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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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.
Full Panelized System
KEB offers a standalone drive panel that includes all the drive, filter, and control necessary to control the motor-generator.
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.
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.
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.
The CAN in Automation (CiA) group has created unique device specifications for certain applications. One example we’ve highlighted before is CiA 417 which defines the CANopen Lift Application. Another is CiA 402 which defines the specification for devices that operate motors. This can include VFDs, Servo Drives, stepper drives, etc.
This post gives an overview of some of the main features of CiA 402, why a person would want to use it, and some considerations.
CiA402 – A Profile for Drives and Motion Control
The CAN bus protocol has had a lot of success since its initial creation for automotive applications. Over time the number of different vendors offering CAN products has increased along with the many different applications that use the protocol.
This has given rise to the need to create specifications for certain applications. Specifications help with interoperability and allow products to be more easily swapped out. They also help reduce development times by creating a common template.
The CiA 402 (also referred to as DS402) profile was created for motion controllers, VFDs, and servo drives that are operating motors. Here are a few important features of the DS402 profile.
CiA 402 defines some basic parameters. This includes identification parameters such as Vendor IDs, Product Codes, Serial Numbers, Fault codes, etc.
Other parameters are related to the motor type (stepper, AC servo) and nameplate information such as Motor rated current and Motor rated speed.
Other parameters exist that are operating mode-specific (more info on modes further on). Example mode-parameters include Target Torque, Max Torque, Max motor speed, etc.
These basic defined parameters function very similarly to EtherNet/IP’s AC Drive Profile. The idea is that the commonly used and required data is defined upfront. Also, the hex addresses for those parameters are defined and are fixed as well. So this basic information from Vendor A and Vendor B will be presented similarly.
Control & Status Words
The CiA 402 profile also defines the structure of the control and status words. The control word contains essential information such as: Enable voltage, Quick stop, Enable Operation, and Fault Reset.
The status word provides information that is sent from the drive device back to the controller. The status word contains information like Fault, Voltage Enabled, Warning, etc.
Both the control and status words leave bits open so they can be defined by the manufacturer. This gives the device manufacturer some flexibility to implement custom functions.
The DS402 profile includes a state machine. The state machine covers the various states a drive can be in. These states include SWITCHED ON, FAULT, OPERATION ENABLE, etc…
The drive’s state can be changed by the master controller over the control word. Or, the state can also be changed in reaction to an event (e.g. fault).
In turn, the current state of the drive is returned to the controller via the statusword. In this way, it is possible for the master control to monitor all drive axes in the case of multi-axis motion applications.
It is important to note that a drive must proceed through the state diagram logically. Therefore, if a person wants to start-up a drive and spin a motor then the drive must logically progress through a series of states until they reach the OPERATION ENABLE state.
Similarly, if the drive enters a fault state, it cannot be immediately run again. Rather, the fault must be cleared by first going into a FAULT RESET state – this can be done over the controlword.
CiA 402 outlines basic operating Modes used in motion control applications. These Modes include Profile Positioning Mode, Velocity Mode, Torque Mode, Homing Mode, etc.
One important thing to note is that a vendor that says they comply with the CiA402 profile might meet parts of the standard, but not the entire specification. You should always verify with the device vendor if their product meets the specific functionality you are looking to implement.
For example, KEB drives like the S6 support the following modes: Profile Position, Velocity, Homing, Cyclic Sync Position, Cyclic Sync Velocity and Homing modes. However, not all of the 30+ homing routines outlined in the 402 specification are currently supported. The most common ones are, but the special-case ones are not.
CANopen over EtherCAT (CoE)
Where does the CiA402 profile fit in with EtherCAT? EtherCAT supports the CiA402 device profile through CANopen over EtherCAT (CoE). In fact, EtherCAT also supports other CANopen device profiles like CiA 406 (encoder profile) and CiA 408 (hydraulic device profile).
