KEB Technology

Residential elevator brakes

KEB is best known in the Elevator market for our Elevator and Regen Drives.  But some are surprised to learn that we also manufacture brakes.


KEB manufactures armature-actuated brakes (not caliper or drum-style brakes) which are well suited for smaller motors used in residential elevator, MRL, and dumbwaiter applications.


This post provides an overview of KEB brakes and why they are well suited for elevator applications.


Spring applied operation

KEB’s Combistop brake product is electrically released and spring-applied.  Sometimes these brakes are referred to as “failsafe brakes” because they will engage when power is removed.  This is the type of operation a designer will want to use in lifting, hoisting, or safety-related applications.


failsafe springset brakes

Spring Applied Brakes – See How they work



Designed and manufactured in the USA

A lot of the advantages KEB brings to the table are because our brakes are engineered and produced outside Minneapolis, MN.  This means that we are able to use our core brake technology and design features as the application requires.


From a supply chain standpoint, this is also a big advantage to our North American customers.  Local manufacturing means that leadtimes are typically shorter and the product is not originating overseas.

onshore manufacturing

Local manufacturing is alive and well at KEB



Quiet operation

One product feature that KEB is able to offer is noise-reduced operation.  A loud ‘clunking’ noise or a rattle from the brake as the elevator car levels is not desireable.


Various design features are incorporated into the KEB brakes which reduces the noise levels.  Overall, this provides a much more pleasant experience for the elevator passenger, especially in a residential or MRL elevator application.


There are actually several different noise reduction options at various performance/cost levels depending on what our customers require.

silenzio theatre brake

KEB can offer brakes rated for <65dB @ 1 meter


NPT fitting for conduit

KEB brakes can be fitted with an NPT fitting which allows the electrical conduit to be run and connected directly to the brake.  Additionally, if needed, we can offer our brakes with extended leads to be fed back to the power supply or elevator controller.

brake NPT Fitting

KEB brakes with NPT fitting



Hand release

Typically, an elevator brake must have the ability to be released even without power (consider a power outage).  For this, KEB brakes can be fitted with a manual hand release.  When the hand release is pulled back, the brake disengages and the shaft is free to rotate.


Manual release spring applied brake

Manual Hand Relesae


When released, the hand release returns to its location and the brake engages.  This operation is sometimes referred to as a “dead-man’s brake” and is an important feature for safety applications.




KEB also offers a microswitch feature on our brakes.  A microswitch is typically used to provide feedback to the controller that the brake has actually engaged.  It adds an element of safety as a brake confirmation is needed before power is cut to the motor.


It also has operational benefits.  When incorporated with the controller and various brake timers, a microswitch can reduce lining wear and allow for a much smoother brake transition.


theatre hoist brake switch

Brake Microswitch




KEB typically also provides mounting flanges with our brakes.  The flange serves two purposes.  Firstly, it provides a suitable friction surface for the friction lining.  This means the surface finish is designed to KEB’s required specifications.  Secondly, it can act as a heatsink if the brake is performing a significant amount of work.


KEB can design and provide custom flanges as well.  A popular option is to use a C-Face flange which can then be mounted onto a C-Face motor end bell.



Double C-Face option

A spring-set variant we also provide for elevator applications is our Double C-Face brake.  The advantage of the Double C-Face brake is that it can be paired together with an off-the-shelf NEMA C-Face motor.  Overall, the solution can be more cost effective especially when an encoder device is added to the equation.  Motors with a brake and encoder are not cheap.

NEMA compliant double c face brake

Double C-Face Brake


KEB Double C-Face brakes are offered up to 256TC frames and are available with different magnet voltage options.



Gear(motor) with brake

The final configuration where our brakes get used in elevator applications is when paired with our integral gearmotors.  The KEB gearmotor product is designed in Germany and assembled here in the US.  The product offering is extremely flexible and has a lot of product options like encoders, shrink disc mounting, and brakes.


