DS Europe 500QD Series User manual

1
INSTRUCTIONS
FOR
THE INSTALLATION AND THE USE
OF THE
LOAD CELL
Mod. S/N
For series: 500QD- 560QDT – QB700 –LD – LT – HC 2000 – BC 300 - MD 5000 –
MB 400 – MR 400 – AP 7000 – ME – MF – 942 (Liftsentry) – 922
LCR 200 – EG – MB490- MP - PT500- KCI
DS Europe
Via F. Russoli, 6 - 20143 MILANO Tel. [phone] r.a Manual N° 180909
Fax [phone]. –02 89.10.145
www.dseurope.com
e-mail: dseurop[email protected]

2
Index
1) P R E L I M I N A R Y R E M A R K S ............................................................................................ 4
2 ) T E R M I N O L O G Y OF THE FINAL TEST CERTIFICATE ................................................. 5
3) TESTS DURING MANUFACTUING .....................................................................................................
4) WORKING PRINCIPLE OF LOAD CELLS ......................................................................................... 8
5) CAUTIONS FOR INSTALLATION AND USE OF LOAD CELLS .................................................. 9
6) MECHANICAL INSTALLATION OF LOAD CELLS ....................................................................... 11
) ELECTRICAL CONNECTIONS OF NOT AMPLIFIED LOAD CELLS ......................................... 16
8) ELECTRICAL CONNECTION OF AMPLIFIED LOAD CELLS ..................................................... 18
9) ELECTRICAL CONNECTIONS OF DIGITAL LOAD CELLS ......................................................... 24
10) PROTECTION AGAINST ELECTRICAL NOISE .......................................................................... 25
11) ENVIRONMENT PROTECTION .................................................................................................... 26
12) TESTS FOR THE APPLICATION OF THE CE MARK ......................................................... 2
13) CONTROLS AND LIFE OF A LOAD CELL ............................................................................. 28
14) POSSIBLE DAMAGES THAT MIGHT HAPPEN TO A LOAD CELL ........................................ 29
S A L E S C O N D I T I O N ................................................................................................................. 31
NOTICE
The information contained in this document is subject to change without notice.
DS Europe shall not be liable for errors contained herein or for incidental or consequential damages in connection with
the furnishing, performance, or use of this material.
No part of this document may be photocopied, reproduced, or translated to another language without the prior written
consent of DS Europe srl.

3
EC CONFORMITY DECLARATION
Applied Directives: 89/336/CEE modified by Directives 92/31/CEE and 93/68/CEE
Standard to which is declared the conformity:
EMC: EN 50081-2: 1994 - Generic emission standard
EN 55011
EN 50082-2: 1995 - Generic immunity standard
ENV 50140
ENV 50141
EN 61000-4-4
EN 61000-4-2
EN 61000-4-8
ENV 50204
Manufacturer: DS Europe srl
Address: via F. Russoli, 6 Milano (Italy)
Type of product: Amplified strain gauge transducers
Models:
500QD - 560QDT – QB700 – LD – LT – HC 2000 – BC 300 - MD 5000MB 400 – MR
400 – AP 7000 – ME – MF – 942 (Liftsentry) – LCR 200 – EG – MB490- MP - PT500- KCI
Year of mark’s apposition: 1997
The product has been tested in a typical configuration, as prescribed in product’s instruction
manual.
DS Europe srl declares that the overlisted product complies with the requirements of the EMC
Directive over mentioned.
DS Europe srl
Milano, 25/11/98 Technical Direction

