Danfoss VLT Training Manual page 36

VLT Installation
5) Wiring
5) Wiring the Drive
c. Motor Wiring
The maximum cable distance between the drive and motor for unshielded cable is
set for 300m (1000 feet). If multiple motors are wired to one drive, the total
distance from the drive to all the motors can not exceed 300m (1000 feet). If
shielded cable is used as pictured above, the distance is dropped to 150m (500
feet). The wires in the shielded cable are more compressed, which means that the
capacitance between the cable and ground is increased. A shorter distance is
therefore needed for proper operation.
A disconnect switch between the drive and motor may be required to meet electrical
codes. During operation if the disconnect switch is opened, no harm is done to the
drive or to the motor. If the disconnect is then closed and the drive is running, the
motor may attempt to draw locked rotor current from the drive. This may cause the
drive to shut down on an over-current fault trip. In order to avoid such a nuisance
trip, it is best to wire an auxiliary contact from the disconnect switch back to the
drive's start circuit. Then, if the disconnect is opened while the drive is running, the
drive immediately shuts off. When the disconnect switch is closed, the drive begins
from a stop and smoothly accelerates the motor to the desired speed.
Rev.02
c. Motor
Output Motor Wiring
• Use Terminals 96 (U), 97(V), 98(W)
• Check maximum motor length, Example: VLT
5000/6000/8000 is 300m (1000') unshielded
• Disconnect OK
Confidential / Property of Danfoss Drives A/S
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North America
Motion Controls