What are passive filters?
Passive filters are devices used in electrical systems to reduce interference and improve POWER QUALITY. These filters operate without the use of active components such as transistors or amplifiers and are designed to attenuate harmonics generated by non-linear loads, thereby reducing the risk of malfunctions and overheating of systems. The use of passive filters improves energy efficiency and protects equipment from damage caused by electrical disturbances.
Harmonics and the problem of network pollution
Harmonics are sinusoidal voltages and currents with a frequency that is a multiple of the fundamental frequency of the distribution system. Their presence in electrical systems causes waveform distortion, leading to various issues such as electromagnetic interference, circuit overload, reduced equipment lifespan, and increased energy losses. In particular, AC-AC and AC-DC drives generate harmonics that degrade power quality on the electrical network, making proper mitigation essential.
IREM’s solution: passive harmonic filters PHF and line reactors LIF
To address harmonic-related issues, IREM has developed the PHF passive harmonic filters and LIF line reactors.
- PHF passive harmonic filters: these filters reduce harmonic distortion in current to values below 5%, preventing overheating and improving power supply quality.
- LIF line reactors: these reactors attenuate harmonics generated by starters and drives, protecting network-connected equipment and improving electromagnetic compatibility.
Motor protection: the new IREM passive filters VTF and SWF
Variable Frequency Drives (VFDs) offer advanced motor control, but they can introduce phenomena that compromise system reliability. High-frequency switching causes stress on winding insulation, while rapid voltage variations (dV/dt) generate voltage spikes that put electrical components under strain. When the distance between the VFD and the motor is long, voltage reflections occur, increasing the stress on windings. Furthermore, interactions with power cables can cause leakage currents, electromagnetic interference, and overheating, reducing overall system efficiency and shortening motor lifespan.
To solve these issues, IREM has developed the new VTF and SWF passive motor filter series, ideal for applications with cable lengths exceeding 250 meters. These filters help extend motor lifespan and improve overall efficiency.
VTF dV/dt Filters: designed to reduce voltage spikes and extend motor winding lifespan. These filters convert pulse width modulation (PWM) signals into a softened voltage waveform, reducing the risk of motor damage. They are particularly suitable for applications with cable lengths up to 250 meters.
- Nominal voltage: 208Vac to 480Vac; 550Vac to 690Vac HV series
- Output frequency: 0 – 100 Hz
- Operating frequency: 0 – 16 kHz
- Line current: 2 to 700A
- Dielectric test phase-to-phase: 2400 Vdc (2 sec.)
- Dielectric test phase-to-ground: 3200 Vdc (2 sec.)
- Protection rating: IP00, with optional IP21, IP54 indoor, or IP54 outdoor enclosure
- Saturation current: 1.5 x nominal current
- Climatic class: -40 /+85° C
- MTBF at 40°C: 250,000 h
SWF Sinusoidal Filters: these filters provide a sinusoidal voltage to motor terminals, eliminating bearing currents and reducing EMC emissions. They are ideal for cable lengths exceeding 250 meters, ensuring more stable and long-lasting motor operation.
- Nominal voltage: 0 to 480 Vac, optionally up to 690 Vac
- Frequency: 0 – 70 Hz
- Nominal current: 2 A to 1000 A
- SWF 2G: f PWM > 2kHz
- SWF 4G: f PWM > 4kHz
- Dielectric test phase-to-phase: 4000 Vdc
- Dielectric test phase-to-ground: 4000 Vdc
- Protection rating: IP00, with optional IP21, IP54 indoor, or IP54 outdoor enclosure
- Saturation current: 1.5 x nominal current
- Climatic class: -40 / +85 °C
- MTBF at 40°C: 250,000 h
The adoption of IREM passive motor filters significantly improves the reliability of drive systems, reduces maintenance costs, and extends motor lifespan. Thanks to these innovative solutions, better POWER QUALITY and more efficient operation of industrial plants and automated systems can be achieved.
