What could be a cause for an electrical DC machine getting too hot during operation?

An electrical DC machine can experience overheating during operation due to several interrelated factors, particularly when both the cooling system malfunctions and there is an increased operational load. A malfunction in the cooling system might prevent the machine from dissipating heat effectively, which can lead to excessive temperature build-up. Simultaneously, an increased operational load causes the machine to draw more current and generate additional heat due to increased power dissipation (I²R losses) in the windings. The combination of these two issues exacerbates the heating problem, leading to a higher risk of damage or failure.

While malfunctioning bearings can lead to excess friction and heat, this isn’t the primary concern with overheating in direct relation to electrical losses. Similarly, inefficient energy conversion can contribute to heating but may not be as immediate a factor in this context as the other issues.