I have a wye-wye connected 300KVA, 12,470/7200X208/120V, 3 phase transformer mounted on the ground using a vault. I have a ground ring installed around the transformer. Per TM 5-811-1/AFJMAN, the secondary nuetral should be taken to a separate gournd rod (separate from the ground ring of the transformer by a distance of 20 feet) if using an ungrounded delta system or single grounded wye system. This reg shows that the secondary nuetral should be taken to the transformer ground ring if using a multiple-grounded wye system.
My understanding of a multiple grounded system is that it is a system set up with multiple ground points throughout the power distribution network, such as grounding at the transformer, the MDP and other points. Would you agree? The necessary grounding configuration of the secondary nuetral depends on the determining if a mulitple grouding system is being employed. Another description I learned is that a multiple grounded system is one in which multiple circuits were employed? Not sure if NEC covers this point.
My understanding of a multiple grounded system is that it is a system set up with multiple ground points throughout the power distribution network, such as grounding at the transformer, the MDP and other points. Would you agree? The necessary grounding configuration of the secondary nuetral depends on the determining if a mulitple grouding system is being employed. Another description I learned is that a multiple grounded system is one in which multiple circuits were employed? Not sure if NEC covers this point.
