The Right Lead for Your Force Measurement

Measuring cables are an essential part of the measuring chain and have a significant influence on the accuracy of the result. Also, potential interferences, such as EMC interferences from electronic devices, inverters or electric motors, play an important role.

The output signal of a strain gauge bridge is principally small: Typically, strain gauges have an output of 2 mV / V; 4 mV / V versions are also available (e.g., U10M and C10 from HBM). Usually, 5 volts are applied as the supply voltage, in order that 10 mV (or 20 mV for sensors with a high output signal) are available when the measuring range is fully utilized. With modern electronics, measurement uncertainties - depending on the environmental conditions - can be measured which are far below 0.1%. From this follows that the small signal needs to be protected by the influences of the electromagnetic environment.

For many years, HBM has been operating an accredited EMC laboratory in which the behavior of force transducers under the influence of electromagnetic fields is checked.

Measures for higher EMC stability

In order to achieve a high standard, the shield of the sensor cable is galvanically connected to the transducer and the measuring amplifier cage. A Faraday cage is formed, and all components of the measuring chain are shielded. In cases where particularly strong electromagnetic fields occur, HBM offers a double shielded cable (Type 139B), which is particularly resistant to interferences.

Accurate work is essential when installing cables. Therefore, a thoroughly cleaning to remove flux residues, the safe shielding of high-frequency interfering signals and flawless soldering joints must be ensured. The installation of the cables follows a detailed work guideline which guarantees EMC safety and high production standards. These measuring leads ensure reliable results in every environment.

In addition to the EMC stability, other technical qualities are important:

  • The cables should be low in capacitance to minimize capacitive crosstalk.
  • The capacitive characteristics of the cables and the insulation characteristics should change as little as possible with the temperature in order that the cable does not have any (or as little as possible) influence on the temperature-dependent measuring properties.
  • If the cables are used on drag chains, they must be mechanically robust.
  • An important requirement is that the cables are stable against common operating materials in the environment of the measurement. This applies particularly to oils that are present in applications near a hydraulic system.
  • Finally, it is important that for small forces a relatively flexible cable is used. Otherwise, the movements of the cable may require forces that are measured even though they are not linked to the process.

HBM measuring cables fulfill most of the features, but no cable can cover all demands completely. For instance, a double-shielded cable can be used for stiffer constructions but is not suitable for drag chains or for the use with small sensors.

 

How do I find the right cable for my force measurement?

There is always a solution for higher temperatures, high demands on precision or even for applications where mechanically very robust cables are required. For this reason, HBM has given the leads for force measurement a new structure:

  • HBM installs the cables and connectors according to the requirements of low susceptibility to interference
  • Solutions are available for all load cells and amplifier systems
  • Three cables with different characteristics provide solutions for almost any measurement task in any environmental condition

Every chain is only as strong as the weakest link! Therefore, the individual components are described precisely in the data sheet. In order to help you with selecting the correct cable, we are happy to consult with you in person.

Cable types K-CAB-F:

Standard cable

Robust measuring cable that is temperature and chemical resistant and has excellent metrological properties. 

  • Up to 85 °C
  • Suitable for use outdoors
  • Highly resistant to machine oils, oil emulsions, seawater, diluted lyes and ozone

Paired shielded cable

Double shielded measuring lead with excellent capacitive symmetry for highly accurate measurements.

  • Suitable for reference measurement tasks and large distances
  • High TF and temperature change
  • Not suitable for drag chains and applications where the cable is moved continuously
  • Lyes, acids and salt water resistant

Highly flexible measuring cable

Highly flexible measuring lead with minimal outside diameter, suitable for mobile use with low force shunt.

  • Only suitable for certain high-precision measurements and only recommended if very low forces are to be measured at stable temperatures and low carrier frequencies
  • Suitable for use outdoors
  • Resistant to a lot of machine oils, oil emulsions, saline water, seawater, diluted lye and ozone
     

Technical Documentation K-CAB-F

Related Products

U10 Force Sensor. Very precise and rugged
Sensor with high bending moment for dynamic and static measurement tasks.
C15 Reference Force Transducer
Extremely precise reference force sensor with a high output signal. Measuring range: 10 to 100 % of its capacity. Class 00 per ISO376.
KDB Force Transducer (EN12390)
KDB special force transducer for verifying testing machines for building materials. EN 12390 compliant. Can be used as a transfer standard up to 3 MN.