2 Safety instructions
2.2 Electrostatic charge
Dentsply Sirona
Operating Instructions Primescan Connect
16
67 97 216 D3801
D3801.201.01.03.02 2022-09
ESD protective measures
ESD protective measures include:
● Procedures for preventing electrostatic charge build-up (e.g. air
conditioning, air moistening, conductive floor coverings and non-
synthetic clothing)
● Discharging the electrostatic charges of your own body on the frame
of the UNIT, the protective ground wire or large metallic objects
● Connecting yourself to ground using a wrist band.
Training
We therefore recommend that all persons working with this system be
instructed on the significance of this warning label. Furthermore, they
also should receive training in the physics of electrostatic discharges
which can occur in the practice and the destruction of electronic
components which may result if such components are touched by
electrostatically charged USERS.
The content of this training is explained in the Chapter "About the
physics of electrostatic charges".
2.2.3
About the physics of electrostatic charges
What is an electrostatic charge?
An electrostatic charge is a voltage field on and in an object (e.g. a
human body) which is protected against conductance to ground
potential by a nonconductive layer (e.g. a shoe sole).
Formation of an electrostatic charge
Electrostatic charges generally build up whenever two bodies are
rubbed against each other, e.g. when walking (shoe soles against the
floor) or driving a vehicle (tires against the street pavement).
Amount of charge
The amount of charge depends on several factors:
Thus the charge is higher in an environment with low air humidity than
in one with high air humidity; it is also higher with synthetic materials
than with natural materials (clothing, floor coverings).
Electrostatic discharge must be preceded by electrostatic charging.
The following rule of thumb can be applied to assess the transient
voltages resulting from an electrostatic discharge.
An electrostatic discharge is:
● perceptible at 3000 V or higher
● audible at 5000 V or higher (cracking, crackling)
● visible at 10000 V or higher (arc-over)
The transient currents resulting from these discharges have a
magnitude of 10 amperes. They are not hazardous for humans because
they last for only several nanoseconds.
Background
Integrated circuits (logical circuits and microprocessors) are used to
implement a wide variety of functions in dental/X-ray/CAD/CAM
systems.
The circuits must be miniaturized to a very high degree in order to
include as many functions as possible on these chips. This leads to
structure thicknesses as low as a few ten thousandths of a millimeter.