4
1) P R E L I M I N A R Y R E M A R K S
1.1 This instruction manual is an integral part of the supply-order and it is delivered with the
material, even if not listed on the invoice and it can be downloaded from www.dseurope.com.
Moreover, it is sent, under request, during the negotiation, whether the Customer tells about
the installation or about the use of the cell.
When several cells are supplied, the quantity of manuals could decrease to one copy, if not
requested the contrary
1.2 The transducers described in the present manual have been designed for general purpose
applications and, consequently, it is not possible to specify for all the possible applications
specific limits of use.
Under the technical impossibility to ascertain the limits of use, it becomes obligatory for the
Customer to put in progress all the safety rules and accessories in order to avoid: damages to
Persons and things and damages for stopping of plants, etc.
In case of risky uses, it is obligatory for the Purchaser and for the User to inform immediately
the Supplier so that he may suggest safety solutions or he may refuse the order and the supply.
1.3 The load cells are only elements of machineries or plants; they are sold in thousands
pieces/year, for disparate applications having them to satisfy different specifications and
standards unknown to the Supplier.
Under these circumstances DS Europe is compelled to refuse any responsibility for the use,
just listing, also on this manual, the most and common precautions for a correct use of its
products.
Furthermore it is pointed out the need for a complete and focused insurance coverage
particularly when these machinaries have as final destination U.S.A. and Canada.
1.4 DS Europe load cells have an high professional quality, they are robust and are designed for
the best in safety and in reliability: the cautions and limitations listed in this manual want to
suggest and to remember to the Customer the importance to avoid damages.
1.5 In the case of instructions and of data different among them, has priority and validity: first
what enclosed with the transducers; second that is listed in this instruction manual, last what
is listed in the bulletin. Our revisions are done following these priorities

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2 ) T E R M I N O L O G Y OF THE FINAL TEST CERTIFICATE
2.1 REMARKS:
The final test certificate is issued only in English.
The various data are processed and printed directly by the computer, so without subsequent
manipulation. As a result they appear with all the decimal numbers (no rounding) although,
sometimes, the last digits are not-significant.
Positive polarity is not indicated, but negative polarity is shown by a minus sign.
The test is done in compression nevertheless differently indicated.
The following text comments only the main parameters of the certificate
2.2 RATED CAPACITY (= Full Scale):
It is the maximum weighing capacity. The unit of measure is the Kilogram force = Kgf =
0,9806 daN, (daN = decaNewton) where 0,9806 is the gravity in Milan.
The full scale (=rated capacity) is to be chosen in order to avoid overloads with static and
dynamic forces well aligned along the load cell measuring axis.
Non linearity and all load cell technical specifications are to be calculated as a percentage
onto the load cell rated capacity and not onto the applied force, that might be much lower
compared to the full scale.
Resolution of the measured value, on electronics display, is depending on the ration between
measured value/load cell rated capacity as well as on electrical noise, mechanical noise
(=vibrations) and on the A/D converter bits of the digitizing electronics.
2.3 SENSITIVITY:
It is expressed in V/V FS (FS = full scale). It is the output voltage when the cell is supplied
with 1 Volt and it is subjected to a weight equal to the full scale capacity value.
Example: 2.01146E-03 V/V FS means 2,011.10-3 V/V FS = 2,011 mV output signal for
each power supply Volt fed to the load cell when Full Scale force is applied.
If load cell is fed 10Vdc power supply and Full scale force is applied onto load cell,
maximum signal will be 20,11mV.

6
2.4 CALIBRATION EQUIVALENT LOAD VALUE
(= Calibration with external electronics):
When yellow load cell conductor (black sheath cable) or grey conductor (grey sheat
DIN47100 cable) with yellow conductor, or pin 5 with 2 of connector, the load cell provides
an electrical signal that simulates a Kg load, applied onto the load cell, written on the load
cell certificate.
Only load cells with not amplified mV signal have a built-in calibration circuit (with the
exception of series BC300 that does not have enough room inside for housing the calibration
circuit).
This calibration procedure can be used only when there is no load or preload or tare onto the
load cell.
Some load cells can be used either in tension and compression therefore the calibration
circuit signal could have an inverted polarity, compared to the normally measured signal,
therefore after calibration it might be needed to reverse the connection of the load cell signal
conductors (example: green with white conductors) in order to get a positive electrical
signal.
The procedure for calibrating the electronic weighing system is as follows:
Introduce the calibration signal.
Adjust the span (=gain) of the signal-conditioner until the digital display shows the
calibration value.
Remove the calibration signal and check the zero; if the zero needs further adjustment still
continue the procedure with successive approximations.
Load cells with inside analog or digital electronics, because of CE regulations, cannot have
the built-in calibration circuit.
Calibration circuit is to be deactivated after calibration: disconnect the calibration
conductors or connector pins (example: disconnect yellow conductor from green and keep
yellow insulated).
2.5 E = EXPONENT OF 10
An example clarifies better the meaning of this datum:
Sensitivity: 2.01146E-03 V/V FS means: 2,011.10-3 V/V FS = 2,011 mV/V FS.

