| 摘要 |
Three-phase electrical energy is supplied over a multi-conductor cable 14 to an electrical submersible pump (ESP) motor 10. A downhole unit 20 is ac-coupled to the cable 14 through the ungrounded Y-point A of the ESP motor windings. Uplink communication of telemetry data is by a scheme providing modulation of an ac carrier generated 103 in the surface unit 20, detected by demodulators 106A-C. Downlink communication of control data is similarly provided by modulation 104A-C of the secondary ac from generator 103. This secondary ac carrier also provides an independent power supply to the downhole devices 20. Communication between surface and downhole units is thus accomplished without extra communication lines and can be maintained even in the event of a ground fault on the power cable 14. |
