and manage the inspection data efficiently. This paper proposes and constructs a health monitoring system for wire rope using image processing. The system consists of a digital camera and a computer. The digital camera takes a photograph of a wire rope and the photograph is analyzed by the computer. The diameter is calculated from the number of pixels of the rope, and red rust is detected by resolving the colour of the photograph into RGB data. Image processing method and examples of inspection are reported in this paper. As a result, the measurement error was less than 1% by adjusting photographing condition.



Jonas Missler1, Thomas Ehrl2, Benedikt Meier2, Stefan Kaczmarczyk3, Oliver Sawodny1.
1University of Stuttgart, Germany. 2thyssenkrupp Elevator Innovation GmbH, Germany. 3University of Northampton, UK.

The design of the new rope-free passenger transportation system (PTS) differs from that of conventional traction lifts. The new propulsion, realized through a linear motor, requires lightweight constructions and thus shapes the design of the PTS. Additionally the possibility of horizontal travel has great influence on the difference between the design of conventional traction lifts and the PTS. Despite the different design, the aim for the rope-free PTS is to achieve all least the same ride quality as modern traction lifts. One important point in achieving the required ride quality is to reduce the vibrations felt by the passengers inside the cabin. In general, the damping concepts of conventional lifts cannot be readily applied to the new design of the PTS. Therefore, a damping concept for the rope-free PTS has to be developed. This paper will present the possibilities of active vibration damping for the PTS and state a selection of possible actuator positions. The paper will focus on the modelling of the active damping components and the control of these damping actuators. The performance of the damping actuators will be evaluated using a simulation with a Multi-Body System of the PTS. The primary disturbance of the PTS for this paper will be the vibrations induced by the guidance.



Tijmen Molema.
Liftinstituut, The Netherlands.

The lift industry is quite old-fashioned in electric / electronic / programmable electronic (E/E/PE) safety: they used the electric safety chain for over more than 30 years. However, since the EN 81-1/2 A1: 2005 amendment the standard allows to use programmable electronics for safety systems (PESS). Also, the code committee decided to implement a subset of the leading norm (IEC 61508) into EN 81 in order to decrease the difficulty and increase the implementation speed: PESSRAL (Programmable Electronic System in Safety Related Applications for Lifts) was born. However, due to cherry picking and skipping the basics the old and even the newest code (EN-81-20/50) makes it possible to create unsafe systems. Where are the potential risks?



Julia Munday.

In the 1970’s engineers were taught the rope life for an electric traction lift depended on traction, groove pressure and rope drag (i.e. fleet angle). Although modern methods of traction assessment where both the static and dynamic forces are considered are an improvement over the old; groove pressure has fallen out of fashion having been superseded by the mandatory requirements for the minimum rope safety factor in EN81 1 and EN81 20 but the effect of rope drag or fleet angle is mostly overlooked today. Why does this matter? Fleet angle can have a huge impact on rope life; the old engineers considered it to have a more deleterious effect on rope life than excessive groove pressure. Experts acknowledge the part it plays by including a correction factor for fleet angle in rope life calculations; but although recommendations for maximum limits were included in BS5655 6:1990, it is conspicuous by its absence in current standards. Before the early 1980s the lift industry, in the UK at least, was very different to how it is today; lift manufacturers designed, installed and maintained their own equipment “in house” and 25-year comprehensive maintenance agreements were not uncommon. As a result, each manufacturer built up a large store of knowledge derived from practical experience which allowed their products and procedures to evolve and led to improvements in the working life of consumables like ropes. Because of the changes in the industry and the vagaries of time this knowledge is slowly disappearing; this paper seeks to pass some of this knowledge on to new generations of engineers where a different perspective may help to solve some of the problems they face today.



Richard Peters, Sam Dean .
Peters Research Ltd, UK.

Lift passengers often travel together in groups rather than alone. In passenger generation for lift simulation these groups are referred to as batches, with the distribution of batch sizes sometimes presented in tabular form. This paper demonstrates how this distribution of batch sizes can be described as a Poisson process. The advantage this has for users of simulation software is that the prospective grouping of passengers can be entered as a single number corresponding to the average batch size. The distribution of batch sizes generated using the new approach is compared with site survey data. Historically, most simulations have ignored grouping, effectively using a batch size of 1. The impact of using a batch sizes other than 1 for simulation results is discussed.



