Danaher Motion B8961, Руководство оператора, Страница: 152 / 158

B8961 and B8962 User Manual
150
Physical Installation
The drawing at right shows an
example of an EMC compliant IDC
servo Smart Drive installation.It is
assumed that the AC line filter and
the Smart Drive ha ve a good RF
ground connection to the cabinet
frame,and that the cables are
shielded and grounded at both ends.
The guidelines outlined above for
grounding and cable separation
should be followed when extending
the concepts illustrated here to
multiple component enclosure
mounting.
As always,it is the responsibility of
the machine builder to properly
install the IDC ser vo drives and
other electrical components making
up the machine before taking the
machine into service.When multiple
electrical components are installed
together on a machine,the radiated
and conducted noise emission levels
can be both greater or less than the levels of the single component.The immunity
levels of the individual components will not be affected.
AC Power Line Filtering
As mentioned above,one of the characteristics of the high power electronics used
in servo drive amplifiers is the broadband noise their switching conducts back on
to the AC input line.There are a couple of ways to reduce the magnitude of the
noise on the AC line.The first is to reduce the switching speed of the drive
electronics,but this would increase the amount of heat the power transistors
would need to dissipate.This in turn would increase the size and cost of the servo
drive.
A second way would be to build an AC filter and/or isolation transformer into every
drive.This solution also increases the size and cost of every drive.A third solution is
to install an AC line filter at the point where the AC power enters the protectiv e
enclosure where the servo drives and other machine control electronics are
mounted.This is the method documented and used by IDC controls.The main
advantage is that the cost and size of the filter can be specifically tailored to the
application at hand, rather than being sized for a “worst case scenario”like an
internal filter circuit.A second advantage is that this externally mounted filter can
be sized to supply multiple drives or other machine control electronics.
The proper installation and sizing of the AC line filter is critical in attaining
acceptable attenuation of the broad band noise caused by the switching power
electronics.