3.6 Electrical Installation
3.6.1 Power Connections
Cabling and Fusing
NOTE!
Cables General
All cabling must comply with national and local regulations on cable cross-sections and ambient temperature. Copper (167°F [75°C])
conductors are recommended.
The power cable connections are laid out as shown below. Dimensioning of cable cross-sections must be done in accordance with the current ratings and
local legislation. See the
Specifications section
for details.
To protect the adjustable frequency drive the recommended fuses must be used or the unit must have built-in fuses. Recommended fuses are listed in
the tables in the fuse section. Always ensure that proper fusing is done according to local regulations.
The AC line input connections are fitted to the line switch if this is included.
NOTE!
The motor cable must be shielded/armored. The use of a non-shielded/unarmored cable is against EMC requirements. Use a shielded/
armored motor cable to comply with EMC emission specifications. For more information, see
EMC specifications
in the
Design Guide
.
See section General Specifications for correct dimensioning of motor cable cross-section and length.
Shielding of cables:
Avoid installation with twisted shield ends (pigtails), as they reduce the shielding effect at higher frequencies. They spoil the shielding effect at higher
frequencies. If it is necessary to break the shield to install a motor isolator or motor contactor, the shield must be continued at the lowest possible HF
impedance.
Connect the motor cable shield to both the de-coupling plate of the adjustable frequency drive and to the metal housing of the motor.
Make the shield connections with the largest possible surface area (cable clamp). This is done by using the supplied installation devices within the
adjustable frequency drive.
Cable length and cross-section:
The adjustable frequency drive has been EMC-tested with a given length of cable. Keep the motor cable as short as possible to reduce the noise level
and leakage currents.
Switching frequency:
When adjustable frequency drives are used together with sine-wave filters to reduce the acoustic noise from a motor, the switching frequency must be
set according to the instructions in par. 14-01.
3 How to Install
VLT
®
Automation Drive FC 300
Instruction Manual High Power
3-36
MG.33.U2.22 - VLT
®
is a registered Danfoss trademark
3
