Siemens SIMATIC Rack PC 840 Manual page 176

Guidelines for Handling Electrostatic
A.1 What Does ESD Mean?
Definition
All electronic components are equipped with high-integrated modules or
components. Conditioned by their technology, these electronic components are
extremely sensitive to overvoltages and therefore to discharges of static
electricity.
The short term ESD has been adopted for these Electrostatic Sensitive Devices/
modules.
Electrostatic sensitive modules are identified by the following symbol:
Caution
!
Electrostatic sensitive devices can be destroyed by voltages which are far below
the limit of perception of human beings. These voltages occur when you touch a
component or the electrical connections of a module without being
electrostatically discharged. The damage which arises in a module as a result of
overvoltage cannot usually be detected immediately, but only becomes apparent
after a lengthy operating period.
A-2
SIMATIC Rack PC 840 Manual
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