Red Lion GEMINI 33 - Manual (Page 30)

ADDITIONAL EMC INSTALLATION GUIDELINES
Although this unit 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 the unit may be different for
various installations. Listed below are some additional EMC guidelines for
successful installation in an industrial environment.
1. The unit should be mounted in a metal enclosure, which is properly
connected to protective earth.
a. If the bezel is exposed to high Electro-Static Discharge (ESD) levels,
above 4 Kv, it should be connected to protective earth. This can be
done by making sure the metal bezel makes proper contact to the panel
cut-out or connecting the bezel screw with a spade terminal and wire to
protective earth.
2. 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 only at the panel where the unit is mounted to earth
ground (protective earth).
b. Connect the shield to earth ground at both ends of the cable, usually
when the noise source frequency is above 1 MHz.
c. Connect the shield to common of the unit and leave the other end of the
shield unconnected and insulated from earth ground.
3. Never run Signal or Control cables in the same conduit or raceway with AC
power lines, conductors feeding motors, solenoids, SCR controls, and
heaters, etc. The cables should be run in 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.
4. 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. In very electrically noisy environments, the use of external EMI
suppression devices, such as ferrite suppression cores, is effective. Install
them on Signal and Control cables as close to the unit as possible. Loop the
cable through the core several times or use multiple cores on each cable for
additional protection. Install line filters on the power input cable to the unit
to suppress power line interference. Install them near the power entry point
of the enclosure. The following EMI suppression devices (or equivalent)
are recommended:
Ferrite Suppression Cores for signal and control cables:
Fair-Rite # 0443167251 (RLC #FCOR0000)
TDK # ZCAT3035-1330A
Steward #28B2029-0A0
Line Filters for input power cables:
Schaffner # FN610-1/07 (RLC #LFIL0000)
Schaffner # FN670-1.8/07
Corcom #1VR3
Note: Reference manufacturer’s instructions when installing a line
filter.
6. Long cable runs are more susceptible to EMI pickup than short cable runs.
Therefore, keep cable runs as short as possible.
7. Switching of inductive loads produces high EMI. Use of snubbers across
inductive loads suppresses EMI.
Snubbers:
RLC #SNUB0000
WIRING CONNECTIONS
After the unit has been mechanically mounted, it is ready to be wired. All
conductors should meet voltage and current ratings for each terminal. Also
cabling should conform to appropriate standards of good installation, local
codes and regulations. It is recommended that power supplied to the unit (AC
or DC) be protected by a fuse or circuit breaker. All wiring connections are
made on removable plug-in terminal blocks. There is a separate terminal
block for the bottom board (TBA), relay board (TBB), count inputs (TBC), and
optional Serial Communications (TBD). When wiring the unit, remove the
terminal block and use the numbers on the label to identify the position
number with the proper function. Simply strip the wire, leaving
approximately 1/4" bare wire exposed (stranded wires should be tinned with
solder). Insert the wire into the terminal and tighten down the screw until the
wire is clamped in tightly. Each terminal can accept up to two 18-gage wires.
After the terminal block is wired, install it in the proper location on the PC
board. Wire each terminal block in this manner.
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