ALTHEN SG-2K-KS-12E Series User manual

2 Channel Strain Gauge Amplifier
SG-2K-KS-12E/24E-xxx
Germany | Switzerland | Au tria
Althen GmbH Mess- & Sensortechnik
Tel: + 49 (0)619 - 70060
[email protected]
Benelux
Althen bv Sensors & Controls
Tel: [phone]
[email protected]
France
Althen / DB Innovation
Tél : [phone]
[email protected]
Sweden
Althen Sensors & Control AB
Tel. [phone]
[email protected]
USA | Canada
Altheris Inc Sensors & Controls Inc.
Tel: [phone]
[email protected]
Other Countrie
please contact us
by email at
[email protected]
www.althen.de
V2.1
eng

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Content
1 General Information 3
1.1 Safety Instructions 3
1.2 Qualified Personnel 3
1.3 Intended Use 3
2 Instructions for using the measuring amplifier 4
3 Technical describtion
4 Termianl Assignment 6
4.2.4 Connecting in 6 wire technology 10
4.3 Analogue output 10
4.3.1 Analogue output voltage 11
4.3.2 Analogue output current 11
4.3.3 Low pass filter 11
 Starting up 12
 .1 Zero-point adjustment range 12
 .2 Adjustment / calibration of the amplifier 13
 .2.1 Correction of the analogue current output 14
 .2.2 Calculation of the amplification determing resistor 14
6 Maintenance 1
7 Old appliance disposal 1
Appendix 16
Datasheet 16
Oder designation 16
Component diagram 17
Component diagram 18

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1 General Information
To ensure reliable and safe operation, the measuring amplifier must be operated in compliance with the
specifications according to this technical description only. These regulations must also be observed if
accessories, that have been ordered from Althen Mess- & Sensortechnik GmbH together with the
measuring amplifier being used.
Notice: Every person who is in charge for the start-up or service of this measuring amplifier must have
read this technical manual and must have understood the safety instructions in particular.
1.1 Safety In truction
When using the amplifier, the legal- and safety regulations for each case of application must be
observed. To avoid risks for the system or the operator the following points are to be considered.
■ If any visual damage or malfunctions are noticed, the measuring system must be switched off
and marked appropriately.
■ Disconnect the supply voltage before opening the device.
■ The complete measuring unit must be protected against contact and influence of
unauthorized persons.
■ In the case of a safety-relevant application, where a potential malfunction could cause
damage to property or persons, it is imperative that an additional, independent monitor is
provided.
■ In combination with sensors, the maximum loads / pressures etc. must never be exceeded.
If you have reasons to assume that safe operation is no longer possible, immediately take the device out
of operation and secure it against unintentional operation.
1.2 Qualified Per onnel
This measuring system must be operated by qualified personnel and in compliance with the relevant
technical specifications only. Qualified personnel include such persons who are conversant with the
setting up, mounting and starting up of the measuring system and who have qualifications that are
appropriate for the tasks they're about to perform.
1.3 Intended U e
Amplifiers from Althen Mess- & Sensortechnik GmbH serve to measure the intended measurand and
the evaluation thereof in combination with one or more sensors. Any other use over and above that is
regarded as non-intended use.

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2 In truction for u ing the mea uring amplifier
Notice: The parameterizations, further information concerning the scaling as well as the customized
analogue output can be found on the additional sheet “Device-Configuration”.
Since this amplifier is a highly sensitive measurement product, it must be used for its intended use as
well as the described operation conditions only. Initial start-up and changes in setup and settings must
be done by qualified personnel only. To prevent interventions / modifications made by unauthorized
personnel, suitable measures must be taken. Both function and calibration buy be checked regularly.
The amplifier is contained in a plastic housing (IP20) designed for DIN top hat rail montage. The
electrical connections are made via screw-clamps and the sensor may be connected in 4- or 6-wire
technology. The amplifier must be operated with a separate power source used for measurement
devices only.
To avoid possible potential equalization currents over the shield of the cable to the following evaluation
unit, this shield should be connected via a suitable capacitor (10nF / 200V).
All connection cables and the amplifier itself must not be installed in proximity to disturbance
(interference / noise) emitting devices or cables.
Overall the shield connections must be done properly to EMC-standards (as short as possible with large
wire cross-section) and connected to a central point (star grounding). In order to not increase the
interference sensitivity of the amplifier, all cables should be kept as short as possible and should not be
extended. Possible cable-bound interferences must be blocked very near the cable ends (evaluation
unit) by suitable measures.
Notice: Changes of the amplifier of any kind demand for the explicit approval of Althen Mess- &
Sensortechnik GmbH. Changes of any kind done without that approval exclude all possible warranty
and/or liability of Althen Mess- & Sensortechnik GmbH.

