RODIX SOLUTION
Good wiring practices for
avoiding electrical noise
problems.
Rodix controls have been designed with a
high degree of immunity to electrical
noise; however, depending on the control
installation, electrical noise can cause
problems. These problems occur in less
than 1% of the product installations. Most
electrical noise problems can be avoided
by following some simple guidelines.
Good wiring practices need to be used to
prevent electrical noise from interfering
with your control’s operation. Another
name for electrical noise is Electro-
Magnetic Interference (EMI).
Symptoms of Electrical Noise
The symptoms of electrical noise would
appear as follows: a brief pause or a brief
“bump” in the vibratory feeder’s output
that the control automatically recovers
from. In rare cases the control will either
stop operating or run continuously at full
power in 120 pulse mode until the power
switch is slowly cycled OFF and ON.
Sources of Electrical Noise
Electrical noise is generated by devices
like relay coils, solenoid valves,
contactors, servo motors, and variable
frequency inverter drives. The electrical
noise is then transferred to another
device by one of three ways. The noise
could be conducted through the power
wires, or capacitively coupled from wire to
adjacent wire, or it is transmitted from the
wires of a noise source.
Solutions for Electrical Noise
1.
Use shielded wires for all I/O (Input
/ Output) signals. The I/O signals may
include: 4-20mA input, Run input, Sensor
input, 0-5VDC input, Interlock input or
AUX output. The shield “drain” wire
should be tied to the chassis in the Rodix
control. The drain wire should be kept
shorter than 2”. Please see the enclosed
picture.
Example of a “drain” wire termination
2.
Never run I/O signal wires in the
same conduit or raceway as AC power
lines such as wires to motors, solenoids,
heaters, welders and Rodix controls, etc.
3.
I/O wires within an enclosure
should be routed as far away as possible
from relays, solenoids, transformers,
power wiring and other noisy equipment.
Keep the I/O signal wires separate from
the control’s input and output power
wiring. Secure the wires in place.
4.
Whenever relays or solenoid
valves are used, install a Snubber on
them to reduce electrical noise. Use a
diode on a DC coil. Use a RC Snubber
on an AC coil.
5. In extremely high EMI
environments, Power Line Filters and
ferrite beads can be effective. Install
ferrite beads on I/O signal wires as close
as possible to the circuit board terminal
strip. Loop the wire through the bead
several times or use several beads on
each wire for additional protection.
RODIX, INC.
23
16
23
rd
Avenue, Rockford, IL 61104
Toll Free (800) 562-1868, FAX (815) 316-4701
E-mail [email protected]
www.rodix.com
2000, 2010 RODIX INC. Solution 408 1/27/2010
RODIX INC.
FEEDER CUBE
RODIX SOLUTION
.408
Drain
Wire
RELAY
COIL
SNUBBER
VAC
104M06QC47
QUENCH-ARC
RECTIFIER
DIODE
RELAY
COIL
1N4006
VDC
+
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