7
3) TESTS DURING MANUFACTUING
Through in-process operations of the cells, at least, 5 operational tests are done, including also: the
strain gauge bridge continuity, the insulation against the body of the cell and the stability of
measure.
When finished, the cells are submitted to several thermal and mechanical cycling; then, during the
final test certification are controlled: the zero unbalance, the creep, the return to zero, the validity
and the stability of the technical specifications.
Periodically, samples taken from production, are submitted to a full cycle of tests, in order to verify
conformity of the production to product’s specifications.
For the over listed all the cells are delivered perfectly working as clearly declared even in the
"final test certificate".

8
4) WORKING PRINCIPLE OF LOAD CELLS
4.1 MEASURED FORCE:
All the load cells (single - axis) measure the force only in the direction of their weighing
axis (= measuring axis). The component vector-forces on other directions not only are
not measured but they can deform the cell, they introduce supplementary errors and they can
destroy it. When a cell is used in a scale or in a weighing system, it is submitted to the
vertical gravity-force due to the weight (= mass) to be measured, therefore the weighing axis
of the cell has to remain perfectly vertical in all the loading and measuring conditions.
4.2.1 In a load cell are acting 2 vector-forces: the force to be measured applied to the cell
and the reaction force of the fixing plane. Both these forces are the resultant (as
value and as direction) of many distributed forces.
Important: the positions of the barycentre (= point of origin) and of the directions of
these two forces must not change during the application of the load; moreover both
these two forces and the axis of measure of the cell must coincide or must be parallel
among them depending on the principle of working of the cell.
Conditions different from the over listed decrease of many times the measure quality.
4.2 DISTANCE BETWEEN THE FORCE AND THE WEIGHING AXES:
The force to be measured is to be aligned along the load cell measuring axis but for some
load cell series it is enough to be parallel, therefore there are four types of load cells:
4.2.2 4.2.1 Series QB 700 - Series 500 QD – Series EG: (for scales) with a
flexing parallelogram.
The point of application of the force can be far, from the weighing axis of the
transducer, up to several centimeters in the QB 700 and EG (see bulletins) and few
centimeters in 500 QD.
This distance is increasing with the area of the flexing parallelogram.
4.2.2. Series MB 400 -MR 400 - MD 5000 - PT500 – 560QDT - KCI: with working
principle = shear.
The point of application of the force can be far 2÷3 mm from the weighing axis of
the transducer, with an error still acceptable for most of the industrial applications.
4.2.3 Series LD - LT – HC7000 - HC 2000 - BC 300 – ME – MF – LCR 200 – MB490 –
MP- AP 7000: with working principle = flexion.
The point of application of the force can be far 1÷2 mm from the weighing axis of
the transducer, with an error still acceptable for most of the industrial applications
Remarks: from the over listed: category 4.2.1. can accept the weighing pan directly
connected to the cell. For the other categories (from 4.2.2 to 4.2.5) it is
always important the use of accessories (spherical joints, chains, etc.) in order
to obtain that both axes always coincide.

9
5) CAUTIONS FOR INSTALLATION AND USE OF LOAD CELLS
5.1 PRELIMINARY REMARKS:
Have to be avoided risks of damages to Persons and things and damages due to the stopping
of machineries and of plants.
For risky uses, during the negotiations or before the installation of the cell or when known, it
is obligatory for the Purchaser and for the User to supply this information so that DS Europe
can renounce to the order and to the delivery of the goods or to give, under the full
responsibility of the User, instructions to reduce or to cancel the risks.
Note: This chapter is referred mainly to high load (= FS) cells.
5.2 CATEGORIES OF RISKS IN THE USE OF THE CELL:
All the accessories introduced to reduce the risks of the use of a load cell have not to
introduce a "by-pass" to the measuring force; they have to act not over the 50% for the FS (=
full scale); they have to bear overloads at least 10 times the FS of the cell and they
have to apply a symmetric and balanced action in case of operation..
5.2.1 Compression load cells:
The use in compression is usually less risky and, when possible, it is preferable to
convert the tension applications into compression ones.
The accessories for the overload and for the torque protections, etc. are made by
metal blocks complete of distance regulation.
They are low cost components manufactured directly by the Customer.
The free play is regulated for an action around 20% over the FS.
5.2.2 Tension load cells:
The use in tension is usually risky, especially for hanging loads.
They need the best care to avoid damages.
In order of priority for tension applications, can be used the Series AP 7000 (the
most advisable), the Series MD 5000, the series 500QD, the series 560QDT, and last
the Series LT, BC 301 – BC 305 (only for static tension applications).
It is advisable to apply joints between load cell and the machine in order to have a
good alignment between the force vector to be measured and the load cell measuring
axis.
For cells used in tension, two complementary stopping blocks have to be actuated:
Overload protector (= block): on which the cell goes to lay for the measure
deformation when the overload exceeds about 20% over the FS (= full scale).
It has to be robust, stiff and in position to bear at least 10 times the FS.
Usually it has a play adjustment so to act when the overload reaches the 20% over
the FS.
Block in case of rupture of the cell: this is made by chains, flexible metal cables,
etc., usually in a group of 2-3-4 symmetrical pieces.
Note: even when the internal parts of the transducers include overload-protections,
in case of danger, external overload protectors must be applied.

