Ac Supply Requirements; Ratings - Emerson Unidrive M400 User Manual

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4.2

AC supply requirements

Voltage:
100 V drive: 100 V to 120 V ±10 %
200 V drive: 200 V to 240 V ±10 %
400 V drive: 380 V to 480 V ±10 %
Number of phases: 3
Maximum supply imbalance: 2 % negative phase sequence (equivalent
to 3 % voltage imbalance between phases).
Frequency range: 48 to 62 Hz
For UL compliance only, the maximum supply symmetrical fault current
must be limited to 100 kA
4.2.1 Supply types
All drives are suitable for use on any supply type i.e TN-S, TN-C-S, TT
and IT.
• Supplies with voltage up to 600 V may have grounding at any
potential, i.e. neutral, centre or corner ("grounded delta")
• Supplies with voltage above 600 V may not have corner grounding
Drives are suitable for use on supplies of installation category III and
lower, according to IEC60664-1. This means they may be connected
permanently to the supply at its origin in a building, but for outdoor
installation additional over-voltage suppression (transient voltage surge
suppression) must be provided to reduce category IV to category III.
Operation with IT (ungrounded) supplies:
Special attention is required when using internal or external
EMC filters with ungrounded supplies, because in the event
of a ground (earth) fault in the motor circuit the drive may not
WARNING
trip and the filter could be over-stressed. In this case, either
the filter must not be used i.e. removed, or additional
independent motor ground fault protection must be provided.
For instructions on removal, refer to Figure 4-10 Installation
of grounding bracket and Figure 4-13 Removal of the size 3
internal EMC filter . For details of ground fault protection
contact the supplier of the drive.
A ground fault in the supply has no effect in any case. If the motor must
continue to run with a ground fault in its own circuit, then an input
isolating transformer must be provided, and if an EMC filter is required it
must be located in the primary circuit.
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.
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 susceptible to disturbance when
connected to supplies with a high rated capacity.
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Line reactors are particularly recommended for use with the following
drive models when one of the above factors exists, or when the supply
capacity exceeds 175 kVA.
Model sizes XXX to XXX have an internal DC choke so they do not
require AC line reactors except for cases of excessive phase unbalance
or extreme supply conditions.
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
4.2.3 Input inductor calculation
To calculate the inductance required (at Y%), use the following equation:
Y V 1
× ×
L
--------- - ------ - ----------- -
=
100 2πfI
3
Where:
I = drive rated input current (A)
L = inductance (H)
f = supply frequency (Hz)
V = voltage between lines
4.3

Ratings

The input current is affected by the supply voltage and impedance.
Typical input current
The values of typical input current are given to aid calculations for power
flow and power loss.
The values of typical input current are stated for a balanced supply.
Maximum continuous input current
The values of maximum continuous input current are given to aid the
selection of cables and fuses. These values are stated for the worst case
condition with the unusual combination of stiff supply with bad balance.
The value stated for the maximum continuous input current would only
be seen in one of the input phases. The current in the other two phases
would be significantly lower.
The values of maximum input current are stated for a supply with a 2 %
negative phase-sequence imbalance and rated at the supply fault
current given in Table 4-2.
Table 4-2 Supply fault current used to calculate maximum input currents
Model
All
Advanced
Technical data Diagnostics
parameters
Symmetrical fault level (kA)
100
UL listing
information
35