Siemens SIMATIC PG 760 PII Manual page 104

Guidelines for Handling Electrostatically-Sensitive Devices (ESD)
A.1 What is ESD?
Definition All electronic modules are equipped with large-scale integrated ICs or
components. 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
voltages 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 results in total damage only after a prolonged period of operation.
A-2
PG 760 PII Programming Device
C79000-G7076-C766-01