Installation Practices For Electromagnetic Compatibility (Emc) Compliance; Installation Practices For Emc Compliance; Wiring Materials For Emc Compliance - Zener MSC-3 Instruction Manual

Installation practices for Electromagnetic Compatibility (EMC) compli-
ance

Installation practices for EMC compliance

The EMC performance of the MSC-3 is installation dependent. For compliance with EMC standards, the
use of a screened power cable between the MSC-3 and the motor is required. Other arrangements that
provide a continuous metallic sheath enclosing only the motor phase conductors and the associated
protective earth (PE) conductor may also be used.
In order to achieve the required electrical performance at high frequencies, it is essential that the screen
of the cable have a 360º connection to both the MSC-3 gland plate and the motor terminal box. The
correct type of metal cable gland to suit the screened cable should be used. The protective earth (PE)
conductor should be terminated in the usual way to meet the local wiring codes at the ground terminals
provided in the MSC-3 and the motor. Isolation switches wired between the MSC-3 and the motor
should be in a metallic enclosure with the power cable screen properly terminated on both sides. Failure
to properly terminate the screened power cable (or alternative metal sheath) will result in a severe
degradation of the screened cables performance at high frequencies and increase the possibility of EMC
problems. The screened motor cable should only contain the phase and earth (PE) conductors of one
inverter and the associated motor. Do not include other conductors inside the screen.
Specific information for the EMC compliant installation of each chassis size is provided on pages 14 -
18.

Wiring materials for EMC compliance

The EMC related properties of the shielded power cable used between the inverter and motor will have
a significant impact on the overall EMC result achieved in any given installation. The EMC performance
of an installation will usually be dominated by the lowest performance section of the inverter to motor
cabling. For this reason it is imperative that appropriate material (including cable glands/terminators)
is used in every part of this cabling. There is a wide range of materials available, and these may be
generally categorised as follows:
Category
1 Screened cable material from
reputable manufacturers
2 Generic materials with well
understood EMC properties.
For example, screwed steel
conduit and MIMS cable
3 Material without specific EMC
performance data.
Armored cables and flexible
conduit systems fall into
this category when there is
no EMC performance data
provided. Note that there are
high performance, fully EMC
specified examples of these
materials available which
would make them part of
category 1.
Technical Data
Technical data will
be available to allow
assessment of the
performance of the
material against
specific criteria
The technical
performance of these
materials is well
understood by analysis
from basic principles.
Specific data has been
reported in reputable
engineering research
journals.
None. Assessment of
the likely performance
by visual inspection is
difficult and unreliable.
IM00120 IM00120
MSC-3 Instruction Manual
Comment
The manufacturer's claimed
data can generally be relied
on, provided that the proper
installation and termination
practices are strictly adhered to.
These materials generally offer
very high performance, provided
that the proper installation and
termination practices are strictly
adhered to.
These materials represent a high
risk category because the EMC
performance is simply unknown.
Apparently similar materials
may have widely differing EMC
performance.
In general, there is no control
of the EMC properties during
design or manufacture because
this is not the intended
application.
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