Zapi DUALACE2 NEW GENERATION User Manual page 60

The second type of immunity, to ESD, concerns the prevention of the effects
of electric current due to excessive electric charge stored in an object. In fact,
when a charge is created on a material and it remains there, it becomes an
"electrostatic charge"; ESD happens when there is a rapid transfer from one
charged object to another. This rapid transfer has, in turn, two important
effects:
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It is always much easier and cheaper to avoid ESD from being generated, rather
than increasing the level of immunity of the electronic devices.
There are different solutions for EMC issues, depending on the required level of
emissions/ immunity, the type of controller, materials and position of the wires
and electronic components.
1) EMISSIONS. Three ways can be followed to reduce the emissions:
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2) ELECTROMAGNETIC IMMUNITY. The considerations made for emissions
are valid also for immunity. Additionally, further protection can be achieved
with ferrite beads and bypass capacitors.
3) ELECTROSTATIC IMMUNITY. Three ways can be followed to prevent
damages from ESD:
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This rapid charge transfer can determine, by induction, disturbs on the
signal wiring thus causing malfunctions; this effect is particularly critical in
modern machines, with serial communications (CAN bus) which are
spread everywhere on the truck and which may carry critical information.
In the worst case and when the amount of charge is very high, the
discharge process can determine failures in the electronic devices; the
type of failure can vary from a temporary malfunction to a definitive
failure of the electronic device.
SOURCE OF EMISSIONS: finding the main source of disturb and work
on it.
SHIELDING: enclosing contactor and controller in a shielded box; using
shielded cables;
LAYOUT: a good layout of the cables can minimize the antenna effect;
cables running nearby the truck frame or in iron channels connected to
truck frames are generally a suggested not expensive solution to reduce
the emission level.
PREVENTION: when handling ESD-sensitive electronic parts, ensure the
operator is grounded; test grounding devices on a daily basis for correct
functioning; this precaution is particularly important during controller
handling in the storing and installation phase.
ISOLATION: use anti-static containers when transferring ESD-sensitive
material.
GROUNDING: when a complete isolation cannot be achieved, a good
grounding can divert the discharge current trough a "safe" path; the
frame of a truck can works like a "local earth ground", absorbing excess
charge. So it is strongly suggested to connect to truck frame all the parts
of the truck which can be touched by the operator, who is most of the
time the source of ESD.
AFNZPxxx – DUALACE2 NEW GENERATION – User Manual