Sirona Dental Systems Gmbh - Sirona orthophos xg 3 Operating Instructions Manual

2 Safety information
2.17 Electrostatic discharge
16
Physics of electrostatic charges
An electrostatic discharge requires prior electrostatic charging.
There is a danger of electrostatic charges building up whenever two
bodies rub against each other, e.g. when:
● walking (soles of shoes against the floor) or
● moving (chair casters against floor).
The amount of charge depends on several factors: The charge is:
● higher at low air humidity than at high air humidity, and
● higher with synthetic materials than with natural materials (clothing,
floor coverings).
The following rule of thumb can be applied to assess the transient
voltages resulting from an electrostatic discharge.
An electrostatic discharge is:
● perceptible at 3,000 V or higher
● audible at 5,000 V or higher (cracking, crackling)
● visible at 10,000 V or higher (arc-over)
The transient currents resulting from these discharges have a magnitude
of over 10 amps. They are not hazardous for humans because they last
for only several nanoseconds.
Tip: 1 nanosecond = 1/1,000,000,000 second = 1 billionth of a second
Voltage differentials exceeding 30,000 volts per centimeter may lead to a
charge transfer (electrostatic discharge, lightning, arc-over).
Integrated circuits (logical circuits and microprocessors) are used in order
to implement a wide variety of functions in a device. 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. Integrated circuits that are
connected to wires leading externally are therefore particularly at risk
from electrostatic discharge.
Even voltages that are imperceptible to the user can cause breakdown of
the structures, thus leading to a discharge current that melts the chip in
the affected areas. Damage to individual integrated circuits may cause
malfunction or failure of the unit.

Sirona Dental Systems GmbH

Operating Instructions ORTHOPHOS XG 3
60 50 681 D3352
D3352.201.05.18.02 04.2016