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5.2.3 Use of the cells under shocks, bumps and vibrations:
Under shocks, bumps and vibrations the applied force is always the product of the
mass applied to the cell multiplied by the acceleration (F = ma) and the cell is easily
loaded over the max acceptable limit and it could break.
The risk of damages is high and always not-qualifiable and submitted to the
frequency and amplitude of the vibrations, to the resonance of the structures, to the
fatigue processing of the materials, etc., usually unknown.
The main cautions to be taken are the following:
Load cells can be used with forces up to 125%FS (FS=Full Scale). Forces to be
measured, are to be well aligned along the load cell measuring axis. Forces can be
applied between 125% and 150% only exceptionally. Full Scales of load cells
(=FS) are to be chosen, in order to be equal or greater than 100% of the force to
be measured.
.
Select a cell more suitable to accept overload (i.e.: prefer the Series AP 7000; on
contrary the Series LT, BC 301 – BC 305 are only for strictly static measures).
Insert overload and stopping blocks as listed in paragraph 5.2.2. Each block has
to bear loads at least 10 times the full scale of the cell and higher loads in case of
free fall or shocks.
For hanging loads has to be introduced also a dumping system to reduce starting
tears and hunting joints to avoid torsion and transversal loads.
It is necessary to apply a mechanical protection that avoids damages to persons
and goods in case of mechanical load cell breaking.
By mechanical or by design tricks avoid that the cell and the structure connected
enter into resonance also for short periods of start and stop of the machine (e.g.
Series LCR 200 and EG). If necessary increase the full scale of the cell.

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•Small measuring ranges (especially the 2-3-6Kg): it is necessary not to apply
overloads, not only during the normal load cell use but also during handling and
mechanical installation.
All these accessories have to be scaled and made by the Customer, in relation to the
applications and the standards imposed.
6) MECHANICAL INSTALLATION OF LOAD CELLS
6.1 FIXING AREA OF THE CELL (See again the paragraph 4.2.1):
The fixing area of the cell has to touch the fixing base always in all its points.
Errors, even of 20÷30% FS, may occur from separated contact points which number and
position change the axis of force in relation to the applied load.
Off centre loads produce measuring errors.
Load cells are calibrated on test benches with adapters that warrant a load cell fixation and
alignment with ±0,05mm e ±1° tolerances.
Mechanical installation is always adding some errors to that one of the load cell therefore a
machine application cannot have only the bare load cell intrinsic error.
Load cell errors are a percentage to be calculated onto their measuring ranges and not onto
the force to be measured that can be much smaller.
In case more than one load cell is used, in the same machine application, then a combined
error is to be considered too.
The main installation cares to be taken are the following:
6.1.1 Fixing base in high strength steel with thickness, at least, 1,5 times that of the cell.
6.1.2 Contact surface flat and finely machined and clean.
6.1.4 Very important: Strong and even clamping of the screws by dynamometric wrench:
to obtain an uniform and extended contact.
Use only high strength steel socket head screws and flat washers.
Safety is usually depending on a correct fixation of screws threads: it is suggested to
use safety systems that prevents their accidental unlocking like by means of lock
nuts.
After initial screw fixing the load cell electrical signal, without load, could shift a bit:
it is necessary to perform a small mechanical cycling with a significant load
(compared to the load cell measuring range) and then adjust the screw clamping
again with the wrench.
6.1.5 For the load cells with low full scales (up to 50 Kg), during the installation, avoid
overloads and torsions that may damage the cell even if it is not electrically
connected.
6.1.6 Mechanical guiding systems, of the measured to force, along the load cell measuring
axis, are to have a low fiction.

