Efficiency; Acoustic Noise - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide
Derating for high altitude, see section on special conditions
EMC standards, Emission
EMC standards, Immunity
See section on special conditions
Control card, USB serial communication:
USB standard
USB plug
Connection to PC is carried out via a standard host/device USB cable.
The USB connection is galvanically isolated from the supply voltage (PELV) and other high-voltage ter-
minals.
The USB ground connection is not galvanically isolated from protection earth. Use only isolated laptop
as PC connection to the USB connector on FC 300 drive.

Efficiency

Efficiency of FC 300 Series (η
The load on the frequency converter has little effect on its efficiency. In general, the efficiency is the same
at the rated motor frequency f
i.e. in case of part loads.
This also means that the efficiency of the frequency converter does not change even if other U/f char-
acteristics are chosen.
However, the U/f characteristics influence the efficiency of the motor.
The efficiency declines a little when the switching frequency is set to a value of above 5 kHz. The efficiency
will also be slightly reduced if the mains voltage is 500 V, or if the motor cable is longer than 30 m.
Efficiency of the motor (η
The efficiency of a motor connected to the frequency converter depends on magnetising level. In general,
the efficiency is just 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 it is controlled by the frequency converter 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 and up, the advantages are significant.
In general, the switching frequency does not affect the efficiency of small motors. Motors from 11 kW
and up have their efficiency improved (1-2%). This is because the sine shape of the motor current is
almost perfect at high switching frequency.
Efficiency of the system (η
To calculate the system efficiency, the efficiency of FC 300 Series (η
the motor (η ):
MOTOR
η = η x η
SYSTEM VLT MOTOR

Acoustic Noise

The acoustic noise from the frequency converter comes from three sources:
1. DC intermediate circuit coils.
2. Integral fan.
3. RFI filter choke.
64
FC 300 Selection
EN 61000-4-2, EN 61000-4-3, EN 61000-4-4, EN 61000-4-5, EN 61000-4-6
)
VLT
, even if the motor supplies 100% of the rated shaft torque or only 75%,
M,N
)
MOTOR
)
SYSTEM
MG.33.B8.02 - VLT ® is a registered Danfoss trademark
EN 61800-3, EN 61000-6-3/4, EN 55011
EN 61800-3, EN 61000-6-1/2,
USB type B "device" plug
) is multiplied by the efficiency of
VLT
1.1 (Full speed)