Appendix B Emi Installation Guidelines - Microscan MS-Connect 5100 User Manual

Appendix B — EMI Installation Guidelines
Although this product is designed with a high degree of immunity to Electromagnetic
Interference (EMI), proper installation and wiring methods must be followed to ensure
compatibility in each application. The type of the electrical noise, source or coupling
method into a unit may be different for various installations. Cable length, routing, and
shield termination are very important and can mean the difference between a successful
or unsuccessful installation. Listed are some EMI guidelines for a successful installation
in an industrial environment.
1. To reduce the chance of noise spikes entering the unit via the power lines, connections
should be made to a clean source. Connecting to circuits that also power loads such
as contactors, relays, motors, solenoids, etc., should be avoided.
2. The unit should be mounted in a metal enclosure, which is properly connected to
protective earth.
3. Use shielded (screened) cables for all Signal and Control inputs. The shield (screen)
pigtail connection should be made as short as possible. The connection point for the
shield depends somewhat upon the application. Listed below are the recommended
methods of connecting the shield, in order of their effectiveness.
a. Connect the shield to earth ground (protective earth) at one end where the unit is
mounted.
b. Connect the shield to earth ground at both ends of the cable, usually when the
noise source frequency is over 1 MHz.
c. Connect the shield to common of the MS-Connect 5100 and leave the other end of
the shield unconnected and insulated from earth ground.
4. Never run Signal or Control cables in the same conduit or raceway with AC power
lines, conductors feeding motors, solenoids, SCR controls, heaters, etc. The cables
should be run through metal conduit that is properly grounded. This is especially
useful in applications where cable runs are long and portable two-way radios are used
in close proximity or if the installation is near a commercial radio transmitter. Also,
Signal or Control cables within an enclosure should be routed as far away as possible
from contactors, control relays, transformers, and other noisy components.
5. Long cable runs are more susceptible to EMI pickup than short cable runs. Therefore,
keep cable runs as short as possible.
6. In extremely high EMI environments, the use of external EMI suppression devices is
effective. The following EMI suppression devices (or equivalent) are recommended:
Ferrite Suppression Cores for signal and control cables:
Fair-Rite part number 0443167251
TDK part number ZCAT3035-1330A
Steward part number 28B2029-0A0
Line Filters for input power cables:
Schaffner part number FN610-1/07
Schaffner part number FN670-1.8/07
Corcom part number 1 VR3
MS-Connect 5100 User's Manual
Appendices
A-3