The CoE functionality is defined by the EtherCAT Technology Group (ETG.6010) and allows the DS 402 profiles to be mapped to EtherCAT. The EtherCAT state machine and the CAN state machine are similar enough with a few small exceptions.
As standard, KEB 6th generation drives like the S6 EtherCAT servo drive include hardware to support both CAN and EtherCAT – customers have the flexibility to choose what they want to use.
KEB Software Tools
KEB has a lot of nice tools on the controller and drive-side that will help a user set-up the CiA402 profile and CoE.
An engineer could use the many PLCopen function blocks and create their own function block for CiA402 control. However, this has already been done for you by KEB engineers.
For our controls products, a function block called KEB_CIA402_DriveControl is included in Combivis Studio 6. The function block includes all the necessary inputs to spin the motor and control through the various supported operating modes.
On the drive side, Combivis includes a nice wizard with a graphical interface. The graphical interface allows a user to see the current machine state the drive is in. The user can also give inputs through the software to progress the drive through the states. This is great for troubleshooting and basic start-ups.
CiA 402 gives a machine builder flexibility. KEB offers a lot of compatible drive solutions for stepper, AC servos, and multi-axis applications. We also offer a lot of nice software tools to help with development and optimizing your machine.
Are you interested in CiA402 or CoE drives? If so, contact a KEB engineer today to discuss our many CiA402 drive options.
Contact an engineer
KEB CiA402 Drive Products
Historically, connecting two different communication networks was handled by a dedicated network gateway. We worked on an application a couple months ago where we were able to implement this gateway functionality in an HMI LC. This is what it looked like.
The customer’s main PLC was an Allen-Bradley communicating with EtherNet/IP (protocol 1). The AB PLC connected to a machine panel that used a KEB HMI LC.
The HMI LC used EtherCAT (protocol 2) to control a 200Hp F6-K EtherCAT VFD.
EtherCAT for the VFD
EtherCAT was chosen because it provides a high-speed CAT5 connection to the drive. Also, programming the drive communication is made easy through the KEB’s EtherCAT communication handler Function Block.
A group of parameters was defined for the EtherCAT process data (PDO). The PDO gives cyclical and high-speed updates on the critical parameters.
Additionally, we implemented the DIN66019 II protocol (protocol #3) which can be used to read/write individual drive parameters. Beyond the fast-channel EtherCAT PDO parameters, this gives the ability to access every KEB drive parameter including fault codes, warnings, etc. It also provides the functionality to do a full upload and download of drive parameters.
The HMI LC can then relay any drive parameter back to the upstream PLC via EtherNet/IP. In short, the HMI LC is acting as a gateway to handle the 3 different communication protocols.
Mix-and-Match other Communication Protocols
This same concept can be extended to the other 40+ protocols supported by the HMI products. This includes Modbus, Profinet, etc. Even serial fieldbus networks Data Highway, DH+, and Profibus are possible.
So why would somebody prefer to implement this solution with the HMI LC instead of a communication gateway? It’s a fair question. The reason is that the HMI LC gives you a lot more flexibility and functionality than the traditional network gateway hardware.
It’s obvious but worth highlighting – The HMI LC adds visualization. In this application, it served as a drive remote operator, displaying speed, load, temperature, drive status and error history.
Additionally, it offers the possibility to display PDF manuals, diagnostics, logs, error history, trending information, etc. You won’t get that with a gateway-only device.
Secure Remote Access with CONNECT™
Each HMI LC ships with a Combivis CONNECT™ Runtime. This allows a secure VPN connection to be made to the machine which improves troubleshooting and diagnostic gathering.
The HMI LC offers the possibility to handle the entire machine control including EtherCAT remote I/O. From that standpoint, it becomes a very good value.
Automatic Drive Download
If a replacement drive needs to be installed at some point in the future, the HMI LC can automatically download the correct program. Again, this functionality is made easy with an included KEB Function Block in the Combivis Studio software. This functionality makes long-term support for the machine easier.
