Red Lion LEGEND - Manual (Page 39)

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. In extremely high EMI environments, additional
measures may be needed. The unit becomes more immune to EMI with fewer
I/O connections. Cable length, routing and shield termination are very
important and can mean the difference between a successful or a troublesome
installation. Listed below are some EMC guidelines for successful
installation in an industrial environment.
1. 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.
2. 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.
3. Signal or Control cables within an enclosure should be routed as far away
as possible from contactors, control relays, transformers, and other noisy
components.
4. 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 #1VB3
Corcom #1VR3
Note: Reference manufacturer’s instructions when installing a line filter.
5. Long cable runs are more susceptible to EMI pickup than short cable runs.
Therefore, keep cable runs as short as possible.
6. Switching of inductive loads produces high EMI. Use of snubbers across
inductive loads suppresses EMI.
Snubbers:
RLC #SNUB0000
WIRING CONNECTIONS
The bottom board has a removable terminal block on the left where the
power connections are made. The optional plug-in relay board also has a
removable terminal block and is located at the bottom right of the unit. The
top board has a removable terminal block where the signal inputs, user inputs,
solid state outputs, and serial communications connections are made. When
wiring the unit, remove the terminal block and use the numbers on the top
label to identify the position number with the proper function. 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. 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 at the rear of the unit.
Wire each terminal block in this manner.
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