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Soviet Nuclear Submarine Electrical Systems: Automated Turbine-Generators

By Bruce Rule - Nov 5, 2014

Circa 1970, the ONI acoustics shop encountered strong disagreement from US Naval Reactors who maintained the Soviets would never use dc motor-driven main coolant pumps in their first generation nuclear submarines (N, H, E) because of coolant leakage. They were right about the leakage but wrong about the use of dc motors as confirmed by the following paragraph from the linked site.

“Remote control equipment became more common. In the second generation submarines (C, V. Y, D), alternating current replaced the direct current used in the submarines of the first generation, and this change made it possible to reduce the size of some of the equipment. Finally, the turbine-generator was automated.”

The above reference to automated turbine-generators (SSTGs) is interpreted to mean a system in which a steam turbine drives an ac-generator that powers most on-board systems (i.e., the HOTEL load) that includes an ac-dc system (SSMG) in which an ac motor drives a dc generator. If there is a failure of the steam supply to the SSTG, the SSMG flips function and, drawing on the battery, becomes a dc-motor that drives an ac-generator to automatically pick up the critical part of the ac load dropped by the SSTG, a capability that, in some circumstances, could avoid a reactor shut-down (scram).

The advantages inherent in such a design suggest the concept may still be in use.