KEB motor with brake and hand release lever


The brakes are again what set KEB apart from other manufacturers.  We are able to offer all of these high-performance brake options (noise reduced, microswitch, etc.) which are very well suited for elevator applications.


And it all comes together packaged with our gearmotor product.  So these are savings to elevator manufacturer in the form of reduced labor and installation time.

gearmotor with brake

Gearmotor equipped with brake



Do you have an application in mind?  Our engineers would be happy to discuss – contact us today!

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Harmonic Filters for Reducing VFD Distortion


VFDs create harmonic distortion. Any VFD using a bridge rectifier inherently draws harmonic current from the utility. The harmonic current draw causes voltage distortion on the mains which can create power quality issues for other electrical loads.


KEB Harmonic Filters are used to reduce VFD distortion and meet IEEE 519 distortion levels. Using a harmonic filter with a VFD reduces the amount of harmonic current, therefore, the voltage distortion on the mains is reduced.


For more how-tos, testimonials, and product announcements, be sure to subscribe to our YouTube channel.




view transcript

Electrical loads like resistors and line fed induction motors draw a sinusoidal current from the supply.


Most commercial VFDs use a 6-pulse bridge rectifier to convert from AC to DC power.  6-Pulse inverters draw a non-sinusoidal input current which then creates distortion on the supply voltage.


The voltage distortion is undesirable because it can negatively affect the operation of other electrical loads.


Critical applications using VFDs like wastewater treatment plants, elevators, and airports might need to mitigate harmonic distortion.  There are a number of ways to address harmonics, but harmonic filters strike a good balance between performance and cost.


KEB’s Z1 (zee-one) Harmonic Filters are designed to meet IEEE (eye-triple-E) 519 (five-nineteen) harmonic levels.  The filters are offered in graduated sizes up to 400Hp.


In order to achieve the best possible performance, KEB offers filters for different electrical mains around the globe.  Filters are available for both 230V and 480Vac mains.  Additionally, filters optimized for both 50Hz and 60Hz mains are offered.


KEB Filters are intended to be used for demanding industrial VFD applications and feature a 150% current overload rating for 60 seconds.


As standard, the units feature overload protection and temperature sensors for the filter windings.


The Z1 filters are 99% efficient at full load.  This is achieved through the use of high quality steel laminations and winding configuration.


KEB’s Z1 filters feature high-performance 3-phase capacitors for increased operating lifetime and reliability.


The harmonic filters use a compact design and flexible mounting concept.  The capacitor bank can be mounted separately from the core – up to 2 meters apart.  This allows a machine builder to flexibly position and mount the components inside an enclosure.


As an option, the large filters are offered in a pre-wired NEMA1 enclosure.


KEB Harmonic filters are UL listed and carry a CE mark to ensure the highest quality and performance.



Remote Monitoring for Elevators | Secure Tools for improved Diagnostics

Many manufacturers offer a remote elevator monitoring option, which includes real-time system information such as car position, status, fault logs and more. This comes as no surprise with the maturation of the internet, cheap server space, and an increasing number of networked devices. Slowly, elevators and escalators are intersecting with the “Internet of Things” (IoT). I will stay away from the promises of IoT in this article. My objective is to 1.)Briefly introduce the concept and possibilities of remote monitoring and IoT in relation to elevators and escalators 2.) Discuss the key features and benefits of KEB’s remote monitoring tools.


Remote elevator monitoring - C6 RouterIoT Fundamentals


What does IoT mean? How is this concept brought to life in elevators? In our world “Things” are the controller, door sensors, load weighers, power drive, etc. Before achieving networking capability using the internet, these devices must be connected at a lower level. Meaning there must be a common hardware (RS485, Ethernet, wireless) and software used by the remote monitoring system to communicate and collect system data. The next challenge is to connect the system to the internet for remote communication. Once this is complete, remote connections are possible and system information can be sent to elevator techs, design engineers, and decision makers instantaneously.


