Efficiency; Acoustic Noise - Danfoss VLT AQUA Drive FC 202 Design Manual

Electrical Installation Con...

10.11 Efficiency

Efficiency of the drive (η
The load on the drive has little effect on its efficiency. In
general, the efficiency is the same at the rated motor
frequency f
rated shaft torque or only 75%, in case of part loads.
The efficiency of the drive does not change even if other
U/f characteristics are selected. However, the U/f character-
istics influence the efficiency of the motor.
The efficiency declines slightly when the switching
frequency is set to a value of above 5 kHz. The efficiency is
slightly reduced when the mains voltage is 480 V, or if the
motor cable is longer than 30 m (98 ft).
Drive efficiency calculation
Calculate the efficiency of the drive at different speeds and
loads based on Figure 10.16. The factor in this graph must
be multiplied with the specific efficiency factor listed in the
specification tables in chapter 7.1 Electrical Data, 380–480 V
and chapter 7.2 Electrical Data, 525–690 V .
1.01
1.0
0.99
0.98
10 10
0.97
0.96
0.95
0.94
0.93
0.92
0%
Figure 10.16 Typical Efficiency Curves
Example: Assume a 160 kW, 380–480 V AC drive at 25%
load at 50% speed. Figure 10.16 shows 0.97 - rated
efficiency for a 160 kW drive is 0.98. The actual efficiency is
then: 0.97x 0.98=0.95.
172
)
VLT
, whether the motor supplies 100% of the
M,N
50% 100%
% Speed
100% load 75% load 50% load
®
VLT AQUA Drive FC 202
Efficiency of the motor (η
The efficiency of a motor connected to the drive depends
on magnetizing level. In general, the efficiency is as good
as with mains operation. The efficiency of the motor
depends on the type of motor.
In the range of 75–100% of the rated torque, the efficiency
of the motor is practically constant, both when the drive
controls it and when it runs directly on the mains.
In small motors, the influence from the U/f characteristic
on efficiency is marginal. However, in motors from 11 kW
(14.75 hp) and up, the advantages are significant.
Typically the switching frequency does not affect the
efficiency of small motors. Motors from 11 kW (14.75 hp)
and up have their efficiency improved (1–2%) because the
shape of the motor current sine-wave is almost perfect at
high switching frequency.
Efficiency of the system (η
To calculate system efficiency, the efficiency of the drive
(η ) is multiplied by the efficiency of the motor (η
VLT
η
SYSTEM

10.12 Acoustic Noise

The acoustic noise from the drive comes from 3 sources:
•
•
•
150% 200%
Table 10.24 lists the typical acoustic noise values measured
at a distance of 1 m (9 ft) from the unit.
25% load
D1h/D3h/D5h/D6h
D2h/D4h/D7h/D8h
E1h–E4h
Table 10.24 Acoustic Noise
Test results performed according to ISO 3744 for audible
noise magnitude in a controlled environment. Noise tone
has been quantified for engineering data record of
hardware performance per ISO 1996-2 Annex D.
A new fan control algorithm for E1h-E4h enlosure sizes
helps improve audible noise performance by allowing the
operator to select different fan operation modes based on
specific conditions. For more information, see
parameter 30-50 Heat Sink Fan Mode.
Danfoss A/S © 01/2018 All rights reserved.
MOTOR)
)
SYSTEM
x η
=η
VLT MOTOR
DC intermediate circuit coils.
Internal fans.
RFI filter choke.
Enclosure size
):
MOTOR
dBA at full fan speed
73
75
80
MG22B222