Beware the cheap HPS tube

[Al B. Fuct]

Eddy currents are magnetic, they don't effect the heat but they do drive the "hum" that makes the ballast noisy.

 

Heating in iron inductor cores or motor/generator armatures is directly due to eddy currents:

 

Eddy Current Losses

 

The core of a generator armature is made from soft iron, which is a conducting material with desirable magnetic characteristics.

Any conductor will have currents induced in it when it is rotated in a magnetic field

. These currents that are induced in the generator armature core are called EDDY CURRENTS. The power dissipated in the form of heat, as a result of the eddy currents, is considered a loss. Eddy currents, just like any other electrical currents, are affected by the resistance of the material in which the currents flow. The resistance of any material is inversely proportional to its cross-sectional area.

 

boldface mine.

 

In a transformer or other iron cored inductor, the iron is stationary but the magnetic field is moving- the result is the same, eddy current losses and hysteresis losses, both evident as heat.