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 2.1 In truction for u ing train gauge en or
Notice: Strain gauge sensors with a small range are extremely sensitivity to improper handling. Force
transducers can be destroyed simply by touching. Same applies for the diaphragms of pressure and
torque sensors. So, bear in mind: handle with care!
Loading the transducer in excess of the nominal range may result in an increased and lasting zero
balance offset as well as damage to the sensor. The same applies to short-term force or pressure
impulses that exceed the nominal range.
To most force transducers the force must be applied centrically in order to avoid shear forces, which
may be harmful to the sensor, or cause measurement inaccuracy. Rounded surfaces, joint heads or
other suitable guides can ensure centric force transmission.
Tightening torqued while mounting any sensors may result in an increased zero balance offset. If the
sensor has been replaced, the calibration of the amplifier must be checked. A new adjustment might be
necessary.
3 Technical de cription
The described 2-channel measuring amplifier serves to supply one or two strain gauge sensors with a
full bridge resistance of 300 ohms or more and the amplification of the sensor signal. The sensors may
be connected in 4- or 6-wire technology Standard analogue outputs are available for further
evaluation. The coarse amplification is determined by an internal resistor and can be fine adjusted by a
potentiometer (V) on front of the amplifier. A second potentiometer (N) on front allows the correction
of the zero point. In addition, a dip-switch allows to change the width of the zero-adjustment range. If
even this expansion of the range should not be sufficient, an internal potentiometer can be adjusted to
add a tare.
The presence of supply / internal operation voltage is indicated by the 2 green LED’s on the front.

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4 Termianl A ignment
The electrical connections are made via screw-clamps. The numbering can be found on the front side
of the amplifier. The maximum wire cross section is 2, mm². Maximum interference immunity is
achieved by direct connection of the cable screen with “clean” and low resistance protective ground
(PG). A lengthening of the cable screen makes the interference immunity considerably worse. The
connection of the screen should be done directly with a cable clamp. If, however, a connection to a PG
is not possible, the cable screen may be connected to clamp 30 of the amplifier (analogue
ground/screen). Anyhow, enough interference immunity is to be ensured.
Terminals “supply ground” and “analogue ground” are isolated galvanically. To unset this isolation
clamp 3 and 4 are to be bridged.
 4.1 Supply voltage
The supply voltage is with version -24E in the range of 18 to 30 VDC and with version –E12 within 10
to 18 VDC. The presence of the supply/ internal operating voltage is indicated by the 2 green LEDs on
the front.
To protect the electronics an (to the supply voltage version corresponding) internal self-healing
“polyswitch-resettable®” fuse is built in. Whether an external additional fuse is necessary is to be
checked. However, an additional external delay fuse of 0, A is recommended.
If the indicator LEDs go off, the supply voltage and possibly existing external protection has to be
checked.
Notice: While switch-on the amplifier it is capacitive. Thus, the switch-on current is greater than the
operating current. This must be taken into consideration when dimensioning and selecting the power
pack, especially if several amplifiers are being wired to the same power source.
PIN
Description
PIN
Description
1
Operating voltage
16
GND
analogue output/Screen
2
GND Operating voltage
17
+ Signal Strain Gauge Transducer Channel 1
3
GND Operating voltage
18
-
Signal Strain Gauge Transducer Channel 1
galvanic isolation
19
+ Strain gauge excitation voltage Transducer Channel 1
4
GND
analogue output
20
+ Strain gauge excitation voltage Transducer Channel
2
n.c.
21
+ Strain gauge excitation voltage Transducer
6
n.c.
22
+ Sense
7
n.c.
23
GND analogue output
8
GND analogue output
24
-
Strain gauge excitation voltage Transducer Channel
1
9
Analogue output channel
-
2 4…20 mA (Ver.
-
420
-
)
2
-
Strain gauge excitation voltage Transducer Channel 2
10
GND analogue output
26
-
Strain gauge excitation voltage Transducer
11
Analogue output channel
-
2 0…10 V
27
-
Sense
12
GND analogue output
28
+ Signal Strain Gauge Transducer Channel 2
13
Analogue output channel
-
1 4…20 mA (Ver.
-
420
-
)
29
-
Signal Strain Gauge
Transducer Channel 2
14
GND analogue output
30
GND analogue output/Screen
1
Analogue output channel
-
1 0…10 V

