Xylem IM167 R8 Aquavar CPC (Centrifugal Pump Control) - Manual (Page 20)

20
Selecting the Power Cables
(copper only)
General Rules
Dimension the mains (input power) and motor cables according to local regulations:
• Do not use aluminum wires.
• The cable must be able to carry the drive load current. See Technical Data for the rated
currents.
• The cable must be rated for at least 70º C (158º F) maximum permissible temperature of
conductor in continuous use. For US, follow local codes for cable size, or refer to NEC table
310.16.
• The inductance and impedance of the PE conductor/cable (grounding wire) must be rated
according to permissible touch voltage appearing under fault conditions (so that the fault
point voltage will not rise excessively when an ground fault occurs).
• 600 VAC cable is accepted for up to 500 VAC concerning the entire AQUAVAR CPC range.
For frame sizes R7 and R8, symmetrical shielded motor cable must be used (figure below). A
four-conductor system used up to 30 kW motors cannot be used.
Compared to a four conductor system, the use of symmetrical shielded cable reduces
electromagnetic emission of the whole drive system as well as motor bearing currents and wear
of bearings.
The motor cable and its PE pigtail (twisted screen) should be kept as short as possible in order
to reduce electromagnetic emission as well as capacitive current.
Motor Cable Shield
To effectively suppress radiated and conducted radio-frequency emissions, the shield
conductivity must be at least 1/10 of the phase 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. The better and tighter the shield, the lower the emission level and the bearing
currents.
Additional US Requirements
Type MC continuous corrugated aluminum armor cable with symmetrical grounds or shielded
power cable must be used for the motor cables if metallic conduit is not used. For the North
American market, 600 VAC cable is accepted for up to 500 VAC. For drives rated over 100
amperes, the power cables must be rated for 70ºC (158ºF).
Insulation Jacket
Copper Wire Screen Helix of Copper Tape Inner Insulation
Cable Core
INSTALLATION
(Frames R1-R6)