12
6.1.7 Load cells are to be installed in application machines where there are relatively low
vibrations (=mechanical noise) that might reduce the measured resolution.
Load cells are to be fixed to machine parts that are not linked, to anything else, by
stiff links (like tubes and cables) that might introduce hysteresis in the measure.
6.1.8 All load cell fixing parts, alignment systems and load guiding systems as well as the
metal plate where load cell is fixed, are to be stiff and with enough thickness
relatively to the applied load.
6.1.9 Nothing is to be interposed between the load cell fixing area and the metal plate
where it is fixed
An incorrect load cell fixation with glue under its fixation area, might introduce non
repeatability a non return to zero errors.
6.1.10 The under listed cells need particular instructions:
Series HC7000, HC 2000 and MP:
The force, to be measured, is to be evenly shared onto the top and bottom contact
surfaces in order to avoid additional errors as well as mechanical damages.
Load is to be applied in order to have it aligned with the hole axis: tubes and screws
are advisable to be used as guiding systems with -0,15mm to -0,3mm tolerances.
It is to be applied an axial bearing on top and bottom of the load cell contact
surfaces, to recover the non parallelism and non planarity of the mechanical fixing
(5° is the maximum allowed misalignment).
The top and bottom contact surfaces are to be clean and well machined.
Load cell is not to move from its fixing position because of vibrations and side
forces: it might be necessary to eventually install load cell onto a housing for the load
cell bottom side.
This load cell housing is to have a 0,3mm larger diameter compared to the bottom of
load cell diameter and its highness is not to touch the load cell external metal lid.
All fixing elements, alignment, force guiding and the metal plate where load cell is
fixed are to be stiff and with enough thickness.
Series MD 5000:
The contact on all the surface of the two external bearings (and not only on two
external contact lines) is imperative; the same on the central loading surface.
The cell has to work always as a supported beam never as a restrained beam even
when different dilatation coefficients of the materials and great temperature changes
occur.
Series LCR 200:
The radial load cell (= web tensiometer) is made up by 3 separated parts: the fixing
base, the central measuring body, the lid.
The measuring axis of the cell coincides with the axis of the connector connected to
the axis of the grub screw on the central body (opposite to the connector).
Make the holes and screw them on the structure in which the cell will be settled.
Split the cell in its parts.
Fasten the fixing base by high strength screws.
Assemble the separated parts and position the measuring axis of the cell with the
resultant of the forces to be measured.

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The body of the cell can rotate, about ±10 degrees, on its axis. Before the final
clamping of the screws of the lid rotate the measuring body so to obtain the
maximum electrical signal output from the cell: this maximum value means the
coincidence of the weighing and of the measuring axes. Now make the final
clamping of the fixing screws of the lid and of the grub screw on the central body.
Important: during the transport and the installation, the cell has not to be submitted to
overloads that can destroy it.
Where possible, it is imperative to settle overload protectors (= blocks) in all the
directions (x-y-z) between shaft or cylinder and frame or other fix points of the
machine.
The overload protectors (blocks) have to be taken away in normal operation.
For the electrical connection of the not amplified cell: see chapter 7.
Series BC 300:
Central pin:
The measuring force has to be applied only on the pin and not on the diaphragm, also
for the models BC 301 – BC 305 with screwed pin.
Moreover the weighing force has to coincide with the pin axis without any
transversal component of the applied force.
External circular bearer:
The support and the fixing have to be limited only to the external circular crown
without extending to the internal area of the cell.
The setting can be done in several ways: by epoxy cements or by a housing without
cement.
Housing: by a hollow with diameter 0,3÷0,6 mm larger than the cell.
Important: assure at least 0,2÷0,3 mm gap for the deformation of the measuring
diaphragm).
Mod.922 and 942 - Liftsentry:
Fasten the link on a surface stressed to flexion (from 10 to 20 Kg/mm² ), if necessary,
reduce the section of the structure.
Choose a measuring point far from junctions by screws or rivets (weld them) the two
fixing surfaces must be coplanar and finely machined without paint.
Smear on them a thin layer of epoxy cement. Tighten diagramally the screws by
means of a dynamometric wrench.
The hysteresis and the non-return to zero of the measure show a slipping of the
surfaces. Do not use elastic washers.
Do not take care of a high residual out-of-zero: set it to zero by software or by the
zero regulation.
Perform a small mechanical cycling, after having fixed the strain links, before
calibration with external electronics.

