ALTHEN SG-2K-IP-12E/24E Series User manual

2 Channel Strain Gauge Amplifier
SG-2K-IP-12E/24E-xxx
Germany | Swit erland | Austria
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 Countries
please contact us
by email at
[email protected]
www.althen.de
V2.1 e
ng

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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 use of the Measuring Amplifier 4
2.1 Instructions for use of strain gauge Sensors
3 Technical Description
4 Terminal Assignment 6
4.1 Supply Voltage 6
4.1.1 Galvanic Isolation 6
4.2 Strain Gauge Excitation Voltage 7
4.3 Analogue Output 7
4.3.1 Analogue output voltage 8
4.3.2 Analogue output current 8
 Starting up 9
 .1 Zero -Point Adjustment 10
 .1.1 Tare – Resistor 11
 .2 Adjustment/Calibration of the amplifier 12
 .2.1 Correction of the Analogue current output 13
 .2.2 Calculation of amplification determing resistor 13
6 Maintenance 14
7 Old appliances disposal 14
Appendix 1
Datasheet 1
Order designation 1
Component Diagram 16
Housing dimensions 17



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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 using accessories, that have been ordered from Althen Mess- & Sensortechnik GmbH
together with the measuring amplifier.
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 Instructions
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
unauthorised 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 Personnel
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 Use
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 Instructions for use of the Measuring 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 technology product, it must be used for its
intended use as well as the described operating 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
must be checked regularly.
The amplifier must be operated with a separate power source used for measurement devices only.
Shielded cables, preferably twisted in pairs should be used only. The EMC-installation instructions
must be complied with.
The amplifier is contained in an aluminum housing which is equipped with an EMC- cover gasket as
well as EMC-cable glands. After initial start-up the lid is to be closed properly. Unused cable glands
must be closed with filler plugs.
The amplifier must be connected to clean ground-potential. Please refer to the EMC-Mounting-
Instructions in order to connect the sensor-shields correctly. To avoid possible potential equalization
currents over the shield of the cable to the following evaluation unit, this shield should be connected
over a suitable capacitor (10 nF / 200 V).
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 disturbance sensitivity of the amplifier, all cables should be kept as short as possible and should
not be extended. Possible cable-bound interferences (i.e. noise) must be blocked very near the cable
ends (evaluation unit) by suitable measures.
If it is to be expected that the amplifier is, as example, cleaned with a high-pressure cleaner/ steam
jet, an additional protection shall be provided.
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 Instructions for use of strain gauge Sensors
Notice: Strain gauge sensors with a small range are extremely sensitive to improper handling. Force
transducers can be destroyed simply by touching. Same applies for the diaphragms of pressure
transducers. 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 may cause measurement inaccuracy. Centric force transmission can
be ensured by rounded surfaces, joint heads or other suitable guides.
Tightening torques while mounting any sensor 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 Description
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 supply voltage of the amplifier is galvanically isolated from analogue output, sensor supply and
sensor signal.
The circuitry is in 4-wire technology. Standard analogue outputs are available for further evaluation.
The amplifier is built in a robust aluminum die cast housing, which is suited for rough and industrial
environment.
The coarse amplification is determined by an internal resistor and can be fine adjusted by a
potentiometer After opening the lid the potentiometer mentioned before as well as the potentiometer
for zero-adjustment allow a correction of the calibration. 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 resistor can be soldered in to add a tare.

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4 Terminal Assignment
The electrical connections are made via cable glands to terminal blocks inside. The terminal
numbering can be found on the pcb. The maximum cable cross-section is 2, mm². The EMC-
installation instruction must be complied with.
Clamp Description Clamp Description
1
Supply voltage
9
Screen/Enclosure
2 Supply Ground 10 +SG-Excitation Transducer Ch-1
3
Supply Ground
11
-
SG
-
Excitation Transducer Ch
-
1
Galvanic insulation 12 +DMS-Signal Transducer CH-1
4
Analogue Ground
13
-
SG
-
Signal Transducer Ch
-
1
Analogue Output 1 (10V/20mA) 14 Screen/Enclosure
6
Analogue Ground
1
+SG
-
Excitation Transducer Ch
-
2
7 Analogue Output 2 (10V/20mA) 16 -SG-Excitation Transducer Ch-2
8
Analogue Ground
17
+SG
-
Signal Transducer Ch
-
2
18 -SG-Signal Transducer Ch-2
Terminals “supply ground” and “analogue ground” are isolated galvanically. To unset this isolation
clamp 3 and 4 are to be bridged.
Notice: The amplifier is to be operated with closed lid only.
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 pcb.
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 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: During switch-on phase the amplifier 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.
4.1.1 Galvanic Isolation
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.

