Hello, everyone (especially current or former USN Electrician's Mates). As some of you probably know the U.S. Navy uses ungrounded shipboard A.C. power distribution in order to ensure "battle short" availability of on-board electronic equipment. In Fig. 3-13 of USN training manual
14344 (available as a downloadable pdf at
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is a simple circuit for determining whether a fault condition (short to ship hull) exists on any phase of a 3-phase system. My question is what is the purpose of hull grounding of the midpoints of the transformer secondaries in Fig 3-13? Thanks for your time and comment. Sincerely,