Danfoss vlt AQUA Instruction Manual page 172

10 Specifications
A2
A3
A5
B1
B2
B3
B4
C1
C2
C3
C4
D1+D3
D2+D4
E1/E2 *
E1/E2 **
* 450 hp [315 kW], 380–480 V AC and 500 hp [355 kW], 525–600 V AC only!
** Remaining E1+E2 power sizes.
*** For D and E sizes, reduced fan speed is at 87%, measured at 200 V.
When a transistor in the inverter bridge switches, the voltage across the motor increases by a du/dt ratio depending on:
- the motor cable (type, cross-section, length, shielded or unshielded)
- inductance
The natural induction causes an overshoot U
circuit. The rise time and the peak voltage U
are especially affected. If the motor cable is short (by a few yards), the rise time and peak voltage are lower.
If the motor cable is long (328 ft [100 m]), the rise time and peak voltage are higher.
In motors without phase insulation paper or other insulation reinforcement suitable for operation with voltage supply (such as an adjustable frequency
drive), fit a du/dt filter or a sine-wave filter on the output of the adjustable frequency drive.
10
10-16
Enclosure At reduced fan speed (50%) [dBA] ***
in the motor voltage before it stabilizes itself at a level depending on the voltage in the intermediate
PEAK
affect the service life of the motor. If the peak voltage is too high, motors without phase coil insulation
PEAK
51
51
54
61
58
-
-
52
55
-
-
74
73
73
82
®
MG.20.M5.22 - VLT is a registered Danfoss trademark
®
VLT AQUA Drive
Instruction Manual
Full fan speed [dBA]
60
60
63
67
70
-
-
62
65
-
-
76
74
74
83