NSG 438
7
3.3.
Effects on the EUT
The most significant interference components of an electrostatic discharge are
of a high frequency nature. The interference paths and effects have to be
assessed in the range from about 30MHz to multi-GHz.
The extremely rapid rise time of a discharge affects an object under test
mostly through:
§
magnetic HF-coupling between electrical conductors in the
electronics and the discharge current path.
§
electrical coupling between the discharge current and signal
lines. A discharge current to the EUT flows proportionally through
all the associated conductors (earth, mains, data lines,
screening, etc.) according to their relative impedance.
Malfunctions in insufficiently immune electronic equipment and systems
make themselves apparent through:
§
program crashes
§
blocking of command sequences
§
incorrect commands, statuses or data being further processed
§
partial system resets (e.g. only in peripheral modules, which lead
to errors that the system does not recognize)
§
disturbance or destruction of interface modules
§
destruction of insufficiently protected MOS components.
ESD (electrostatic discharge) testing usually shows up all the weak spots
in the HF-range of a piece of equipment simultaneously. The uses to which
the NSG 438 ESD simulator can be put hence go way beyond those called
for in standard-conform applications.
This instrument provides the engineer with a means to detect sources of
error caused by unsuitable earthing, poor ground connections, insulation
problems, etc.
The generator also serves as a reliable aid for localizing hidden wiring
faults during acceptance trials on installations.
Use can also be made of the instrument as an insulation tester to
determine the breakdown voltage of switches, relay contacts, insulators,
etc.
