Beckhoff KS2791 Operator's manual

Documentation | EN
KL2791/KS2791
Single channel speed controller terminals for single-phase AC
motors
2022-12-12 | Version: 2.2.0

Table of contents
KL2791/KS2791 3Version: 2.2.0
Table of contents
1 Foreword....................................................................................................................................................5
1.1 Notes on the documentation .............................................................................................................5
1.2 Safety instructions.............................................................................................................................6
1.3 Documentation issue status ..............................................................................................................7
2 Product overview ......................................................................................................................................8
2.1 Introduction .......................................................................................................................................8
2.2 Basic function principles....................................................................................................................9
2.3 Technical data.................................................................................................................................10
2.4 LED displays ...................................................................................................................................11
3 Mounting and wiring ...............................................................................................................................12
3.1 Instructions for ESD protection .......................................................................................................12
3.2 Installation on mounting rails...........................................................................................................13
3.3 Disposal ..........................................................................................................................................15
3.4 Connection ......................................................................................................................................16
3.4.1 Connection system........................................................................................................... 16
3.4.2 Wiring ...............................................................................................................................17
3.4.3 Contact assignment ......................................................................................................... 19
3.5 Notes on operation..........................................................................................................................20
4 Application examples - overview...........................................................................................................22
4.1 KL2791 - application example.........................................................................................................22
4.2 KL2791-0011 - application example................................................................................................23
5 Configuration Software KS2000 ............................................................................................................24
5.1 KS2000 - Introduction .....................................................................................................................24
5.2 Parameterization with KS2000........................................................................................................26
5.3 Register...........................................................................................................................................28
5.4 Settings ...........................................................................................................................................29
5.5 Process data ...................................................................................................................................31
6 Data structures........................................................................................................................................33
6.1 Process image ................................................................................................................................33
6.2 Control and status bytes .................................................................................................................33
6.3 Register overview............................................................................................................................35
6.4 Register description ........................................................................................................................36
6.5 Examples of Register Communication ............................................................................................38
6.5.1 Example 1: Reading the firmware version from register 9 ............................................... 38
6.5.2 Example 2: Writing to an user register ............................................................................. 38
7 Appendix..................................................................................................................................................42
7.1 Support and Service........................................................................................................................42

Table of contents
KL2791/KS27914 Version: 2.2.0

Foreword
KL2791/KS2791 5Version: 2.2.0
1 Foreword
1.1 Notes on the documentation
Intended audience
This description is only intended for the use of trained specialists in control and automation engineering who
are familiar with the applicable national standards.
It is essential that the documentation and the following notes and explanations are followed when installing
and commissioning these components.
It is the duty of the technical personnel to use the documentation published at the respective time of each
installation and commissioning.
The responsible staff must ensure that the application or use of the products described satisfy all the
requirements for safety, including all the relevant laws, regulations, guidelines and standards.
Disclaimer
The documentation has been prepared with care. The products described are, however, constantly under
development.
We reserve the right to revise and change the documentation at any time and without prior announcement.
No claims for the modification of products that have already been supplied may be made on the basis of the
data, diagrams and descriptions in this documentation.
Trademarks
Beckhoff®, TwinCAT®, TwinCAT/BSD®, TC/BSD®, EtherCAT®, EtherCATG®, EtherCATG10®, EtherCATP®,
SafetyoverEtherCAT®, TwinSAFE®, XFC®, XTS® and XPlanar® are registered trademarks of and licensed by
Beckhoff Automation GmbH. Other designations used in this publication may be trademarks whose use by
third parties for their own purposes could violate the rights of the owners.
Patent Pending
The EtherCAT Technology is covered, including but not limited to the following patent applications and
patents: EP1590927, EP1789857, EP1456722, EP2137893, DE102015105702 with corresponding
applications or registrations in various other countries.
EtherCAT® is registered trademark and patented technology, licensed by Beckhoff Automation GmbH,
Germany.
Copyright
© Beckhoff Automation GmbH & Co. KG, Germany.
The reproduction, distribution and utilization of this document as well as the communication of its contents to
others without express authorization are prohibited.
Offenders will be held liable for the payment of damages. All rights reserved in the event of the grant of a
patent, utility model or design.

