LORENZ MESSTECHNIK DV-14 User manual
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 1 of 11
Operation Manual
for Torque Sensors
For below and similar Types
DV-14 DH-15 D-2431
DFW-25 DFW-35 D-2223 D-2268
D-2209 DF-30 D-2553
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 2 of 11
Imprint
Manufacturer, PlaceLorenz Messtechnik GmbH, D-73553 Alfdorf.
Valid for... Static Torque Sensors
Copyright © 2006 Lorenz Messtechnik GmbH, Alfdorf.
Reprint Interdiction Reprints, even in extracts, only with written authority.
Modification Technical changes reserved.
References in this Text
1.6 Warning Notes; Page 4
Attention must be paid to the accident prevention regulations of the trade associations.
During operation the safety precautions must be serviceable.
4 Mechanical Assembly; Page 6
Caution: During the assembly inadmissibly large forces may not act on the sensor or the
couplings. At small torques (< 20 N·m) connect the sensor electrically during the assembly
and observe the signal, the measurement signal may not exceed the limit values.
During the assembly, the sensor must be supported to protect it from falling down.
Caution at permutation of drive side and measuring side.
4.1 Sensors up to 15 N·m; Page 6
Sensors with nominal torques up to 15 N·m are very sensitive regarding overload;
therefore treat the sensors with great caution.
6.1 Engaging; Page 8
The warming-up period of the torque sensor is approx. 5 min.
6.4.2 Natural Resonance; Page 9
Operation of the device in natural resonance can lead to permanent damages.
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 3 of 11
Contents
1Read First.............................................................................................................................................. 4
1.1 Safety and Caution Symbols.......................................................................................................... 4
1.2 Intended Use.................................................................................................................................. 4
1.3 Dangers.......................................................................................................................................... 4
1.3.1 Neglecting of Safety Notes..................................................................................................... 4
1.3.2 Remaining Dangers................................................................................................................ 4
1.4 Reconstructions and Modifications................................................................................................ 4
1.5 Personnel....................................................................................................................................... 4
1.6 Warning Notes ............................................................................................................................... 4
2Term Definitions.................................................................................................................................... 5
2.1 Terms............................................................................................................................................. 5
2.2 Definition of the Pictograms on the Torque Sensor....................................................................... 5
3Product Description............................................................................................................................... 5
3.1 Mechanical Setup........................................................................................................................... 5
3.2 Electrical Setup.............................................................................................................................. 5
4Mechanical Assembly............................................................................................................................ 6
4.1 Sensors up to 15 N·m .................................................................................................................... 6
4.2 Flange Connection......................................................................................................................... 6
4.3 Shaft Connection............................................................................................................................ 6
4.4 Inside Square and Outside Square................................................................................................6
5Electrical Connection............................................................................................................................. 7
5.1 Pin Connection............................................................................................................................... 7
5.2 Free Cable Ends............................................................................................................................ 7
5.3 Cable.............................................................................................................................................. 7
5.4 Shielding Connection..................................................................................................................... 7
5.5 Extension Cable............................................................................................................................. 8
5.6 Running of Measuring Cables........................................................................................................ 8
6Measuring.............................................................................................................................................. 8
6.1 Engaging........................................................................................................................................ 8
6.2 Direction of Torque......................................................................................................................... 8
6.3 Static / Quasi-Static Torques......................................................................................................... 8
6.4 Dynamic Torques........................................................................................................................... 8
6.4.1 General................................................................................................................................... 8
6.4.2 Natural Resonances............................................................................................................... 9
6.5 Disturbance Variables.................................................................................................................... 9
6.6 Calibration Control (Option).......................................................................................................... 9
7Maintenance........................................................................................................................................ 10
7.1 Maintenance Schedule ................................................................................................................ 10
7.2 Trouble Shooting.......................................................................................................................... 10
8Decommission..................................................................................................................................... 10
9Transportation and Storage ................................................................................................................ 10
9.1 Transportation.............................................................................................................................. 10
9.2 Storage......................................................................................................................................... 11
10 Disposal........................................................................................................................................... 11
11 Calibration........................................................................................................................................ 11
11.1 Proprietary Calibration.............................................................................................................. 11
11.2 DKD-Calibration........................................................................................................................ 11
11.3 Re-Calibration........................................................................................................................... 11
12 Data Sheet....................................................................................................................................... 11
13 Literature.......................................................................................................................................... 11
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 4 of 11
1 Read First
1.1 Safety and Caution Symbols
Caution:
Injury Risk for Persons
Damage of the Device is possible
Note:
Important points to be considered
1.2 Intended Use
Torque sensors are intended for the measurement of torques. This measurand is further suitable for
control tasks. The valid safety regulations should be absolutely respected. The torque sensors are not
safety components in the sense of the intended use. The sensors need to be transported and stored
appropriately. The assembly, commissioning and disassembling must take place professionally.
