Tandem Permanent Magnet ESP Motor Shaft Alignment
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Solution Overview
Problem
Permanent magnet ESP motors cannot be operated in tandem due to the need for rotational alignment of pole magnets, which is challenging given the enclosed nature of the rotors and the absence of visible rotor sections.
Innovation Solution
The use of alignment means such as coupling irregularities, shaft irregularities, coupling keyways, shaft keyways, indicia, and orientation slots to ensure rotational alignment of magnetic poles between the upper and lower tandem motors before securing their housings together, allowing for proper operation and synchronization of the drive shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnet ESP motors are connected in tandem to increase horsepower, then the power output is improved, but the rotational alignment of pole magnets becomes difficult to achieve due to enclosed rotors
Solution Approach 1:
A coupling device with alignment features serves as an intermediary between the upper and lower motor shafts. The coupling includes a coupling keyway and shaft keyways that act as mediators to transmit and establish the correct rotational alignment orientation from one shaft to the other, enabling precise pole magnet alignment without direct visual inspection
Solution Approach 2:
Alignment features such as coupling keyways and shaft keyways are pre-configured in specific orientations before the motors are assembled in tandem. This preliminary setup ensures that when the shafts are connected, the pole magnets are automatically aligned in the correct rotational position without requiring complex adjustment procedures during installation
2Reliability
If the rotor sections are enclosed in housing for protection, then the reliability is improved, but the visibility of rotor sections for alignment purposes is lost
Solution Approach 1:
The coupling device acts as an external intermediary that establishes rotational alignment without requiring visibility of the enclosed rotor sections. The coupling keyway and shaft keyway system provides a mechanical reference system that bypasses the need to see the pole magnets themselves, allowing alignment to be achieved through the coupling interface alone
Solution Approach 2:
The visual/mechanical inspection method for alignment is replaced with a keyed mechanical connection system. Instead of visually detecting rotor position or manually aligning visible components, the system uses pre-configured keyways and keys to mechanically enforce the correct rotational orientation, substituting visual detection with mechanical constraint
Data Source
AI summary
An electrical submersible well pump assembly has first and second permanent magnet motors. The first motor drive shaft is connected to a coupling that has internal splines for receiving an externally splined end of the second motor drive shaft. Alignment devices rotationally align magnetic poles of the first drive shaft with the magnetic poles of the second drive shaft prior to securing the housings of the first and second motors together. The alignment devices may be a coupling irregularity in the internal splines that is at a controlled orientation relative to the magnetic poles of the first shaft and a shaft irregularity in the external splines that prevents the second drive shaft from fully engaging the coupling unless the shaft irregularity is in a specified rotational position relative to the coupling irregularity.