Foreword
KL2791/KS27916 Version: 2.2.0
1.2 Safety instructions
Safety regulations
Please note the following safety instructions and explanations!
Product-specific safety instructions can be found on following pages or in the areas mounting, wiring,
commissioning etc.
Exclusion of liability
All the components are supplied in particular hardware and software configurations appropriate for the
application. Modifications to hardware or software configurations other than those described in the
documentation are not permitted, and nullify the liability of Beckhoff Automation GmbH & Co. KG.
Personnel qualification
This description is only intended for trained specialists in control, automation and drive engineering who are
familiar with the applicable national standards.
Description of instructions
In this documentation the following instructions are used.
These instructions must be read carefully and followed without fail!
DANGER
Serious risk of injury!
Failure to follow this safety instruction directly endangers the life and health of persons.
WARNING
Risk of injury!
Failure to follow this safety instruction endangers the life and health of persons.
CAUTION
Personal injuries!
Failure to follow this safety instruction can lead to injuries to persons.
NOTE
Damage to environment/equipment or data loss
Failure to follow this instruction can lead to environmental damage, equipment damage or data loss.
Tip or pointer
This symbol indicates information that contributes to better understanding.

Foreword
KL2791/KS2791 7Version: 2.2.0
1.3 Documentation issue status
Version Comment
2.2.0 • Chapter Product overview updated
• Chapter Technical data updated
• Chapter Contact assignment updated
• Chapter Register overview updated
• Document structure updated
2.1.0 • Chapter Technical data updated
• Document structure updated
• Chapter Instruction for ESD protection added
• Chapter Disposal added
• New title page
• Update revision status
2.0.0 • Migration
1.2.0 • Set mode leading edge phase control added
• Installation and wiring updated
• Technical data updated
• Preface updated
1.1.0 Increased power rating of 200VA for KL2791 and KL2791-0011 approved
1.0.0 First public issue
0.1 First internal preliminary version
Firmware and hardware versions
Version of the
documentation
KL2791, KS2791, KL2791-0011, KS2791-0011
Firmware Hardware
2.2.0 05 09
2.1.0 05 09
2.0.0 3A 05
1.2.0 3A 05
1.1.0 1B 03
1.0.0 1A 00
0.1 1A 00
The firmware and hardware versions (delivery state) can be taken from the serial number printed on the side
of the terminal.
Syntax of the serial number
Structure of the serial number: WWYYFFHH
WW - week of production (calendar week)
YY - year of production
FF - firmware version
HH - hardware version
Example with serial number 24 08 1A 00:
24 - week of production 24
08 - year of production 2008
1A - firmware version 1A
00 - hardware version 00

Product overview
KL2791/KS27918 Version: 2.2.0
2 Product overview
2.1 Introduction
Fig.1: KL2791 - Single channel speed controller terminals for single-phase AC motors
In many industrialized countries, electric motors account for more than the half the current consumption,
which means there is huge energy-saving potential.
With the aid of speed control, it is quite easily possible to reduce the energy consumption to the level that is
actually required, thereby avoiding energy waste.
Beckhoff has extended its Bus Terminal system for this purpose. The KL2791 Bus Terminal is suitable for
use as a speed controller for single-phase AC motors up to 100VA.
In addition to energy conservation speed reduction offers noise reduction and increased motor service life.
The speed controller is extremely compact and is housed in a standard bus terminal with a width of 12mm.
The KL2791 Bus Terminal can be used in any bus system that is supported by the Beckhoff Bus Terminal
system.
It is designed for direct connection of low-power, single-phase AC motors.
The KL2791 enables speed reduction of typical motors such as capacitor motors, universal motors and
shaded-pole motors.
The KL2791-0011 is a version without power contacts (see ladder diagram on the right). This can be used
for 230V even without a special power feed terminal.
Other KS2791 variants feature pluggable wiring.

