Latest Trends in Lift Control Systems

Integrated, Contactorless, Plug’n’play, Remote Access

33 years ago, when the design and production of the first lift control system in our country took place, the main goal was to solve frequent fault incidence and short lifetime problems of relay-based control panels. Over time, the evolving technology has helped control systems offer different facilities and make the job of lift technicians easier. Various functions have been developed which helped to decrease and facilitate the connections in the lift wiring, and to reduce and simplify the settings, to prevent the faults both during the installation phase and maintenance phase. Modern control systems equipped with CAN-Bus serial communication, which was first seen in 2000 in our country, have become almost a standard implementation today.

 Integrated

With the introduction of VF drivers (inverters) and gearless motors for lift applications, whose costs have decreased over the years, VF driven lifts have become the major choice in new elevators, whereas the two-speed and hydraulic drive systems getting very rarely preferred. Efforts to reduce the energy consumption of elevators as a consequence of increasing environmental awareness and of rising energy costs were undoubtedly a factor for this evolution, as well. As a result of these developments, VF drivers have been introduced in almost all new elevators. VF drivers brought advantages such as energy saving, comfort, high floor level accuracy, but made it difficult for elevator technicians’ job. They had to adjust comfort and floor level settings by going through complicated menus spending a long time. Even though elevator-dedicated VF drives made these operations easier, some settings were required to adjust separately on both the driver’s menu and the control system’s menu, one modified parameter value in the former could make it mandatory to make a change of the settings in the latter.

Lift controller and driver manufacturers have developed some communication methods and protocols to enable the collaboration of these two products to overcome these challenges, such as Can Open, DCP. However, this method did not make things exactly easier. By combining, the manufacturers began to think about solutions that would enable the management of the controller and the driver by a single “mind” by combining the two of them in one device. Moreover, by combining them in one device the components needed to interface the two products to each other become redundant, which reduces the material cost. In addition, savings in the labor and cable costs which were necessary used to connect them together are obtained, and the single device takes up less space in the lift control panel (switch box), resulting in a smaller size.

When all these advantages come together, the “integrated lift controllers” that combine the lift controller and the VF driver in one body are born. During the commissioning of the lift, the settings become much easier to do in the single menu of the integrated controller. Integrated lift controllers that emerged as cheaper and easy-to-use option quickly began to replace discrete configurations.

In fact, today, the integration rate has increased and the second generation integrated systems have started to come into play. The latest generation integrated lift controllers offer some functions and safety features required by the latest lift safety standards, such as countermeasures for prevention of UCM

(Uncontrolled car movement), and door contacts bridging circuits required for approaching/leveling the floor level with open door. Thanks to these second-generation integrated systems, there are only a few other components in the lift control panel else than the integrated device, such as a power supply, some fuses and terminals for external connections. Hence, the production of a compact and lower cost lift control panel becomes very easy.

Contactorless

One of the ways to make the lift control panel smaller and cheaper is to replace some bulky and costly components used in it with software/hardware electronic solutions. Thanks to some methods that the safety standard allows with the condition that the design to be certified through an EU type examination, there is no longer the need for the use of the two contactors to safely cut the motor power. This feature is called STO (Safe-torque-off) that immediately stops the generation of the power that VF drivers transfer to the lift motor and leaves the engine without energy in case the elevator safety circuit is disconnected.

Motor contactors are not used in the lift control panels with a STO-VF driver or STO-integrated controller, resulting in significant material, labor and space savings (See image 1).

Another important advantage of contactorless use is the absence of the noise that contactors create when they switch. This advantage is particularly important in machine roomless (MRL) lifts, where the contactor noise spreads throughout the building via the lift shaft, because the control panel is mounted inside the lift shaft or as a recess the shaft wall (See image 2).

 Some integrated control systems can have a back-up power input, such as UPS or batteries, and they automatically switch to back-up power when the mains power is cut off. In this way, it is also possible to save two further contactors who disconnect the mains and transfer the lift to the back-up power.

Plug’n’play

One of the most time-consuming and error-causing jobs in elevator installation is the realization of electrical connections. Connecting many cables to the right terminals one by one, checking them, correcting errors, fixing the problems caused by errors requires a significant time. In addition, this work must be done by trained and experienced personnel. But it’s getting harder and harder to find staff at this level, and their cost is increasing.

Lift controller manufacturers have developed methods to reduce the number of cables and connections to reduce this time and to make connections quick and error-free.

Serial communication and plug-in solutions

One of the most common solutions to reduce the number of cables is the serial communication based on the technique of sending data over a small number (usually 2) of cables in a sequentially encoded way, which would be otherwise carried with many parallel cables in conventional ways. In this way, savings are achieved in both material cost by using less number of cables, and labor and time due to the significant reduction in the number of connections. In addition, if plug-in connectors are used for connections, the connection time gets further shorter, and errors due to incorrect connections are avoided.

Serial communication elevator systems are based on a network among various components of the elevator like a of computer network. Between these components, the data must be transferred correctly without losing the integrity of it. Among the various options introduced for serial data transfer, CAN-Bus have become the most preferred method in lift applications, because CAN-Bus can transmit lossless data even at long transfer distances in distributed structures that is open to exposure to electromagnetic interference, such as the lift wiring.