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 4.1.1 Galvanic I olation
The supply voltage of the amplifier is galvanically isolated from analogue output, sensor supply and
sensor signal. To unset this isolation, clamp 3 and 4 have to be bridged.
 4.2 Strain gauge excitation voltage
The described measuring amplifier is able to supply one or two strain gauge transducer. Any strain
gauge full bridge with a bridge resistance of 300 ohms or more may be connected. The transducer can
be supplied with a bipolar voltage of either ± V (= 10 V) or ± 2, V (= V). This value can be selected
by internal DIP-switches and with 2 potentiometers for fine adjustment.
DIP switch S-101/S102 on Althen 73
1 2 Strain gauge feeding voltage
ON OFF ± Volt (=10 Volt)
OFF ON ±2, Volt (= Volt)
 4.2.1 Connection in 4- or 6-wire technology.
The described measuring amplifier allows to connect the transducer in either 4-or 6-wire technology.
The excitation voltage received by the sensor has great influence on the sensor signal. So, if, with a
very long cable, or by lengthening of it, the excitation voltage drops even by a slight value, the signal
drops accordingly. If the amplifier together with the sensor has been factory calibrated, a longer cable
should pose no problem. But if the cable is shortened or lengthened after calibration the calibration will
void.
It is preferred to connect the sensor in 6-wire technology, if the cable is to be lengthened, because the
2 additional wired measure the excitation voltage directly at the sensor and the amplifier adjusts the
exc. voltage accordingly.
DIP
-
switch S
-
101, S
-
102
Potentiometer fine adjustment

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 4.2.2 Connection in 4-wire technology.
Notice: When connecting in 4-wire technology the jumpers J1 and J2 must be set. Otherwise, the
transducer might get damaged resp. destroyed.
The values in the calibration certificate of the sensor have been recorded with the attached cable. So,
this cable must not be shortened, because it would increase the sensor signal and therefore change
the accuracy.
With a sensor without a cable the values of the certificate have been recorded right at the connector. In this case
a connection in 6 wire technology is recommended.
Pic. 1: Connection in 4-wire technology
SG-Amplifier
SG-Signal
Internal jumpers
J1 and J2
+Sense
+SG-Excitation
-Sense
-SG-Excitation
Transducer cable
3 0 Ohm

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 4.2.3 Lengthening a cable in 4-wire technology
As mentioned above the connection should be in 6 wire technology if the sensor comes with no hard-
mounted cable or the existing cable is to be lengthened.
Example: The sensor has been calibrated with an excitation of 10,000 V.
Pic. 2: Connection in 4-wire technology; drop of SG-Excitation voltage caused by cable lengthening (0, Ohm)
In the picture above the original cable has been lengthened and this additional cable results in a
resistance increasing of 0, ohms. Thus, the excitation voltage drops by 0,03 V (resp. 30 mV) which
results a measurement inaccuracy of 0,3 %.
Pic. 3: Sensor with 4 wire cable. Lengthened with 6 wire cable
In the picture above the cable has been lengthened with a 6-wire cable, so the voltage drop of 30 mV
is corrected by the amplifier by measuring the actual voltage at the end of the original cable.
SG-Amplifier
SG-Signal
SG-Excitation voltage
9,97 V
+Sense
+SG-Excitation
-Sense
-SG-Excitation
Transducer cable
SG-Excitation voltage
10,00 V
R wire=0, Ohm
R wire=0, Ohm
3 0 Ohm
Cable lengthening
SG-Amplifier
SG-Signal
SG-Exctiation voltage
10,00 V
+Sense
+SG-Excitation
-Sense
-SG-Excitation
Transducer cable
SG-Excitation voltage
10,03 V
3 0 Ohm
R wire=0, Ohm

