Avid Technology MV3000 DELTA, Техническое руководство

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T1689 Technical Manual Rev 07 PDS Design
MV3000 Air Cooled DELTA Suitability of Motors
Page 103
4. PDS DESIGN
4.1 SUITABILITY OF MOTORS
Motors with Insulation Peak Voltage Withstand ratings of 1200 V (400 V motors), 1500 V (500 V motors) and
2250 V (690 V motors) can be operated with rectifier-fed drives without risk to the motor winding insulation,
for cable lengths up to 500 m (1640 ft.). Such motors are available from reputable manufacturers, as standard
motors up to 500 V and with an enhanced insulation system for voltages greater than 500 V up to 690 V. For
lower quality motors, a dv/dt filter will be required.
The DC link voltage in an AEM drive is higher than the DC link voltage in a diode rectifier-fed drive. For the
default DC link voltage, motors with Insulation Peak Voltage Withstand ratings of 1420 V (400 V motors), 1560
V (480 V motors), 2000 V (600 V motors) and 2250 V (690 V motors) can be operated with AEM drives without
risk to the motor winding insulation, for cable lengths up to 500 m (1640 ft.). Such motors are available from
reputable manufacturers, as standard motors up to 415 V and with an enhanced insulation system for voltages
greater than 415 V up to 690 V. For lower quality motors a dv/dt filter will be required.
The maximum dV/dt at the DE
LTA power module terminals can be 20kV/μs. The use of output sharing reactors
or the use of dV/dt filters will result in the dV/dt at the output terminals of the converter being lower than this.
The distributed inductance and capacitance of the motor cables will further reduce this dV/dt see at the motor
terminals, dependent upon the installation.
In applications where the rated voltage of the motor is lower than the supply voltage, the motor insulation
must comply with the requirements for the supply voltage. For example, a 600 V motor used on a drive fed
from 690 V must comply with the insulation requirements for a 690V motor.
NOTE: If a high control bandwidth (Vector control) is required from the MV3000e drive, dv/dt filters cannot be
used. Cable the motor directly to the drive.
4.2 SUITABILITY OF MOTOR CABLES
To avoid EMC problems, the motor cable should be screened (e.g. NYCWY according to VDE 0276 or steel wire
armoured) or fully enclosed in metallic trunking. The screen or metallic trunking must be continuous
throughout its length and be connected directly to both the drive enclosure and the motor.
Where the current rating of the drive is beyond the capability of an overall screened or armoured 3-core cable,
several 3-core cables should be connected in parallel, as shown in Figure 4–1. It is important that the phase
currents are evenly distributed across the cables - it is not permissible to run the whole of each phase current
down one cable. The screen or armour of each cable must be bonded to both the drive enclosure and the
motor.
U
V
W
DC+
DC-
U
V
W
M
Figure 4–1. – Parallel Cables For High Current Ratings
If unscreened cables are run within metallic trunking, the following points need to be taken into account:
•
The cables should be run in trefoils, each trefoil carrying one cable of each phase. This is to avoid
unequal sharing of current between cables.
•
Where the trunking is not large enough to take all the cables, each trunking should carry an equal
number of trefoils.
•
The metal trunking must be bonded to the drive enclosure and to the motor.