Avoiding Noise-Generating Devices; Control Techniques Variable -Speed Drives - Emerson E2 Einstein Manual

2 Avoiding Noise-Gen-
erating Devices
There are a number of electrical devices com-
monly used in supermarkets and buildings that gener-
ate noise.
• Motor starters, contactors, or other electrical equip-
ment that switches ON and OFF. Switching heavy
electrical loads ON and OFF will generate noise.
• Inverters for variable-speed motors. Inverters gener-
ate a constant amount of high levels of noise.
• Fluorescent light ballasts. Light ballasts also generate
constant noise.
• Arc welders (excessive intermittent noise).
The best way to eliminate network noise coming
from a noise-generating device is to keep all net-
worked devices and cable runs as far away from the
device as possible. Cable runs should be routed
around noise-generating devices, and the E2 (as well
as the devices the E2 is networked with) should be
physically located far away from noise-generating
devices.
The minimum distance devices and cabling
should be kept away from noise generators is 1 ft.
(0.3m) with 5 ft. (1.5 m) being the ideal minimum
distance. The minimum distance may be more or
less depending on the amount of noise generated by
the device - refer to the device's user manual for
more information.
2.1. Control Techniques Vari-
able-Speed Drives
E2 controllers whose versions are 2.40F01 and
above feature the ability to communicate with certain
models of Control Techniques variable-speed drives
(VSDs) using a MODBUS network connection.
Control Techniques and CPC both require all
VSDs that will network with E2 controllers to be
installed with line filters to minimize noise. If install-
ing an E2 network into a site that already has
installed VSDs, verify the drives were installed with
line filters before networking them to an E2. Contact
your Control Techniques representative to obtain line
filters and assistance with installation.
2 • E2 Controller Wiring Practices
In addition, CPC requires that all MODBUS net-
work connections to Control Techniques VSDs use a
CT Drive Interface (P/N 535-2725). This assembly,
which plugs into the RJ45 MODBUS jack on the
VSD, provides the noise filtering circuitry recom-
mended by Control Techniques, and it also provides
a screw terminal connector for easier daisy chaining
to the MODBUS network.
For further information on noise abatement when
using Control Techniques VSDs, consult the manu-
facturer's instructions and follow all recommended
guidelines for installing the drive and reducing noise.
Furthermore, when using VSDs, it is highly recom-
mended you follow the EMI-resistant wiring guide-
lines outlined in Section 7.3., EMI-Resistant RS485
Network Grounding Practices.
026-1903 Rev 4 19-APR-2010