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525 Programmable Motion Controller
Magnetic Coil Noise
All relay coils, solenoid coils, electrical brakes and similar devices must be
suppressed. The placement of the noise suppressor should be as close to the coil as
possible.
In the case of DC coils, a diode is installed across the coil in a direction that will
cause the voltage transient to be supressed by the diode.
Figure 3 Magnetic Coil Noise (DC Line)
In the case of AC coils a capacitor and resistor are installed across the coil to
suppress the unwanted transient.
Figure 4 Magnetic Coil Noise (AC Line)
The specific values of resistance and capacitance may vary depending on the
inductance of the coil. Consult the relay manufacturer for the proper values to use.
These suppressor networks greatly extend the life of the contacts controlling the
coil because the transient energy, which can easily reach 1000 volts, shunts
through the suppressor rather than arcing across the controlling contacts as they
open.
I/O Wiring Layout
All signals to and from the 525 PMC must be connected with an electrical grade
insulated wire to withstand the application environment. Although each signal
input and output was designed for high noise immunity, careful wire routing within
the enclosure will help cut down electrical noise between I/O lines and noise
emitting conductors.
High voltage (>50V) must be separated from low voltage wiring in order to
minimize cross talk. High voltage signals should be run in a separate conduit
physically separated from the low voltage signals. In addition, any high current
carrying conductors should be twisted to minimize noise emission.
Conductor lengths should be as short as possible to reduce noise and losses in the
system. Input/output wiring can be safeguarded against noise by a shielded cable.
Brake leads should be treated as power conductors and run within the armature
conduit or raceway.
Shielding
When shielding cable it is important to know the difference between the types of
shielding available. A braid shield is the most effective way to minimize the effects