Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 116)

Publication GMC-RM001A-EN-P — July 2001
A-14 Noise Control Supplement
Figure A.13
Typical dynamic brake contactor interconnections
Note: Exposed power wiring conductors that are not shielded are a source of RFI noise. Keep exposed conductors as
short as possible and isolated from sensitive devices and wiring.
Note: The safety ground (GND) and shield connections are permanently connected. This is essential for electrical
safety.
Note: Unbraid all cable shields and bond together, connecting directly to the grounded terminal or stud. Do not use
the shield drain wire for this bonded connection.
Reducing Dynamic Braking Circuit Noise
Because the contactor and resistors are connected to the motor power
leads they carry the most intense noise levels in the system and
require special treatment to avoid noise related problems. Refer to the
guidelines below to reduce dynamic braking noise.
• Mount unshielded components and wiring in the very-dirty zone.
• Use shielded cable as much as possible. In some low-risk
applications it may be acceptable to twist the wires together
instead of shielding.
U
V
W
U
V
W
1
1
1
2
3
1
1
1
Resistor
Resistor
Resistor
Contactors
Unbraided shield
Grounded terminal or stud
Isolated terminal
Enclosure wall
Motor Drive
ATTENTION
!
Implementation of safety circuits and risk assessment
is the responsibility of the machine builder. Please
reference international standards EN1050 and EN954
estimation and safety performance categories. For
more information refer to Understanding the
Machinery Directive (publication SHB-900).