Pyrolysis when Polyester instead is used will result much less effective due to stability of polyester polymer. High magnitude clearings could results in “carbon” byproducts (soot). This would mean that in the operation life, the current flowing through such a conductive path could cause the capacitor to fail. Such a self-healing property of film capacitors that is strongly high efficient for polypropylene dielectric makes such a technology to be declared open mode fail and suitable for applications across the line and in connection to the mains. This also means that in case of a high pulse coming from the mains, polypropylene offers a much better behavior, means safety, than polyester.