Issue 1/2004
01/02/04
interlift 2003 – In retrospect
Dipl.-Ing. Harro Streng
A tour through the halls at the interlift 2003, held at the Augsburg Trade Fair Center from October 14 to 17, 2003, might have left the impression that this fair was little more than a replay of those in years past. With a wide variety of components and the complete demonstration lifts which have become an integral part of the exhibits, the picture seemed quite familiar at first glance. Closer observation made it clear to the professional visitor, however, that the range of items on offer had been expanded.
Category: Issue 1/2004
Posted by: Editor
Quite apparent was the larger number of exhibitors who are not “native” to elevator engineering but who were displaying special solutions originating in other fields and modified for elevatoring. Among the supply firms which have already entered and are active in the elevator engineering market, increasing numbers of “construction kit” and system solutions were to be found, these going well beyond the original range of offerings.
It could be ascertained that non-European exhibitors have clearly selected the 95/16/EC Lifts Directive and the 98/37/EC Machinery Directive for use as engineering guidelines. Even though these two directives have become legally binding only in the EC/EU countries, they seem to be serving as “signposts” well beyond this local frame of reference. Mentioned in particular here is the Annex 1 appended to each of the directives, in which safety and health requirements are enumerated, often with reference to an additional inspection to be carried out by a so-called notified body situated inside the EC. Any assembler domiciled in Germany is required to apply the national implementation of the above-mentioned directives, these being embodied in the Twelfth Implementing Order to the Equipment Safety Act (Elevator Code) and the Ninth Implementing Order to the Equipment Safety Act (Machinery Code).
Only if this aspect is taken into account will one understand that various testing agencies were included among the exhibitors, some of which have already been recognized as “notified bodies.” They offer their services not only in conjunction with certification of components in preparation for marketing, but also to satisfy the expanded safety assessment required during subsequent operations. Measurement procedures and methods are used there which are intended to simplify such inspections. Computer-aided diagnostics concepts are used not only for the safety inspection, but also to evaluate elevator performance and ride quality. These diagnosis options can be expanded to include even remote diagnosis and monitoring and to implement an emergency call management system. It is above all in this segment that exhibitors not traditionally involved in elevator engineering were represented.
An emergency call originating in an elevator car can be transmitted by analog telephone or ISDN circuits, wireless telephony and radio. The adequacy of the redundancy required to achieve reliability when transmitting this information varies. It is in this sector that further developments and new research vectors can be expected to emerge in the future. It is extraordinarily difficult for the future user to select from the multitude of systems being offered the one best suited to his needs, particularly since this implies commitment to a specific manufacturer which will be more or less binding over a longer term. Whether this will be the assembly company or the owner/operator will differ from case to case.
Just like the European EN 81 standards (Part 1 for traction lifts and Part 2 for hydraulic lifts), the type of drive selected lays down fundamental premises for the elevator concept. All the types of drives not covered by the EN 81 family of standards can nonetheless be erected as per the Lifts Directive or the Machinery Directive so as to be in compliance with applicable regulations. All passenger lifts falling within the Directive’s scope of applicability, to include freight lifts where persons accompany the payload, are covered here. All freight elevators and systems which could be used for passenger conveyance but which do not fall within the scope of applicability for the Lifts Directive will have to be engineered in accordance with the Machinery Directive.
Although Annex 1 to each of the directives has to be observed in regard to the safety and hazard-prevention requirements which have to be satisfied prior to putting a device on the market, it has been determined again and again that elevators on display had been engineered in accordance with the Machinery Directive but which were actually intended to serve passenger conveyance purposes. Often, however, the safety and health requirements of Annex 1 of the Machinery Directive are not observed in full in such cases since there are no standards for the many special-design solutions which are possible. Here one must note that the degree of understanding for the need for safety and standards compliance is not equal in all the countries, and that elevator users’ behavior may also differ, so that non-observance of certain regulations or even violations of regulations in the Directive itself might be characterized as acceptable as the result of a safety and hazards analysis. Such analyses of safety and hazards do indeed focus on identifying dangerous aspects but they also evaluate the probability with which such a hazardous situation might arise. Such views, in some cases diverging, could be recognized in various complete systems on display. Affected above all is the sector comprising elevators for the handicapped or simplified “home lifts” with vertical travel paths. Inclined lifts with chairs following the contours of home stairways are also among the familiar topics found at the fair.
Just as the name “interlift” implies, this is an international trade fair and thus is not aimed exclusively at the German or even the European market. A look at the documentation provided by individual exhibitors shows how actively they are distributing their products internationally, as well, be it via their own subsidiaries in many of the world’s countries or by way of technical offices which have been taken under contract.
