Emc; Emission - Zapi EPS-AC0 SWs&ENC User Manual

7.9 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 the lengths and the
paths of the electric connections and the shields. This situation is beyond
ZAPI's control. Zapi can offer assistance and suggestions, based on its years
experience, on EMC related items. 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 represents the studies and the
tests on the electromagnetic energy generated or received by an electrical device.
Emission refers to the energy radiated from the controller and the harness.
Immunity can be divided in two main branches: rejection from external
electromagnetic fields and from electrostatic discharges (ESD).
So the analysis works in three directions:

1) Emission

2) Electromagnetic Immunity
3) ESD rejection.
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When possible it is strongly recommended preventing Emission and Immunity
problems by locating the controllers inside a metallic enclosure. In most
cases, a truck with a metallic enclosure will avoid EMC problem.
7.9.1 Emission
Emission refers to the electromagnetic disturbances that the device generates in
the surrounding space. Countermeasure should be adopted to prevent the
propagation of those disturbances. We talk about "conduction" issues when guiding
structures such 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 which are working at high frequency and generate RF
energy. Wires and cables are responsible for the spreading of this RF
disturbance because they works as antennas, so a good layout of the cables and
their shielding can solve the majority of the emission problems.
Three ways can be followed to reduce the emissions:
1) SOURCE OF EMISSIONS: finding the main source of disturbs and works on it.
2) SHIELDING: enclosing contactor and controller in a shielded box; using
shielded cables.
3) 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 frame is
generally a suggested not expensive solution to reduce the emission level.
AEMZP0EA - EPS-AC0 SWs&ENC - User Manual Page - 33/95