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9.1.9 Solutions to Common EMC Interference Problems
AC drive generates very strong interference. Although EMC measures are taken, interference
may still exist due to improper cabling or grounding during use. When AC drive interferes with
other devices, adopt the following solutions.
Interference Type Solution
Leakage
protection switch
tripping
● Reduce carrier frequency.
● Shorten length of the AC drive cables.
● Wind ferrite core around the drive input cable except PE cable.
● For tripping at the moment of power-on, cut off the large capacitance
to ground on power input side by disconnecting grounding terminal
of external or built-in lter and disconnecting grounding terminal of Y
capacitance to ground of input terminals.
● For tripping during drive running or when drive enabled, take leakage
current suppression measures (install a leakage current lter, install
safety capacitor + wind ferrite core).
AC drive
interference
during running
● Connect motor housing to PE of AC drive.
● Connect PE of AC drive to PE of grid.
● Wind power input cable with ferrite core.
● Add a safety capacitor or ferrite core to interfered signal terminal.
● Add an extra common ground.
Communication
interference
● Connect motor housing to PE of AC drive.
● Connect PE of AC drive to PE of grid.
● Wind power input cable with ferrite cores.
● Add a matching resistor between communication cable source and load.
● Add a common grounding cable besides communication cable.
● Use a shielded cable as communication cable and connect cable shield to
common grounding point.
● Adopt daisy chain mode for multi-node communication and reserve
branch length of less than 30 cm.
I/O interference ● Enlarge capacitance at low-speed DI. A maximum of 0.11 uF capacitance
is suggested.
● Enlarge capacitance at AI. A maximum of 0.22 uF is suggested.
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