14
To increase the flexion of the link the User can apply the following installation tricks
(increase the flexion: up to 2 times):
•Two spacer blocks (height: 10÷15 mm.): each settled under the fixing ends of the
link. They increase the distance from the neutral axis of the structure.
•Two spacer-extension blocks: each settled as above. They increase either distance
from the neutral axis (as above) or the distance between the fixing ends of the
link.
Both the blocks have to be welded to the structure. They are made by the User or
supplied by DS Europe.
Mod. LD:
Force to be measured is to be evenly shared on the top spherical surface of the
centering pin.
It is recommended to use the ALD saddle adapter.
Mod AP7000:
The elongated load cell metal frame means that load cell can be influenced by side
forces and off center loads.
All side or off centre loads can produce dangerous situations because of concentrated
mechanical strains that might yeld the load cell metal frame as well as break it.
With compression forces, it is necessary to completely fix the load cell threads up to
the ledge in order to avoid damages due to the combined bending and compressive
stress.
With tension forces the fixing top and bottom planes can be farther, compared to
compression, using in any case all available threads.
An axial bearing is to be used in case of tension forces for correctly guiding the load
along the load cell measuring axis.
The load cell metal frame has high stiffness and resonant frequencies (can change
between the many models).
AP7000 can withstand in a good way vibrations.

15
6.2 PANS, PLANES AND STRUCTURES OF WEIGHING (see paragraph 4.2.1):
Cells with pan directly connected and solid with the load cell (i.e.: QB 700 and EG):
The pan has to be very stiff.
Flexions of about 1 mm at the edges may reduce even 10 times the measure accuracy.
To avoid increase of weight of the pan: bending beads or the use of aluminium die-
casting pans are suggested.
Cells with overhanging structures (i.e.: Series LD - MB 5000 – HC 2000 - ME –MF –
BC 300-PT500 – MP – MB490 – 560QDT- 500QD):
The applied force has to be always coincident with the weighing axis. Transversal
components of the force or torque moments introduce errors and may damage the cell.
It is advisable: the use of saddles (LD Series), spherical heads, thrust spherical plain
bearings (HC 2000), rod ends, etc. and of stiff and strong overhanging structure welded
together and never connected by screws or riveted joints.
A flexion or a displacement of few millimetres of the barycentre of the applied force may
introduce errors of 5÷20% FS.
6.3 WEIGHING SYSTEM WITH SEVERAL CELLS (see again the paragraph 4.2.1.):
The distance among the cells brings to the solution of the following installation problems:
Important: with several cell systems use only not-amplified load cells (see par. 8.1.2).
6.4.1 The radial movement between the upper structure of the cell and the lower one, due
to the difference of the thermal and mechanical expansion of the two structures: this
problem is usually limited as the upper structure is, in general, in steel and the lower
structure (= the bed-plate) is in the same metal or in reinforced concrete which has the
same coefficient of thermal expansion of the steel.
If possible, for round reservoirs lay radially the reinforcing rods. The remaining
expansion difference may be compensated by saddles, or by thrust spherical plain
bearings or by roller plates.
6.4.2 Flexion of the upper structure due to the load: it is compensated by strengthening of
the structure, by tie rods, by rod ends, by spherical bearings, etc.
In case of weighing vertical reservoirs, if possible, settle the shelfs with the load cells
at half the height, that is, at the same elevation of the barycentre of the tank.
In general, the technical cares applied on the installation are important elements to
define the quality results of the weighing system.