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4.2.4 Connecting in 6 wire technology
Notice: When connecting in 6 wire technology the bridges between sense and excitation clamps must
be removed. Otherwise the 6-wire technology does not have the desired effect.
Pic. 4: Connection in 6-wire technology
4.3 Analogue output
The following standardized analogue outputs, depending on the ordered option, are available:
Version …010:
The output is: 0 … +10 Volts (max 1 mA)
Version …B10:
The output is: ± 10 Volts (max 1 mA)
Version …420:
The output is: 4 … 20 mA (max 00 ohms)
Other analogue outputs available on request. For parameter settings, further information concerning
scaling, or customized analogue outputs, please refer to the additional sheet “Allocation / Device
Configuration).
SG-Amplifier
SG-Signal
+Sense
+SG-Excitation
-Sense
-SG-Excitation
Transducer cable
3 0 Ohm
R
wire=0, Ohm
R
wire=0, Ohm

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4.3.1 Analogue output voltage
The analogue voltage output can be picked up on the corresponding clamps. See chapter 4 “Terminal
Assignment”.
In combination with a transducer which is capable to handle tension and compression forces an
analogue output of ± 10 volts is available. If a unipolar voltage is needed with such a sensor, it is
possible to set the zero point of the transducer to volts of the output. This zero-point elevation is also
necessary for the analogue current output.
4.3.2 Analogue output current
The analogue current output can be picked up on the corresponding clamps. See chapter 4 “Terminal
Assignment”:
The analogue current output is not capable of going below 4 mA, therefore when adjusting the
designated zero-point, the output signal has to be set slightly higher than that, just in order to check if
said signal does not virtually hang below 4 mA. If the output reacts immediately it can be set back to
4 mA, otherwise the signal of the transducer has to be checked. If the current of 4 mA does not
increase while loading a force to the transducer the polarity of the signal has to be checked. If this is of
negative polarity the signal wires need to be interchanged.
If the circuit of the analogue current output is open somehow, this is indicated by a red LED on the
front.
4.3.3 Low pa filter
In order to suppress unwanted high frequency disturbances (interferences), a low pass filter can be
switched on. The DIP-switches on pcb “Althen 34” have to be set accordingly.
DIP switch S-101/S201 on Althen 34
1
2
Low
-
pass filter
ON OFF Filter on
OFF ON Filter off

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5 Starting up
If an adjustment (A-K-1K / A-D-1K) has been ordered in combination with the amplifier(-s) and/or
transducers(-s), a slight fine adjustment may be necessary nonetheless. This is due to possible various
environmental influences as well as to mounting etc.
If any visual damage or malfunctions are noticed, the measuring system must be switched off and
marked appropriately.
■ Mounting transducer and amplifier
■ Connect transducer to the amplifier
■ Connect multimeter to analogue output
■ Connect supply voltage – consider pin assignment
■ Allow the system about 30 min. to warm up
■ Check function and calibration of the system
Notice: The allocation of transducer / amplifier is to be complied with. After replacing a transducer,
the calibration has to be checked.
It is to be noted that there is a slight dependence between zero-point adjustment and amplification
(gain).
5.1 Zero-point adju tment range
It is to be noted that there is a slight dependence
between zero-point adjustment and amplification (gain).
The zero-point adjustment range is approx. ± 10 %.
This range can be changed by setting the dip-switch
according to the table below:
Notice: A base load reduces the remaining load capacity by just that value. Overloading may cause
damage!
Base load/ tare + maximum load to measure < capacity of transducer
DIPx02-1 DIPx02-2 DIPx02-3 DIPx02-4 Range
ON ON ON ON ± 10 %
ON
OFF
OFF
ON
± 30 %
ON OFF ON OFF - … 0 %
OFF
ON
OFF
ON
+ … 0 %

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5.2 Adju tment / calibration of the amplifier
In order to adjust or calibrate the amplifier at least one multimeter has to be connected to one of the
analogue outputs.
Inspection:
■ Unload the measuring device.
■ Connect the multimeter (refer to chapter 4 “Terminal Assignment”).
■ Set the analogue output to 0 Volts resp. 4 mA.
■ Load the measuring device (i.e. the transducer) at least 3 times fully.
■ Load the device with 80 % of its maximum load.
■ Check if the analogue outputs comply with the load and is in the designated specs.
■ If not, the measurement system might need to be recalibrated. Above that, the installation
position and the overall setup might need an inspection.
Adjustment / Calibration:
The coarse amplification, and thus the voltage output, is determined by an internal resistor (RG) and
can be fine adjusted by a potentiometer (P-102 and P-202). To adjust the current output, which follows
the voltage output, the potentiometer P-10/11 and P-20/21 are to be used. (See next chapter.)
Before the calibration a warm-up time of approx. 30 mins should be kept. The measuring device is to
be unloaded.
Unloaded means with:
Force transducers: no applied force at all
Pressure transducers no pressure, except atmospheric influence
■ In this unloaded state adjust the zero-point with the potentiometer P-01.
■ Apply a defined load. (by calibrated weights, pressure generator etc.)
■ Adjust the analogue output corresponding to the applied load.
In order to reach the required accuracy, it may be necessary to repeat these steps.