Precise and easy levelling using smart sensors 

Magnetic contacts, which are used to determine deceleration points and to ensure stopping at floor level in lifts, are among the important sources of failure. These components, which have mechanical contacts, deteriorate after a certain period of time and cause the lift to fail. In addition, setting the floor alignment with these insensitive contacts is a difficult and time-consuming process.

Thanks to the electronically-based non-contact magnetic sensors developed, both the problem of life is overcome and the position of the car can be determined more precisely. In this way, solutions that do not fail easily, allow precise floor alignment and facilitate the adjustment process are provided. These sensors can communicate with the control system via CAN-Bus, simplifying the connections and the floor alignment adjustment (See Image 3).

Smart pushbuttons and indicators

Approximately 80 % of the connections in a lift are the ones to the pushbuttons and indicators in the lift car and at the landings. Therefore, in order to get sufficient

• Completion of electrical connections of the elevator in 80 %shorter time
• Avoiding component damages caused by connection errors, and time losses to fix them
• No need for technicians with high skills to make electrical connections, instead, employment of lower cost staff
• No unexpected extra costs at the field for electrical connections because cost of the material to be used for electrical connections is already known in advance,
• Significant savings in cable costs (e.g. on a flexible car cable) via reduced number of connections
• Significant cable and labor savings in duplex group elevators by transferring the data of the LOPs of both elevators via a single cable (possible in the controller of some manufacturers)

Inevitability of smart COP/LOPs at lifts for handicapped conforming EN 81-70

As you already know, at each building half of the lifts (at least one) must be designed for the use of handicapped.

In these lifts, which must be designed in conformity with the accessibility standard EN81-70, employment of smart COP/LOPs are almost inevitable to meet the requirements of the code, because meeting such requirements with conventional COP/LOPs may require quite complicated solutions. For example, the standard requests that at each call registering in car or landing call buttons a beep must be sounded informing that the call is registered. The beep is still required when the call button is pressed again even when a call was already registered at that button. But, if there is a condition which prevents the call being registered such as the lift being in inspection mode or out of service, the beep mustn’t be sounded. As you may imagine, to meet this requirement with conventional pushbuttons the information if the lift is out-of-service or not must be transferred to the pushbuttons and beeping must be controlled with it. Besides, solutions which recognize if a call was already registered at the pressed button are necessary. Of course, manufacturers may develop other solutions.

However, smart COP/LOPs already have these features. Furthermore, some of them offer voice announcement in the car. All the lift installer has to do is downloading the voice files in accordance with building to the memory card.

Advanced functions that can be performed through CAN-Bus and smart buttons

The presence of smart pushbuttons and indicators in the car and on landings in continuous communication with the lift control system makes it possible or easier to perform some advanced functions.

Functions such as,

• providing controlled access to the elevator via an ID card or smart mobile devices,
• adding facial recognition, voice recognition features,
• providing contactless use in the elevator,
• carrying out controlled disinfection of the car interior,
• establishing special operation regimes (e.g. defining different access permissions for day and night, serving different floors on working days and weekends),
• providing service priority to some the floors when necessary,
• providing visual and audible information that can be constantly updated to passengers in the car,
• collecting data for control and statistical purposes from various points of the elevator and making measurements, are now possible via intelligent pushbuttons and indicators, and sensors that work in coordination with an advanced lift control system.

Remote Access

Since a modern lift control system is actually a sort of computer specialized in its job, it also offers the possibility to interchange data with remote points over the internet. Today, it has become possible to monitor the operation of an elevator by connecting to its lift control system from a remote center or from a smart mobile device (phone, tablet, PC), to see the occurred faults, and to intervene remotely to the lift provided that it does not create a security breach.

Increase in maintenance quality and efficiency

In this way, it is aimed to control the maintenance teams better, and to use them more efficiently. It may be possible to solve the elevator failures in a shorter time by providing a more efficient solution thanks to the fact that the team, that will fix the faults at the field, is aware of the type of failure in advance.

In this way, both the efficiency of the maintenance company and the quality of the maintenance service provided will be improved. The maintenance company can better control its own teams and their maintenance quality, and increase customer satisfaction by providing more reliable maintenance and failure reports to the buildings they serve.

Preventive maintenance

One of the advantages of remote accessibility is that it can provide information for preventive care, which has become increasingly popular in recent years. The intelligent elevator control system can continuously monitor the elevator’s wear-out points and collects statistical data about them, or measures some values. It then sends these data and measurements to a remote monitoring center. The preventive maintenance application at the monitoring center analyzes data from the elevator, calculates the levels of wear in various parts and alerts the maintenance company or building management for elevator parts and components approaching the end of their predicted lifetime. In this way, the elevator may be prevented from getting out of service as a result of a failure due to the lifetime of a certain component, because it will be possible to replace that component in advance before causing a failure of the lift.

Development Never Ends

The advanced features and functions mentioned above will undoubtedly become ordinary in a few years, and over time different trends and requirements will create demand for new functions and features. Lift control systems, which are becoming smarter and easier to use, will continue their development and evolve towards meeting new demands. The vital importance of elevators (at least in the near future) will continue to be part of our daily life as a reality that does not change, but we will not content ourselves with the fact that they can save us from the stairs, and always demand more from them.