2-25
2-2 Wiring
2
Design
You can achieve highest filter installation quality by considering:
Lowest impedance to ground: Connecting it with a grounding conductor of the lowest impedance
or parallel/multiple short ground connections if not possible. The cross section of each single pro-
tective conductor terminal must be designed for the required nominal load.
Avoid ground loops: Conductor loops act like antennas, especially when the encompass large
areas. Consequently: (1) Avoid unnecessary conductor loops and (2) Avoid parallel arrengement of
"clean" and interference-prone conductors over longer distances.
Use EMC filters only in grounded systems: The line filters have been developed for use in
grounded systems. Use of the line filters in ungrounded systems or locations without proper ground
quality is not recommended, beacuse in these applications: (1) Low current to ground increases, (2)
The effect of the filter is reduced and (3) The amount of line-conducted and radiated interference
increases in proportion to elementary frequency in frequency inverter.
Consider motor cable length: The amount of line-conducted interference also increases as motor
cable length increases. Output chokes may be required to countermeasure this effect.
Disconnect internal RFI filter: Always when using external mount EMC filter make sure internal
filter is disabled (figure corresponds to a 400V, 55kW case.)
Minimizing radiated interference
The 3G3RX frequency inverters meet the limits of EN61800-3, C1/C2/C3, for radiated interference,
if the specified line filter is used and installation is performed according to our instructions, and
internal line filter is disabled. Installing inverters only with integrated filters will achieve a limited C3
class category, of application in a limited range of systems, and with limited cable lengths and
allowable carrier frequencies.
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