With over 40 communication drivers, the HMI LC can act as a gateway between two different networks. But the HMI LC is much more than a gateway. The HMI LC offers a lot of value and is a scalable product that increases a machinery OEM flexibility and maintainability.
If you are interested in more information on the HMI LC contact a KEB engineer today.
Email KEB America
In this post, I’ll describe the process I use for sizing gearboxes and geared motors.
To make the selection, I am using KEB’s software sizing program called KEB-DRIVE. KEB-DRIVE is free and easy to use. If interested to follow along, you can download a copy of the software.
1. Consider the application requirements
Before you begin selecting a geared motor, you first need to consider and know the application requirements. This is not a comprehensive list but gives a general idea of the common considerations.
Torque & Speed
- What torque and speed are required at the output of the gearing?
- What does the typical torque profile look like?
- Is the loading more or less steady – or will the gearing experience shock loading?
- What electrical power do I have (three phase, 50 or 60Hz, Voltage)?
- What is the duty of the application?
- If I need more motor overload – can I rate for a reduced duty like S2 or S3?
- Does the application require position, torque or speed control?
- Will the motor be run across the line or with a VFD?
- Will the motor hold the load at 0 speed indefinitely (e.g. hoisting application)?
- Does the motor need a spring-set brake on it?
- Does it need a feedback device like an encoder?
- How will the gearmotor be mounted to the machine – foot mounted, shaft mounted, flange mounted?
- Are there space constraints?
- Does the output axis need to be inline or at a right angle
- What environment is the gearmotor going into (e.g. caustic washdown, saltwater, sensitivity to noise, etc.)?
- What are the ambient temperature ranges during operation?
- Does it require special ingress protection (washdown, outdoors, etc.)?
- Is this a food processing application that will require food grade lubricants and grease?
2. Select the correct gear technology for the application
Configurations in KEB-Drive start at the top left. On the left, you’ll see drop-downs to select different gear types and sizes.
KEB offers 4 main types of gearing:
4 Types of KEB Gearing
|“Style”||Gear Type||Output||Efficiency (%)|
Helical-Worm and Helical-Bevel will provide right angle outputs. Helical-worm can be cost advantageous for larger reduction ratios. Helical-bevel has the advantage of better efficiency, which can possibly equate to a smaller motor.
There is also an option available to leave off the gearing if are just interested in selecting a servo or induction motor.
3. Motor Selection (Size, voltage, frequency)
Working to the right, I then select the size of the motor I want. Options for both Induction motors and AC Servo motors are listed. Here is a comparison of the advantages between servo and induction motors.
There is a tab that allows you to select the stator winding information – specifically, the rated voltage and frequency. KEB has the ability to offer special windings outside of what is listed. Last year I worked on a 380V/60Hz installation in South Korea – who knew!
Larger motors will provide more torque. As you increase the motor size, you’ll see the torque information is updated in torque/speed drop-down.
4. Adjust the Torque/Speed selection
Is it a speed reducer? Or a torque Increaser? It’s both – higher gear ratios will provide lower output speeds and higher torques. Use the drop down to see all the different possible configurations with the selected gearbox/motor combo.
There is a limit to the options that KEB-Drive will show. Only options with a service factor of 1.0 or greater are displayed.
Note: If you have selected a motor winding that is rated for both 50 and 60Hz, you will see two values listed for the speed and torque. The 50Hz rating will be reflected with the slower rpm output.
5. What is the gearing Service Factor and why is it important?
The gearing service factor (SF) is the ratio between the:
In other words, Service Factor provides a relative comparison to how much capacity the gears have in the current configuration.
A SF of 1.0 means the gears will have a nominal output torque equal to that of their rating. Selecting a motor/gear configuration with a SF of less than 1.0 is not advised. This means the gears will be undersized when operated at the nominal point. This could also indicate that the motor selected is too large.
