Burster 8631 User manual

OPERATION MANUAL
Precision torque sensor
Model 8631
Manufacturer:
© 2023
burster
präzisionsmesstechnik gmbh & co kg
burster
präzisionsmesstechnik gmbh & co kg
All rights reserved
Talstrasse 1 - 5
Postfach 1432
76593 Gernsbach
Germany
76593 Gernsbach
Germany
Valid from:
June 14, 2023
Tel.: [phone]
Fax: [phone]
Email: [e-mail]
www.burster.de
4402-BA8631EN-5999-061529

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Warranty disclaimer
All information in the present documentation was prepared and compiled with great care and reproduced
in accordance with effective control measures. This documentation may contain errors, and the
information it contains and the corresponding technical data are subject to change without notice.
Reproduction of any part of this documentation or its processing or revision using electronic systems is
prohibited without the manufacturer’s prior written approval.
Components, devices and measurement sensors made by burster präzisionsmesstechnik (hereinafter
referred to as the “product”) are the result of targeted development and meticulous research. From the
date of delivery, burster provides a warranty for the proper condition and functioning of these products
covering material and production defects for the period specified in the warranty document accompanying
the product. However, burster waives any guarantee or warranty obligations or any additional liability for
consequential damages caused by improper use of the product, in particular the implied guarantee of
success in the market as well as the suitability of the product for a particular purpose. Furthermore,
burster assumes no liability for direct, indirect or incidental damages or for consequential or other
damages arising from the provision and use of the present documentation.
Trademark information
Intel Pentium® is a registered trademark of Intel Corporation. Windows®, Excel® are registered
trademarks or trademarks of Microsoft Corporation in the United States and/or other countries. All brand
or product names mentioned in this document are trademarks or registered trademarks of their respective
trademark owners. By mentioning these trademarks, burster präzisionsmesstechnik gmbh & co kg is not
laying claim to trademarks other than its own.

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Contents
1. For your safety........................................................................................................................ 6
1.1 Symbols used in the operation manual ........................................................................... 6
1.1.1 Signal words.......................................................................................................... 6
1.1.2 Pictograms ............................................................................................................ 6
1.2 General safety instructions .............................................................................................. 7
2. Introduction............................................................................................................................. 8
2.1 Intended use .................................................................................................................... 8
2.2 Customer service............................................................................................................. 8
2.2.1 Customer service department............................................................................... 8
2.2.2 Contact person...................................................................................................... 8
2.3 Ambient conditions .......................................................................................................... 9
2.3.1 Storage.................................................................................................................. 9
2.3.2 Cleaning ................................................................................................................ 9
2.4 Personnel......................................................................................................................... 9
2.5 Contents of pack .............................................................................................................. 10
2.6 Unpacking ........................................................................................................................ 10
2.7 Warranty .......................................................................................................................... 10
2.8 Modifications and maintenance ....................................................................................... 11
3. Device design and general information ............................................................................... 12
3.1 Definitions ........................................................................................................................ 12
3.2 Mechanical design ........................................................................................................... 12
3.3 Electrical design............................................................................................................... 12
3.3.1 8631 torque sensor with bridge output ................................................................. 13
3.3.2 8631 torque sensor with amplifier ......................................................................... 15
3.4 Static and quasi-static torques......................................................................................... 16
3.5 Dynamic torques .............................................................................................................. 17
3.6 Interference...................................................................................................................... 18
3.7 Troubleshooting table ...................................................................................................... 18
4. Installation............................................................................................................................... 20
4.1 Mechanical installation..................................................................................................... 20
4.1.1 Preparing for alignment and fitting ........................................................................ 21
4.1.2 Installation options ................................................................................................ 22
4.2 Electrical connection ........................................................................................................ 22
4.2.1 Power supply......................................................................................................... 22
4.2.2 Pin-out of the electrical socket .............................................................................. 23
4.2.3 Pin-out of the USB connector ............................................................................... 23
4.2.4 Power supply for the 8631 torque sensor fitted with USB .................................... 24
4.2.5 Power supply for the 8631 torque sensor with built-in electronics via the circular
connector .............................................................................................................. 24
4.2.6 Power supply for the 8631 torque sensor without built-in electronics................... 24
4.2.7 Cable..................................................................................................................... 24
4.2.8 Connecting the shield ........................................................................................... 25

