User Manual

Harmonic distortion damages

equipment and creates a host

of other problems

The use of variable speed drives (VSD) in HVAC systems has proven both efficient

and cost-effective. However, the generation of harmonic currents on the AC line

can lead to problems and increased installation cost.

Building design specifications often require compliance with local installation

guidelines and standards such as IEEE519.2 (USA), EA G5/4 (UK and Hong Kong),

EN 61000-2-2 (Europe) and IEC (AS/NZ) 61000-3-6 (used globally). The purpose of

these guidelines / standards is to provide acceptable limits of harmonic current and

voltage distortion allowed back into the public power system. In many cases, this

requires the use of some method to reduce the harmonic currents produced by

standard VSDs. Conventional methods of harmonic current reduction from VSDs

require extra hardware, space and cost. A new type of VSD from Siemens – speci-

fically designed for HVAC applications – provides a method for reducing the line

harmonic currents without the need for additional components.