Why Does a 12-Lead 230/460V Motor Run at 380V 50Hz Without De-Rating? Ground Role?

A discussion centers on why a standard 12-lead 230/460V 60Hz motor can operate at 380V 50Hz without de-rating, using a special connection involving grounding. The motor's 12 leads are connected as follows: Leg 1 (2-8), Leg 2 (3-9), Leg 3 (1-7), with leads 4, 5, 6, 10, 11, and 12 tied together and connected to ground. A note mentions operating at 1.732 times the low voltage, implying a neutral voltage over 600V that must be solidly grounded. The connection is neither a standard Wye, Delta, nor Star configuration, and the manufacturer’s instructions only reference an internal connection diagram without detailed explanation. Concerns arise about measuring continuity or apparent shorts between leads and ground, which may be due to measuring across motor coils at DC. The grounding role is critical for safety and proper operation at the elevated voltage level. Reference to a NEMA standard diagram for 12-lead motors is suggested for further understanding. No specific model or brand details are provided.
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