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4.2.9 Running cables ..................................................................................................... 25
4.3 Measurement operation................................................................................................... 27
4.3.1 Switching on.......................................................................................................... 27
4.3.2 The torque direction .............................................................................................. 27
4.3.3 Check function (for 8631 with instrumentation amplifier) ..................................... 28
4.3.4 Dual-range sensor ................................................................................................ 28
5. Calibration and adjustment................................................................................................... 29
5.1 Factory calibration ........................................................................................................... 29
5.2 Calibration certificate with accreditation symbol.............................................................. 29
5.3 Recalibration.................................................................................................................... 29
6. Taking out of use.................................................................................................................... 30
7. Technical data ........................................................................................................................ 31
7.1 Electromagnetic compatibility .......................................................................................... 31
8. Accessories available ............................................................................................................ 31
9. Disposal................................................................................................................................... 32

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1. For your safety
The following symbols are used in this operation manual to warn of hazards.
1.1 Symbols used in the operation manual
1.1.1 Signal words
The following signal words are used in the operation manual according to the specified hazard
classification.
DANGER
High degree of risk: indicates a hazardous situation which, if not avoided, will result in death or
serious injury.
WARNING
Moderate degree of risk: indicates a hazardous situation which, if not avoided, may result in death or
serious injury.
CAUTION
Low degree of risk: indicates a hazardous situation which, if not avoided, could result in minor or
moderate injury.
NOTICE
Property damage to the equipment or the surroundings will result if the hazard is not avoided.
Note: It is important to heed these safety notices in order to ensure you handle the model 8631 torque
sensor correctly.
IMPORTANT: Follow the information given in the operating manual.
1.1.2 Pictograms
Electric shock hazard.
Observe the advice for protecting the model 8631 torque sensor.

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1.2 General safety instructions
The model 8631 torque sensor is state of the art, and is safe to operate. However, if the 8631 torque
sensor is not used or operated as intended, it may present a hazard.
DANGER
Electric shock hazard!
The following instructions must be followed to prevent electric shock and
injuries:
•In order to achieve high measuring sensitivity, the model 8631 torque sensor
was not designed with the usual safety factors (2 … 20) for machine designs.
For applicable overload factors, see the data sheet.
•Observe accident prevention regulations, including for accessories used.
•Use the model 8631 torque sensor only in non-safety-critical applications.
•The 8631 torque sensor must not be used for medical purposes.
•Only use the model 8631 torque sensor outside of potentially explosive areas
(Ex protected areas).
NOTICE
The following points must be observed to prevent injuries and damage to
property:
•The limits for permissible mechanical, thermal and electrical loads are shown in the
data sheet. These limits must not be exceeded. Take these limits into account when
planning the measuring arrangement, and during installation (preferably with the
display for the torque connected) and operation.
•Impacts and shocks may damage the model 8631 torque sensor (e.g. if it is
dropped). Exercise due care when handling and fitting the 8631 torque sensor.
•Torque peaks in excess of the permissible overload may destroy the torsion shaft.
Make sure that such peaks do not occur, or ensure that they are absorbed.
•Avoid excessive torques, bending moments or axial loads.
•Support the model 8631 torque sensor while it is being fitted.
•When measuring dynamic torques, operating the 8631 torque sensor close to its
natural resonance will result in permanent damage. The frequency of dynamic
torques must lie below the resonant frequency of the mechanical structure.
•Limit the peak-to-peak variation of dynamic torques to 70 % of the rated torque.