Product overview
KL2791/KS2791 9Version: 2.2.0
2.2 Basic function principles
Fig.2: KL2791 - Basic function principles
The motor is switched on and off with a practice-proven mains-synchronous pattern, so that the motor
consumes less power and the speed falls significantly.
This method is well suited to motors with fixed loads, such as pumps and fans, in order to achieve a control
range for the flow rate from 10% to 100%.
The KL2791 Bus Terminal enables direct connection of single-phase AC motors up to 100VA.
In this way the speed of capacitor, universal and shaded-pole motors can be reduced simply.
The set values are specified via the process data. The required output power is specified via a 16bit
representation. 3 different setting modes are available:
• Full-wave control
• Leading edge phase control is ideal for smooth operation
• Mixed control
Full-wave control is used for targeted switching on and off at optimized points in time.
This protects the connected motor and is particularly suitable for drives with a quadratic load characteristic,
such as fans or pumps.
Leading edge phase control is ideal for smooth operation.
Mixed control offers a compromise between smooth operation and motor protection.
NOTE
Please follow the operation instructions
Also read the Notes on operation [}20] in the chapter Mounting and wiring.

Product overview
KL2791/KS279110 Version: 2.2.0
2.3 Technical data
Technical data KL2791, KL2791-0011 KS2791, KS2791-0011
Mains voltage 230VAC
Power rating 200VA (W), max. 0.9A
Load types Single-phase AC motors
Types of control Full-wave control, mixed control
Resolution 1%
Leakage current (OFF state) < 1mA
Electrical isolation 500V (K-bus /field voltage), 3750VAC (1min.)
Power supply for the electronics via the K-bus
Current consumption from K-bus typically 95mA
Bit width in the input process image 1 x 16bit data, 1 x 8bit status
Bit width in the output process image 1 x 16bit data, 1 x 8bit control
Configuration via the Bus Coupler or the controller
Weight approx. 60g
Permissible ambient temperature range
during operation
0°C ... + 55°C
Permissible ambient temperature range
during storage
-25°C ... + 85°C
Permissible relative air humidity 95%, no condensation
Dimensions (W x H x D) approx. 15mmx100mmx70mm (width aligned: 12mm)
Mounting on 35mm mounting rail conforms to EN60715
Vibration/ shock resistance conforms to EN60068-2-6/ EN60068-2-27
EMC immunity/ emission conforms to EN61000-6-2/ EN61000-6-4
Protection class IP20
Installation position variable
Pluggable wiring No yes
Approvals/markings* CE, UKCA, EAC
*) Real applicable approvals/markings see type plate on the side (product marking).

Product overview
KL2791/KS2791 11Version: 2.2.0
2.4 LED displays
Fig.3: LED displays
LED Display
K-Bus run (green) off no data transfer on the K-bus
on Data transmission on the K-bus is active
Sync (green) off • Terminal is not synchronized with the mains*
on • Terminal has synchronized itself with the mains*
ON (green) off Process data are zero
on Process data are not zero
Error (red) on A load-side overcurrent was detected
*) Synchronization with the mains can only occur if a load is connected!
WARNING
Risk of electric shock!
With the Sync LED switched off mains voltage may still be present at the KL2791 output!
At this stage, the synchronization was not yet performed!

Mounting and wiring
KL2791/KS279112 Version: 2.2.0
3 Mounting and wiring
3.1 Instructions for ESD protection
NOTE
Destruction of the devices by electrostatic discharge possible!
The devices contain components at risk from electrostatic discharge caused by improper handling.
• Please ensure you are electrostatically discharged and avoid touching the contacts of the device directly.
• Avoid contact with highly insulating materials (synthetic fibers, plastic film etc.).
• Surroundings (working place, packaging and personnel) should by grounded probably, when handling
with the devices.
• Each assembly must be terminated at the right hand end with a KL9010 bus end terminal, to ensure the
protection class and ESD protection.
Fig.4: Spring contacts of the Beckhoff I/O components

