Electrical Installation Of Motor Cables; Danfoss A/S © Rev. 05/2014 All Rights Reserved; Preparing Gland Plates For Cables - Danfoss VLT HVAC Drive FC 102 Design Manual

How to Install
continued with the lowest possible HF
impedance.
F frame requirements
F1/F3 requirements
Motor phase cable quantities must be multiples of 2,
resulting in 2, 4, 6, or 8, to obtain an equal number of
wires attached to both inverter module terminals. The
cables are required to be equal length within 10%
between the inverter module terminals and the first
common point of a phase. The recommended common
point is the motor terminals.
F2/F4 requirements
Motor phase cable quantities must be multiples of 3,
resulting in 3, 6, 9, or 12, to obtain an equal number of
wires attached to each inverter module terminal. The wires
are required to be equal length within 10% between the
inverter module terminals and the first common point of a
phase. The recommended common point is the motor
terminals.
F8/F9 requirements
The cables are required to be equal length within 10%
between the inverter module terminals and the first
common point of a phase. The recommended common
point is the motor terminals.
F10/F11 requirements
Motor phase cable quantities must be multiples of 2,
resulting in 2, 4, 6, or 8, to obtain an equal number of
wires attached to both inverter module terminals. The
cables are required to be equal length within 10%
between the inverter module terminals and the first
common point of a phase. The recommended common
point is the motor terminals.
F12/F13 requirements
Motor phase cable quantities must be multiples of 3,
resulting in 3, 6, 9, or 12, to obtain an equal number of
wires attached to each inverter module terminal. The wires
are required to be equal length within 10% between the
inverter module terminals and the first common point of a
phase. The recommended common point is the motor
terminals.
F14 requirements
Motor phase cable quantities must be multiples of 4,
resulting in 4, 8, 12, or 16, to obtain an equal number of
wires attached to each inverter module terminal. The wires
are required to be equal length within 10% between the
inverter module terminals and the first common point of a
phase. The recommended common point is the motor
terminals.
Output junction box requirements
The length, minimum 2.5 meters, and quantity of cables
must be equal from each inverter module to the common
terminal in the junction box.
MG16C202
Design Guide
NOTICE
If a retrofit application requires an unequal number of
wires per phase, consult the factory for requirements
and documentation or use the top/bottom entry side
cabinet busbar option.

5.2.3 Electrical Installation of Motor Cables

Screening of cables
Avoid installation with twisted screen ends (pigtails). They
spoil the screening effect at higher frequencies. If it is
necessary to break the screen to install a motor isolator or
motor contactor, continue the screen at the lowest
possible HF impedance.
Connect the motor cable screen to both the decoupling
plate of the frequency converter and to the metal housing
of the motor.
Make the screen connections with the largest possible
surface area (cable clamp) using the installation devices in
the frequency converter.
If it is necessary to split the screen to install a motor
isolator or motor relay, continue the screen with the
lowest possible HF impedance.
Cable-length and cross-section
The frequency converter has been tested with a given
length of cable and a given cross-section of that cable. If
the cross-section is increased, the cable capacitance, and
thus the leakage current, may increase. Reduce the cable
length accordingly. Keep the motor cable as short as
possible to reduce the noise level and leakage currents.
Switching frequency
When frequency converters are used together with sine-
wave filters to reduce the acoustic noise from a motor, the
switching frequency must be set according to the sine-
wave filter instruction in 14-01 Switching Frequency.
Aluminum conductors
Do not use aluminum conductors. Terminals can accept
aluminum conductors but the conductor surface has to be
clean and the oxidation removed and sealed by neutral,
acid-free grease before the conductor is connected.
Additionally, the terminal screw must be retightened after
two days due to the softness of the aluminum. Maintain a
gas tight joint connection to prevent oxidation.

5.2.4 Preparing Gland Plates for Cables

1.
2.
3.
4.
Danfoss A/S © Rev. 05/2014 All rights reserved.
Remove the gland plate from the frequency
converter.
Provide support for the gland plate around the
hole being punched or drilled.
Remove debris from the hole.
Mount the cable entry on the frequency
converter.
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