Stress control structure for optical fibers in a high voltage environment

A stress control structure including one or more optical fibers adapted to be placed in a region or regions of high stress electrical field, or elsewhere, comprising:

• a longitudinal stress control structure that is strong, stiff, centrally-located in and provides support for the stress control structure, and is electrically insulative at the highest voltage the device is designed for or having a higher dielectric constant;
• wherein the longitudinal structure is within, at least, at or near or within one end, the high stress electrical field so as to create within the longitudinal structure, the high stress electrical field;
• one or more electric field stress control layers comprised of a high permittivity rubber or other high permittivity, flexible, insulative material, disposed tightly around and along the length of, or a portion of the length of, the longitudinal structure and creating a reduction of the high stress electrical field down to a lower stress or zero stress electrical field;
• a first layer of conformable, dielectric material, disposed against the one or more stress control layers;
• the one or more optical fibers disposed against the first layer of conformable dielectric material and extending approximately the length of the longitudinal structure or longer, or at least from the high stress electrical field to the lower stress or zero stress electrical field, as the case may be;
• a second layer of conformable, dielectric material placed against the first layer of conformable, dielectric material and covering the at least one or more optical fibers at least from the high stress electrical field to the lower stress electrical field or zero stress electrical field, as the case may be;
• wherein the one or more optical fibers are contained tightly between the first and second layers of conformable dielectric material;
• and
• a flexible outer protective layer which may be unitary or comprised of sections.

A stress control structure including one or more optical fibers adapted to be placed in a region or regions of high stress electrical field, or elsewhere, the stress control structure comprising:

• a longitudinal structure that is strong, stiff, centrally-located in the stress control structure, and is electrically insulative, at the highest voltage the device is designed for or of a higher dielectric constant;
• wherein said longitudinal structure is disposed at one end in or near an electrical sensor assembly adapted to be attached to a high voltage cable and to sense current or voltage or both, in the high voltage cable, and providing the one or more optical fibers, whereby when the electrical sensor assembly is in operation, the high stress electrical field caused by the high voltage cable creates in the one end of the longitudinal structure, the high stress electrical field;
• one or more electric field stress control layers comprised of a high permittivity rubber or other high permittivity, flexible, insulative material tightly-fitted around the longitudinal structure along the length of or at least a portion of the length of the longitudinal structure and creating a reduction from the high stress electrical field down to a lower stress or zero stress electrical field, as the case may be;
• a first layer of conformable, dielectric material, disposed against the one or more stress control layers and extending for approximately the length of the longitudinal structure or at least from the high stress electrical field to the lower stress or zero stress electrical field, as the case may be;
• wherein the one or more optical fibers, which are associated with the electrical sensor assembly, extend approximately the length of the longitudinal structure or longer and are disposed against the first layer of conformable dielectric material;
• a second layer of conformable, dielectric material, covering the at least the one or more optical fibers for approximately the length of the longitudinal structure or at least from the high stress electrical field to the lower stress or zero stress electrical field, as the case may be;
• wherein the one or more optical fibers are contained tightly between the first and second layers of conformable dielectric material;
• and
• wherein is included a highly weather-resistant, hydrophobic, flexible outer layer comprising a tight-fitting, highly electrically insulating sleeve, wherein the sleeve extends approximately the length of the longitudinal structure or longer.

A method of protecting one or more optical fibers supported by a longitudinal structure having at least one end thereof in a high stress electrical field, the method comprising the steps of:

• reducing the electrical stress in the direction of the length of the longitudinal structure to a lower stress electrical field, or to a zero stress electrical field of ground level;
• dielectrically insulating the optical fibers at least from the high stress electrical field to the lower stress electrical field or zero stress electrical field, by at least one conformable layer of dielectric material and removing or minimizing the number and size of air gaps along or near the optical fibers;
• and
• providing a tight-fitting, exterior, insulative layer extending at least the length of the longitudinal structure.

A stress control structure including one or more optical fibers that are adapted to be located at least partially in a region of high stress electrical field, the stress control structure comprising:

• a longitudinal structure that provides support for the stress control structure, and is electrically insulative at the highest voltage the device is designed for or having a higher dielectric constant;
• one or more electric field stress control layers comprising a high permittivity rubber or other high permittivity, flexible, conformable, insulative material, tightly-fitted around at least a portion of the length of the longitudinal structure, and creating a reduction along the longitudinal structure from the high stress electrical field down to a lower stress electrical field or zero stress electrical field;
• the one or more optical fibers being disposed against the one or more stress control layers;
• and
• one or more layers of conformable, dielectric material, covering at least the one or more optical fibers, such that the one or more optical fibers are contained tightly between the layer of conformable dielectric material and the one or more conformable electric field stress control layers.