The possibilities to utilize this connection are virtually endless ranging from remote troubleshooting to faster shutdown response times. An example could be a high profile job with intermittent elevator shutdowns. The only clue is a generic “NO Drive ON” fault from the controller, and unfortunately, the drive has no faults in the log since the last shutdown. Now the game begins of replacing components one-by-one hoping the problem is resolved. All parties involved become increasingly frustrated. Now let’s say the system has a modern-day remote monitoring system and is monitoring the drive IO. When the system faults with a “NO Drive ON” fault a detailed log is emailed to the responsible elevator technician. The log proves the DRO Relay from the drive is actually picked during this fault but still the signal isn’t getting to the controller. The prints show the DRO relay is in series with a pilot relay. Now the technician can eliminate incorrect controller signaling, faulty drive, and look at the wiring and pilot relay between the DRO relay and controller. The connected system will reduce the time and money spent on troubleshooting and replacing other components with specific fault diagnostics relayed in real-time.


The ability to connect, collect, and analyze the data from an elevator or escalator benefits all stakeholders involved. Unfortunately, in practice, this isn’t as easy as it sounds. Finding compatible hardware and software is difficult, and collecting a mass of data without knowledge of how to analyze it is unhelpful. Most importantly, the system must be secure and the information on it must be private to the world. The implementation of a remote maintenance system requires careful planning and design. KEB offers help with secure remote connections to systems using VPN technology and data collection with COMBIVIS Connect™ and a line of Industrial Routers, HMIs and PLCs.


KEB’s Remote Access Solution


KEB’s C6 Router, HMI, and PLCs offer the possibility for remote connections as standard. Each of these products is equipped with the proper hardware to connect to systems with Ethernet and serial ports (RS232/422/485). Many suppliers offer compatible hardware; the differentiating technology between KEB’s solution and competitors is the COMBIVIS Connect architecture and COMBIVIS Studio HMI software.

The COMBIVIS Connect architecture is composed of three interconnected components: the control center (PC application), runtime (software on KEB hardware), and server infrastructure. Working together, a secure end-to-end connection between the control center and system network is generated via a virtual private network (VPN).


COMBIVIS Connect Architecture


The relationship between the control and runtime is a client-server type, where the control center is the client, and the runtime is the server. The KEB server infrastructure acts as an intermediary point to discover, reach, and authenticate connections. Using outbound connections to an access server the control center sends user credentials and a list of devices registered to the customer’s account. At the same time the runtime sends its availability with encrypted identification certificates with outbound connections. It is important to note that passwords are never stored in the control center or server databases. Instead, they are stored as an encrypted hash value, which must match the hash value stored on the access server. Additionally, all connections use SSL/TLS protocol for encrypted data transfer ensuring data confidentiality. When a user connects to a device all security credentials are exchanged and the access server routes traffic to a relay server which acts as a bridge and common point for data transfer. To eliminate bottlenecks and ensure reliable connections, KEB has relay servers located all over the world. The relay server is always selected by the access server based on load and proximity.


Finally, when a VPN connection has been established, the runtime serves an IP address within the same physical machine network to a virtual Ethernet adapter installed by the control center. Therefore the control center PC is a true member of the machine network and can access any devices on it as if it were physically connected to an Ethernet or serial cable. For example, if a C6 Router is connected to a remote PLC, the user running the control center can perform a device scan with the associated PLC software and connect to the PLC.


Remote elevator monitoring - COMBIVIS Connect architecture

click to enlarge


What is unique about this technology? Traditional VPN technology uses a central VPN server as an intermediary point between a VPN client and remote network. All data must pass through the central VPN server at all times. COMBIVIS Connect eliminates the need for a central VPN server and establishes a true virtual end-to-end connection, only using a relay server as an intermediary to route traffic. Not only is this more efficient but data traffic will never be seen or managed by KEB as even the traffic through the relay server is fully encrypted.


