Moisture seal for high voltage insulator
High voltage insulators are disclosed, along with related methods of manufacture and use. The disclosed high voltage insulators include a core strength member joined to one or more end fittings and secured with one or more elastomeric members. A plastic body surrounds the core strength member, the elastomeric member, and at least a portion of the end fitting. In particular, the plastic body is molded over the elastomeric member(s) and, upon cooling, the plastic body exerts a radial compressive force on the underlying elastomeric member(s) to seal the joint of the high voltage insulator and protect it from moisture, even throughout temperature fluctuations in the field.
1. A high voltage insulator comprising:
a rod-shaped core strength member;
at least one end fitting having a base and a neck with an internal cavity configured to retain a portion of the core strength member;
at least one elastomeric member positioned on an outer surface of the at least one end fitting;
a plastic body surrounding the core strength member, the at least one elastomeric member, and the neck of the at least one end fitting;
the neck including a channel formed in an outer surface of the end fitting to retain the elastomeric member; and
a lip positioned next to the channel and farther away from the base than the channel,
wherein the plastic body surrounds the channel, lip and elastomeric member, and wherein the plastic body exerts a radial compressive force on the at least one underlying elastomeric member.
2. The high voltage insulator of claim 1 , wherein the core strength member is implemented with fiberglass.
3. The high voltage insulator of claim 1 , wherein the plastic body is implemented with a thermoplastic.
4. The high voltage insulator of claim 3 , wherein the thermoplastic is selected from the group consisting of: high density polyethylene (HDPE), linear low density polyethylene (LDPE), polypropylene, polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), acrylic (e.g., polymethyl methacrylate), polycarbonate, polyvinylidene fluoride (PVDF), and combinations thereof.
5. The high voltage insulator of claim 1 , wherein the plastic body includes a plurality of fins.
6. The high voltage insulator of claim 5 , wherein the fins are positioned parallel to one another.
7. The high voltage insulator of claim 1 , wherein the one or more elastomeric members are formed of a material selected from the group consisting of: rubber, silicone, polybutadiene, isoprene, neoprene, polychloroprene, butyl rubber, fluorosilicone, ethylene-vinyl acetate (EVA), and combinations thereof.
8. The high voltage insulator of claim 1 , wherein the one or more elastomeric members are toroidally shaped.
9. The high voltage insulator of claim 8 , wherein the one or more elastomeric members each have a circular cross-section.
10. The high voltage insulator of claim 1 , wherein the one or more end fittings are each formed of a metal.
11. The high voltage insulator of claim 1 , wherein the high voltage insulator includes one end fitting and one elastomeric member.
12. The high voltage insulator of claim 1 , wherein the high voltage insulator includes two end fittings and two elastomeric members.
13. A method of forming a high voltage insulator, the method comprising:
joining a core strength member and one or more end fittings together;
positioning one or more elastomeric members onto the one or more end fittings to form an assembly;
molding a plastic body over the assembly such that the plastic body covers the core strength member, the one or more elastomeric members, and at least a portion of the one or more end fittings; and
allowing the molded plastic body to cool to form the high voltage insulator with one or more elastomeric members that are continuously radially compressed by the surrounding plastic body.
14. The method of claim 13 , wherein the plastic body contracts at least 1% during cooling.
15. The method of claim 13 , wherein the one or more elastomeric members are each positioned in a channel on an outer surface of the one or more end fittings.