Zapi COMBI AC0, Руководство пользователя

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simulate external undesired disturbances and verify the electronic devices
response.
3) The second type of immunity,
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 happen when there is a rapid transfer from a
charged object to another. This rapid transfer has, in turn, two important
effects:
-
this rapid charge transfer can determine, by induction, disturbs on the
signal wiring and thus create malfunctions; this effect is particularly
critical in modern machines, with serial communications (canbus) which
are spread everywhere on the truck and which carry critical informations.
- 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 an intermittently malfunction to a completely
failure of the electronic device.
U
IMPORTANT NOTE: it is always much easier and cheaper to avoid ESD
from being generated, than to increase the level of immunity of the
electronic devices.
There are different solutions for EMC issues, depending on level of emissions/
immunity required, the type of controller, materials and position of the wires and
electronic components.
4)
EMISSIONS
. Three ways can be followed to reduce the emissions:
A) SOURCE OF EMISSIONS: finding the main source of disturb and work
on it.
B) SHIELDING: enclosing contactor and controller in a shielded box; using
shielded cables;
C) 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 is generally a suggested not expensive solution to reduce
the emission level.
5)
ELECTROMAGNETIC IMMUNITY
. The considerations made for emissions
are valid also for immunity. Additionally, further protection can be achieved
with ferrite beads and bypass capacitors.
6)
ELECTROSTATIC IMMUNITY
. Three ways can be followed to prevent
damages from ESD:
A) 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.
B) ISOLATION: use anti-static containers when transferring ESD-sensitive
material.
C) GROUNDING: when a complete isolation cannot be achieved, a good
grounding can divert the discharge current trough a “safe” path; the