• • • EDITOR’S CHOICE • • •
Reactors and Filters are essential to ensure reliability of Variable Frequency Drives and provide protection for
Motors: A Selection Guide By Bharath M S, power quality engineer and Prashanth G, engineer – product management, EMI Solutions Pvt Ltd
rotecting Variable Frequency Drives (VFD) and motors from power surges and transients is one of the most critical priorities to ensure reliable operation of a drive system. There are several sub-components within the VFD and motor which are sensitive to irregularities in power such as voltage spikes, line distortions, current surges or harmonics. VFDs are widely used to control pumps and compressors and are the most common drive in use today.
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Different types of reactors and filters are employed to regulate these distortions. They are as follows:
• Line Reactor • Dv/Dt Reactor • Harmonic Filter • Dv/Dt Filter • Sine Filter
By using these devices either separately or in combination, the service life of the motor and VFD can be increased. It also improves the system performance and reliability of the drive system.
Depending on the output voltage of the motor drive, the cable length and layout are also important factors that influence voltage spikes. The appropriate reactor or filter chosen for the specific cable length can help mitigate this issue.
This article explores the functions, differences and applications of the different types of reactors and filters available to machine builders and systems integrators.
Different types of Reactors
and Filters • Reactors – are basically inductors. Electromagnetic devices that consist of steel core electrical grade laminations and copper inductor coils. The coil forms a magnetic field as current flows through it, which limits the rate of rise of current. Depending on whether they are installed at the input side or output side of the VFD, they are known as line or load reactors.
Fig 1 – Different types of Reactors and Filters. 10 ELECTRICAL ENGINEERING • OCTOBER 2024
• Filters – are a combination of inductance and capacitance. They are electromagnetic devices which consist of a passive L-C circuit that offer protection from harmonic disturbances and transients. They may have longer range protection compared to reactors.
electricalengineeringmagazine.co.uk
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