Kollmorgen Mounting
SERVO
STAR
®
SP3 Power Block
10
•
Filters are provided with an earth connection. All ground connections should be tied to
ground.
•
Filters can produce high leakage currents.
Filters must be earthed before connecting the
supply!
•
Do not touch filters for a period of 10 seconds after removing the power supply.
Motor Line Filtering
Motor filtering may not be necessary for CE compliance of SERVO
STAR
systems. However,
this additional filtering increases the reliability of the system. Poor non-metallic enclosure
surfaces and lengthy, unbonded (or unshielded) motor cables that couple noise line-to-line
(differential) are some of the factors that may lead to the necessity of motor lead filtering.
Motor lead noise is either common-mode or differential. The common-mode conducted currents
occurs between each motor lead and ground (line-to-neutral). Differential radiated currents exists
from one motor lead to another (line-to-line). The filtering of the lines feeding the motor
provides additional attenuation of noise currents that may enter surrounding cables and
equipment I/O ports in close proximity.
Differential mode currents commonly occur with lengthy motor cables. As the cable length
increases, so does its capacitance and ability to couple noise from line-to-line. While every final
system is different and every application of the product causes a slightly different emission
profile, it may become necessary to use differential mode chokes to provide additional noise
attenuation to minimize the radiated emissions. The use of a ferrite core placed at the drive end
on each motor lead (shown in the diagram below), attenuates differential mode noise and lowers
frequency (30 to 60 MHz) broadband emissions to within specifications. Kollmorgen
recommends a Fair-Rite P/N 263665702 (or equivalent) ferrite core. Wrap each motor lead
through the core several times as shown in the figure below:
Never wrap a ground lead through a core.
V
From Drive
To Motor
Common Mode
Filtering
From Drive Output
To motor
Differential Mode Filtering
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