Conversely, there are manufacturers from far outside the EU who market their products through representatives situated inside the EU. In this sector additional competitive pressure has come to bear in comparison with the previous exhibition, this being found in the fields of doors, cars, motors, drives and controls, and this is reflected in the items on display.
Simple passenger lifts with rated loads of 225 kg, for example, travelling at speeds of up to 0.6 m/s and exhibiting any of a variety of drive concepts serve to promote space-saving installation. Reductions in both pit depths and the unobstructed height of hoistway overhead are taken into account in engineering, in some cases making reference to the soon-to-be-published EN 81-21, which will deal with the installation of passenger lifts in existing structures. Elevators for passenger conveyance can also be built according to the Machinery Directive for operation at speeds not exceed-ing 0.15 m/s. Platform lifts such as this or elevators with a car which is only partially enclosed may, however, not be dispatched with passengers. This is permissible only when the moving platform is equipped with a so-called “deadman control” with which the elevator is kept in motion in response to continuous pressure on a travel control button. The final stop is effected by hoistway contacts corresponding to the individual landings. This describes the extensive field of freight lifts which may at the same time serve as passenger elevators and the special solutions as “home lifts.”
These cars and platforms, only partially enclosed, may be engineered for either vertical or inclined conveyance. Problems are to be found here less in the range of lift devices being offered than in safe and sound distribution and transfer of loads to the structure or the subfloor or subsoil. The data on loading, required by the structural engineer, are in some cases available only on special request. The actual problem is found in the installation situation in structures, particularly where the elevator’s footprint overlaps other traffic areas. The options for situating such designs outdoors, in front of or behind buildings, are often problematic because of difficulties in constructing foundations for the rails and providing safety shielding for persons outside the shaftway. A conveyor cab on a suspended cableway shows an alternate solution here.
Whereas in the past 3-phase asynchronous motors were almost the only drive sources available for a traction or hydraulic lift, this year a large number of 3- phase synchronous units were shown, with or without gearing, depending on the specifics of the application. The old asynchronous motors with an attached gearbox are nonetheless still in place in a large number of systems. Something which is amazing is the way in which 3-point bearings for the drive sheave shaft have survived among many vendors.
The magnetic material for permanent magnets has become more affordable in recent years and this has prompted a renaissance in synchronous motors for elevator drive systems, too. Alongside their good magnetic properties, however, these permanent magnets can be tricky and none of the machine manufacturers much cares to admit this or even to describe the limits for use. If a 3-phase asynchronous motor was severely overheated in the past, it could continue to be used without damage once it had cooled down, provided that the insulation on the windings had not been degraded. Exceeding the winding temperature could be largely precluded by employing thermal sensors. This is somewhat more difficult in synchronous designs since, depending upon the structure of the magnet, they are sensitive to temperatures to varying degrees and can then sacrifice a part of their magnetic power. Given controls with sufficient efficacy this, however, might not even be noticed immediately. It would be necessary only to deliver increased motor current for later operations.
Moisture represents a further problem for these permanent magnets. Condensed water can also damage such magnets. Casting the magnet package in plastic will not suffice here, since the casing can never be entirely impervious to diffusion. The differences between simple, pressed, magnetized steel filings and high-alloy magnetic materials can bring about a certain degree of resistance to moisture. Uniform criteria for evaluating motors such as this are not available to date. Each manufacturer uses different techniques to depict the strengths of his product.
Synchronous motors are quite often shown in a gearless design. The drive sheave may be attached directly to one end of the motor shaft while a brake disk is installed on the other end. An alternate is a single-sided arrangement in which the drive sheave and the brake disk are both located on the same end of the shaft. The synchronous units are also found, however, coupled in the classical fashion with a downline worm gear unit or in a particularly compact design incorporating planetary gearing. The latter solution was to be seen in one exhibit at the fair as a “construction kit” to be installed in the car frame for an elevator without a separate machine room. Where a step-down transmission is inserted between the synchronous motor and the drive sheave, the motor can run faster (to an extent corresponding to the step-down ratio) and this will reduce the costs for the motor while cutting the amount of energy needed to keep the brakes open. By contrast, the gearless designs offer the advantage that there are simply fewer components to be inspected and maintained. Since in the case of “roomless” traction elevators concepts for the head of the hoistway have already been protected by numerous patents, locating the drive in the car frame or even in the counterweight frame was a niche which could be utilized; this was also the case for a cantilevered solution with the drive (both geared and gearless) at the top of the shaft.