Gabriela Roivainen1, Jaakko Kalliomaki1, Antti Lehtinen2, Jukka Tanttari3.
1KONE Corporation, Finland. 2FSDynamics, Finland. 3VTT Technical Research Center of Finland, Finland.

In order to fully understand the implication on the lift design, set by the noise requirement inside the car, in buildings that have not yet been built, KONE has developed an acoustic model of the lift, using a multi-disciplinary approach. The approach is based on a hybrid model combining structural finite element (FEM); computational fluid dynamics (CFD); boundary element (BEM) and statistical energy analysis (SEA); to cover both low and relatively high frequency acoustical domains in a sufficiently detailed model with a reasonable computational time. A special attention has been paid for modelling the noise sources. Structure borne sources due to rollers guides and ropes were applied on the system by computing the point mobilities using FEM and measuring the vibration velocity response at the same excitation points. Air borne sources due to flow-induced noise were computed using an incompressible transient CFD analysis. The resulting time variable air surface pressure was then applied on the car walls. The surface pressure spectra were used both directly (the convective source) and as a source for the acoustic propagation (giving the acoustic source). The sound reflection in the shaft, that is a significant contributor, was modeled using BEM. The time variable air pressure of the car surface was used as an excitation of the air in the shaft and the results were applied as an acoustic power input on the car surfaces. All the sources: structure-borne and air-borne were applied as power inputs in the SEA model, where the sling, car, doors, fairings and leaks were simulated. After validation, the hybrid model now allows the users to quantity and rank noise contribution of each source and make predictions based on changes in the lift structure, shaft design and car running parameters.



Mirko Ruokokoski, Marja-Liisa Siikonen.
KONE Corporation, Finland.

In the lift planning phase of a building, the number of lifts, their sizes and speeds are selected. Traditional performance criteria for the selection are the nominal travel time as well as the handling capacity and interval. These criteria are usually assessed in an up-peak traffic situation since up-peak is in general the most demanding traffic situation and for an up-peak situation the values of the criteria can be calculated by using the theoretical round-trip time formula. For simple buildings, the suitable lift installations can be pre-calculated and the results combined in a graph. From a selection graph the most appropriate lift configuration can be read for the given number of served floors and population. This paper describes in detail the creation of the selection graphs and discusses when the lift selection based on a graph is valid and when more sophisticated analysis methods such as simulations are needed.



Nishant Singh, Stefan Kaczmarczyk.
The University of Northampton, UK.

The current trends towards the design of lighter cars for high-speed lift systems and multiple car lift systems have encouraged the design of more aerodynamic efficient car geometries. Lighter lift cars are susceptible to aerodynamic drags and piston effects. On the other hand the issue of piston phenomena affecting smoke control in traditional lift shaft configurations have been studied extensively. Considering the complexity of multiple car, multidirectional shafts and the susceptibility of lighter cars to aerodynamic drag and piston effects, it is important that relevant analysis is developed to determine the aerodynamic effects arising in those systems. With advances in the field of Computational Fluid Dynamics (CFD), it is now possible to compute 3D compressible large eddy simulation for a multi-car lift systems. A better understanding of piston effect in the context of lighter and faster multi-car systems is necessary to further calculate the impact of these forces on lighter structures. In this paper a coupled Fluid-Structure Interaction (FSI) model is developed based on stiffness and damping of the system and boundary values from transient CFD study. This study will help understand the impact of excitations due to aerodynamic forces and understand the effect of aerodynamic drags and piston forces in the multi-car shaft systems.



Rory Smith.
The University of Northampton, UK.

Around the Pacific Rim, the potential for earthquakes to severely damage lifts has been recognized for decades. EN 81-77, enacted in November 2013 now brings seismic standards to the rest of the world. This code addresses the seismic risks to lifts and establishes standards for mitigation. The code is explained in practical terms, examples of seismic damage, particularly in California, are explored, and the reduction in damage that has occurred in subsequent earthquakes as a result of new codes enacted after each major earthquake are examined.



Undine Stricker-Berghoff.
ProEconomy, Germany.

