Method for thermally enhancing injection of power cables

A method for enhancing the dielectric properties of an electrical cable section having a central stranded conductor with an interstitial void volume, the conductor being encased in a polymeric insulation jacket with an elastic limit, the cable section having a first closable high-pressure connector attached at one end thereof and a second closable high-pressure connector attached at the other end thereof, each of the first and second connectors providing fluid communication to the void volume, the method comprising:

• (a) opening both the first and second connectors and introducing a first quantity of at least one dielectric property-enhancing fluid via the first connector sufficient to substantially fill the interstitial void volume during a first time;
• (b) closing the second connector and introducing an additional second quantity of the dielectric property-enhancing fluid via the first connector at a selected pressure less than the elastic limit of the polymeric insulation jacket during a second time;
• (c) closing the first connector with the second connector remaining closed to confine the first and second quantities of the dielectric property-enhancing fluid within the void volume at the selected pressure;
• and
• (d) heating the cable section by imposing a potential of no more than about 500 volts across a portion of the conductor between the ends of the cable to heat the dielectric property-enhancing fluid introduced into the interstitial void volume during at least a portion of the first and second times.

A method for enhancing the dielectric properties of an electrical cable section having a central stranded conductor with an interstitial void volume, the conductor being encased in a polymeric insulation jacket with an elastic limit, the cable section having a first closable high-pressure connector attached at one end thereof and a second closable high-pressure connector attached at the other end thereof, each of the first and second connectors providing fluid communication to the void volume, the method comprising:

• (a) opening both the first and second connectors and introducing a first quantity of at least one dielectric property-enhancing fluid via the first connector sufficient to substantially fill the interstitial void volume during a first time;
• (b) closing the second connector and introducing an additional second quantity of the dielectric property-enhancing fluid via the first connector at a selected pressure less than the elastic limit of the polymeric insulation jacket during a second time;
• (c) closing the first connector with the second connector remaining closed to confine the first and second quantities of the dielectric property-enhancing fluid within the void volume at the selected pressure;
• and
• (d) imposing an electrical potential across a portion of the conductor between the ends of the cable to heat the dielectric property-enhancing fluid introduced into the interstitial void volume during at least a portion of the first and second times, with the proviso that the polymeric insulation jacket temperature remains below about 90° C.

A method for enhancing the dielectric properties of an electrical cable section having a central stranded conductor with an interstitial void volume, the conductor being encased in a polymeric insulation jacket with an elastic limit, the cable section having a first closable high-pressure connector attached at one end thereof and a second closable high-pressure connector attached at the other end thereof, each of the first and second connectors providing fluid communication to the void volume, the method comprising:

• (a) opening both the first and second connectors and introducing a first quantity of at least one dielectric property-enhancing fluid via the first connector sufficient to substantially fill the interstitial void volume during a first time;
• (b) closing the second connector and introducing an additional second quantity of the dielectric property-enhancing fluid via the first connector at a selected pressure less than the elastic limit of the polymeric insulation jacket during a second time;
• (c) closing the first connector with the second connector remaining closed to confine the first and second quantities of the dielectric property-enhancing fluid within the void volume at the selected pressure;
• and
• (d) imposing a potential across a portion of the conductor between the ends of the cable to heat the dielectric property-enhancing fluid introduced into the interstitial void volume during at least a portion of the first and second times, wherein the conductor temperature is increased about 10 to about 50° C. above the ambient temperature.