Sometimes, the application is very difficult with regards to Duty, Shock loading, Temperature, etc. (look at step 1 – application requirements). In this case, it is advisable to select a very high SF which compensates for the factors that will stress, wear, and possibly damage the gearing.
Manufacturers typically provide a table of typical applications. Many also list a multiplication factor based on duty. It is advised that difficult applications like a Rock Crusher have a SF in the 3.0 range or higher. Relatively easy applications like fans with light duty might have a SF closer to 1.0. It often becomes a trade-off between safety factor and cost.
At this point, if the selection is not able to meet the required torque, speed, and SF of the application, you’ll need to return to step 2 and select a different gear and motor combination. Or conversely, if the motor or gear appear to be oversized, then you can return to step 2 in order to optimize.
6. Select gearmotor options (mounting style)
This section allows a user to select how the geared motor will be mounted. The flexibility of mounting is one reason that the KEB integral gearmotor solution has been so popular. Users can select a unit with an output shaft. Or a shaft mounted unit with a hollow bore. Mounting feet and mounting flanges can also be selected.
For shaft mount applications, a nice option is a shrink disk mounting. KEB’s shrink disc mounting provides a zero backlash connection between the gearbox and machine shaft. Assembly and disassembly are very easy.
To go along with the flexibility-theme, users can select either English or Metric units on the shaft/bores. If you don’t see the exact option you want in the configurator, then I suggest contacting a KEB engineer to explore what is possible. We are able to offer a lot of customer flange and bore designs if the customer wants.
This section also includes the lubrication used in the gearbox. A number of different lubricants are possible depending on the application requirements. Consult the KEB gearmotor manual but the temperature ranges for the lubricants is listed. For food and packaging applications, a USDA food-grade lubricant is available.
Below that is a list of checkboxes that can be selected. Gearing options like low backlash and protection covers are possible.
7. Choose the motor options
This is where a user selects the motor options. Options like a motor on the brake. Or, the type of encoder for closed loop applications. Even the type of motor fan can be selected here.
8. General options
Next, the general options can be defined. These are special requirements that can be easily selected in the configurator. This includes a second nameplate, condensation drain hole, etc, The conduit box orientation and the fitting location are also defined here.
Finally, the paint treatment can be selected here. The number of applications and thickness of paint is defined. Consult the KEB gearmotor catalog for the specifications. Added protection is possible with the P1, P2, or P3 options. These would be good options to consider for washdown, outdoor, and maritime gearmotor applications.
The paint color is also defined here. Gray and black are most commonly requested so they are standard options. But we can paint to whatever color the customer specifies. In the case of a special, contact KEB.
9. Gather 3D models and dimensional drawings
The last option is the mounting position of the gearmotor. This is important as it determines the oil fill level of the gearmotor and venting.
At this point, the user can explore additional tabs in KEB-DRIVE in order to get more information. Of note, the customer can get extra motor information including the efficiency values, nominal torque, and inertia values.
The Dimensions tab includes a drawing with critical dimensions and 3D .step models.
KEB-Drive is a useful tool because it is easy to use and selections can be made very quickly. However, please note that these are only the commonly requested features. There are many more possibilities KEB can offer like absolute or safety encoders, quiet brakes for theatre or elevator applications, custom flanges, etc.
If you have specific needs feel free to consult with a KEB gearmotor engineer and we’d be happy to help with your application.
There are a number of issues that arise when a VFD and motor are mounted far apart. A previous post went over voltage spikes due to dV/dt of the drive’s PWM switching. The answer to that problem was a dV/dt choke or sinewave filter.
For closed loop applications, another problem that can arise when a drive and motor are located far apart has to do with the encoder signals. Specifically, the voltage drop experienced on encoder signals.
This post will outline the problems of long feedback cable runs and how to address them.
Voltage Drop of Encoder Signals
The encoder cable is basically a transmission line carrying the encoder signal from the encoder device to the encoder card on the VFD. The encoder cable has some impedance which is a characteristic of the cable design.