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2. Introduction
IMPORTANT: Read the operation manual carefully before using the equipment, and keep it for future
reference.
2.1 Intended use
The model 8631 torque sensor measures static and dynamic torques. This measured quantity is suitable
for open-loop and closed-loop control functions. The respective upper range value is shown on the type
plate.
Both the low mass of the model 8631 torque sensor and its high torsional rigidity are an advantage when
measuring dynamic torques. However, you need to pay attention to the spring constant and the cut-off
frequency of the model 8631 torque sensor with such measurements. You can find both of these in the
data sheet. For more information on estimating the resonant frequency and measuring dynamic torques,
see section 3.5 Dynamic torques on page 17.
The model 8631 torque sensor is maintenance-free. The electrical measurement signals can be
transmitted to a remote higher-level electronic system, where they can be displayed, recorded, processed
and used for control and regulation tasks.
Use the model 8631 torque sensor only for measuring torque.
Do not use the 8631 torque sensor in safety-critical applications or for medical purposes.
The model 8631 torque sensor is not intended for use as a safety device.
2.2 Customer service
2.2.1 Customer service department
For repair inquiries, please call our customer service department on [phone].
Please have the serial number to hand. The serial number is the only way to clearly identify the technical
version of the instrument so that we can provide help quickly. You will find the serial number on the type
plate of the model 8631 torque sensor.
2.2.2 Contact person
If you have any questions relating to the model 8631 torque sensor, please contact your representative or
go directly to burster präzisionsmesstechnik gmbh & co. kg.
Head office
burster präzisionsmesstechnik
gmbh & co kg
Talstrasse 1 - 5
76593 Gernsbach
Germany
Phone: [phone]
Fax: [phone]
Email: [e-mail]

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2.3 Ambient conditions
•Avoid radiant heat or cooling from one side.
•Protect the 8631 torque sensor from moisture.
•The 8631 torque sensor is not resistant to chemical agents. Do not use the sensor in a
corrosive environment.
•Keep the bearings and connectors free of dust, dirt and other foreign matter.
2.3.1 Storage
Use clean packaging to package the model 8631 torque sensor. The 8631 torque sensor must be stored
under the following conditions:
•Dry atmosphere
•No condensation
•No dust
•Temperature between 0 °C and 60 °C.
2.3.2 Cleaning
NOTICE
Do not immerse the 8631 torque sensor in water or hold it under running water. Do not
use strong cleaning agents as these may damage the 8631 torque sensor. Clean the
model 8631 torque sensor using a dry cloth.
Ensure that the shaft and mating parts are completely clean and have no traces of
lubricants at the time of fitting. Use a solvent such as acetone to clean the shafts before
fitting. Make sure there is no foreign matter on the shafts at fitting.
2.4 Personnel
Personnel must be familiar with the relevant regulations. They must follow these regulations. Only trained
personnel who are familiar with the applicable safety regulations are permitted to operate the model 8631
torque sensor.

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2.5 Contents of pack
•Torque sensor model 8631
•Mating connector
•Digital operation manual on our website (www.burster.com)
•Digital data sheet on our website (www.burster.com)
•Optional: USB cable
2.6 Unpacking
DANGER
Electric shock hazard!
Never connect up the 8631 torque sensor if the sensor shows signs of damage
incurred in transit. Only ever use the 8631 torque sensor under the conditions
specified in this operation manual.
Inspect the model 8631 torque sensor for damage. If you suspect that the unit has been damaged during
shipping, notify the delivery company within 72 hours.
The packaging should be retained by a representative of the manufacturer and/or the delivery company.
The model 8631 torque sensor should be shipped only in its original packaging or in packaging capable of
providing an equivalent degree of protection. The model 8631 torque sensor must be held securely
(immovable) in its packaging.
2.7 Warranty
burster präzisionsmesstechnik gmbh & co kg provides a manufacturer’s warranty for a period of 24
months after delivery.
Any repairs required during this time will be made without charge. This does not include damage arising
from improper use.
Please note the following when sending the model 8631 torque sensor in for repair:
•If there is a problem with the sensor, please describe the fault in as much detail as
possible.
•Technical specifications subject to change at any time without notice.
We also state explicitly that we do not accept liability for consequential damage.
•The instrument must always be dispatched in suitable packaging.

