Zapi ACE0 2mC, User Manual

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Page – 42/155 AF6ZP0CA – COMBIAC0 & ACE0 2uC – User Manual
5.3 EMC
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EMC and ESD performances of an electronic system are strongly
influenced by the installation. Special attention must be given to lengths,
paths and shielding of the electric connections. These aspects are beyond
of Zapi control. Zapi can offer assistance and suggestions on EMC related
problems, basing on its long experience. However, ZAPI declines any
responsibility for non-compliance, malfunctions and failures, if correct
testing is not made. The machine manufacturer holds the responsibility to
carry out machine validation, based on existing norms (EN12895 for
industrial truck; EN50081-2 for other applications).
EMC stands for Electromagnetic Compatibility, and it deals with the
electromagnetic behavior of an electrical device, both in terms of emission and
reception of electromagnetic waves that may cause electromagnetic interference
with the surrounding electronics or malfunctions of the device itself.
So the analysis works in two directions:
1) The study of the emission problems, the disturbances generated by the
device and the possible countermeasures to prevent the propagation of that
energy. We talk about “conduction” issues when guiding structures such as
wires and cables are involved, “radiated emissions” issues when it is studied
the propagation of electromagnetic energy through the open space. In our
case the origin of the disturbances can be found inside the controller with the
switching of the MOSFETs at high frequency which can generate RF energy.
However wires have the key role to propagate disturbs because they work as
antennas, so a good layout of the cables and their shielding can solve the
majority of the emission problems.
2) The study of the immunity can be divided in two main branches: protection
from electromagnetic fields and from electrostatic discharge. The
electromagnetic immunity concerns the susceptibility of the controller with
regard to electromagnetic fields and their influence on the correct work made
by the electronic device. There are well defined tests which the machine has
to undergo. These tests are carried out at determined levels of
electromagnetic fields, simulating external undesired disturbances and
verifying the response.
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:
-
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.