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4.2 Strain Gauge Excitation Voltage
The described measuring amplifier serves to supply one or two strain gauge transducers. Any strain
gauge full bridge with a bridge resistance of 300 ohms or more may be connected. The transducer
can be supplied with either 10 VDC or VDC unipolar voltage. This value can be selected by solder
points (LP-0 B1 / LP-0 B) for coarse, and with potentiometers (P 01B1 / P 01B) for fine adjustment.
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).
LP
Exc.
set 10 VDC
not set
VDC

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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. However, if an unipolar voltage is needed anyway, 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.
An open circuit of the analogue current output is indicated by a red LEC on the pcb.

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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) it may be necessary for a slight fine adjustment 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 assignment 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).

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5.1 Zero -Point Adjustment
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:
S01-1 S01-2 S01-3 S01-4 corresponding to the analogue voltage output
ON ON ON ON -1,4 V … +1,4 V
ON
OFF
OFF
ON
-
V
…
+ V
ON OFF ON OFF +0,6 V … +6, V
OFF
ON
OFF
ON
-
6, V
…
-
0,6 V
 

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5.1.1 Tare – Resistor
A potential base load can be electrically suppressed by an additional resistor on the pcb, if an
expansion of the zero-point adjustment range is not sufficient. (R tara )
The value of the resistor can be found in the table below. The resistor is then to be soldered to the
solder pins (R tara ) on the pcb. In addition, the solder point (LP-04) has to be set to + or –,
corresponding to the tare-load.
R TARA [kΩ] Range
180
+1 Volt or
-
1 Volt
100 +1,6 Volt or -1,6 Volt
47
+3 Volt or
-
3 Volt
20 + Volt or - Volt
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
or
Capacity of the sensor – base load / tare = maximum load to measure
 

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5.2 Check/Adjustment of the amplifier
In order to check or adjust the amplifier, at least one multimeter has to be connected to one of the
analogue outputs. Please refer to page “component diagram”.
Before a check or an adjustment, a warm-up time of approx. 30 mins should be kept.
Functional Check:
■ 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 with full load.
■ 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 adjusted. Above that, the installation
position and the overall setup might need an inspection.
Adjustment:
■ 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 with full load.
■ Load the device with 80 % of its maximum load.
■ Check if the analogue outputs comply with the load and is in the designated specs.
The analogue output value, corresponding to the load is to be set by a qualified person by
using 02B(1).
*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 by using potentiometer 03B(1).
In order to reach the required accuracy, it may be necessary to repeat these steps.

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5.2.1 Correction of the analogue current output
The minimum of analogue current output is 4 mA. A lower current is not possible. When calibrating, the
zero-point current has to be set to 4,1 mA with the potentiometer “NULLPUNKT”. Now the range of the
current output can be set to 16 mA by using the potentiometer P-03. With an adjusted range of 16 mA
the output has to read 20,1 mA at maximum load. After adjusting the range, the zero shall be set back
to 4,0 mA.
5.2.2 Calculation of amplification determining resistor
The amplification is:
Gtotal = Gdifferential amplifier x Goutput stage
The amplification of the output stage is adjustable with the potentiometer P-02 (GAIN). The
adjustable range is:
G output stage = 9, … 10,
Calculation of the coarse amplification resistor RG (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
R G =
0 kOhm
(
1V
10 V x 0,002 V
-1)
= 1282 Ohm

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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 appliances disposal
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
Datasheet
Number of measuring channels: 2 (full bridge resistance >300 Ω)
Supply voltage: 12E - 0 … 18 VDC
24E - 18 … 30 VDC Electronic protected against reversal voltage
Isolating proof
voltage input to
output: 200 V Higher isolated proof voltage on request
Power consumption: max. W
Strain gauge excitation supply: + VDC / +10 VDC
Analogue output: 0 … 10 V / ±10 V
4 … 20 mA
max. 1 mA (short-period proof)
max. 00 Ω
Limit frequency (-3 dB): 1 kHz optional up to 30 kHz
Input resistance: >3 MΩ
Max. input sensitivity: 100 mV/V at ± VDC excitation supply
Non-linearity: ±0.0 % FSO
Electrical connection: EMC-cable gland on internal terminal block
Enclosure: EMC-aluminium diecast enclosure (IP66)
Dimension (B x H x D): 220 x 70 x 140 mm
Weight: approx. 1 00 g
Temperature, storage: -20 °C … +60 °C
Temperature, operating: -20 °C … + 0 °C

Order designation
SG-2K-IP-… Dual channel strain gauge amplifier in a EMC-aluminum diecast enclosure (IP66)
…
-
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: 4 … 20 mA
…-GFxx Limit frequency optionally up to 30 kHz
No declaration (GFxx) for standard version 1 kHz

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Component Diagram
Zero
Channel 01
Gain
Channel 01
Zero
Channel 02
Gain
Channel 02
Supply Voltage
Ground (Supply )Voltage
Ground (Supply )Voltage
Ground Analogue Output
Analogue Output Channel 1
Ground Analogue Output
Analogue Output Channel 2
Ground Analogue Output
Shield / Housing
+Excitation
–Excitation
+Signal
-Signal
Shield / Housing
+Excitation
–Excitation
+Signal
-Signal

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Housing dimensions
Subject to modifications.
All information describe our products in general form.