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Installation 2-19
IQ 2000/5000 Installation Manual
AC Line Filter Selection
Selection of the proper filter is only the first step in reducing conducted emissions. Correct filter
installation is crucial to achieving both EMI attenuation and to ensure safety. All of the following
guidelines should be met for effective filter use.
1. The filter must be mounted close to the drive input terminals. This is particularly
important for higher frequency emissions (5-30 MHz). If the distance exceeds 600 mm (2
ft), then a strap should be used to connect the ground between the drive and filter,
rather than a wire.
2. The wires connecting the AC source to the filter should be shielded from, or at least sep-
arated from other high power cables (i.e. connection between the drive and the filter,
motor power cable, etc.). If the connections are not segregated from each other then the
EMI on the drive side of the filter can couple over to the source side of the filter, thereby
reducing or eliminating the filter effectiveness. The coupling mechanism can be radia-
tion, or stray capacitance between the wires. The best method of achieving this is to
mount the filter where the AC power enters the enclosure. Figure 2.14 contrasts a good
installation with a poor one.
When multiple power cables enter an enclosure, an unfiltered line can contaminate a
filtered line external to the enclosure. Therefore all lines must be filtered to be effective.
The situation is similar to a leaky boat. All the holes must be plugged to prevent sinking.
3. If the filter is mounted excessively far from the drive, it may be necessary to mount it to
a grounded conductive surface (the enclosure) to establish a high frequency (HF) con-
nection to that surface. To achieve the HF ground, the surface interface between the fil-
ter and the structure should be free from paint or any other insulator. This may require
paint removal from the inside of a cabinet or panel.
Intro
F
IGURE
2.14
AC Line Filter Installation
!
WARNING: Large leakage currents exist in AC line filters. The
filter must be grounded properly before applying power. Filter
capacitors retain high voltages after power removal. Before han-
dling the equipment, voltages should be measured to determine
safe levels. Failure to observe this precaution could result in
severe bodily injury.
AC
LINE
RADIATED
EMI
DRIVE
RADIATED
EMI
FILTER
CONDUCTED EMI
CONDUCTED EMI
POOR
AC
LINE
DRIVE
RADIATED
EMI
FILTER
CONDUCTED EMI
GOOD