Brick Motion Controller Hardware Reference Manual
SYSTEM WIRING
WARNING:
Installation of electrical control equipment is subject to many regulations including national, state, local, and industry guidelines and rules. General recommendations can be stated but it is important that the installation be carried out in accordance with all regulations pertaining to the installation.
Noise Problems
When problems do occur often it points to electrical noise as the source of the problem. When this occurs, turn to controlling high-frequency current paths. If the grounding instructions do not work, insert chokes in the motor phases. These chokes can be as simple as several wraps of the individual motor leads through a ferrite ring core (such as Micrometals T400-26D). This adds high-frequency impedance to the outgoing motor cable thereby making it harder for high-frequency noise to leave the control cabinet area. Care should be taken to be certain that the core’s temperature is in a reasonable range after installing such devices.
Wiring Earth-Ground
Panel wiring requires that a central earth-ground location be installed at one part of the panel. This electrical ground connection allows for each device within the enclosure to have a separate wire brought back to the central wire location. Usually, the ground connection is a copper plate directly bonded to the back panel or a copper strip with multiple screw locations. The Brick Motion Controller is brought to the earth-ground via the fourth pin on the J1 connector, located at the bottom of the unit through a heavy gauge, multi-strand conductor to the central earth-ground location.
Earth Grounding Paths
High-frequency noises from the PWM controlled power stage will find a path back to the drive. It is best that the path for the high-frequency noises be controlled by careful installation practices. The major failure in problematic installations is the failure to recognize that wire conductors have impedances at high frequencies. What reads 0 Ohms on a DVM may be hundreds of Ohms at 30MHz. Consider the following during installation planning:
1.Star point all ground connections. Each device wired to earth ground should have its own conductor brought directly back to the central earth ground plate.
2.Use unpainted back panels. This allows a wide area of contact for all metallic surfaces reducing high frequency impedances.
3.Conductors made up of many strands of fine conducts outperform solid or conductors with few strands at high frequencies.
4.Motor cable shields should be bounded to the back panel using 360-degree clamps at the point they enter or exit the panel.
5.Motor shields are best grounded at both ends of the cable. Again, connectors using 360-degree shield clamps are superior to connector designs transporting the shield through a single pin. Always use metal shells.
6.Running motor armature cables with any other cable in a tray or conduit should be avoided. These cables can radiate high frequency noise and couple into other circuits.
