Harmonic Distortion in Supply Line

General Solutions to the harmonics problem are:

Special Transformers:

There are several special types of transformer connections which can cancel harmonics. For example, the traditional delta-wye transformer connection trap all the triplen harmonics (third, ninth, fifteenth, twenty-first, etc.) in the delta. Additional special winding connections can be used to cancel other harmonics on balanced loads. These systems also use more copper. These special transformers are often specified in computer rooms with well balanced harmonic producing loads such as multiple input mainframes or matched DASD peripherals.

K-rated transformers are also used to accomodate additional heat caused by harmonics I.

Filtering:

special electronic tracking filters can work very well to eliminate harmonics. These filters are presently relatively expensive but should be considered for thorough harmonic elimination.

The Hershey Solution:

The standard Hershey System incorporates broadband harmonic filtering to mitigate the effects of harmonics in the system and render them to a harmless level, thereby helping to release KVA capacity in the transformer, while protecting conductors from overheating, improving the operation of plant equipment and reducing the losses caused by the harmonics.

This is accomplished through the application of variable, non-saturable, zig-zag reactors both at the source of the harmonic currents (load) and at the transformer in the mainframe unit. Furthermore, if harmonics of excessive magnitude exist, optional specific harmonic filtering can be employed.

Oversizing neutral conductors:

In three phase circuits with shared neutrals, it is common to oversize the neutral conductor up to 200% when the load served consists of non-linear loads.