Electricity and Control March 2016

PLANT MAINTENANCE, TEST + MEASUREMENT

AFE EMI

– Active Front End

– Electromagnetic Interference IGBT – Insulated Gate Bipolar Transistor PLC – Programmable Logic Controller PWM – Pulse Width Modulation RFI – Radio Frequency Interference THD – Total Harmonic Distortion VSD – Variable Speed Drive

Abbreviations/Acronyms

Conclusion Understanding the often subtle differences between various harmonic filtering technologies can yield better cost savings, reduce complexity and prolong equipment life. Getting your head around what options are available really is worth it in the long run.

Controllers (PLCs) and telemetry and communications networks to nuisance trip and malfunction. In addition, although this unit may at first seem to eliminate harmonics, it must be noted that with the AFE in addition to the VSD, there are now two drives in the circuit producing twice the heat. This means twice the heat and, with a 200 kW AFE, it soon adds up. For the panel builder/ system integrator, bigger cooling systems are needed to cope with the excessive heat. Shunt-active Active filters provide the most efficient harmonic compensation in a compact unit that has little loss, is insensitive to grid conditions, cannot be overloaded and is easy to retrofit. All of this comes at a slightly higher cost, which is offset by the better return on investment over the longer term.

Reference [1] IEEE-591. 1992. Recommended practices and requirements for harmonic control in electrical power systems.

John Mitchell, is global business development manager at CP Automation. He has experience in engineering, marketing

and sales across major industry sectors. Enquiries: Email john.mitchell@cpaltd.net