Abstract: An electrical insulation body formed of a polymer binder highly filled with electrically non-conductive inorganic inert filler particles, including in excess of 85% of such particles. Such high loading is facilitated by grading the particles in nonhomogeneous sizes including relatively large ones and by use of polymer binders of relatively low viscosity.

Abstract: A high-voltage DC transmission system and method is characterized by a minimum filtering requirement as to ripple as well as to surge and harmonics. Use of a superconducting generator directly coupled to rectifying means eliminates the requirement of a step-up transformer and allows operation at high frequency for minimizing ripple (and related filtering).

Abstract: A heat pump for cooling or heating a conditioned space includes an underground heat pipe laid into a hole in the ground back-filled with soil. The heat transfer of the soil is improved by dispersing highly water-absorbent hydrophilic polymeric gel particles soaked with water around the heat pipe. The water-soaked particles preferably are coated with a water-impermeable film. The water may also be entrapped in liquid form in small bags. Also, a water impermeable sheath may be formed around the back-fill soil to minimize evaporation from the particles.This is a division of application Ser. No. 718,348 filed Aug. 27, 1976, now U.S. Pat. No. 4,042,012.

Abstract: Underground electrical equipment such as a transformer or cable is prevented from thermal runaway by back-filling the trench in which it is laid with a soil which includes water entrapped in highly water-absorbent hydrophilic polymeric gel particles soaked with water. The water-soaked particles preferably are coated with a water-impermeable film. The water may also be entrapped in liquid form in small balloon-like containers. Also, a water impermeable sheath may be formed around the back-fill soil to minimize evaporation from the particles.

Abstract: A heat pump for cooling or heating a conditioned space includes an underground heat pipe laid into a hole in the ground back-filled with soil. The heat transfer of the soil is improved by dispersing highly water-absorbent hydrophilic polymeric gel particles soaked with water around the heat pipe. The water-soaked particles preferably are coated with a water-impermeable film. The water may also be entrapped in liquid form in small bags. Also, a water impermeable sheath may be formed around the back-fill soil to minimize evaporation from the particles.