Mounting and wiring
KL2791/KS2791 13Version: 2.2.0
3.2 Installation on mounting rails
WARNING
Risk of electric shock and damage of device!
Bring the bus terminal system into a safe, powered down state before starting installation, disassembly or
wiring of the bus terminals!
Assembly
Fig.5: Attaching on mounting rail
The bus coupler and bus terminals are attached to commercially available 35mm mounting rails (DIN rails
according to EN60715) by applying slight pressure:
1. First attach the fieldbus coupler to the mounting rail.
2. The bus terminals are now attached on the right-hand side of the fieldbus coupler. Join the compo-
nents with tongue and groove and push the terminals against the mounting rail, until the lock clicks
onto the mounting rail.
If the terminals are clipped onto the mounting rail first and then pushed together without tongue and
groove, the connection will not be operational! When correctly assembled, no significant gap should
be visible between the housings.
Fixing of mounting rails
The locking mechanism of the terminals and couplers extends to the profile of the mounting rail. At
the installation, the locking mechanism of the components must not come into conflict with the fixing
bolts of the mounting rail. To mount the mounting rails with a height of 7.5mm under the terminals
and couplers, you should use flat mounting connections (e.g. countersunk screws or blind rivets).

Mounting and wiring
KL2791/KS279114 Version: 2.2.0
Disassembly
Fig.6: Disassembling of terminal
Each terminal is secured by a lock on the mounting rail, which must be released for disassembly:
1. Pull the terminal by its orange-colored lugs approximately 1cm away from the mounting rail. In doing
so for this terminal the mounting rail lock is released automatically and you can pull the terminal out of
the bus terminal block easily without excessive force.
2. Grasp the released terminal with thumb and index finger simultaneous at the upper and lower grooved
housing surfaces and pull the terminal out of the bus terminal block.
Connections within a bus terminal block
The electric connections between the Bus Coupler and the Bus Terminals are automatically realized by
joining the components:
• The six spring contacts of the K-Bus/E-Bus deal with the transfer of the data and the supply of the Bus
Terminal electronics.
• The power contacts deal with the supply for the field electronics and thus represent a supply rail within
the bus terminal block. The power contacts are supplied via terminals on the Bus Coupler (up to 24V)
or for higher voltages via power feed terminals.
Power Contacts
During the design of a bus terminal block, the pin assignment of the individual Bus Terminals must
be taken account of, since some types (e.g. analog Bus Terminals or digital 4-channel Bus Termi-
nals) do not or not fully loop through the power contacts. Power Feed Terminals (KL91xx, KL92xx
or EL91xx, EL92xx) interrupt the power contacts and thus represent the start of a new supply rail.
PE power contact
The power contact labeled PE can be used as a protective earth. For safety reasons this contact mates first
when plugging together, and can ground short-circuit currents of up to 125A.

Mounting and wiring
KL2791/KS2791 15Version: 2.2.0
Fig.7: Power contact on left side
NOTE
Possible damage of the device
Note that, for reasons of electromagnetic compatibility, the PE contacts are capacitatively coupled to the
mounting rail. This may lead to incorrect results during insulation testing or to damage on the terminal (e.g.
disruptive discharge to the PE line during insulation testing of a consumer with a nominal voltage of 230V).
For insulation testing, disconnect the PE supply line at the Bus Coupler or the Power Feed Terminal! In or-
der to decouple further feed points for testing, these Power Feed Terminals can be released and pulled at
least 10mm from the group of terminals.
WARNING
Risk of electric shock!
The PE power contact must not be used for other potentials!
3.3 Disposal
Products marked with a crossed-out wheeled bin shall not be discarded
with the normal waste stream. The device is considered as waste
electrical and electronic equipment. The national regulations for the
disposal of waste electrical and electronic equipment must be observed.

