Eaton MMX11 Series - Sinusoidal Filters

04/10 MN04020001Z-EN
Sinusoidal filters
173
Sinusoidal filters
The sinusoidal filter SFB removes high-frequency components
above the set resonance frequency from the frequency inverter
output voltage (a figure 134). The output voltage of the
sinusoidal filter (a figure 133) achieves a sinusoidal shape with
a slight superimposed ripple voltage. The THD factor of the
sinusoidal voltage is normally 5 to 10 %. The noise of the motor is
considerably reduced.
Advantages of the sine-wave filter:
• Length of shielded motor cable
- max. 200 m with mains voltages up to 480 V +10 %
- max. 400 m with mains voltages up to 240 V +10 %.
• Extended lifespan like that of a mains-operated motor.
• Low noise generation.
Figure 131: Sine-wave filter SFB 400/…
Figure 132: Circuit diagram sinusoidal filter
Figure 133: Output voltage to motor
U
2
: Inverter output voltage
U~: Simulated sinusoidal voltage
M
3 h
200 V/div 1 ms/div
Uh
U
2
Figure 134: High-frequency components of the output voltage
a without sinusoidal filter
b with sinusoidal filter
f: Rotating field frequency
n: Order of the harmonics
a
b
n
f
05 10 15 20 25 30 35 40 45