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

VLT® AQUA Drive FC 202
Design Guide

10.12 Efficiency

Efficiency of the drive (n )
VLT
The load on the drive has little effect on its efficiency. In general, the efficiency is the same at the rated motor frequency f
the motor supplies 100% of the rated shaft torque or only 75%, for example if there are part loads. This also means that the efficien-
cy of the drive does not change even if other U/f characteristics are selected. However, the U/f characteristics influence the efficien-
cy of the motor. The efficiency declines a little when the switching frequency is set to a value of above 5 kHz. The efficiency is also
slightly reduced if 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 the graph in
graph by the specific efficiency factor listed in the specification tables in :
1.02
1
0.98
0.96
0.94
0.92
0.9
0% 50%
Illustration 79: Typical Efficiency Curves
Example: Assume a 160 kW, 380–480/500 V AC drive at 25% load at 50% speed. The graph shows 0.97 - the rated efficiency for a
160 kW drive is 0.98. The actual efficiency is then: 0.97x0.98=0.95.
The MyDrive ecoSmart tool helps to calculate the efficiency, refer to www.ecosmart.danfoss.com.
® ™
Efficiency of the motor (η
MOTOR
The efficiency of a motor connected to the drive depends on the 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 effi-
ciency of the motor is practically constant, both when the drive runs the motor and when it runs directly on mains. In small motors,
the influence from the U/f characteristic on efficiency is marginal. However, in motors from 11 kW (15 hp) and up, the advantages
are significant. Typically, the switching frequency does not affect the efficiency of small motors. Motors from 11 kW (15 hp) and up
have their efficiency improved (1–2%) because the shape of the motor current sine-wave is almost perfect at high switching fre-
quency.
Efficiency of the system (η
SYSTEM
To calculate the system efficiency, the efficiency of the drive (η
η = η x η
SYSTEM VLT MOTOR

10.13 Acoustic Noise and Airflow

Table 89: Acoustic Noise Ratings
Enclosure size
A1
A2
A3
A4
A5
B1
B2
B4
C1
144 | Danfoss A/S © 2020.09
100% 150% 200%
% speed
)
)
50% fan speed [dBA]
(1)
51
51
51
51
54
61
58
52
52
Illustration
100% Load
75% Load
50% Load
25% Load
) is multiplied by the efficiency of the motor (η
VLT
Full fan speed [dBA]
60
60
60
60
63
67
70
62
62
Electrical Installation
Considerations
even if
M,N,
79. Multiply the factor in this
):
MOTOR
(1)
AJ300847815559en-000101 / 130R0337