Regulation circuitry attuned to the particulars of the drive motor is quite essential to reliable drive functioning. That is why in the meantime most motor manufacturers and makers of frequency regulation systems refer specifically to matching products in each case. Often they have coordinated the interface between the motor and the controls or even sell only complete kits. The operating controls are in some cases included in such construction kits. Even where a complete component assembly group is being offered, it is worthwhile to check in detail for completeness since an engineering evaluation of the requirements of the application will be required for the individual case. The scope of such engineering support is not the same for all manufacturers.
One particular problem is resistance to interference – electromagnetic compatibility (EMC). The length and the location of the shielded cable are to follow exactly the specifications issued by the manufacturer of the regulation system. The engineering support provided by the manufacturer or the component dealer can only point out this necessity. Final responsibility for correct execution lies with the assembly company, which has to follow instructions painstakingly. Not all the models exhibited were entirely in conformity in this regard.
In the case of gearless drives, great attention has to be devoted to the problem of the brake disk at the sheave, and this is also true for questions associated with changing out the drive sheave. As for brakes, one finds today, in addition to the traditional jaw brakes, ever increasing numbers of disk type brakes, with differing brake pads. Only in isolated cases was reference made to the very high degree of system efficiency in gearless systems. Since these systems respond very quickly to influence by the control system, rapid response is found not only during normal operations but also in the case of malfunctions or defects. This means that a broken conductor can under certain circumstances very quickly create a hazardous operating status in so far as the regulation circuits offered in the construction kit do not interact with the controls to specifically take account of this kind of malfunction.
While the thought of doing away with a separate mechanical space originally emerged from a traction lift concept, various manufacturers of hydraulic units have in the meantime also devised solutions for which a separate machine room is not absolutely necessary. Simply installing the hydraulic power equipment in a niche in the hoistway wall does not always satisfy the fire codes. A suitable switchgear cabinet, which may also include a pump unit, can often be mounted directly on the outside of the hoistway wall, provided that the cabinet is sufficiently compact in design. Thus hydraulic systems can be seen as almost “roomless” if a cabinet such as this is kept locked and will thwart attempts at unauthorized access. Using proportional valves or a hydraulic counterweight when regulating hydraulic systems such as this makes it possible to bring the connected load for a hydraulic lift down close to that for a traction lift. As regards acceleration and deceleration properties, hydraulic lifts as a rule exhibit lower values than do traction lifts. The user and the assembly company have to be fully aware of this point.
Among the traction lifts on display the visitor occasionally found that experience with the classical roped elevator, in regard to the longevity of the suspension ropes, was not always taken into account. The ratio of rope diameter to sheave diameter is only one of the factors which come into play here. It is also a known fact that all additional changes in or reversals of rope running direction will tend to shorten rope life. If a roomless elevator drive is to be installed in an extremely confined space and if the distance to the corresponding deflection and reversing pulleys is too short, then this will also have an effect on service life. This means that the user may well be surprised to find that the economical drive, in terms of the initial investment, will later trigger additional costs. This is aggravated by the fact that certain roping patterns prove to be an extreme impediment to service work whenever repairs are needed. The assembly company should pay particular attention to this factor when procuring component assemblies. The retirement age of the cables can be determined by wire breaks at the outer strands. Vee grooves promote this type of wear particularly where the pulleys are closely spaced. If the ropes are jacketed in plastic, then it is necessary to adopt additional measures in regard to determining the time for replacement and this is usually the case for novel suspension means.
Hoistway and car doors from a number of countries were on display, and these in many different designs. Most of the diverse door lock designs had been certified by notified bodies. All the items on display exhibited excellent manufacturing quality, no matter which countries they might have come from. As regards the hoistway doors, it is possible to draw upon the DIN 18090/91/92 engineering standards in Germany; fire tests had often been carried out in various countries. The sliding door is quite clearly the predominant design, but hinged doors are still found occasionally where it is desirable to reduce the hoistway dimensions, particularly when installing elevators in existing structures. These hinged doors can be fitted with a power opener to assist the handicapped but here the door’s opening arc may necessitate additional safety measures, depending on the situation prevailing at the installation site. In the car, then, there will be either no door at all or a multi-panel telescoping door, depending on the application.
To be mentioned as a solution for a special situation is a door panel which has been further developed in both engineering design and manufacturing technology so that, where one of the outer surfaces is exposed to the sun’s direct rays, deformation resulting from the asymmetrical heating and which could interfere with proper functioning is suppressed.
To keep children’s hands from being pulled between the panels of glass doors, a solution was shown in which the door glass was made opaque as the car approached. Another solution suspends the door opening cycle whenever a hand comes into contact with the door. Neither of these solutions is, however, yet available in mass production.