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Gain
5.2.1 Correction of the analogue current output
The calibration of the amplifier in general is done with the
potentiometers on the front. This basic calibration adjusts the
analogue voltage output. The analogue current output follows
the voltage output. Thus, the analogue current output does not
need to be corrected – it is been done right in the factory. If,
however, the current output does need an adjustment, it can be
done by 2 potentiometers inside the amplifier.
5.2.2 Calculation of the amplification determing re i tor
The amplification is:
G total = G differential amplifier x G output stage
The amplification of the output stage is adjustable with the potentiometer P-02 (GAIN). The adjustable
range is:
G output stage = 9, … 10, Volts
Calculation of the coarse amplification resistor R G (applies for 10 Volts output):
G differential amplifier =
1000 mV
Exc. (V) x Signal (
mV
V
)
R G =
0 kOhm
(G differential amplifier –1)
Example:
Transducer: 2, 000 mV/V (0,002 V/V)
Excitation: 10,000 V the 2 resistors
R G =
0 kOhm
(
1V
10 V x 0,002 V
-1)
= 1282 Ohm
Zero

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6 Maintenance
The flawless function and calibration of the whole measuring system is to be checked regularly. This
inspection is also necessary after every repair or change of any component of the measurement
system.
7 Old appliance di po al
According to European and German law, it is prohibited to dispose of old electronic
devices by household waste, but must be collected and disposed of separately.
Amplifiers and measurement units manufactured and sold by Althen Mess- & Sensortechnik GmbH
serve B2B purposes only. Therefore, those old appliances must not be given to the communal disposer,
but must be given back to the seller or disposed of properly. If you need any further information, please
contact your local authorities.
These measures serve to protect the environment and allow recycling and recovery of valuable
materials. Furthermore, do electronic devices contain substances that may cause damage to the
environment if burned or dumped with normal household waste.

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Appendix
Data heet
Number of measuring channels: 2 (full bridge resistance > 300 ohms)
Supply voltage: 12E - 10 … 18 VDC
24E - 18 … 30 VDC Electronic protected against voltage reversal
Isolating proof voltage input to output: 200 V Higher isolated proof voltage on request
Power consumption: max. W
Strain gauge excitation supply: ± 2, VDC / ± VDC
Analogue output 0 … 10 V / ±10 V
4 … 20 mA
max. 1 mA (short-period short-circuit proof)
max. 00 Ω
Limit frequency (-3 dB): 1 kHz (10 Hz with low pass filter) optional up to 30 kHz
Input resistance: >3 MΩ
Max. input sensitivity: 100 mV/V at +10 VDC excitation supply
Non-linearity: ±0.0 % FSO
Electrical connection: Pluggable Screw clamps
Housing: Plastic enclosure for top hat rail mounting (IP20)
Dimension (B x H x D): 100 x 73,2 x 118,2 mm
Weight: 4 0 g
Temperature, storage: -20 °C … +60 °C
Temperature, operating: 0 °C … + 0 °C
Order de ignation
SG
-
2K
-
KS…
2 channel strain gauge
-
amplifier in plastic housing for
DIN
-
top hat rail mounting
(IP20)
…-12E-… Supply voltage: 10 … 18 VDC
…
-
24E
-
…
Supply voltage: 18 … 30 VDC
…-010-… Analogue output: 0 … 10 V
…-B10-… Analogue output: ± 10 V
…
-
420
-
…
Analogue output: 0 … 10 V and 4 … 20 mA
…GFxxx frequency limit up to 30 kHz
…no declaration standard version 1 kHz

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Component diagram

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Component diagram
Subject to modifications.
All information describe our products in general form.