Security precautions don’t stop with VPN connections. KEB developed the COMBIVIS Connect architecture based on industrial cyber security standards ISA 99, and IEC 62442. COMBIVIS Connect’s architecture was proven to be secure and compliant with cyber security standards as it successfully passed an audit by an independent 3rd party German security organization Protect GmBH.


Control Center features


Luckily, the complexity of the secure connection mechanism utilized by COMBIVIS Connect is always hidden to the user. Management of the control center is user-friendly yet contains many features to ensure asset security.


The control center is the PC application used by the remote user, each of which will belong to a customer account called the “Domain”. Each domain can be organized in a hierarchy of folders, devices, users, groups, and firewall policies. Subfolders inherit users and firewalls of root folders but are completely private to other subfolders. This feature is very useful for managing a large number of devices. For example, a contractor can create folders for specific jobs or routes. They can then create users for the technicians responsible for each job or route in a specific folder. When each technician logs into the domain, they can only view devices within the folder they are given permission to access. KEB devices can also be viewed, configured, and accessed within the control center. Even before connecting to a remote network the control center uses several features to control and prevent unintended device connections with user management, firewall policies, and activity audits.


Remote elevator monitoring - Connect Domain overview

click to enlarge



User management


First, the domain account is private and can only be accessed by users with a username and password. Each domain account has an administrator that can manage all users and groups by defining special permission profiles for all users. Permission profiles define the rights for, domain administration, device installation, network security configuration (firewall policy creation), and device access. Device access rights can be further defined by limiting device actions such as remote network access, read remote files, write remote files etc. The domain administrator also has an option to track the activity of all users, and devices using an audit feature.


Remote elevator monitoring - user permissions




For complete visibility of all domain activity, the audit tool tracks all user and device interactions. This provides a complete record of who connected to what device, for how long, and what they did (VPN connect, transfer file, etc.). Additionally, a log on each device is kept with similar information.


Remote elevator monitoring - COMBIVIS Connect audit


Firewall policies


In addition to end to end-to-end VPN connections, traffic to and from each remote device can be further limited by the creation of firewall policies. Firewall policies can restrict traffic by MAC address , and Ethernet type. Depending on the Ethernet type further restrictions can be applied such as protocol, IP address and port. All policies can be defined as one-way or two-way which adds protection to the remote user’s network.


Data collection


Remote monitoring systems become more powerful and useful with data collection. Data collection and visualization can be performed using KEB products with HMI runtime installed. COMBIVIS Studio HMI is the software tool utilized to develop HMI projects for data logging and visualizations. COMBIVIS Studio HMI includes over 40+ common software drivers to interface with a variety of systems including Modbus, BacNet, and OPC UA. This data can be logged continuously with configured data loggers. Data files can then be abstracted using the control center, or through scheduled emails from the device. It is also possible to push out data to cloud databases such as Microsoft Azure, or Amazon Web Services (AWS) using MQTT protocol for advanced analytics. Instant notification to faults and shutdowns is possible with configurable alarms. Alarms can be associated with specific variables to send out an SMS or E-mail to alert techs of faults. Lastly, real-time visualizations can be created and viewed. The control center offers remote viewing of HMI projects running on the desktop of the C6 Router or C6 HMI.


Remote elevator monitoring - data collection

click to enlarge


In conclusion, elevators and escalator systems can greatly benefit from remote monitoring systems. With many different options on the market today, careful planning should be taken when deciding to undertake such a development. Trusted and well tested tools should be utilized in such a system. KEB offers a wide range of proven hardware and software tools for integration into remote elevator monitoring systems.


Colin Zauner
Controls Application Engineer


This article originally appeared in Elevator World Magazine, January 2018.


MQTT – modern data transmission for Industry 4.0

IIoT and Analytics - C6 RouterA fully-networked factory floor is the future of automation and manufacturing. Robots, cobots, and information going into and out of the cloud are helping us create better products faster and with more accuracy. The key to reaping the benefits of Industry 4.0 trends and the Industrial Internet of Things is communication.


