Danfoss VLT AutomationDrive FC 361 Series User Manual

7.9 IT Mains
Mains supply isolated from ground
If the drive is supplied from an isolated mains source (IT
mains, oating delta, or grounded delta) or TT/TN-S mains
with grounded leg, the RFI switch is recommended to be
turned o via parameter 14-50 RFI Filter on the drive and
parameter 14-50 RFI Filter on the lter. For more detail, see
IEC 364-3. In the o position, the lter capacitors between
the chassis and the DC link are cut o to avoid damage to
the DC link and to reduce the ground capacity currents,
according to IEC 61800-3.
If optimum EMC performance is needed, or parallel motors
are connected, or the motor cable length is above 25 m
(82 ft), Danfoss recommends setting parameter 14-50 RFI
Filter to [ON]. Refer also to the Application Note, VLT on IT
Mains. It is important to use isolation monitors that are
rated for use together with power electronics (IEC
61557-8).
7.10 Eciency
Eciency of the drive (η
VLT
)
The load on the drive has little eect on its eciency. In
general, the eciency is the same at the rated motor
frequency f
M,N
, whether the motor supplies 100% of the
rated shaft torque or only 75%, in case of part loads.
The eciency of the drive does not change even if other
U/f characteristics are selected. However, the U/f character-
istics inuence the eciency of the motor.
The eciency declines slightly when the switching
frequency is set to a value of above 5 kHz. The eciency is
slightly reduced when the mains voltage is 480 V, or if the
motor cable is longer than 30 m (98 ft).
Drive eciency calculation
Calculate the eciency of the drive at dierent speeds and
loads based on Illustration 7.15. The factor in this graph
must be multiplied by the specic eciency factor listed in
the specication tables in chapter 5.1 Electrical Data,
380-480 V.
1.0
0.99
0.98
0.97
0.96
0.95
0.93
0.92
0% 50% 100% 200%
0.94
Relative Eciency
130BB252.11
1.01
150%
% Speed
100% load 75% load 50% load 25% load
Illustration 7.15 Typical
Eciency Curves
Example: Assume a 160 kW, 380–480/500 V AC drive at
25% load at 50% speed. Illustration 7.15 shows 0.97 - rated
eciency for a 160 kW drive is 0.98. The actual eciency is
then: 0.97x 0.98=0.95.
Eciency of the motor (η
MOTOR
)
The eciency of a motor connected to the drive depends
on magnetizing level. In general, the eciency is as good
as with mains operation. The eciency of the motor
depends on the type of motor.
In the range of 75–100% of the rated torque, the eciency
of the motor is practically constant, both when the drive
controls it and when it runs directly on the mains.
In small motors, the inuence from the U/f characteristic
on eciency is marginal. However, in motors from 11 kW
(15 hp) and up, the advantages are signicant.
Typically the switching frequency does not aect the
eciency of small motors. Motors from 11 kW (15 hp) and
up have their eciency improved (1–2%) because the
shape of the motor current sine-wave is almost perfect at
high switching frequency.
Eciency of the system (η
SYSTEM
)
To calculate system eciency, the eciency of the drive
(η
VLT
) is multiplied by the eciency of the motor (η
MOTOR
):
η
SYSTEM
=η
VLT
x η
MOTOR
7.11
Acoustic Noise
The acoustic noise from the drive comes from 3 sources:
•
DC intermediate circuit coils.
•
Internal fans.
•
RFI
lter choke.
Table 7.11 lists the typical acoustic noise values measured
at a distance of 1 m (9 ft) from the unit.
Enclosure size dBA at full fan speed
J8 73
J9 75
Table 7.11 Acoustic Noise
Test results performed according to ISO 3744 for audible
noise magnitude in a controlled environment. Noise tone
has been quantied for engineering data record of
hardware performance per ISO 1996-2 Annex D.
Electrical Installation Con... Design Guide
MG06K102 Danfoss A/S © 03/2019 All rights reserved. 49
7 7

Danfoss VLT AutomationDrive FC 361 Series Specifications

General

Brand	Danfoss
Model	VLT AutomationDrive FC 361 Series
Category	DC Drives
Language	English