Self-Guiding Instrument Carrier for Generator Inspection
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Solution Overview
Problem
The challenge in maintaining and inspecting large electrical generators is the costly and time-consuming process of accessing the rotor, which requires minimizing outage time, and existing inspection devices are cumbersome and prone to failure due to complex sensing and control systems.
Innovation Solution
A self-guiding instrument carrier system that utilizes the internal ferromagnetic and non-magnetic rail-like structures within the generator to passively guide tools or inspection devices without sensors or active control systems, relying on magnetic forces for self-centering and movement, allowing for reliable operation within the confined annular gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If complex sensing and control systems are used to guide inspection devices through the annular gap, then guidance capability is improved, but device complexity and reliability deteriorate
Solution Approach 1:
The instrument carrier uses passive self-guidance through magnetic interaction with the generator structure. The ferromagnetic instrument carrier is automatically attracted to follow the curved path between stator and rotor without requiring active sensors, motors, or control systems. The generator's own magnetic field serves as the guidance mechanism, making the system self-guiding and eliminating complex control equipment.
Solution Approach 2:
The patent replaces active mechanical guidance systems (sensors, motors, control electronics) with passive magnetic attraction. Instead of using electronic sensing and actuation to guide the device, the system relies on the natural magnetic attraction between the ferromagnetic carrier and the generator's magnetic field, substituting complex mechanical-electrical systems with a simpler magnetic field interaction.
2Measurement precision
If complex sensing and control systems are used for guidance, then guidance precision is improved, but reliability deteriorates due to potential failures
Solution Approach 1:
The instrument carrier automatically follows the magnetic field path without requiring active control systems that could fail. The passive magnetic attraction ensures the carrier naturally adheres to the intended path between stator and rotor, eliminating reliance on sensors, processors, and actuators that are potential failure points.
Solution Approach 2:
The design anticipates potential failures of active control systems by eliminating them entirely. By using passive magnetic guidance from the start, the system prevents potential failures before they can occur, ensuring reliable operation in the confined and potentially harsh environment of the generator annular gap.
3Measurement precision
If active control systems with sensors are used, then guidance accuracy is improved, but space requirements increase
Solution Approach 1:
The patent extracts and eliminates the bulky sensors, motors, and control electronics from the instrument carrier design. By removing these active components and relying on passive magnetic attraction to the generator structure, the carrier achieves guidance functionality without the space-consuming hardware that would be required for active control systems.
Solution Approach 2:
The generator's own magnetic field performs the guidance function that would otherwise require dedicated sensors and control systems on the instrument carrier. This self-service approach allows the carrier to be compact since it doesn't need to carry its own active guidance equipment - the environment provides the guidance mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces the complexity and reliability issues of existing systems by enabling independent, sensor-free guidance and movement within the generator, ensuring high availability and minimizing maintenance downtime.
Implementation Method 1
The instrument carrier is made of ferromagnetic material and can be passed through the annular gap under magnetic force from the stator and/or rotor
Implementation Method 2
guidance of the instrument carrier in the axial direction on the rotor surface and stator surface, respectively. Any magnet will be drawn by the magnetic force from the non-magnetic bars to the ferromagnetic bars
Data Source
AI summary
Removal of the rotor of a large electrical machine is costly and time consuming, and in particular the outage time of a power plant, which is needed for the removal of a generator rotor, is very expensive and should be minimized. To avoid opening of the generator for inspection and maintenance instrument carriages can be used. A method allows the reliable guidance for an in-situ instrument carrier inside the annular gap of a generator and a corresponding instrument carrier. The method avoids the use of sensors and active control systems for the guidance of the instrument carrier. A passively self-guiding system and method takes advantage of the internal structure of a generator and uses the passive centering properties of magnets to guide the instrument carrier through the annular gap of a generator.