Power quality and harmonics have been a developing and growing concern as buildings have become more reliant on technology, the ever-increasing utilisation of digital control systems, and the drive towards more efficiency.  In recent years, harmonics from buildings have caused issues to supply networks, and authorities now require owners of large buildings to take measures to limit harmonic distortion being imposed on to the utility grid network, and to protect their own internal power network.

Harmonics are generated by almost all equipment connected to the power system (plant motors, fans/pumps, variable speed drives, elevators/escalators, lighting control gear/lamp types, lighting control systems, UPS equipment, IT equipment, PC/laptops/LED screens, security/general equipment, etc.). Most buildings will be full of harmonic generating equipment.

One of the key issues and consideration for building owners is the impact of variable speed drives (VFDs) on the power quality of the buildings. JPW has been involved in a number of survey projects where VFDs and the associated active filters were causing significant power quality issues within the development.

VFDs are an integral part of MEP installations and benefits include controllability and substantial energy savings; however, they produce harmonic voltage distortion.

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