To keep children’s hands from being pulled between the panels of glass doors, a solution was shown in which the door glass was made opaque as the car approached. Another solution suspends the door opening cycle whenever a hand comes into contact with the door. Neither of these solutions is, however, yet available in mass production.
As regards safety concepts for the door’s leading edge, greater numbers of diverse solutions were presented where non-parallel light beams create a “curtain of light” which, in an infrared version, is not visible to the human eye. The installation of such light curtains can be either stationary, at the car, or at the door panels themselves. A special solution for inclined lifts replaces the classical door coupler with an infrared coupler of redundant design; it clears the opening cycle for operation only after all the conditions prescribed for opening have been met. In regard to the cars, various construction kits and custom designs were to be seen, including a glass lift in a very appealing design. One particular eye-catcher was the form selected by Professor Colani for a plastic shell inside a car, with complementing designs for the command and indicator devices.
Although control circuitry is ever more often being included in a system package, there are vendors who offer controls only and they place particular value on later monitoring and testing. In regard to interfaces there is a particular initiative being promoted by a group of manufacturers who favor standardization of the “CAN-OPEN” bus system. Reference was made to this bus system at a number of booths but the work is still in its infancy since the associated products are not yet ready for volume production. According to the concept behind this, all the command and display devices, including the controls, can be connected via a standardized bus. It is also to provide operators with the ability to access inspection and testing information, regardless of who may have manufactured individual components. This system is to be augmented later with safety equipment.
Always a part of the control system is the registration of the position of the cab in the hoistway. The systems used for this purpose differ. Some systems require a “learning trip” following a power outage while others have the positions stored in memory and this will have to be noted when making emergency trips. One non-contacting position registration system on display featured a laser beam which determines the position with a simple distance measurement and thus requires no calibration trip.
In particular in the field of command transmitters there are also, and in addition to the classical vendors, “outsiders” (defense technology, other industry applications) who are looking to serve elevator engineering from other industries. Reliability and resistance to vandalism are mentioned here as special yardsticks whose value has become recognized through practical experience. Many manufacturers are already referencing the draft standards – EN 81-70, EN 81-71, EN 81-72 – which have not as yet been universally implemented. Whether these components are attached directly to the control panel and are wired ready for attachment to connector plugs or whether the cover plate contains no such components but just the appropriate openings will vary from case to case. One specialty was seen in hand rail units with integrated command transducers and illuminated panels. Small, flat screens from 8 to 15 inches (diagonal measurement) and intended for use as special displays and information sources or as command transducers were also to be found among the items on offer.
As regards safety components, to be mentioned here are safeties of various designs and origin, including the associated triggering mechanisms. Safeties which can stop a downward fall or prevent an “upward fall” can today be deemed to represent the state of the art. One specialty is a speed limiter which travels with the car, which is mounted in the same way as the roller type guides, and which trips the safeties directly.
Companies outside the traditional elevator industry in particular showed a variety of sensor element designs. These ranged from optical and inductive to capacitance, pressure-sensitive and ultrasound-sensitive elements.
Various concepts were shown which involved uninterruptible power supplies to enable passenger rescue; this represents a special application situation for synchronous motors but also for hydraulic drives in some cases. Novel designs, often for smaller construction components and devices which could quite apparently be used in elevators to good effect, were seen at various booths. This then represents a supply source for the interested visitor, provided that he is himself capable of further evaluating and implementing the application.
One specialty field to be mentioned at this point is smoke detection in the hoistway. Here, using a system which is in and of itself known in the trade, ducts are used to extract the air from the hoistway in case of fire. Where the air is found to contain smoke an evaluation unit will cause a smoke extraction hatch to be opened. It is possible to ventilate the hoistway even when there is no fire simply by keeping this hatch open.
In addition to the familiar component suppliers who in some cases offered solutions drawing upon their own manufacturing capacities or utilizing a fixed program of bought-in components and who also provide engineering consulting, there are also other dealers who simply market the products without being fully cognizant of the details of the application. Components which are expressly designated as replacements for parts made by certain companies are sometimes not made by the original producers; they will have to be critically examined where safety-related parts are involved.
In retrospect we find that there were no major, spectacular innovations to be seen at the fair but instead an amazingly large number of fine detail solutions and further refinements of previous technologies, many of which will be of great assistance to the skilled user. The Lifts Directive, now stating objectives in safety technology, has quite apparently given the inventive spirit again and again openings for devising new solutions, while patents have in many cases inspired even better work-around concepts.
The interlift 2003 provided a good representation of all this.
1/2004