1.3 Dangers
The torque sensor is fail-safe and corresponds to the state of technology.
1.3.1 Neglecting of Safety Notes
At inappropriate use, remaining dangers can emerge (e.g. by untrained personnel). The operation manual
must be read and understood by each person entrusted with the assembly, maintenance, repair,
operation and disassembly of the torque sensor.
1.3.2 Remaining Dangers
The plant designer, the supplier, as well as the operator must plan, realize and take responsibility for
safety-related interests for the sensor. Remaining dangers must be minimized. Remaining dangers of the
torque measurement technique must be pointed out.
1.4 Reconstructions and Modifications
Each modification of the sensors without our written approval excludes liability on our part.
1.5 Personnel
The installation, assembly, commissioning, operation and the disassembly must be carried out by
qualified personnel only. The personnel must have the knowledge and make use of the legal regulations
and safety instructions.
1.6 Warning Notes
Attention must be paid to the accident prevention regulations of the trade associations.
During operation the safety precautions must be serviceable.
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 5 of 11
Flange
Torsion Body
SG
2 Term Definitions
2.1 Terms
Measuring Side:
Shaft connection in which the torque to be measured is applied. Usually this side has the smallest
moment of inertia.
Drive Side:
The shaft end on the opposite side of the measuring side with the larger moment of inertia.
At static torque sensors the housing is fastened on this side.
Low Torque Resistance Side:
The shaft of the arrangement (drive, load) which can be turned considerably smaller with torque than the
nominal torque of the torque sensor M << Mnenn .
2.2 Definition of the Pictograms on the Torque Sensor
The measuring side of the torque sensor is designated as follows:
Measuring side:
or M
More information can be found on the data sheet if needed.
3 Product Description
The sensor measures static and dynamic torques. The mounting position of the torque sensor is
horizontally or vertically.
Caution: it is to be differentiated between measuring side and drive side, see data sheet of the sensor:
http://www.lorenz-sensors.com
3.1 Mechanical Setup
The sensors do not contain rotary parts.
They consist of a torsion body with different connection
possibilities (flanges, shafts, square, hexagonal etc.). The
torsion body, applied with strain gauges, is protected by a
housing. A plug or a cable connection is fixed at the housing.
3.2 Electrical Setup
The strain gauge full bridge is directly connected at the
plug or at the cable.
Optionally a calibration control can be integrated. For
this, the SG full bridge gets detuned by an external
switch in such a way, that at the output the measuring
signal, which is corresponding to the positive nominal
torque, can be measured.
R
k
R
1
R
2
R
4
R
3
Supply +
Control
Signal +
Signal -
Supply -
external switch
SG
Sensor External
Basic sketch of the strain gauge full bridge
with option calibration control
M
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 6 of 11
4 Mechanical Assembly
It is to be differentiated between measuring side and drive side of the sensor. The housing is fixed at the
drive side of the sensor.
• The cable connection can influence the torque measurement.
• At dynamic measurements, the measured value can be influenced by the inert masses of the
housing.
Measuring side – see corresponding data sheet.
4.1 Sensors up to 15 N·m
Sensors with nominal torques up to 15 N·m are very sensitive regarding overload; therefore
treat the sensors with great caution.
1. Connect the sensor electrically during the assembly and watch the signal; the measuring signal
may not exceed the limit values.
2. Align the arrangement before the parts are firmly connected.
3. Mount the sensor at the low torque resistance side first, then at the stationary side. (This
avoids impermissibly large torques from acting on the sensor.)
4. Counter-hold by hand, so that impermissibly large torques or disturbance variables can not act on
the torque sensor.
4.2 Flange Connection
Before the assembly, flanges must be cleaned with dissolver (e.g. acetone), no foreign particles may
adhere to them. The surface of the flange must indicate a evenness of at least 0.02 mm.
Tighten screws consistently. The flange may not slip while torque is applied (surface pressure), if
necessary use fitting bolts.
