Siemens SIMATIC RF300 System Manual page 118

Planning the RF300 system
4.6 Guidelines for electromagnetic compatibility (EMC)
Relay coils
Contactors
Figure 4-14
Note
Suppressing interference sources
Suppress all coils in the cabinet. Make sure to include valves and motor brakes. Make sure that
you test fluorescent lamps in the control cabinet separately.
4.6.7 Electrostatic discharges
This section describes how electrostatic discharges typically occur in RFID and how you can avoid
them.
Plastic is increasingly being used in both conveyor systems and transport units. The risk of
electrostatic charging has therefore increased.
Electrostatic discharge (ESD) occurs as a result. This is caused by the transfer of electrical charge
between bodies of different electrostatic potential. The cause of the potential difference is
usually a charge arising from frictional electricity.
4.6.7.1 Generation/formation
A widespread cause of electrostatic charge generation/formation is frictional electricity. This
occurs when two materials with different potential differences rub against each other. Electrons
are transferred from one of the material to the other in the process. A classic example of this is
when a balloon is rubbed on a person's hair, which causes the hair to become electrostatically
charged and to stand up. But electrostatic charges also occur when walking across a carpeted
floor due to the friction between the shoe soles and the carpet. In industry, the effect often
occurs in conveyor systems, e.g. when plastic pallets are transported over a roller conveyor.
The diagram below shows that the formation and level of electrostatic charge depends on the
materials and the ambient conditions (relative humidity). A combination of synthetic fibers and
dry atmosphere particularly promotes charging.
118
Suppression of inductance
Valves
Brakes
System Manual, 02/2021, C79000-G8976-C345-09
SIMATIC RF300