Filter types
vacon • 17
Local contacts: https://www.danfoss.com/en/contact-us/contacts-list/
Recommendations:
Figure 8, Table 7 and Table 8 show the filter and motor requirements based on the nominal voltage
level and IEC & NEMA motor standards.
Figure 8. IEC 60034-25-ed3: Limiting curves of impulse voltage U
pk
as a function of the peak rise time t
r
,
measured between two motor phase terminals.
• Curve A 500/690 V = Typical electrical machines
• Curve B 500/690 V = Electrical machines with older insulation system
Table 7. Recommendations of dU/dt usage based on the voltage class and motor insulation system
Table 8. Recommendations of dU/dt usage based on the voltage class and NEMA motor insulation
system, NEMA MG1, Part 31
Nominal voltage U
n
Filters and motor isolation requirements
U
n
≤ 420 V
No filters required if the motor insulation is according to curve A 500 V - IEC60034-25
420 V ≤ U
n
≤ 500 V
dU/dt filter is needed for motor insulation according to curve A 500 V - IEC60034-25
or
No filters required if the motor insulation is according to curve A 690 V - IEC60034-25
500 V ≤ U
n
≤ 690 V
dU/dt filter is needed for motor insulation according to curve A 690 V - IEC60034-25
or
No filter if motor is wound with medium voltage technology - form wound
For motors with U
n
≥ 600 V
U
peak
= 3.1 × U
n
For motors with U
n
< 600 V
U
peak
= 2.04 × U
n
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
U
pk
[
k
V
]
t
r
[µs]
A 690V
B 690V
A 500V
B 500V
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