In an ideal setup every component in the chain is able to communicate quickly, clearly, and reliably with the end user. If the data received isn’t up to par, all promises of remote monitoring and commissioning, advanced reporting, and real-time analytics go out the window.


The C6 Industrial VPN Router from KEB was designed for IIoT. It’s flexible, affordable, rugged, and secure. And now, the router is able to transmit data using MQTT protocol.


About MQTT protocol


Message Queue Telemetry Transport, or MQTT, was developed by Andy Stanford-Clark of IBM and Arlen Nipper of Arcom in 1999. The protocol is meant to be used in situations where a small code footprint is required, and the network capabilities are limited – like in small devices or automation systems with widely distributed components. It’s lightweight and uses minimized data packets to efficiently send information between several receivers.


This type of protocol clearly isn’t a new development, but the explosion of Internet-connected devices and Software as a Service (SaaS) has made it extremely relevant and attractive to systems engineers and software developers.


There are many frameworks and open-source platforms that have implemented MQTT. The crux of the Internet of Things is that data is stored and managed in a secure location that the user can access on demand without needing to host it themselves. You couldn’t ask for a better application for MQTT protocol.


Smartphone apps, like Facebook Messenger, need to be small, fast, and efficient enough to avoid draining the user’s battery and data plan which is why they chose to use MQTT as a model for sending data between users.


In 2015, Amazon Web Services announced AWS IoT, a cloud platform based on MQTT. It’s easy to set up, and has nearly unlimited potential uses. With Amazon’s slick, familiar AWS interface and established presence in the tech world, AWS IoT is a great way for new developers to become familiar with cloud-based applications and the pub/sub method of data transmission.


How MQTT transmits your data


Model of pub/sub messaging protocol


MQTT is a publish/subscribe (pub/sub) messaging protocol that works on top of the TCP/IP protocol. A broker is used to connect clients that are subscribed topics to clients who publish messages to those topics. Many clients may be subscribed to the same topic, and each can use the published data differently, as the application requires. For example, the data could be added to a database, emailed, posted to social media, or saved as a text file. The pub/sub messaging architecture contrasts the more traditional request/response architecture. The request/response model requires all devices to be connected, which significantly increases data traffic.


Topics in MQTT are easy to establish and subscribe to. Nothing needs to be configured – simply publish the message and the topic is created. Topics are arranged in hierarchies similar to a filesystem and the protocol is able to recognize two wildcard values (+ for a single hierarchy, # for all remaining levels), so information can reach a range of topics with only one message.


mqtt - transmitting data

Subscribers receive information from the broker


For Quality of Service (QoS) MQTT recognizes three levels: QoS 0, QoS 1, and QoS 2. For example, with Qos 0 the client fires off a message to the broker without acknowledgment that the message was received. With Qos 1 the client can send a message until the broker acknowledges the message has been reiceved. The strength of this mechanism is that MQTT can guarantee the delivery of a message and possibly resend the message in high latency networks. Higher levels of QoS are available with other protocols, but in the interest of keeping the transmission fast and latency low only these are used.


Another feature of the protocol allows the developer to create a message to attach to the client with instructions for what the broker should do in the case of an unexpected disconnect. The authors describe this feature as the “last will and testament” message. If no ping request or information is received within the set time limit indicating a loss of network activity, the LWT is executed.


The simplicity of the protocol’s operation is one if its greatest assets. Turnover of personnel is a reality in most industries, as are tight deadlines, scope creep, and constantly changing technology. By using MQTT in an application a developer is choosing a protocol that will be simple to install and maintain, and easy for new personnel to learn. In addition to the efficiency of straightforward data transmission, MQTT has several advantages in IIoT settings.


Diagnostic equipment used in waste water treatment facilities can communicate with monitoring devices and data loggers using IIoT.


The phrase “Internet of Things” was coined in 1999 – the same year Stanford-Clark and Nipper developed the MQTT protocol. But the idea of cloud-based services or operations was developed nearly two decades before that. If the Internet could send messages between two computers, it could surely be used to send messages between other types of machines.


