Red Lion GEMINI 2 - Manual (Page 35)

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 extremely high EMI 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 count inputs, bottom board, optional relay board,
and optional 20 mA current loop. When wiring the unit, remove the terminal block
and refer to the “Block Diagram” to identify the terminal block position number
with the proper function. Simply strip the wire, leaving approximately 1/4" bare
wire exposed (standard wires should be tinned with solder). Insert the wire into the
terminal and tighten down the screw until wire is clamped in tightly. Each terminal
can accept up to two 18-gage wires. After the terminal block is wired, install in
proper location on board. Wire each terminal block in this manner.
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