Overload Protection - Siemens SIWAREX WL230 Operating Instructions Manual

3.4

Overload protection

NOTICE
Irreparable faults and damage to the load cells
If load cells are used beyond the maximum working load or the maximum transverse load, this
can cause irreparable faults and even fracturing of the load cell or the compact mounting unit.
● When using load cells with small rated loads, always provide overload protection in order
Overload protection in the measuring direction
You protect load cells against vertical overload by placing a stop screw under the point where
force is introduced. The stop screw limits the measuring path of the load cell.
For load cells with high rated loads, the risk of an unintentional overload is not as great. Take
into consideration possible additional loads when dimensioning the load cells.
Another method for protecting load cells from an overload is to over-dimension the load cells.
Overload protection in the transverse direction
For the load cells with a load foot, the weight force is introduced into the load cells via bearing
surfaces. Up to a certain degree, these bearing surfaces allow lateral movement of the load
bearing implement or a change in its length as a result of expansion due to heat. They generate
a restoring force corresponding to the deflection, which re-centers the load bearing implement.
This freedom of movement is desired and necessary for accurate weighing.
If the transverse force is so great that it exceeds the restoring force of the bearing unit and thus
the deflection limit, appropriate protective measures are required. Pendulum limiters or guide
elements are suitable for this, for example.
Set the pendulum limiters in such a way that the maximum deflection is not exceeded in any
direction. The figure below shows the overload protection in the transverse direction using two
examples.
Figure 3-2
BB-S SA
Operating Instructions, 03/2020, A5E47358100-AA
to protect the load cells from becoming damaged. You need overload protection for both
the measuring direction and the transverse direction.
Pendulum limitation with a maximum deflection of 4 mm as exemplified by two weighing
platforms
Application planning
3.4 Overload protection
15