Each new machine that gets added to the Internet of Things highlights engineering’s capability to build and embed CPUs in to the things we use every day. As the CPUs get smaller and faster, the lightweight properties of MQTT become a greater advantage. With limited overhead and minimized data packets, the CPUs resources can be used on other functions rather than devoting it to communication.


Flexibility in data types is another big advantage. This is the reason MQTT can be used in so many types of applications. Once the subscribed client receives the data message, it can do whatever the programmer wants with the data. The publish client also has flexibility in the type of data they will send – binary, JSON, XML, etc. – so the subscribed client doesn’t need to use resources to edit or convert the data before they can use it.


Another benefit is the availability of cloud-based platforms developers can use to build out their MQTT applications. IoT has a lot of appeal in its ability to keep data in off-site, third-party locations, potentially saving the integrators and end users the costs of building and maintaining their own server. Popular platforms like Amazon Web Services and Microsoft Azure can handle the message broker part of the equation as well as hosting and storing data from the application. Using familiar services from established tech companies means the integrator has access to a wealth of knowledge from the company itself, as well as many other users who share their tips and tricks online.


The Industrial IoT and secure communication


Security is an important consideration for IoT devices in an industrial setting. Though it may add overhead to the data transmission, keeping networks secure is worth the extra bulk for many system engineers. Even with its small code footprint and small packet size MQTT is capable of some authentication and security features that allow for data integrity and authentication. However it’s worth noting these features are not required for data transmission.


Whether security functions must be implemented or not is defined by the message broker. It’s up to the client to provide the functionality depending on the broker to which it will ultimately transmit data.


KEB’s MQTT client implements the highest data security features as standard. The C6 Router can use TLS, SSL, authentication, and authorization security features when communicating with the broker. Authentication – usernames and passwords, identifiers, certificates – and authorization – publish and subscribe permission settings – are done on the application layer. TLS and SSL settings are done on the transmission layer. By default, data is sent over non-encrypted TCP, but TLS can be used if encryption is required.


There are many consumer and commercial uses for IoT, but its use in manufacturing is what’s powering the fourth industrial revolution, or Industry 4.0. At KEB we design and build products that will get clients into the modern industrial world with all of the right technology. Each component of the C6 automation line is ready to network with other KEB products or integrate into an existing system, and we’re constantly making improvements based on industry innovations and trends.


KEB applications engineers are experts on IIoT and how to make it work for you. Contact us today for more information.


Send us an email


More C6 products for IIoT


Embedded control

IIoT for analysis using Combivis Connect

COMBIVIS connect software

Gearmotors for packaging applications

KEB has years of experience providing high quality, long lasting gearmotors for packaging applications. We offer a wide range of motor and gearbox combinations with numerous mounting and protection options allowing you to customize the selection that best fits your application.  Our gearmotors combine high quality German engineering with local assembly and customization ensuring timely delivery and a product well suited for the North American market.


Gearing Configurations


KEB offers 5 different gearing configurations.  Two of the most commonly specified in the packaging industry are:


Helical Bevel – providing a right angle output and a high efficiency gearbox (94-96%); perfect choice for economical conveyor type applications.  KEB’s high quality gearing is prepared to DIN 3990 specifications.  Gearboxes are available with solid or hollow output shafts.


gearmotors for packaging - helical bevel gearmotor

Helical bevel gearmotor with keyed output shaft


Planetary – inline or right angle with integer gear ratios, low backlash, high torque density and high efficiency (97%+); perfect for precision applications requiring tight positioning control.  Our planetary gearing has multiple output shaft options, lifetime lubrication, and pairs perfectly with a KEB servo motor.


gearmotors for packaging - planetary gearheads

KEB inline planetary gearheads


Other gearing configurations offered by KEB include: Helical Inline, Helical Offset and Helical Worm



IP65+ and Food Grade Solutions


KEB gearmotors can be provided with extra seals, epoxy and protective paint for use in washdown applications.  They can also be supplied with food grade lubricants.  This makes them an extremely durable yet economical solution for washdown and food grade applications that don’t require a full SST solution.



gearmotors for packaging - nema input speed reducer and helical offset gearbox

KEB helical offset gearbox. Great space saver for tight applications allowing output shaft to come back alongside the motor

Gearbox Only Solutions


If you already have a preferred motor supplier, KEB is able to provide the gearbox only with various options for the input configuration.  Both NEMA and IEC inputs are available, along with inputs for servo motors.