4.3 Shaft Connection
The shafts must be cleaned with dissolver (e.g. acetone) before the assembly, no foreign particles may
adhere to them.
The hub must fit corresponding to the connection.
4.4 Inside Square and Outside Square
The inside and outside square must be cleaned before the assembly. No foreign particles may adhere to
them.
Caution: During the assembly inadmissibly large forces may not act on the sensor or the
couplings. At small torques (< 20 N·m) connect the sensor electrically during the assembly and
observe the signal, the measurement signal may not exceed the limit values
During the assembly the sensor must be supported to protect it from falling down.
Caution at permutation of drive side and measuring side.
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 7 of 11
5 Electrical Connection
5.1 Pin Connection
6-pin Function
1 SG- excitation -
2 SG- excitation +
3 Shield
4 SG- signal +
5 SG- signal -
6 100% calibration
control
7-pin Function
1 SG- excitation -
2 SG- excitation +
3 Shield
4 SG- signal +
5 SG- signal -
6 100% calibration
control
7 -
View: socket on soldering side
5.2 Free Cable Ends
Wire Function
green Excitation (-)
brown Excitation (+)
yellow Signal (+)
white Signal (-)
grey Control
netting Shield
5.3 Cable
Only use a shielded cable with preferably small capacity. We recommend measuring cables from our
product range. They have been tested in combination with our sensors and meet the metrological
requirements.
5.4 Shielding Connection
In combination with the sensor and the external electronics, the shield forms a Faraday Cage. By this,
electro-magnetic disturbances do not have any influence on the measurement signal.
At potential difference problems we recommend to ground the sensor.
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 8 of 11
5.5 Extension Cable
Caution: depending on bridge resistance and wire cross section, the measuring cable length enters into
the characteristic value of the sensor. Therefore order the sensor together with the extension cable and
the calibration at Lorenz Messtechnik GmbH.
Dependence of the characteristic value on the cable length:
Wire-cross
section Cable resistance
per m
Deviation per m
cable length at
bridge resistance
350 Ω
Deviation per m
cable length at
bridge resistance
700 Ω
Deviation per m
cable length at
bridge resistance
1000 Ω
0,14 mm² 0,28 Ω0,08% 0,04% 0,028%
0,25 mm² 0,16 Ω0,046% 0,023% 0,016%
0,34 mm² 0,12 Ω0,034% 0,017% 0,012%
Cable resistance = 2 x resistance of the cable length (both feed lines of the sensor).
The sensors with the ordered cable length are calibrated at Lorenz Messtechnik GmbH. Therefore the
cable length does not need to be considered in this case.
5.6 Running of Measuring Cables
Do not run measuring cables together with control or heavy-current cables. Always assure that a large
distance is kept to engines, transformers and contactors, because their stray fields can lead to
interferences of the measuring signals.
If troubles occur through the measuring cable, we recommend to run the cable in a grounded steel
conduit.
6 Measuring
6.1 Engaging
The warming-up period of the torque sensor is approx. 5 min. Afterwards the measurement can be
started.
The warming-up period of the torque sensor is approx. 5 min.
6.2 Direction of Torque
Torque means clockwise or clockwise torque if the torque acts clockwise when facing the shaft end. In
this case a positive electrical signal is obtained at the output.
Torque sensors by Lorenz Messtechnik GmbH can measure both, clockwise and counter-clockwise
direction.
6.3 Static / Quasi-Static Torques
Static and/or quasi-static torque is a slowly changing torque.
The calibration of the sensors occurs statically on a calibration device.
The applied torque may accept any value up to the nominal torque.
6.4 Dynamic Torques
6.4.1 General
The static calibration procedure of torque sensors is also valid for dynamic applications.
Note: The frequency of torques must be smaller than the natural frequency of the mechanical
measurement setup.
The band width must be limited to 70 % of the nominal torque.
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 9 of 11
6.4.2 Natural Resonances
Estimate of the mechanical natural frequencies:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛+⋅⋅
⋅
=
21
011
21JJ
cf
π
f0
J1, J2
c
= Natural frequency in Hz
= Moment of inertia in kg*m²
= Torsional rigidity in Nm/rad
Further methods for the calculation of natural resonances are corresponding purchasable programs or
books (e.g. Holzer-Procedure, Dubbel, Taschenbuch für den Maschinenbau, Springer Verlag)
Operation of the device in natural resonance can lead to permanent damages.
