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ELECTRICAL CABLING AND CONNECTIONS
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6
6.
ELECTRICAL CABLING AND CONNECTIONS
6.1
Power unit
How the power connections of Vacon NX Liquid-Cooled units are implemented depends on the size of the
unit. The smallest NX Liquid-Cooled unit (CH3) has terminal blocks for the connections. In all other units,
the connection is established using cables and cable clips or bolting the busbars together.
The main circuit diagrams of each NX Liquid-Cooled drive chassis you will find in Appendix 2 and Appendix
3.
6.1.1
Power connections
Use cables with heat resistance of at least +70
°
C. The cables and the fuses must be sized according to the
drive nominal OUTPUT current that you can find on the rating plate. Sizing according to the output current
is recommended because the drive input current never significantly exceeds the output current. Installa-
tion of cables according to UL regulations is presented in Chapter 6.1.8.
In chassis CH5 and greater, the field cables (both motor and mains) shall be connected to a specific cable
connection block (optional equipment). However, inside a switchgear, the cable connection can be made
directly to the drive.
Table 6-7 shows the minimum sizes of the Cu-cables and the corresponding aR fuse sizes.
If the motor temperature protection of the drive (see Vacon All in One Application Manual) is used as an
overload protection, the cable shall be chosen accordingly. If three or more cables are used in parallel
each cable requires a separate overload protection.
These instructions apply only to cases with one motor and one cable connection from the frequency con-
verter or inverter to the motor. In any other case, ask the factory for more information.
6.1.1.1
Mains cable
The mains cables of the size CH31 are connected to terminal blocks (see Figure 5-4) whereas busbar con-
nection is used for greater sizes, see drawings on pages 29 to 37. Mains cable type for EMC level N in Table
6-1.
6.1.1.2
Motor cable
In order to avoid current sharing disbalance it is imperative to use symmetrical motor cables. Vacon
also recommends to always use shielded cable whenever possible.
The motor cables of the size CH31 are connected to terminal blocks (see Figure 5-4) whereas busbar con-
nection is used for greater sizes, see drawings on pages 29 to 37. Motor cable type for EMC level N in Table
6-1.
Ask factory for more information on the use of ferrite cores with the motor cable in order to protect the
motor bearings against motor bearing currents.
For information on control cables see Chapter 6.2.2.1 and Table 6-1.
