The frequency converter will automatically derate the
rated output current I
VLT,N,
when the switching frequen-
cy exceeds 4.5 kHz.
In both cases, the reduction is carried out linearly,
down to 60% of I
VLT,N
.
Vibration and shock
The frequency converter has been tested according to
a procedure based on the following standards:
IEC 68-2-6: Vibration (sinusoidal) - 1970.
IEC 68-2-34: Random vibration broad-band -
general requirements.
IEC 68-2-35: Random vibration broad-band -
high reproducibility.
IEC 68-2-36: Random vibration broad-band -
medium reproducibility.
The frequency converter complies with requirements
that correspond to conditions when the unit is mounted
on the walls and floors of production premises, as well
as in panels bolted to walls or floors.
Air humidity
The frequency converter has been designed to meet
the IEC 68-2-3 standard, EN 50178 item 9.4.2.2/ DIN
40040 class E at 40 °C.
UL Standard
This device is UL-approved.
Efficiency
To reduce energy consumption it is very important to
optimize the efficiency of a system. The efficiency of
each single element in the system should be as high
as possible.
Efficiency of frequency converters (•
INV
)
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
M,N
, regardless of whether
the motor supplies 100% rated shaft torque or only
75%, e.g. in case of part loads.
This also means that the efficiency of the frequency
converter does not change even if other U/f charac-
teristics are chosen. However, the U/f characteristics
influence the efficiency of the motor.
The efficiency declines a little when the switching fre-
quency is set to a value above 4.5 kHz (parameter 411
Switching frequency
). The rate of efficiency will also be
slightly reduced at a high mains voltage (480 V), or if
the motor cable is longer than 25 m.
Efficiency of the motor (•
MOTOR
)
The efficiency of a motor connected to the frequency
converter depends on the sine shape of the current. In
general, the efficiency is just as good as in mains op-
eration. The efficiency of the motor depends on the
motor type.
In the range of 75-100% of the rated torque, the effi-
ciency of the motor is practically constant, both when
it is controlled by the frequency converter and when it
runs directly on mains.
In general, the switching frequency does not affect the
efficiency of small motors.
MG.27.E2.02 - VLT is a registered Danfoss trademark
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