16
7) ELECTRICAL CONNECTIONS OF NOT AMPLIFIED LOAD CELLS
7.1 CABLE OR CONNECTOR?
For outdoor applications and for all the industrial environments, the cable connection is
preferable.
The mating connector, even if sealed, has always inside dead volumes with air and
the air, due to the thermal variations, exchanges humidity which, in long periods, brings
oxidations on the electrical contacts, electrical jumpers of moist dust acting directly on the
strain-gauge bridge and, consequently, introducing shifts of the zero and instability of the
measure.
7.2 ELECTRICAL CONNECTION:
Load cells without built
-
in electronics (mV/V
output
)
Meaning Black sheath cable Grey sheath
D N47100 cable Connector
Load cells
BC301-2-3
Load cells
BC304-5
- Power supply Black Brown 4 Green Black
+ Power supply Red Yellow 1 Red Red
- Signal White White 3 Colourless White
+ Signal Green Green 2 Blu Green
Calibration Yellow Grey 5
Calibration
activation Yellow+Green Grey+Green 5+2
The screening sheath is not connected to the body of the cell.
7.3 POWER SUPPLY OF LOAD CELLS WITHOUT BUILT-IN ELECTRONICS:
The standard and recommended voltage is: 5 or 10 V stabilized.
The cells can accept up to 15 V.
The upper voltage value is limited: by the heat dissipation capability of the sensors, by the
ambient temperature and by the warm-up time wanted.
In the "final test" the cells are tested with excitation: 10 V.
The highest the power supply, the highest the electrical signal but the longer it will be
necessary to wait to reach thermal stability (=warm up time) of electrical signal because of
heating due to flowing electrical current.
The external power supply generator is to have a low over imposed ripple noise (linear
generators are to be preferred to switching types).

17
Exceptions are the button cells models BC 301 – BC 302 – BC 303. Due to their extreme
compactness and its poor thermal dissipation capability, it is advisable an excitation voltage
from 1 to 5 Volts.
To increase the thermal dissipation: bond the cell at the base by conductive cement and, by
conductive silicon grease, fill the air gap between the upper surface of the cell (=
diaphragm) and the weighing surface (separated together by the thickness of the central
weighing pin).
7.5 Load cells without built-in electronics are not amplified and do not have any zero and gain
setting.
Most of these load cells have the built-in calibration circuit.
In case cable color codes do not match the electronics connection codes, it is recommended
to consider valid the connection codes (conductor colors and terminal numbers) listed in the
load cell final test certificate, then what is listed in this manual and lastly what is listed in the
technical bulletin. (par. 1.5).
7.6 SIGNAL CONDITIONER:
Are recommended amplifiers with high stability; linearity, low noise and thermal drift;
with high impedance (>1 MOhm) and differential input (Mod. EL625–EL621–EL624).
The "span" (= gain) regulation has to be large enough to convert, on a digital display, the
electrical signal outputs into physical values (Kg, tons, etc.).
The signal conditioners with microprocessor are preferable (Mod. AN401Plus – Pitagora
– SAP - 699).

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8) ELECTRICAL CONNECTION OF AMPLIFIED LOAD CELLS
8.1 FOREWORD
8.1.1. Series 500 QD; 560QDT; LD; LT; AP 7000 (from 10 up to 100tons FS), PT500,
EG, MD5000 and MP can be made with built-in amplifier electronics.
Series AP 7000 is usually made with built-in analog amplifier electronics (models
from 250Kg up to 5ton FS are miniaturized and do not have enough room inside for
housing the amplifier electronics).
Load cells AP7000, MD5000 and HC2000 have a 1mV/V typical sensitivity (without
amplifier electronics) instead of the usual 2mV/V typical value: these series are
normally under loaded, compared to their mechanical margins, in order to allow a
higher safety against ruptures.
8.1.2 8.1.2. In weighing system with several cells and a summing unit, use cells not
amplified with a summing signal unit mod. Pitagora. The mod. Pitagora can sum
up to eight load cell signals, at the same time, by singularly calibrating each of them
in order to allow a high accuracy.
The amplified cells are not suggested as they are, usually, at different temperature
conditions and the thermal drift of each amplifier and of each stabilizer, even if low,
may add together in the summing unit.
8.1.3 To satisfy the CE directives the amplified load cells have not the calibration lead.
8.2 CHOICE OF THE INTERNAL AMPLIFIER:
Two categories of amplifiers are available of which are listed the advantages and the dis
advantages.:
The external power supply generator is to have a low ripple electrical noise (linear
generators typically have lower noise than switching types).
Series AP7000 load cells can have inside an analog amplifying electronics only for 10 to
100 tons full scale, but those from 250Kg up to 5tons have only 1mV/V typical sensitivity
because they do not have inside enough room left for any electronics.
8.2.1. Voltage amplifiers:
- A 5 = supply voltage: from 10,5 V to 28 Vdc; Signal output = ± 5 Vdc FS
- A 1 = supply voltage: from 18 V to 28 Vcc; Signal output = ±10 Vdc FS
The Model -A5 is preferable to the Model -A1, as the heat to be dissipated inside the
cell is lower.
EG and 560QDT can have only built-in analog amplifier electronics with positive
outputs 0 to +5 or 10V and not negative.

