Atec Haefely-AXOS Series - Manual (Page 3)

3 Expandable Test Systems
THE STANDARDS
IEC/EN 61000-4-5 Surge Combination Wave 1.2/50µs...8/20µs
Surge events can be generated by lightning phenomena, switching transients or the
activation of protection devices in the power distribution system. A surge itself is
influenced by the propagation path taken so that impulses from the same event may
have different forms depending upon where a measurement is taken. Combination
Wave Generators (CWG) simulate a surge event in power lines close to or within
buildings. Mostly the disturbances are tolerable because they are single events.
IEC/EN 61000-4-4 Electric Fast Transients, EFT/Burst
Industrial measurement and control equipment nearly always use conventional
control units containing relays or other electro-mechanical switching devices.
Fluorescent lamp ballast units, insufficiently suppressed motors (hair dryers, vacuum
cleaners, drills, etc.) are found everywhere in the public power supply. All of these are
primarily inductive loads which generate interference when switched on or off. EFT
events, can cause microprocessor units to malfunction or reset, with corresponding
disruption to normal operation.
IEC/EN 61000-4-11 Voltage Dips and Interrupts
Voltage failures occur following switching operations, short-circuits, response of
fuses and when running up heavy loads. The quality of the electrical power supply is
increasingly becoming a central topic of discussion. The interference sources in the
mains, caused by electronic power control with non-linear components e.g. thyristors
are used more frequently in domestic appliances such as hotplates, heating units,
washing machines, television sets, economy lamps, PCs and industrial systems with
speed-controlled drives.
IEC/EN 61000-4-9 Pulsed Magnetic Field
Under normal operating conditions, an AC current generates a steady magnetic field
so that equipment, such as monitors, close to AC power lines could suffer interference.
Under fault conditions, a sudden high current level can result in a short duration ma-
gnetic field. Lightning strokes or short circuit fault currents in the power network can
generate high level short duration magnetic fields.