Sinusoidal Filters

The Sinus Filter Plus ++® is a combination of conventional differential and common-mode filters and is connected to the DC-link circuit to provide a low impedance path back to the source of the parasitic currents. Spindle-bearing currents in the motor originate from the DC-link and so protection of the mechanical system is ensured. In addition to the reduction of switching disturbances, radio frequency interference on the input side of the inverter is also reduced and the general EMC is greatly enhanced.

In long cable lengths, such as those necessary for use in heat pumps or high-rise buildings, the common-mode disturbances take the path of lowest impedance back to earth. These disturbances can also cause the inaccurate and unacceptable measurement of water flow rates. Again, this problem can be solved by using the Sinusfilter Plus++®.

In any application where long cable runs and common mode RF interference cause massive problems, the Sinusfilter Plus++® is the best choice for providing long-term protection of mechanical equipment, and also insurance for the plant operator against costly repairs, or in the worst case replacement of a complete system.

Advantages:

• Longer cable runs can be used between the frequency inverter and motor
• Higher switching frequencies < 8 kHz
• Reduction of audible noise
• Reduction of cable losses
• Removes the need for additional filters on the input side of the inverter (which already has an integrated filter)
• Reduction of radiated emissions from cables
• Allows use of unshielded cables
• Prevention of harmful leakage currents

For long cables, the Block Sinusoidal Filter converts the distorted voltage waveform into a smooth sine curve (ripple is smoothed down to 3-5%). When used in conjunction with screened cable, this filter will remove most symmetric and asymmetric noise.

Filter Type Sinusodial Filter