Guidelines For Handling Electrostatically Sensitive Devices - Siemens SIMATIC S5 TD 390 Manuel

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Guidelines for Handling Electrostatically Sensitive Devices

(ESD)
What is ESD?
VSLI chips (MOS technology) are used practically all
SIMATIC/TELEPERM modules. These VSLI components are, by their
nature, very sensitive to overvoltage and thus to electrostatic discharge:
They are therefore defined as
Electrostatically Sensitive Devices: "ESD".
ESD is the abbreviation used internationally.
The following warning label on the cabinets, subracks and packing
indicates that electrostatically sensitive components have been used and
that the modules concerned are susceptible to touch:
ESDs can be destroyed by voltage and energy levels which are far below
the level perceptible to human beings. Such voltages already occur when
a component or a module is touched by a person who has not been
electrostatically discharged. Components which have been subjected to
such overvoltages cannot, in most cases, be immediately detected as
faulty; the fault occurs only after a long period in operation.
An electrostatic discharge
– of 3500 V can be felt
– of 4500 V can be heard
– must take place at a minimum of 5000 V to be seen.
Just a fraction of this voltage can already damage or destroy an electric
component.
TD 390
C79000–A8576–C292–01
Tables and Technical Data
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