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2.8 Modifications and maintenance
Note: The warranty shall be deemed void immediately if you open or dismantle the model 8631
torque sensor during the warranty period.
The model 8631 torque sensor does not contain any parts that are intended to be serviced by the user.
Only the manufacturer’s own qualified personnel are permitted to open the model 8631 torque sensor.
It is not permitted to make any changes to the model 8631 torque sensor without the written agreement of
burster präzisionsmesstechnik gmbh & co kg. burster präzisionsmesstechnik gmbh & co kg does not
accept liability for damages or injury if this condition is disregarded.
Our recommendations
•Check cables and connectors annually.
•It is up to you as the user to determine the recalibration interval. We recommend that you
check the 8631 torque sensor after no longer than 12 months. You can find further
information in section 5 Calibration and adjustment on page 29.
Maintenance schedule
Action Frequency Date Date Date
Check cable and connector 1x annually
Calibration < 26 months
Check the attachment (flanges
and shafts) 1x annually
Check the sensor < 12 months

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3. Device design and general information
The figures given for the full dimensions, mass and power depend on the version of the 8631 torque
sensor. Please refer to the data sheet for specific figures.
3.1 Definitions
Test side
The test side is the mechanical connection of the model 8631 torque sensor in which the torque to be
measured is induced.
This end has the smaller moment of inertia.
On the model 8631 torque sensor, the test side is marked “TEST SIDE” on the shaft hub.
Figure 1: Test side, model 8631 torque sensor
Drive side
The drive side is the opposite side to the test side, and the housing is mounted via this side. The model
8631 torque sensor is also mechanically connected on this side.
3.2 Mechanical design
The 8631 torque sensor does not contain any rotating parts. The shaft is joined directly to the housing on
the drive side. Strain gages are mounted on the shaft, which acts as the torsion bar in the 8631 torque
sensor. The torque is applied to the shaft end labeled “TEST SIDE”. The housing provides protection for
the sensitive measurement electronics.
Figure 2: Basic design of the 8631 torque sensor
3.3 Electrical design

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DANGER
Electric shock hazard!
Because of size constraints, the supply voltage, output voltage and USB socket are
not galvanically isolated. This means that the device has common digital and analog
grounds, which are connected to the housing.
Thanks to its modular design, the 8631 strain-gage torque sensor can be configured exactly to suit the
application required:
•mV/V with standardized output signal
•mV/V with non-standardized output signal and burster TEDS
•±10 V output signal, configuration via USB
•±10 V output signal, configuration and measurement via USB
With the built-in amplifier option, the 8631 torque sensor outputs directly a torque-proportional voltage of
0 ... ±10 V. The Micro USB port can be used to configure the 8631 torque sensor. For instance it is
possible to set a filter frequency, configure averaging and set a tare function. With the USB option, in
addition to the voltage output, the measurement function is available via USB as well. The sensor comes
with the DigiVision PC software for performing measurements and data archiving, and drivers for
DASYLAB and LabVIEW are available. Integration into custom software is possible via DLL. The burster
TEDS option (Transducer Electronic Data Sheet; a memory chip containing sensor-specific data and
characteristics) allows rapid configuration of compatible evaluation units (instrumentation amplifiers,
indicators/meters, process controllers etc.)
3.3.1 8631 torque sensor with bridge output
The 8631 torque sensor with bridge output has a 7-pin circular connector. This connector is used to
supply the sensor with its required rated excitation voltage and to output the measurement signal in
mV/V. The supply voltage must be kept absolutely constant. Conventional power supplies cannot
guarantee this consistency to an adequate degree. Use an instrumentation amplifier, indicator or process
controller that can provide a stabilized supply voltage and processes the mV/V signal.
Torque sensor model 8631-XXXX-VXX3X0
The model 8631-XXXX-VXX3X0 torque sensor provides a standardized output signal, i.e. all model 8631-
XXXX-VXX3X0 torque sensors provide the same rated output for each measuring range. Each measuring
range has a different rated output, however.
Torque sensor model 8631-XXXX-VXX4X0
The 8631-XXXX-VXX4X0 torque sensor provides all the functions of the 8631-XXXX-VXX3X0 torque
sensor plus an internal burster TEDS chip. The burster TEDS chip stores all the characteristic data for the
8631-XXXX-VXX4X0 torque sensor, the model name and serial number. This ensures Plug&Play
capability of the 8631-XXXX-VXX4X0 torque sensor with suitable indicating instruments such as the
TRANS CAL 7281 and DIGIFORCE®9311 or DIGIFORCE®9307, dispensing with the time-consuming
task of configuration.