No matter which type of gearing you choose, KEB gearmotors are extremely flexible and customizable.  They can be prepared with special flanges, output shafts, bearings, shrink discs, shaft couplers, encoders, etc.  Various electrical connectors (e.g., Harting connectors) can be provided for easy installation and quick connect/disconnect for applications with difficult wire routing.  Terminal box and power connection locations can also be configured to your application’s needs.


Shafts can be prepared for an encoder and/or brake, or supplied with a KEB encoder and spring applied brake.  KEB spring-applied brakes are very flexible with options including manual hand release, microswitch for engagement verification and/or wear monitoring, high energy friction linings for applications requiring repeated stops of large loads, IP65 protection for washdown or outdoor applications, along with many more options.  With over 45 years of experience making spring applied motor brakes KEB is able to offer just about any configuration you could require to pair with our gearmotors.


gearmotors for packaging - motor with brake and hand release lever

KEB motor with brake and hand release lever



KEB’s high quality, customizable gearmotor offering makes us well equipped to handle all of your gearmotor needs.  We are excited to partner with you for your next packaging application!


If you’d like to learn more about KEB gearmotors for packaging applications please contact a KEB sales engineer today.


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Energy Recovery Systems – Using High Speed Generators to capture Energy

KEB’s Energy Recovery Systems are interesting to highlight because they combine a lot of our unique leading-edge technology.  The systems also highlight the breadth of KEB products and our ability to integrate them together to provide a comprehensive turnkey solution.


For the scope of this post, an Energy Recovery System (ERS) or Energy Conversion System (ECS) is an electronic system that controls turbomachinery and converts energy from some process.  The process involves converting high-frequency electrical power to something usable on the mains or building power (e.g. 50 or 60Hz).  Typical processes could be geothermal, air separation, or waste heat recovery.



Application Overview

KEB’s Energy Recovery System functions like this.  A KEB load drive controls the speed of the generator.  The set speed is controlled via a master control system.  When the process gas is introduced, the load drive regulates the generator speed.  As energy is returned to the electrical system, the Active Front End (AFE) is able to return energy to the building power or utility.


energy recovery system


A big highlight of the system is the simple control for the process operator.  Rather than trying to regulate the pressure and flow of the process gas, the KEB load drive regulates the generator speed.



High-Speed Turbomachinery

High-speed motor/generator applications are demanding.  Control instabilities and imperfections that are masked at low speeds can become critical at high speeds. KEB has a lot of experience running high-speed asynchronous and synchronous generators.


The turbomachinery used in energy recovery processes typically use specialty high-speed generators.  The generators are usually equipped with special magnetic bearings or airfoil bearings and can spin in excess of 100,000 rpm.  The advantage of using high-speed generators is that they are extremely compact, efficient, and have high power density.


KEB drives are capable of outputting frequencies up to 1600Hz which is required to run these generators/motors.  But it is not only the listed output frequency and hardware that separates KEB from other drive vendors.  KEB’s SCL™ algorithm provides better speed and torque regulation than commonly used V/Hz control.  Another advantage is that SCL does not require encoder feedback – this is difficult to acheive at high speeds.


SCL-optimized generator control creates less rotor heating and increased energy output   —  this benefits the motor manufacturer and the user.


SCL offers a lot of flexibility with parameter adjustments as well – this allows the KEB system to work with a variety of different generator types and designs characteristics.


