ABB recommends the use of conduit for power wiring to the drive and between the drive
and the motor(s). Due to the variety of application needs, metallic and non-metallic conduit
can be used. ABB prefers the use of metallic conduit.
The following table shows examples of various materials and methods for wiring the drive
in the intended application. See NEC 70 along with state and local codes for the appropriate
materials for your application.
In all applications, ABB prefers the use of symmetrical shielded VFD cable between drive
and motor(s).
Metal conduit
Couple separate parts of a metal conduit together: bridge the joints with a ground conductor
bonded to the conduit on each side of the joint. Also bond the conduits to the drive enclosure
and motor frame. Use separate conduits for input power, motor, brake resistor, and control
wiring. Do not run motor wiring from more than one drive in the same conduit.
￭ Power cable shield
If the cable shield is used as the sole protective earth (PE) conductor, make sure that its
conductivity agrees with the PE conductor requirements.
To effectively suppress radiated and conducted radio-frequency emissions, the cable shield
conductivity must be at least 1/10 of the phase conductor conductivity. The requirements
are easily met with a copper or aluminum shield. The minimum requirement of the motor
cable shield of the drive is shown below. It consists of a concentric layer of copper wires
with an open helix of copper tape or copper wire. The better and tighter the shield, the lower
the emission level and bearing currents.
Insulation jacket1
Helix of copper tape or copper wire2
Copper wire shield3
Inner insulation4
Cable core5
Selecting the control cables
￭ Shielding
Only use shielded control cables.
Use a double-shielded twisted pair cable for analog signals. This type of cable is
recommended for the pulse encoder signals also. Use one individually shielded pair for
each signal. Do not use common return for different analog signals.
Guidelines for planning the electrical installation 81
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