ELECTRICIAL n Fig. 1 shows the harmonics of a 22kW VSD without a choke. Fig. 2 shows the harmonics of the same drive with a 2% choke. Fig. 3 shows the same drive with a 4% choke. THDI (total harmonic current distortion) reduction at full-rated load reductions is approximately 19% and 36%, respectively. Fig. 4: the input current reduction for 2% and 4% chokes. For 2%, the reduction is 8.7%, and for 4%, it is 17.2%. to prevent overheating during operation. Water-cooled versions can be used in areas with controlled ambient temperatures or space issues. n Installation location Install chokes close to the VSD to minimise impedance and maximise e ectiveness. High ingress protection (>IP54) chokes can be combined with modern standalone drives and mounted in control rooms without needing enclosures. When placed between the power supply and the VSD, chokes provide impedance that limits the harmonic currents generated by the drive's non-linear load, reducing the RMS current. RMS current is the practical value of the varying current over time; the system consumes less power to deliver the same performance, leading to lower energy consumption and operating costs (Fig. 4). Input chokes are vital in VSD applications, o ering the signicant benets outlined above. By enhancing power quality, extending equipment lives, and improving motor performance, input chokes contribute to industrial electrical systems’ eciency and reliability. Careful selection and implementation are essential to maximise these benets and ensure compliance with industry standards. In some applications, they can reduce input currents by up to 17%. n products and solu We specialise in p ncod tions for oviding e r der s&se n s o r s - g ea rboxes - servo & stepper drive automating - couplings - a c t u a t o r s - supe s & motors - motion control & your world since 1985 ps er metering pum &HMIs Motor Technolog your specific ne T. +44 (0)161 2 gyLtd. eeds. E. info@m 2177100 www.m motec.co.uk motec.co.uk
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