Nidec Commander C200 Power Installation Manual page 52

Unusual hazards can occur on ungrounded supplies with more than one source, for example on
ships. Contact the supplier of the drive for more information.
If an SI-Applications Plus module is installed in the drive, then the drive must not be used
on a corner-grounded or centre-grounded delta supply if the supply voltage is above
300 V. If this is required, please contact the supplier of the drive for more information.
WARNING
4.2.2 Supplies requiring line reactors
Input line reactors reduce the risk of damage to the drive resulting from poor phase balance or
severe disturbances on the supply network.
Where line reactors are to be used, reactance values of approximately 2 % are recommended.
Higher values may be used if necessary, but may result in a loss of drive output (reduced torque at
high speed) because of the voltage drop.
For all drive ratings, 2 % line reactors permit drives to be used with a supply unbalance of up to 3.5 %
negative phase sequence (equivalent to 5 % voltage imbalance between phases).
Severe disturbances may be caused by the following factors, for example:
• Power factor correction equipment connected close to the drive.
• Large DC drives having no or inadequate line reactors connected to the supply.
• Across the line (DOL) started motor(s) connected to the supply such that when any of these
motors are started, the voltage dip exceeds 20 %.
Such disturbances may cause excessive peak currents to flow in the input power circuit of the drive.
This may cause nuisance tripping, or in extreme cases, failure of the drive.
Drives of low power rating may also be suscept ble to disturbance when connected to supplies with a
high rated capacity.
When required, each drive must have its own reactor(s). Three individual reactors or a single three-
phase reactor should be used.
Reactor current ratings
The current rating of the line reactors should be as follows:
Continuous current rating:
Not less than the continuous input current rating of the drive
Repetitive peak current rating:
Not less than twice the continuous input current rating of the drive
52
Unidrive M/HS Frame 5 to 6 Power Installation Guide
Issue Number: 8