Planning the electrical installation 59
Conduit
Couple separate parts of a conduit together: bridge the joints with a ground conductor
bonded to the conduit on each side of the joint. Bond the conduits also to the drive
enclosure and motor frame. Use separate conduits for input power, motor, brake resistor,
and control wiring. When conduit is employed, type MC continuous corrugated aluminium
armor cable or shielded cable is not required. A dedicated ground cable is always
required.
Note: Do not run motor wiring from more than one drive in the same conduit.
Armored cable / shielded power cable
Six conductor (3 phases and 3 ground) type MC continuous corrugated aluminum armor
cable with symmetrical grounds is available from the following suppliers (trade names in
parentheses):
• Anixter Wire & Cable (Philsheath)
• BICC General Corp (Philsheath)
• Rockbestos Co. (Gardex)
• Oaknite (CLX).
Shielded power cables are available from Belden, LAPPKABEL (ÖLFLEX) and Pirelli.
Selecting the control cables
Shielding
All control cables must be shielded.
Use a double-shielded twisted pair cable for analogue signals. This type of cable is
recommended for the pulse encoder signals also. Employ one individually shielded pair for
each signal. Do not use common return for different analogue signals.
A double-shielded cable is the best alternative for low-voltage digital signals but single-
shielded twisted pair cable (Figure b) is also usable.
Signals in separate cables
Run analogue and digital signals in separate, shielded cables.
Never mix 24 V DC and 115/230 V AC signals in the same cable.
Signals allowed to be run in the same cable
Relay-controlled signals, providing their voltage does not exceed 48 V, can be run in the
same cables as digital input signals. It is recommended that the relay-controlled signals be
run as twisted pairs.
a
Double-shielded twisted pair
cable
b
Single-shielded twisted pair
cable
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