F5 VFD lineup

SCL™ is offered with Standard KEB drive hardware


Another reason KEB is well suited for high-speed drive applications is that of our experience designing and supplying sinewave filters.  A sinewave filter cleans up the drives PWM output and provides a sinusoidal waveform to the motor winding.  This also helps reduce motor heating which is critical to a high-performance system.

sinewave filter output

KEB Sinewave filters are important and reduce rotor heating in the generator



Air-Cooled or Water-cooled

KEB offers both air and water cooled drives.  Many times, there will be liquid cooling in the system already.  Liquid-cooled drives offer a number of advantages especially if the systems will be installed at high altitudes or in high ambient temperatures.


Air-cooled versions are often preferred for their simplicity.  The point is that KEB can provide both solutions, depending on the application needs.



High Power – with scalable offerings

The purpose of installing an Energy Recovery System is to lower overall energy usage and save the facility money.  This means that smaller systems will likely not provide sufficient ROI and warrant the investment.  And at some power threshold, the systems become economically feasible.


KEB does high power well.  This means the energy recovery concept can be easily scaled across different power ranges.  With optimization, it becomes easier to make a business case for investing in an energy conversion system.

Large VFDs

KEB drive technology scales to large power



KEB offers Active Front End (AFE) technology with low harmonic distortion (THiD).  AFE is of interest to those looking to generate power back to the mains.  The clean generated power will not create issues for other electrical loads and the power factor can even be compensated as needed.


energy recovery UL 1741

KEB’s AFE system allows high quality power to be returned to the supply



Full Panelized System

KEB offers a standalone drive panel that includes all the drive, filter, and control necessary to control the motor-generator.

energy conversion VFD panel

Compact energy recovery cabinet


A C6 HMI LC provides drive diagnostics and the ability to make parameter adjustments.   The HMIs ship with a CONNECT runtime which means the systems can provide remote access.  This gives the possibility to provide remote maintenance and future PLC upgrades.


energy conversion system screen

KEBs HMI LC provides secure remote access and provides clear system diagnostics


The HMI LC can also act as a network gateway.  This means the KEB panel can tie in with the processes master control via another network protocol like Modbus, EtherNet/IP, or Profinet.



Turnkey Solution

KEB can provide individual components but this is a case where a lot of thought has already been put in and engineered into a complete turnkey solution.


The KEB conversion system includes a grid protection relay and an EMI filter to mitigate high-frequency noise.  Also, there is provision to detect an emergency situation and then safely disconnect the system.  These are features that would need to be considered and implemented anyway.  In this case, they are already engineered by KEB into a system that can be easily integrated into the process and quickly implemented into a customer system.



Do you want to discuss more? Contact a KEB engineer today.


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High Speed Elevator in Long Island City NY | Machine Room Vids #06


In this episode we give an overview of a high speed elevator machine room in a rapidly changing area of NYC – Long Island City. Many dated industrial buildings are being replaced by high rise buildings.


We visit a machine room where KEB Elevator Drives are running 1000FPM cars and using regenerative drives.


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So Long Island City is just on the on the east side of the East River across from Manhattan. The area is booming with buildings so a lot of new high-rises are going up in the area. As you look around you can see a lot of tall buildings going in, residential towers replacing a lot of old industrial areas.


Hi I’m Tony Heiser with KEB America. Today I’m visiting One Queens Plaza South Tower in Long Island City in New York. This particular building has MCEI control KEB F5 elevator drives and R6 line regen units and imperial PM gearless AC machines. Cars here 1000FPM.


With space as a premium a lot of these industrial areas are being ripped down and high-rise buildings are going up to accommodate many times for rental units and housing units. Being that space is a premium you have to build higher and with the higher rises you need a faster elevators, higher speed elevators. Often in the 500FPM to 1200FPM range.


A lot of the buildings that we’re seeing in Long Island City is that are going up are the high-rise buildings and many of them are at the thousand foot per minute threshold.

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