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”). Electric Cables are available in either flat or round configurations.
An electric submersible cable is mainly compounded by a cable conductor, insulation, jacket, braid & covering and armor. These cable compounds are for protection against corrosive fluids and severe environments.
Cable selection involves the determination of Cable Size, Type and Length.
The proper cable size is dependent on combined factors of voltage drop, amperage and available space between tubing collars and casing.
- Cable Voltage Drop:
The following graph shows an example of Cable Voltage drop plot to determine the voltage drop in cable. At the selected motor amperage and the given downhole temperature, the selection of a cable size that will give a voltage drop of less than 30 volts per 1000 feet is recommended. This curve will also enable you to determine the necessary surface voltage (motor voltage plus voltage drop in cable) required to operate the motor.