What Is Esd - Siemens SIMATIC ET 200L Manual

Guidelines for Handling Electrostatically Sensitive Devices (ESD)
C.1

What is ESD?

Definition All electronic modules are equipped with large-scale integrated ICs or com-
ponents. Due to their design, these electronic elements are very sensitive to
overvoltages and thus to any electrostatic discharge.
These Electrostatically Sensitive Devices are commonly referred to by the
abbreviation ESD.
Electrostatically sensitive devices are labeled with the following symbol:
Caution
!
Electrostatically sensitive devices are subject to voltages that are far below
the voltage values that can still be perceived by human beings. These volt-
ages are present if you touch a component or the electrical connections of a
module without previously being electrostatically discharged. In most cases,
the damage caused by an overvoltage is not immediately noticeable and re-
sults in total damage only after a prolonged period of operation
C-2
.
ET 200L Distributed I/O Device
EWA-4NEB 780600902-05