There are three types of torque sensors used in mud logging system,
mechanical torque sensroe, electromagnetic sensor or TDS torque
sensor. A mehcanical torque sensor is a pressure transmitter
actuall; the working priciple is same to the principle introduced
in paragraph 4.3.1. In WELLSTAR, wiring points are assigned on
junction box 1 for a mechanical r and an electromagnetic torque
sensor with *4V power supply, and wiring points are assigned on
junction box 4 for a TDS torque sensor without power supply.
Principle:
Base on the "Hall Effect", a bypass circuit can be adopted to
measure the armature current directly. This by measuring the
current through to an electrical motor for rotary table with a
bypass circuit, the variations of the string torque corresponding
to the current variations can be measured indirectly. Here a
electromagnetic torque sensor provides a bypass circuit once
powered.
