As per API RP11S5, cable jackets are protective coverings used to mechanically shield the insulation from the downhole environment. The jacket materials protect the insulation from mechanical abuse associated with handling. Some jacketing material may provide secondary insulation. The most used types of jackets in submersible pump cable are made of: EPDM elastomers or nitrile.
As per API RP11S5, cable insulation isolates the electrical potential between conductors and other conducting materials. Insulation also minimizes leakage current from the conductors.
Insulation selection depends on many factors mainly related to produced fluids properties and well behavior; such as: gas type and concentration, well environment, gas to oil ratio, pressure cycling, exposure to downhole chemicals…
There are two classes of cable insulation materials used in oil and gas industry:
The AC current is carried from the surface to the motor using either copper or aluminum cable conductors. For ESP applications, four sizes of conductors have been standardized: #1, #2, #4 and #6 AWG.
AWG stands for “American Wire Gauge”.
Power losses and operating temperature decrease by increasing the conductor size for a given current. Moreover, for a given conductor size increasing current will increase both the power losses and cable operating temperature.
As shown in the figure below, the main cable consists of three conductor wires extending from the top of the motor flat lead extension to the wellhead banded to the production tubing. The ESP cable carries current (amperage) from the motor controller at the surface down to the motor.
