Siemens SIMATIC S5-90U, Системное руководство

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S5-90U/S5-95U Active and Passive Faults in Automation Equipment/ESD Guidelines
Electrostatic charging of objects and persons
Every object with no conductive connection to the electrical potential of its surroundings can be
charged electrostatically. In this way, voltages up to 15000 V can build up whereas minor charges,
i.e. up to 100 V, are not relevant.
Examples:
• Plastic covers up to 5000 V
• Plastic cups up to 5000 V
• Plastic-bound books and notebooks up to 8000 V
• Desoldering device with plastic parts up to 8000 V
• Walking on plastic flooring up to 12000 V
• Sitting on a padded chair up to 15000 V
• Walking on a carpet (synthetic) up to 15000 V
Limits for perceiving electrostatic discharges
An electrostatic discharge is
• perceptible from 3500 V
• audible from 4500 V
• visible from 5000 V
A fraction of those voltages is capable of destroying or damaging electronic devices.
Carefully note ad apply the protective measures described below to protect and prolong the life of
your modules and components.
General protective measures against electrostatic discharge damage
• Keep plastics away from sensitive devices. Most plastic materials have a tendency to build up
electrostatic charges easily.
• Make sure that the personnel, working surfaces and packaging are sufficiently grounded when
handling electrostatic sensitive devices.
• If possible, avoid any contact with electrostatic sensitive devices. Hold modules without touching
the pins of components or printed conductors. In this way, the discharged energy cannot affect
the sensitive devices.
EWA 4NEB 812 6115-02b
D-3