Acoustic Noise; Du/Dt Conditions - Danfoss VLT HVAC Drive FC 102 Design Manual

Electrical Installation Con...
Example: Assume a 160 kW, 380–480 V AC drive at 25%
load at 50% speed. Illustration 10.25 shows 0.97 - rated
efficiency for a 160 kW drive is 0.98. The actual efficiency is
then: 0.97x 0.98=0.95.
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
(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 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
=η
SYSTEM VLT

10.13 Acoustic Noise

10 10
The acoustic noise from the drive comes from 3 sources:
•
DC link coils.
•
Internal fans.
•
RFI filter choke.
Table 10.36 lists the typical acoustic noise values measured
at a distance of 1 m (9 ft) from the unit.
Enclosure size
1)
E1–E2
2)
E1–E2
F1–F4 and F8–F13
Table 10.36 Acoustic Noise
1) P450–P500, 525–690 V only.
2) All other enclosure E models.
Test results performed according to ISO 3744 for audible
noise magnitude in a controlled environment. Noise tone
190
)
MOTOR
)
SYSTEM
x η
MOTOR
dBA at full fan speed
Danfoss A/S © 11/2017 All rights reserved.
®
VLT HVAC Drive FC 102
has been quantified for engineering data record of
hardware performance per ISO 1996-2 Annex D.

10.14 dU/dt Conditions

NOTICE
To avoid the premature aging of motors that are not
designed to be used with drives, such as those motors
without phase insulation paper or other insulation
reinforcement, Danfoss strongly recommends a dU/dt
filter or a sine-wave filter fitted on the output of the
drive. For further information about dU/dt and sine-wave
filters, see the Output Filters Design Guide.
When a transistor in the inverter bridge switches, the
voltage across the motor increases by a dU/dt ratio
depending on:
•
•
The natural induction causes an overshoot U
motor voltage before it stabilizes itself at a level
depending on the voltage in the DC link. The rise time and
the peak voltage U
):
MOTOR
In particular, motors without phase coil insulation are
affected if the peak voltage is too high. Motor cable length
affects the rise time and peak voltage. For example, if the
motor cable is short (a few meters), the rise time and peak
voltage are lower. If the motor cable is long (100 m (328
ft)), the rise time and peak voltage are higher.
The switching of the IGBTs causes the peak voltage on the
motor terminals. The drive complies with the demands of
IEC 60034-25 regarding motors designed to be controlled
by drives. The drive also complies with IEC 60034-17
regarding normal motors controlled by drives.
74
High-power range
83
The power sizes in Table 10.37 and Table 10.38 at the
80 appropriate mains voltages comply with the requirements
of IEC 60034-17 regarding normal motors controlled by
drives, IEC 60034-25 regarding motors designed to be
controlled by drives, and NEMA MG 1-1998 Part 31.4.4.2 for
inverter-fed motors. The power sizes in Table 10.37 and
Table 10.38 do not comply with NEMA MG 1-1998 Part
30.2.2.8 for general-purpose motors.
The motor cable (type, cross-section, length
shielded or unshielded).
Inductance.
affect the service life of the motor.
PEAK
in the
PEAK
MG16C302