Redundant downhole sensor system with voltage controlled switching

摘要

A redundant sensor system monitoring an electric submersible pump in a wellbore includes a plurality of sensors 9 located downhole, a single power cable 7 to the surface and a voltage detector switch 52 for switching power between the sensors. A power supply 40 at the surface selectively produces a plurality of DC voltages under control of a voltage selector switch 42. Voltage detector switch 52 detects the applied voltage and switches on the appropriate sensor 9. If the sensor fails, voltage selector 42 changes the power supply voltage to a different level. This is detected by voltage detector switch 52 which switches off the failed sensor and switches on the redundant sensor. The two sensors may be identical. High voltage testing can also be performed without damage to the sensors because voltage detector switch 52 only switches on the sensors in response to the low voltages produced by supply 40.