Red Lion CSPID - Manual (Page 4)

4
EMC INSTALLATION GUIDELINES
Although Red Lion Controls Products are 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 troublesome
installation. Listed are some EMI guidelines for a successful installation in an
industrial environment.
1. A unit should be mounted in a metal enclosure, which is properly connected
to protective earth.
a. The mounting clip that connects to the DIN rail should have the DIN rail
connected 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 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 module 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 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.
4. Long cable runs are more susceptible to EMI pickup than short cable runs.
Therefore, keep cable runs as short as possible.
5. In extremely high EMI environments, the use of external EMI suppression
devices such as Ferrite Suppression Cores for signal and control cables is
effective. The following EMI suppression devices (or equivalent) are
recommended:
Fair-Rite part number 0443167251 (RLC part number FCOR0000)
TDK part number ZCAT3035-1330A
Steward part number 28B2029-0A0
6. To protect relay contacts that control inductive loads and to minimize radiated
and conducted noise (EMI), some type of contact protection network is
normally installed across the load, the contacts or both. The most effective
location is across the load.
a. Using a snubber, which is a resistor-capacitor (RC) network or metal oxide
varistor (MOV) across an AC inductive load is very effective at reducing
EMI and increasing relay contact life.
b. If a DC inductive load (such as a DC relay coil) is controlled by a transistor
switch, care must be taken not to exceed the breakdown voltage of the
transistor when the load is switched. One of the most effective ways is to
place a diode across the inductive load. Most RLC products with solid
state outputs have internal zener diode protection. However external diode
protection at the load is always a good design practice to limit EMI.
Although the use of a snubber or varistor could be used.
RLC part numbers: Snubber SNUB0000
Varistor ILS11500 (Littelfuse#V130LA20AP) or
ILS23000 (Littelfuse#V275LA40AP)
Note: Reference manufacturer’s instructions when installing any EMI
suppression device.
7. Also care should be taken when connecting input and output devices to the
instrument. When a separate input and output common is provided, they
should not be mixed. Therefore a sensor common should NOT be connected
to an output common. This would cause EMI on the sensitive input common,
which could effect the instruments, operation.
Visit RLC’s web site at www.redlion.net for more information on EMI
guidelines, Safety and CE issues as they relate to Red Lion Controls products.
HARDWARE
CSPID1 ONLY
ANALOG OUTPUT OPTION
Select either Voltage or Current output by placing the output jumpers in the
appropriate location. The output jumpers are located on the side of the CSPID1
module.
CSPID2 ONLY
INPUT JUMPERS
Select the desired input type for each channel by positioning the jumper
appropriately. For thermocouple inputs, the jumper position can be ignored.
RTD
RTD
20mA
10V
10V
20mA
2
1
5
ATTACH THE MODULE BASE
TO THE DIN RAIL
4
3
1
2
ATTACH MODULE TO BASE
INSTALLATION
SEPARATE BASE
FROM MODULE
Voltage Current
The unit shall be installed inside a UL Listed Industrial Control Panel or similar type of enclosure. A minimum 3.2 mm distance
shall be maintained between the hazardous live parts of the equipment and accessible parts of the fire/electrical enclosure.