Siemens PC 870 - Manual (Page 45)

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SIMATIC Panel PC 670 / 870 Operating Unit, Equipment Manual
Edition 07/01
Appendix B: ESD Guidelines
What does ESD mean?
Virtually all present-day modules incorporate highly integrated MOS devices or
components. Due to the technologies used, these electronic components are very
sensitive to overvoltages and consequently therefore to electrostatic discharge:
These devices are referred to in German as Elektrostatisch Gefährdeten
Bauelemente/Baugruppen: EGB.
The more frequent international designation is:
ESD (Electrostatic Sensitive Device).
The following symbol on plates on cabinets, mounting racks or packages draws
attention to the use of electrostatic sensitive devices and thus to the contact sensi-
tivity of the assemblies concerned:
ESDs may be destroyed by voltages and energies well below the human percep-
tion threshold. Voltages of this kind occur as soon as a device or an assembly is
touched by a person who is not electrostatically discharged. Devices exposed to
such overvoltages cannot immediately be detected as defective in the majority of
cases since faulty behavior may occur only after a longer period of operation.
Precautions against electrostatic discharge
Most plastics are capable of carrying high charges and it is therefore imperative
that they be kept away from sensitive components!
When handling electrostatic sensitive devices, make sure that persons, workplaces
and packages are properly grounded!
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