Mounting and wiring
KL2791/KS279116 Version: 2.2.0
3.4 Connection
3.4.1 Connection system
WARNING
Risk of electric shock and damage of device!
Bring the bus terminal system into a safe, powered down state before starting installation, disassembly or
wiring of the bus terminals!
Overview
The bus terminal system offers different connection options for optimum adaptation to the respective
application:
• The terminals of ELxxxx and KLxxxx series with standard wiring include electronics and connection
level in a single enclosure.
• The terminals of ESxxxx and KSxxxx series feature a pluggable connection level and enable steady
wiring while replacing.
• The High Density Terminals (HD Terminals) include electronics and connection level in a single
enclosure and have advanced packaging density.
Standard wiring (ELxxxx / KLxxxx)
Fig.8: Standard wiring
The terminals of ELxxxx and KLxxxx series have been tried and tested for years.
They feature integrated screwless spring force technology for fast and simple assembly.
Pluggable wiring (ESxxxx / KSxxxx)
Fig.9: Pluggable wiring
The terminals of ESxxxx and KSxxxx series feature a pluggable connection level.
The assembly and wiring procedure is the same as for the ELxxxx and KLxxxx series.
The pluggable connection level enables the complete wiring to be removed as a plug connector from the top
of the housing for servicing.
The lower section can be removed from the terminal block by pulling the unlocking tab.
Insert the new component and plug in the connector with the wiring. This reduces the installation time and
eliminates the risk of wires being mixed up.
The familiar dimensions of the terminal only had to be changed slightly. The new connector adds about 3
mm. The maximum height of the terminal remains unchanged.

Mounting and wiring
KL2791/KS2791 17Version: 2.2.0
A tab for strain relief of the cable simplifies assembly in many applications and prevents tangling of individual
connection wires when the connector is removed.
Conductor cross sections between 0.08mm2 and 2.5mm2 can continue to be used with the proven spring
force technology.
The overview and nomenclature of the product names for ESxxxx and KSxxxx series has been retained as
known from ELxxxx and KLxxxx series.
High Density Terminals (HD Terminals)
Fig.10: High Density Terminals
The terminals from these series with 16 terminal points are distinguished by a particularly compact design,
as the packaging density is twice as large as that of the standard 12mm bus terminals. Massive conductors
and conductors with a wire end sleeve can be inserted directly into the spring loaded terminal point without
tools.
Wiring HD Terminals
The High Density Terminals of the ELx8xx and KLx8xx series doesn't support pluggable wiring.
Ultrasonically “bonded” (ultrasonically welded) conductors
Ultrasonically “bonded” conductors
It is also possible to connect the Standard and High Density Terminals with ultrasonically “bonded”
(ultrasonically welded) conductors. In this case, please note the tables concerning the wire-size
width [}18]!
3.4.2 Wiring
WARNING
Risk of electric shock and damage of device!
Bring the bus terminal system into a safe, powered down state before starting installation, disassembly or
wiring of the bus terminals!

Mounting and wiring
KL2791/KS279118 Version: 2.2.0
Terminals for standard wiring ELxxxx/KLxxxx and for pluggable wiring ESxxxx/KSxxxx
Fig.11: Connecting a cable on a terminal point
Up to eight terminal points enable the connection of solid or finely stranded cables to the bus terminal. The
terminal points are implemented in spring force technology. Connect the cables as follows:
1. Open a terminal point by pushing a screwdriver straight against the stop into the square opening
above the terminal point. Do not turn the screwdriver or move it alternately (don't toggle).
2. The wire can now be inserted into the round terminal opening without any force.
3. The terminal point closes automatically when the pressure is released, holding the wire securely and
permanently.
See the following table for the suitable wire size width.
Terminal housing ELxxxx, KLxxxx ESxxxx, KSxxxx
Wire size width (single core wires) 0.08 ... 2.5mm20.08 ... 2.5mm2
Wire size width (fine-wire conductors) 0.08 ... 2.5mm20.08 ... 2.5mm2
Wire size width (conductors with a wire end sleeve) 0.14 ... 1.5mm20.14 ... 1.5mm2
Wire stripping length 8 ... 9mm 9 ... 10mm
High Density Terminals (HD Terminals [}17]) with 16 terminal points
The conductors of the HD Terminals are connected without tools for single-wire conductors using the direct
plug-in technique, i.e. after stripping the wire is simply plugged into the terminal point. The cables are
released, as usual, using the contact release with the aid of a screwdriver. See the following table for the
suitable wire size width.
Terminal housing High Density Housing
Wire size width (single core wires) 0.08 ... 1.5mm2
Wire size width (fine-wire conductors) 0.25 ... 1.5mm2
Wire size width (conductors with a wire end sleeve) 0.14 ... 0.75mm2
Wire size width (ultrasonically “bonded" conductors) only 1.5mm2 (see notice [}17])
Wire stripping length 8 ... 9mm