6.5 Disturbance Variables
By disturbances, measured value falsifications can occur by
• Vibrations,
• Temperature gradients in the torque sensor,
• Temperature changes,
• Electrical disturbances,
• Magnetic disturbances,
• EMC (electromagnetic disturbances),
Therefore avoid these disturbance variables by decoupling of vibrations, covers, etc.
6.6 Calibration Control (Option)
By a control resistance, a signal is generated in the
sensor which corresponds to the nominal value of
the sensor.
Advantage:
Re-Calibrations are reduced. Before each
measurement the zero point and the nominal value
can be checked.
Function:
By applying positive SG supply, the measuring
bridge is electrically detuned, so that at the output a
measuring signal of 100% of the nominal value is
available.
Optionally 50%, 80% possible.
Use calibration control at unloaded torque sensor, only.
c
J1J2
R
k
R
1
R
2
R
4
R
3
Supply +
Control
Signal +
Signal -
Supply -
external switch
SG
Sensor External
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 10 of 11
7 Maintenance
7.1 Maintenance Schedule
Action Frequency Date Date Date
Control of cables and connectors 1x p.a.
Calibration < 26 months
Control of fixation (flanges, shafts) 1x p.a.
7.2 Trouble Shooting
This chart is used for searching for the most frequent errors and their elimination.
Problem Possible Cause Trouble Shooting
No signal No sensor excitation • Outside of permissible range
• Connect excitation
• Cable defect
• No mains supply
Signal output connected wrong • Connect output correctly
• Evaluation electronics defect
Sensor does not react to
torque Shaft not clamped • Clamp correctly
No power supply • Outside of permissible range
• Connect supply
• Cable defect
• No mains supply
Cable defect
• Repair cable
Connector connected wrong • Connect correctly
Signal has dropouts Cable defect • Repair cable
Zero point outside of tolerance Cable defect • Repair cable
Shaft mounted distorted • Mount correctly
Distorted shaft string • Release from distortion
Strong lateral forces • Reduce lateral forces
Shaft overloaded
• Send to manufacturer
Wrong torque indication Calibration not correct • Re-calibrate
Sensor defect
• Repair by manufacturer
Torque shunt
• Eliminate shunt
8 Decommission
• All sensors must be dismantled professionally.
• Do not strike sensor housings with tools.
• Do not apply bending moments on the sensor, e.g. through levers.
• The torque sensor must be supported to avoid falling down during the dismantling.
9 Transportation and Storage
The transportation of the sensors must occur in suitable packing.
For smaller sensors, stable cartons which are well padded are sufficient (e.g., air cushion film, epoxy
crisps, paper shavings). The sensor should be tidily packed into film.
Larger sensors should be packed in cases.
9.1 Transportation
Only release well packed sensors for transportation. The sensor should not be able to move back and
forth in the packing. The sensors must be protected from moisture.
Only use suitable means of transportation.
LORENZ MESSTECHNIK GmbH Obere Schloßstr.131
73553 Alfdorf 07172 / 93730-0
Fax 07172 /93730-22
Internet: www.lorenz-sensors.com Page 11 of 11
9.2 Storage
The storage of the sensors must occur in dry, dust-free rooms, only.
Slightly lubricate shafts and flanges with oil before storing (rust).
10 Disposal
The torque sensors must be disposed according to the valid provisions of law.
For this, see our “General Terms and Conditions” www.lorenz-sensors.com
11 Calibration
At the time of delivery, torque sensors have been adjusted and tested with traceable calibrated measuring
equipment at factory side. Optionally, a calibration of the sensors can be carried out.
11.1 Proprietary Calibration
Acquisition of measurement points and issuing of a calibration protocol Traceable calibrated measuring
equipment is being used for the calibration. The sensor data are being checked during this calibration.
11.2 DKD-Calibration
The calibration of the sensor is carried out according to the guidelines of the DKD. The surveillance of the
calibrating-laboratory takes place by the DKD. At this calibration, the uncertainty of measurement of the
torque measuring instrument is determined. Further information can be obtained from Lorenz
Messtechnik GmbH.
11.3 Re-Calibration
The recalibration of the torque sensor should be carried out after 26 months at the latest.
Shorter intervals are appropriate:
• Overload of the sensor
• After repair
• After inappropriate handling
• Demand of high-quality standards
• Special traceability requirements
12 Data Sheet
See www.lorenz-sensors.com
13 Literature
Dubbel, Taschenbuch für den Maschinenbau, Springer Verlag
This manual suits for next models
9
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