Small Component, Big Impact
How earthing straps improve the electromagnetic compatibility of machines and systems
Whether it concerns the design of control cabinets in machine and plant construction, the conception of industrial robots or automation technology: electromagnetic compatibility (EMC) is becoming increasingly important across all sectors. The reason: electrical machines are built to be more and more compact, they are working in closer proximity to each other and finally, they are performing increasingly complex tasks. As a result, the amount and speed of data being transmitted via the cabling is increasing as well as the required frequencies. This produces magnetic fields which in turn cause interference currents and voltages - so-called EMC interference. Error messages, problems with data transmission and even machine failures can be the consequences.
To prevent this, designers of machines and plants develop customised earthing concepts. The discharge of unwanted currents and voltages is intended to minimise magnetic fields and ensure a failure-free operation. One small, inconspicuous component is particularly important for this: the earth strap. It consists of a braid of copper wires and connects machine and system parts where magnetic fields can arise with a reference potential. This allows currents and voltages to flow away easily without affecting the EMC of the installation.
An earth strap must meet the following requirements:
- High current carrying capacity
- Low resistance and low impedance
- Mechanical strength
Due to their shape, the flat earth straps in many cases are more suitable than round conductors. They can easily be installed in tight machine housings, are flexible and resistant to tension, torsion and vibration. Earth straps are also used in the automotive industry - and even in aerospace: in 2008, for example, the launch of an Ariane rocket was postponed by one day specifically to check the earth straps inside the space shuttle. This demonstrates how important these small components are.