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Schematic diagram
Figure 3: Model 8631-XXXX-VXX3X0 output mV/V
Model 8631-XXXX-VXX4X0 output mV/V and TEDS
The housing of the 8631 torque sensor must be grounded.

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3.3.2 8631 torque sensor with amplifier
The 8631 torque sensor with built-in amplifier has two connectors, offering alternative options for
operation:
1. 7-pin circular connector, and
2. Micro USB socket
Schematic diagram
Figure 4: Model 8631-XXXX-VXX0X0 output 0 ... ±10 V incl. configure via USB
Model 8631-XXXX-VXX1X0 output 0 ... ±10 V incl. configure/measure via USB
Note: Shield, - Excitation, - Signal and USB GND are connected to the housing.
IMPORTANT: The housing of the 8631 torque sensor must be grounded.
Torque sensor model 8631-XXXX-VXX0X0
The Micro USB socket on the 8631-XXXX-VXX0X0 torque sensor is used for configuring the 8631-XXXX-
VXX0X0 torque sensor, or specifically its analog output. Disconnect the plug from the circular connector
while configuration is in progress to prevent ground loops. The 8631-XXXX-VXX0X0 torque sensor is
supplied with power via the USB cable in this operating mode.
The following options can be configured:
a) The averaging function
You can set here the number of individual measured values to be used to form an arithmetic mean. The
value can be set in the range N = 1 to N = 50 000. When N = 1, averaging is not performed. In this case,
the voltage value at the output is refreshed every 10 µs. This corresponds to 10 000 digitizations per
second.
So if you select N = 50 000, for example, then a measuring time of 5 seconds is needed for a new voltage
value at the output (50 000 x 10 µs = 5 s). Disable the low-pass filter if you set a value N ≠ 1.
b) The low-pass filter
The low-pass filter is a digital filter designed as a first-order low-pass filter.
Apart from the “OFF” setting, you can select various cut-off frequencies:
•OFF
•5 Hz
•10 Hz
•25 Hz

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•50 Hz
•100 Hz
•200 Hz
•400 Hz
•1 kHz
Set the averaging value to N = 1 if you select a cut-off frequency ≠ OFF.
The cut-off frequency is the frequency at which the output signal is attenuated by -3 dB, corresponding to
about 70.7 % of the signal at very low frequencies.
Factory settings
•Averaging: N = 100
•Low-pass filter: OFF
Programming instructions
The dedicated interface manual (Precision torque sensor model 8631 – Interfaces manual) available at
www.burster.com contains precise details of the programming instructions. When using the DigiVision PC
software, you can configure the sensor via the user interface.
Version 8631-XXXX-VXX1X0
The model 8631-XXXX-VXX1X0 torque sensor provides all the functions of the 8631-XXXX-VXX0X0 plus
the option to read the measured values via the USB port. When using the DigiVision PC software, you
can configure the sensor and display and record the measured values via the user interface. You can use
the DigiVision Light version free of charge and download it via the download area on our website
www.burster.com. You can find more information about the DigiVision software and its use in the
accompanying operation manual (https://bit.ly/3Ls86wO).
NOTICE
•Choose to use either the circular socket or the USB socket, but not both, to avoid
ground loops.
•Choose between the voltage output or USB for measurement readings. Doing both at
once is not possible.
3.4 Static and quasi-static torques
Static and quasi-static torques change their value only slowly or not at all. As long as they are below the
rated torque, these torques can take any value.

