| Operation & maintenance
Hidden in plain sight: the risks of shaft misalignment
Often a relatively small error, but with system-wide consequences, shaft misalignment remains one of the most persistent and underestimated reliability risks in power generation. While widely recognised across general industry, its impact is amplified in power stations, where turbines, generators, and auxiliary systems operate continuously under high loads and thermal variation. This article examines how misalignment affects critical assets in fossil fuelled, nuclear, and hydroelectric plants, supported by real-world case studies, and highlights the growing importance of precision alignment in improving efficiency, supporting grid stability, and advancing decarbonisation objectives
Terry C. Southall Global Brand and Distribution Manager, Hamar Laser Instruments, Inc.
In power generation, reliability is fundamental to operational performance, grid stability, and economic viability. Even small inefficiencies can translate into measurable losses in megawatt output, increased fuel consumption, or unplanned outages. Among the many contributors to these risks, shaft misalignment remains one of the most common, and most preventable. Misalignment occurs when the rotational centrelines of coupled machines are not collinear. While often measured in thousandths of an inch or microns, the forces generated by misalignment scale rapidly with machine size, speed, and load. These forces increase a bearing’s reaction loads, induce shaft bending, and generate vibration signatures that propagate across the machine train. Over time, the cumulative effect is reduced efficiency, accelerated wear, and increased probability of failure.1, 2
Power stations are vulnerable Power stations operate under conditions that amplify both the likelihood and severity of misalignment. Continuous duty cycles ensure that any alignment error is constantly imposing stress, while large rotating masses magnify the resulting forces. Thermal growth further complicates alignment. As turbines,
Figure 1. Thermal growth shifts alignment during operation
casings, and structures heat up, components expand at different rates. A machine aligned at ambient conditions may shift significantly when operating temperature is reached, causing it to run outside acceptable tolerances during normal operation.3
This shift between cold and
operating conditions is illustrated in Figure 1. In multi-component trains, such as gas turbine, gearbox, and generator systems, these shifts
can propagate across multiple couplings, compounding the issue.
Quantifying the impact Misalignment introduces measurable penalties in both mechanical performance and energy efficiency. Even moderate misalignment increases internal forces, elevates bearing loads, and drives additional friction within the system, all
www.modernpowersystems.com | October 2026 | 29
All images, graphs and tables: Hamar Laser Instruments, Inc.
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