| 摘要 |
An electric motor for powering downhole tools comprises a first stator (33) including a first set of coil windings (73), a second stator including a second set of windings, an axially located rotatable shaft (92) including a first magnetic element and a second magnetic element, a sealed annular chamb er defined by a first tube (96), and an second tube concentrically inside the first tube. The first and second stators are located in the annular chamber, and the first magnetic element being aligned with the first stator such that the first stator when energised can act upon the first magnetic element, and the second magnetic element being aligned with the second stator such that t he second stator when energised can act upon the second magnetic element.</SDOA B>
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