Zapi COMBI AC1 User Manual page 21

switching of the mosfets which are working at high frequency and genera
RF energy, but wires and cables have the key role to propagate the
disturbs because they works as antennas, so a good layout of the
and their shielding can solve the majority of the emission problems.
2) The study of the immunity can be divided in two main branch
from electromagnetic fields and from electrostatic discharge.
The electromagnetic immunity concern the susceptibility of the controller
with regard to electromagnetic f
made by the electronic device.
There are well defined tests which the machine has to be exposed to.
These tests are carried out at determined levels of electromagnetic fields, to
simulate ex
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 a
"electrostatic charge"; ESD happen when there is a rapid transfer from a
charged
effects:
-
-
IMPORTANT NOTE: it is always much easier and cheaper to avoid ESD from
b eing 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 ty
e lectronic components.
1 ) EMISSIONS. Three ways can be followed to reduce the emissions:
A)
B)
C)
2) ELECTROMAGNETIC IMMUNITY. The considerations made for emissions
are valid also for immunity. Additionally, fu
with ferrite beads and bypass capacitors.
AEQZP0BA – COMBI AC1 - User Manual
ternal undesired disturbances and verify the electronic devices
object to another. This rapid transfer has, in turn, two important
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 spre ad 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
failure of the electronic device.
pe of controller, materials and position of the wires and
SOUR CE OF EMISSIONS: finding the main source of disturb and work
on it.
SHIELDING: enclo sing 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 is gene
the emission level.
ields and their influence on the correct work
intermittently malfunction to a completely
rally a suggested not expensive solution to reduce
rther protection can be achieved
te
cables
es: protection
n
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