Installation 2-21
IQ 2000/5000 Installation Manual
The primary propagation route for EMI emissions from a drive is through cabling. The cables
conduct the EMI to other devices, and can also reradiate the EMI. For this reason, cable segre-
gation and shielding are important factors in reducing emissions. Cable shielding can also
increase the level of immunity for a drive.
Where shielded cables are unterminated as the cable connection passes through the wall of the
cabinet, the shield must be bonded to the cabinet wall to prevent noise picked up by the shielding
inside the cabinet from being radiated outside the cabinet by the cable. Where shielded cables
are terminated using connectors, the shield must not be grounded inside the connector through
a drain wire, or noise on the shield will couple onto the signal conductors inside the connector.
Connectors should have conductive backshells and the shield should be terminated to ground
only through the backshell. The following suggestions are recommended for all installations,
especially since they are inexpensive.
1. Use a shielded motor cable that is terminated at both ends. The shield should be con-
nected to the GBB or chassis at the drive end, and the motor frame at the motor end. The
coaxial configuration provides magnetic shielding, and the shield provides a return
path for HF currents which are capacitively coupled from the motor windings to the
frame. If power frequency circulating currents are an issue, a 250 VAC capacitor should
be used at one of the connections to block to 50/60 Hz currents while passing HF cur-
rents.
2. Signal cables (encoder, serial, analog) should be routed away from the motor cable and
power wiring. Separate steel conduit can be used to provide shielding between the sig-
nal and power wiring. Do not route signal and power wiring through common junc-
tions or raceways.
3. Signal cables from other circuits should not pass within 300 mm (1 ft) of the drive.
4. The length or parallel runs between other circuit cables and the motor or power cable
should be minimized. A rule of thumb is 300 mm (1 ft) of separation for each 10 m (30 ft)
of parallel run. The 300 mm (1 ft) separation can be reduced if the parallel run is less
than 1 m (3 ft).
5. Cable intersections should always occur at right angles to minimize magnetic coupling.
6. Do not route any cables connected to the drive directly over the drive vent openings.
Otherwise the cables will pick up the emissions leaked through the vent slots.
7. If you construct your own motor cable, a 4-conductor cable should be used, with the 4
conductors twisted. The ground conductor must be attached to the motor and drive
earth terminals. The shield must be separately terminated according to the guidelines
for the specific drive.
8. The encoder mounted on the brushless servo motor should be connected to the ampli-
fier with a cable using multiple twisted wire pairs and an overall cable shield. Standard
Electro-Craft encoder cables are offered that are terminated in various lengths. If build-
ing your own cable, be sure to connect the cable shield to the motor case and to the
amplifier chassis through the connectors for a complete 360° connection (per the cable
assembly diagram) otherwise noise on the encoder signals can cause faults in the drive.
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