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Advantages:
- The Voltage stabiliser, inside the cell, keep insensible the excitation of the cell
to the voltage drops due to the length and to temperature changes of the
connection-cable.
With power voltages around 15 Vdc, distances cell/electronics of several
kilometres are acceptable!
- The internal amplifier and the high voltage output (± 5 V) bring the signal
insensible to the external noise (great Signal/Noise ratio).
Disadvantages:
none.
8.2.2 Current amplifier (see paragraph 8.6 and further diagram): (2 - wires)
- A 4 = supply voltage (= Vps): from 15 to 40 Vdc; Signal output: 4-20 mA;
(Typical power supply is 24Vdc filt. Stab. with an external RL=250 Ohm load
resistance)
Advantages:
- As for the voltage amplifiers (-A5; -A1).
- Saving (insignificant) of a lead in the connecting cable.
- Immunity to electrical noise on the cable and to drop of voltage due to cable
resistance.
Disadvantages:
- Low output signal from the strain-gauge bridge, very high amplifier gain and,
consequently, high sensitivity to the electrical disturbances of the signal before
amplification reduce the potential resolution.
In fact: excitation of the bridge (at zero load) =V=RI = 350 · 3 · 10-3 = 1,05 V;
when, R= bridge resistance = 350 Ohm; I= 3mA (see Note below)
From which: bridge output signal = 2 · 1,05 = 2,1mV FS
against 2 · 10 = 20 mV/FS of the -A1 amplifier) (about 10 times less).
- Limitation on the choice of the further electronics.
Note: the total circuit at zero load is 4mA of which about 3 mA for the
bridge and about 1 mA for the internal current amplifier.

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8.3 ELECTRICAL CONNECTION OF AMPLIFIED LOAD CELLS:
The table lists the colours of the leads of the cable and the numbers of the pins of the
connector.
The amplified load cells are supplied by cable excepted the Series AP 7000 (models with 10
up to 100tons FS), 500QDT, 560QDT, LD, LT and LCR 200 that can be supplied also with
connector.
In order to maintain the greatest protection against electromagnetic disturbances, in relation
to CE mark, for the amplified load cells is duty for the User/Installer the grounding of the
cable screen toward the electronic side and the grounding of the metallic body of the load
cell.
Load cells with built-in analog amplifier (outputs 0 to ±5V and 0 to ±10V)
Meaning Black sheath cable Grey sheath D N47100 cable Connector
Common Black Brown 4
+ Power supply Red Green 1
+ Signal White White 2
Load cells with built-in analog amplifier (outputs 4-20mA)
Meaning Black sheath cable Grey sheath D N47100 cable Connector
Common Black Brown 4
+ Power supply Red Green 1
+ Signal Red Green 1
8.4 ZERO AND GAIN REGULATIONS:
8.4.1 Important: the gain (= span) regulation is done at the final test by DS Europe and it
cannot be regulated by the Customer.
A regulation of it changes the values of sensitivity and of calibration listed on the
"final test certificate" enclosed with the cell.
8.4.2 Wait for a warm-up period of, at least, 30 minutes before doing the regulation of the
zero and the further use of the cell.
8.4.3 The regulations of "zero" and of "gain" are by multi turn potentiometers (=
trimmers); they are reachable by screwed holes on the body of the cell, protected by
a sealing screw. (Remember the point 8.4.1).
8.4.4 The amplifier and the potentiometers are immersed in silicon gel, which is not an
handicap for the regulation. For the regulation, a screwdriver (with shank: 1,5÷2
mm) bores the gel which, by itself, closes again when the screwdriver is pulled out.