Electro-Magnetic Interference (Emi) - Siemens MICROMASTER Eco Reference Manual

EMC
ELECTRO-MAGNETIC
INTERFERENCE (EMI)
The inverters are designed to operate in an
environment where a high level of Electro-
Magnetic Interference (EMI) can be expected.
Usually, good installation practices will ensure
safe and trouble-free operation. If there are any
problems, the following guidelines may prove
useful. In particular, grounding of the system at
the inverter, as described below, may prove
effective. The figures at the end of this section
illustrate how filters should be installed and
connected.
• Ensure that all equipment in the cubicle is well
earthed using short, thick earthing cable
connected to a common star point or busbar.
It is particularly important that any control
equipment (such as a BMS), that is connected
to the inverter is also connected to the same
earth or star point as the inverter via a short,
thick link. Flat conductors (e.g. braids or
metal brackets) are preferred as they have
lower impedance at high frequencies.
Connect the return earth from motors
controlled by the inverter directly to the earth
connection (PE) on the associated inverter.
• On the MIDIMASTER Eco, use saw-tooth
washers when mounting the inverter and
ensure that a good electrical connection is
made between the heatsink and the back
panel, removing paint if necessary to expose
bare metal.
• Wherever possible, use screened leads for
connections to the control circuitry. Terminate
both the ends of the cable neatly, ensuring
that unscreened wires are as short as
possible. Use cable glands whenever
possible and earth both ends of the screen on
the control cable.
• Separate the control cables from the power
connections as much as possible, using
separate trunking, etc. If control and power
cables need to cross, arrange the cables so
that they cross at 90° if possible.
• Ensure that contactors in the cubicle are
suppressed, either with R-C suppressors for
AC contactors or 'flywheel' diodes for DC
12-6
contactors, fitted to the coils. Varistor
suppressors are also effective. This is
particularly important if the contactors are
controlled from the output relay on the
inverter.
• Use screened or armoured cables for the
motor connections and ground the screen at
both ends via the cable glands.
• If the drive is to be operated in an Electro-
magnetic noise-sensitive environment, the RFI
filter should be used to reduce the conducted
and radiated interference from the inverter.
For optimum performance, there should be a
good conductive bond between filter and
metal mounting plate.
On no account must safety regulations be
compromised when installing inverters!
ECO REFERENCE MANUAL