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Altivar 21

Altivar 21. C- less Techology. Harmonics?.

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Altivar 21

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  1. Altivar 21 C-less Techology

  2. Harmonics? What are harmonics?Harmonics are multiples of some base frequency, each having a frequency and amplitude. For example our electrical system is 50 hertz so the 3rd harmonic is 150 hertz and the 5th harmonic is 250 hertz. Each harmonic is sinusoidal and as such repeats through a system. What causes harmonics?Harmonic in our electrical systems today are caused by nonlinear loads such as variable speed drives. These harmonics are introduced to the system through the way the load draws current.

  3. Why does a VSD Produce Harmonics? • The VSD’s input rectifier draws a nonsinusoidal current which produces harmonics on the electrical network • The magnitude of the current harmonics is determined by the charging characteristics of the DC Bus capacitors

  4. What are the Problems Harmonics can Create? • Increase of total input RMS current • Voltage distortion on the power supply (voltage harmonics) • Degradation of the power factor • Overload on the transformer, cables, components • Disturbance to sensitive surrounding equipment • Overload on power factor correction capacitors • Risks of resonance • High Neutral Currents

  5. Three + Phase Power C - D C Link Rectifier Inverter ATV21 Solutions to Harmonic Distortion Levels C-less Technology • DC bus capacitor value is reduced to 2-3% of standard AC drive capacitor value • DC bus capacitor current is reduced, lowering input current harmonics

  6. Main Features of C-Less Technology • Better THID compared to standard AC drive with Line Reactor or DC Choke with no added cost or size • Lowest cost for harmonic mitigation • Meets IEC harmonics standard with THID < 48% • However there is more DC bus voltage ripple therefore slight output current and torque ripples. • This is not a limitation on Variable Torque HVAC applications.

  7. 3-5 5-10 5-16 35-48 THDI % 60-130 30-35 • Summary • ATV21 C-Less technology is the optimized cost and size solution for standard THID complying to IEC standard • ATV61 passive filter has the best cost/performance ratio when low THID is required

  8. Q Presentation Finished

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