Red Lion GCM422 - Manual (Page 2)

2
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
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. 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. DC power to the unit should be relatively clean and within the specified
limits. Connecting power to the unit from circuits that power inductive
loads that cycle on and off, such as contactors, relays, motors, etc., should
be avoided. This will reduce the chance of noise spikes entering the DC
power connection and affecting the unit.
2. 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 unit 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 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 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 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 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.
INSTALLATION ENVIRONMENT
The unit should be installed in a location that does not exceed the
maximum operating temperature and provides good air circulation. Placing
the unit near devices that generate excessive heat should be avoided.
INSTALLATION
The power and 20 mA current loop connections should be made with 24
gauge, multi-conductor, shielded cable. Wire insulation should be stripped to
approximately 1/4 inch (stranded wires should be tinned with solder).
Accessing the terminal block and jumper is accomplished by removing the
four screws and nuts that hold the two case halves together. If the jumper
needs to be re-positioned, it should be done with NO power applied to the
module (module is shipped from factory in the 422 position). Connect the
power and 20 mA loop wires to the appropriate terminal block pins. The cable
is then routed through the groove at the rear of the module. Install the two
screws and saddle washers into the slots at the 25 pin D-connector. Position
the two case halves together, and secure with the four screws and nuts. Refer
to figure 1 below for assembly.
FIGURE 1