I have been examining the US EPA documents about PCB oil used in condensers. Sprague is stated to have used a PCB oil with trade name Clorinol, Cornell Dubiler used Dykanol, Aerovox used Hyvol, and Sangamo used Diaclor. This is from Table 4-3 on page 4-11 (Image 67 of 346) of .
The only type of condenser produced by Spraque which contained Clorinol that I could find were AC condensers used as motor run/start capacitors. Curiously at least two of this type of capacitor are still available for sale on EBay (for example Sprague OVD-4300 30 MF 440 VAC).
One of the comments from which I found particularly interesting was: ¡°Worked at Sprague electric in Vermont as a designer in R and D. The Black Beauty went through many iterations, i.e. dielectrics, insulators, encapsulation material. While they look the same their properties are quite different, and their construction; i.e., winding of the foils, the mandrill size, and tension foils overlays dielectric thicknesses, all made up the voltage and capacitance and frequency ratings the encapsulation material effects. Most were made to customer orders and specifications while there¡¯s some (which were) generic their specifications were very broad.¡± So Sprague Black Beauty capacitors were a trade name for a variety of tubular film capacitor types of varying electrical and material properties that evolved over their life time.