The cable resistance should be listed on the manufacturer’s cable data sheet. The resistance is usually listed as some value per length – (e.g. Ohms/meter or Ohms/ft.). The longer the cable the more resistance it will have. And the more cable resistance, the more voltage drop the signal will have.
Let’s look at an example. Assume a worst-case scenario of a 200mA current draw. Using the data above for a 75-meter application, a TTL signal will lose 1.05V due to the voltage drop.
The most commonly used incremental encoders are the TTL type and have a target “on” voltage level of 5V. However, the drive’s encoder card will have an acceptable range on the voltage level that the drive or encoder input will accept. For example, KEB’s encoder cards recommend a minimum of 4.75V for the “High” TTL signal.
If there is too much voltage drop the TTL signals, you will get erratic operation and nuisance trips – the worst kind and a pain to troubleshoot. A common error is that the A or B channel compliment does not match the respective channel. With KEB Combivert F5 inverters, this will result in the E.EnC1 fault.
So if you are experiencing random encoder faults and suspect too much voltage drop, here are 7 things you can do to address the issue.
1. Use a Shorter cable
This one is simple but is worth mentioning because it might be the easiest to implement – if possible, use a shorter feedback cable. I’ve seen many applications where they use a “standard” cable or something they have on the shelf. The result is they use a much longer encoder cable than they really need.
An excessively long feedback cable can also couple unwanted noise and introduce other issues. So, use the shortest possible encoder cable that is practical for the application.
2. If powered from the VFD – Increase the supply voltage
Some encoders receive power from the drives control/encoder card. The Push-Pull type TTL encoders will output a signal amplitude that is proportional to its supply voltage (i.e. there is no regulated supply onboard). With these types of encoders, there are effectively two conductor voltage drops – the supply, and the return.
KEB’s F5 drive uses a fixed 5.2V supply to power the encoder. The idea is that the extra .2V compensates for some voltage drop. Some other encoder cards have means to increase the supply voltage.
If possible, you can adjust the encoder card supply voltage up. Just be sure to use a voltmeter to measure the supply voltage and check the encoder specs to make sure a higher voltage is permitted.
3. Apply power at the encoder
Another option (if supported by the encoder) is to apply the supply power directly to the encoder. Since the supply is directly applied to the encoder, this allows only one voltage drop on the feedback signals – effectively cutting the total voltage drop in half compared to the initial example.
Check your encoder datasheet to see how the encoder can be powered. Some encoders can only be powered from the drive’s encoder card. However, other encoders are designed to allow a direct power source. Some might even allow a higher input voltage like 24V but then regulate the output voltage accordingly (e.g. 5V).
So do check the encoder data sheet and see what the input power options are.
4. Consider using HTL logic
A “High” or “On” level for HTL logic is defined between 15V and 30V, with a target of 24V. KEB F5 HTL encoder cards will have a regulated 24V supply that can be used to power the encoder. Because the HTL signal is higher, it can support more of a voltage drop before hitting the lower “On” threshold.
HTL provides much more room for voltage drops – 9V from the regulated supply to the lower threshold (24V-15V = 9V). Compare that with TTL’s range of only 3V from supply to lower “High” threshold (5V-2V).
Just be sure that the drive’s encoder card supports an HTL input or the card could be damaged.
5. Use an encoder cable with lower resistance
KEB offers special encoder cables for long distance runs. The cables use larger conductors so they have less resistance. Less Ohms/meter will result in less voltage drops on the feedback signal.
6. Use a signal repeater
Another option is to use a signal repeater. Signal repeaters were commonly used before real-time fieldbuses like EtherCAT were available. They function by splitting, amplifying and conditioning the encoder signal.
KEB offers a signal repeater like this (00F4072-2008) that can be used for long run and multi-follower applications.
7. Use Fieldbus I/O – Like KEB’s Counter module
Another option is to use a fieldbus encoder module to transfer the data.