Mounting and wiring
KL2791/KS2791 19Version: 2.2.0
3.4.3 Contact assignment
WARNING
Risk of injury through electric shock and damage to the device!
Bring the Bus Terminals system into a safe, de-energized state before starting mounting, disassembly or
wiring of the Bus Terminals!
Fig.12: Contact assignment
Terminal point No. KL2791, connection for KL2791-0011, connection for
Output 1 Load (internally connected with terminal point 5) Load (internally connected with
terminal point 5)
L1 2 Phase (internally connected with terminal point 6
and power contact for L1)
Phase (internally connected with
terminal point 6)
N 3 Neutral conductor (internally connected with
terminal point 7 and power contact for N)
Neutral conductor (internally
connected with terminal point 7)
PE 4 Protective conductor (internally connected with
terminal point 8 and power contact for PE)
Protective conductor (internally
connected with terminal point 8)
Output 5 Load (internally connected with terminal point 1) Load (internally connected with
terminal point 1)
L1 6 Phase (internally connected with terminal point 2
and power contact for L1)
Phase (internally connected with
terminal point 2)
N 7 Neutral conductor (internally connected with
terminal point 3 and power contact for N)
Neutral conductor (internally
connected with terminal point 3)
PE 8 Protective conductor (internally connected with
terminal point 4 and power contact for PE)
Protective conductor (internally
connected with terminal point 4)

Mounting and wiring
KL2791/KS279120 Version: 2.2.0
Power feed terminal
A power feed terminal can supply several speed controller terminals.
NOTE
The mains voltage should only be supplied via a power feed terminal that is suitable for
230VAC/120VAC!
To supply the mains voltage (230VAC/120VAC) for the power contacts, it is essential to use a power feed
terminal that is designed for 230VAC/120VAC (e.g.:KL9150, KL9160, KL9250, KL9260)!
Bus Couplers, Bus Terminal controllers and power feed terminals for 24V are not suitable for the supply of
mains voltage into the power contacts!
They are specifically designed for voltages up to 24V and would be destroyed if 230VAC/120VAC was ap-
plied to their power contacts!
Separation terminal
If 24V and 230VAC/120VAC are to be used on the power contacts in a Bus Terminal block, the
KL9080 separation terminal can be used in order to clearly separate the potential blocks visually
from each other.
Short-circuit limitation
The speed controller terminals feature short-circuit limitation. The current is limited to approx. 10 to 15A.
Normally triggering of the fuse is therefore prevented.
The short circuit current flows for less than 0.5ms and is switched on automatically. After a short circuit was
detected the KL2791 tries to switch the system on again and tests the line with a low voltage. Once the short
circuit has been rectified, the speed controller terminal returns to the previous control value.
Short circuits on the line should always be avoided and never be induced deliberately! The short circuit puts
the components in the speed controller terminal under stress. A high number of short circuits reduces the
service life of the speed controller terminal!
Fuses
The speed controller terminal can be protected with fuses up to 10A.
The speed controller terminal protects itself from damage due to short circuit or overload. This built-in
protection is triggered in the event of a short circuit on the connecting line between the speed controller
terminal and the load.
NOTE
Use overload protection!
However, overload protection must still be provided. The fine-wire fuse often used in devices with trans-
formers must not be bridged or changed in its value. This could lead to overheating of the transformer.
3.5 Notes on operation
Intended use
Mains supply
The KL2791 speed controller terminal is designed for direct mains operation (230VAC/120VAC) without up-
circuit transformer.
NOTE
No upstream transformers!
Excessive inductances in the supply line for the speed controller terminal lead to destruction of the speed
controller terminal in the event of a short circuit!
Automatic load detection does not operate reliably with an upstream transformer.