Choosing a good quality metallized film capacitor can save more worry and effort in reactive power compensation, while judging the quality of capacitors can generally be from many angles: personnel, machinery and equipment, raw materials, process methods, environment, test methods, etc. From my experience in the capacitor industry, capacitor raw materials, especially metallized capacitor films, are the most important factors affecting the quality of capacitors.

Types of metallized capacitor films for power capacitors

As one of the important media of power capacitors, the metallized film is closely related to the actual service life of capacitors.

There are two kinds of metallized capacitor films: pure aluminium metallized capacitor films and zinc aluminium metallized capacitor films.

On the square resistance of capacitor metallized capacitor film

The square resistance of metallized capacitor film is simply understood as the resistance of metallized capacitor film, which also affects the capacitor.

Generally speaking, the thinner the metallized layer of metallized capacitor film, the greater the square resistance and the stronger the self-healing of capacitor metallised polyester film, but the corresponding current carrying capacity will also decrease and the loss of metallized layer will increase.  On the contrary, the thicker the metallized layer of the metallized capacitor film, the smaller the square resistance and the greater the current carrying capacity.

So is there a way to do it both ways? In view of the above situation, a gradually changing square resistance metallized film appeared in the market, that is, the thickness of metallized capacitor film gradually showed a decreasing trend, which made the current density on the plate evenly distributed. Therefore, the self-healing and withstand voltage of capacitors with gradually changing square resistance are much better than those of ordinary capacitors.