KEB’s encoder module allows the input of up to 2 TTL encoder signals. The encoder signal is wired to the module where it is converted and transferred via the EtherCAT bus.
One big advantage with this solution is the low cost of a CAT5/6 cable. The cabling cost will be much less than a long encoder cable. The second advantage is that the position is now on the bus and available for use by the control without any other handling.
One consideration with this implementation is the input delay. The listed value for the input delay on the KEB module is 1ms. This will be suitable for most motion applications but you’ll want to verify it with your individual application.
I’d be interested to hear of other solutions or problems you’ve encountered. Leave your comments below.
Have questions? – Contact a KEB Application Engineer today.
Electric motor brakes are used to decelerate or hold motor loads when the power is cut intentionally or accidentally. KEB has been supplying motor brakes since our founding – this gives us more than 45 years of experience.
Beyond our core brake technology, KEB is able to offer custom designs which help motor manufacturers during assembly and meet the application requirements. This post gives an overview of KEB’s motor brake technology and some of the value-add we provide motor OEMs.
DC Spring-Set Brakes
KEB specializes in the design and manufacture of DC spring-set brakes. Compared to AC Brakes, DC brakes offer a number of advantages including: simple operation with no linkages, less adjustments needed, less ongoing maintenance.
When we replace AC brakes, it is typically in those really demanding braking applications where there is a high cycling rate. The solenoid and linkages in the AC types do not stand the abuse and wear or fail prematurely.
KEB can offer brake coils wound for any voltage including battery power machines using 12VDC and 24VDC. Using a KEB bridge rectifier, AC power is easily converted to DC power for the brake.
Motor Brakes to handle Tough Applications
KEB brakes are designed for demanding industrial applications. Our friction linings and coil voltage tolerance all have internal safety factors built-in. This becomes important for demanding and safety-critical applications. As standard, KEB’s spring-set brakes are CSA listed and UL can also be designed for.
KEB can offer special brake solutions as the application requires. We can offer IP65 brakes for washdown and outdoor installations. We can offer high energy brakes for applications where the brake is required to stop very large loads repetitively.
We offer silent brakes for theatre hoists and elevator motors that are noise sensitive. We offer special brakes for applications in moist and humid environments.
If you have a demanding application, chances are we already designed a solution for the applications.
Because we have internal design capabilities here in Minneapolis, we can customize our brakes to meet the requirements of the motor design.
Most commonly, KEB supplies the brake assembly and our customer mounts it to the outside of a prepared end bell or mounting flange. Optionally, KEB can provide the mounting flange or NEMA C-Face adapter plate.
We have also done designs where the brake is mounted inside the motor housing (e.g. servo motor brake). The advantage is that the customer is able to get an IP65 designed brake. However, this should be used for holding brake applications only as the brake is not easily serviceable.
Besides the mounting flange, we can also provide other customized options. We can provide extra long leadwires if needed, or special connectors. Additionally, we can provide special hubs or rotors that are located off motor shaft features (step or snap ring).
Double C-Face Brakes
One option customers like for both new and retrofit installations is KEB’s Type 17 Double C-Face Brake. The Double C-Face Brake is a power-off DC spring-set brake. The deisgn includes an integral NEMA input flange and output flange and shaft.
This brake is typically mounted in between a NEMA C-Face motor and a gearbox. Some customers prefer this brake as it is modular and the gearbox, brake, and motor can all be serviced or replaced individually.
The Type 17 brake is offered with a variety of different magnet voltages and includes a conduit box for making the wiring connection. As standard, this product is designed with NEMA 4 protection and includes a manual hand release.
The product can be paired with 56C through 286TC NEMA motors.
Electric motors are used in a wide variety of applications, with most of them requiring a brake. With KEB’s history, experience, and reputation of supplying the highest quality of brakes we are confident that we can find the brake for your application.
Even if you have a custom application requiring a different brake style (permanent magnet or power on brake) – feel free to contact us and one of our Engineers will take a look and specify the correct brake for your application.