Dynamometric measuring device for a drill pipe

Dynamometric measuring device for a rotating drill pipe comprising:

• a plurality of sensors disposed in a groove in the rotation drill pipe, each of said sensors providing means for outputting a measurement signal over a respective measurement channel;
• a first electronic circuit attached to the rotating drill pipe for conditioning the signals supplied by these sensors and including a stage of follower-amplifiers of very low output impedance;
• a commutator-brush assembly for transmitting the signals from the first electronic circuit attached to the rotating drill pipe to a fixed part, said commutator-brush assembly including a commutator mounted on the rotating drill pipe and a fixed-brush assembly mounted on the fixed part;
• and
• a second electronic circuit mounted on the fixed part, wherein said circuit comprises on an output side of the fixed-brush assembly, means including a stage follower-amplifiers of very high input impedance for receiving said signals transmitted to the fixed part and for thereby causing transmission of the signals from the first electronic circuit attached to the rotating drill pipe to be carried out at zero current, and, on an output side of each follower-amplifier, a separation circuit for a DC component and a separation circuit for an AC component of each of said signals.