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3.5 Dynamic torques
A dynamic torque changes very rapidly and can even oscillate. In this case the frequency of the torque
must remain well below the resonant frequency of the mechanical structure as a whole.
NOTICE
Resonance hazard
Operating the 8631 torque sensor or the entire test setup close to its resonant frequency
will result in permanent damage. Keep the torque frequency well below the resonant
frequency of the mechanical test setup. Limit the peak-to-peak torque variation to 70 %
of the rated torque.
We recommend that you measure dynamic torques only if they do not exceed 70 % of the rated torque.
The characteristics of your signal analysis and control systems must be taken into account during
dynamic testing.
Estimating the mechanical resonant frequency
As a first approximation, the resonant frequency of the entire test setup depends on the spring constant
“c” of the model 8631 torque sensor and the moment of inertia “J” of the attached components.
Figure 5: Resonant frequency model
f
0
:
Resonant frequency in Hz
J:
Moment of inertia in kg
*
m2
c:
Spring constant in Nm / rad
Another method you can use to calculate resonant frequencies is the Holzer-Tolle method.

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3.6 Interference
Possible sources of interference:
•Temperature change
•Temperature gradient
•Vibration
•Spurious forces
•EMC
•Electrical interference
•Magnetic interference
•Angular, axial or radial shaft misalignment
IMPORTANT: Take suitable measures to counter these sources of interference because otherwise they
may cause an incorrect measurement result, e.g. provide covers or take measures to
isolate from vibration.
3.7 Troubleshooting table
This table contains the most common faults and errors with relevant corrective actions.
Fault Possible cause Remedial action
No signal
No power supply Connect supply
Outside permitted range Check supply
No mains supply Connect supply
Cable faulty Repair cable
Signal output not connected
correctly
Connect output correctly
Electronic evaluation circuit
faulty
Repair or replace
Sensor does not respond to
torque
Shaft not clamped Clamp correctly
No power supply Connect supply
No mains supply Connect supply
Outside permitted range Check supply
Cable faulty Repair cable
Plug not connected correctly Connect plug correctly
Signal drops out Cable faulty Repair cable
Zero point out of tolerance
Cable faulty Repair cable
Shaft under tension when fitted Fit correctly
Tension on shaft Release tension
Strong off-axis loads Reduce off-axis loads

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Shaft overloaded
Return the 8631 torque sensor
to the manufacturer
Torque reading incorrect
Calibration not correct Recalibrate
8631 torque sensor is faulty
Return to manufacturer for
repair
Torque bypass Remove bypass
Torque fluctuations
Vibrations Isolate from vibrations
Air movements Fit cover

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4. Installation
4.1 Mechanical installation
NOTICE
Avoid excessive torques, bending moments or axial loads.
Excessive torques, bending moments or axial loads may damage the 8631 torque
sensor.
•Connect the electrical cable to the 8631 torque sensor during fitting and monitor the
measurement signal. This signal must remain within the permitted range.
•Support the 8631 torque sensor during fitting to make sure it does not drop, and do
not resort to hammering to aid installation.
Make sure you fit the 8631 torque sensor the correct way round. The housing is fitted to the drive side of
the sensor. The side of the 8631 torque sensor to be used for measurement is labeled “TEST SIDE”:
Figure 6: Test side, model 8631 torque sensor
If you get the ends mixed up you must expect the following effects:
•The cable connection will affect the measurement.
•The inertial masses of the housing will affect the measurement.