Five years of professional life in the lift business in Germany brought up the idea to look into details. After intensive search the results are disillusioning: Nearly none of the European Elevator Associations, “Big 4” or SMEs are aware of the topic and its consequences. Though - certainly - the few women in the industry feel that the topic is important for themselves and their career, it is also vital for the future of the lift industry taking into account the dramatically rising demand for qualified personnel. The public presentation will help the next generation of women stepping “out of the shade”. Statistics give an impression of the female “force” in Europe, generally. More males are working than women, mostly in the higher ranking and better paid jobs. A questionnaire and a direct mailing to females in the lift industry brought some more detailed answers and also interviews. One was a lead representing the lift world in the UK. The speech will focus the results of the study on four relevant topics: Associations as a mirror of the elevator industry, support from the stronger sex, women speaking for themselves and the question whether women are looking into a brighter future soon.



Hiroya Tanaka1, Satoshi Fujita1, Asami Ishii1, Kazuhiro Tanaka2, Yoichi Ogawa2.
1Tokyo Denki University, Japan, 2Toshiba Elevator Corporation, Japan.

Lifts are essential for means of vertical transportation. In recent years, lifts to be installed in high-rise buildings have long travel, thus the lift ropes are longer. High-rise buildings have longer natural period than conventional buildings. As lift ropes become longer, the natural period of the lift ropes become longer and get closer to the natural period of the building. Consequently, the lift ropes are hooked to the equipment of well wall when the lift ropes vibrate by an external force, such as a strong wind and earthquake. Secondary damage such as containment of passengers and lift service stop may occur. It has become a problem. For example, The Great East Japan Earthquake in 2011, 2015 cases of problem such as catch and damage of lift ropes have been reported. However, operation of lifts after earthquakes are required. Therefore, this study constructs an analytical method capable unified evaluation and comparison. And we aim to build method to prevent catching by vibration reduction measures of the lift ropes. In this report, we examine effectiveness of lifts using intermediate transfer floors for damage reduction of ropes. In the analysis, the maximum displacement of the main rope and compensation rope was examined when the travel is divided from 2 to 4. The calculated results of the analysis confirmed that dividing the travel reduces the response of the main rope. On the other hand, the response of compensation rope was reduced by finely dividing the travel. It was confirmed that dividing the travel is effective for reducing the response of the rope. In the future, we will consider the optimal way of dividing the travel.



Darren Vandermeulen, Jeremy Landraud, Martine Duchampt.

Saving energy is a worldwide challenge. It is an important part of building design development to seek to reduce energy consumption. A lift machine is designed with a certain power in order to lift a load at the required speed. A standard lift is balanced at about 50%, such that when the lift is half full, it is the same weight as the counterweight. Often the lift is more lightly loaded, which means that the lift machine is moving an unnecessarily heavy counterweight. In 90% of usage, the car load is under or equal to 50%, therefore some energy is lost in order to move the counterweight. With the same power machine, a lift balanced at 32%, saves energy, or performance can be improved by adapting the travel speed of the lift. For every lift travel, motor torque is monitored by the inverter to calculate the real load in the car. Sometimes the car travels slower than the rated lift speed, but more often it runs faster. Reducing the lift balancing up to 32% can save energy consumption up to 30%. This research applies a gearless synchronous three-phase 220V motor. The Variable Speed lift is connected to the three phases 400V or single phase 220V power supply network. The system is compatible with all other renewable energy power supplies. Solutions incorporating photovoltaic solar energy are currently being investigated.



Benjamin Watson.
Otis Elevator, USA.

The VDI and ISO standards provide a systematic frame work for evaluating and ranking the energy consumption of various lift systems. Both sets of standards approximately model the drive system (motor and inverter) with a constant efficiency where the power lost is directly proportional to the shaft power out. The efficiency of the real system is, of course, dependent on the operating point. This paper explores the effect of the constant efficiency assumption by comparing the calculated energy consumption of the ISO and VDI models to a more complete model that includes the dependence on operating point. The magnitude of the deviation depends partially on the type of equipment used; permanent magnet motors can be reasonably approximated as constant efficiency, but efficiency of induction motors is highly dependent on the operating point. The paper also quantifies the customer value by relating the energy consumption calculations to operating cost.