placeholder · manufacturer · 5.imimg.com (IndiaMART)Sine Wave Filters
A sine-wave (sine) filter is a low-pass LC filter fitted on the output of a PWM variable-frequency drive that smooths the drive's chopped PWM waveform into a near-sinusoidal voltage and current at the motor terminals.
Overview
A sine-wave (sine) filter is a low-pass LC filter fitted on the output of a PWM variable-frequency drive that smooths the drive's chopped PWM waveform into a near-sinusoidal voltage and current at the motor terminals. By removing the high-frequency carrier content it eliminates the steep dV/dt and reflected-wave voltage spikes (which can exceed 1,300 V at the motor) that erode winding insulation and bearings, and it permits very long motor cable runs — typically 300 m to 500 m and beyond — without derating. Compared with a dV/dt filter, a sine filter delivers a far cleaner waveform (motor-current harmonic content typically under 2%), reducing motor heating, audible noise, and EMI. Buyers specify a sine filter for long-lead, submersible-pump, multi-motor or noise-sensitive installations where motor protection and a true sinusoidal supply are required.
Specifications
| Output waveform | near-sinusoidal; motor current harmonic content typically < 2%; voltage THD ~5% max at full load |
|---|---|
| Voltage class | 200-240 V / 380-480 V / 525-600 V / up to 690 V, 3-phase |
| Motor/power range | ~1.5 HP up to ~700 HP (sub-kW to several hundred kW) |
| Rated current | continuous 100% RMS; intermittent 150% for 1 minute (typical) |
| Fundamental/output frequency | tuned for 0-50/60 Hz drive output; carrier (switching) typically 2-8 kHz, filter cut-off below carrier |
| Cable length capability | up to 300-500 m+ between drive and motor |
| Topology | 3-phase LC low-pass (series reactor + shunt capacitor, optional damping) |
| Enclosure | IP00 chassis to IP21/IP54 cabinet; reactors per IS 2026 / IEC 60076-6 |
| Cooling | natural or forced air; insulation class H / 180°C typical |
| Applicable standards | IEC 60076-6 (reactor), IEC 61800-3 (drive EMC) |
Applications
- VFD-fed motors with long cable runs (hundreds of metres)
- Submersible pumps and borewell / dewatering pumps
- Multi-motor installations fed from one drive
- Older or rewound motors with weak insulation needing protection
- Noise- and EMI-sensitive sites (reduced motor whine and bearing currents)
- Long-distance conveyor, fan and pump drives
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