Why must be grounded transformer core, and only allow a little ground

Why must be grounded transformer core, and only allow one-point earthing - 2019 03 - 30 15:05:16 transformer iron core transformer must be grounded to prevent in operation or when doing the experiment, due to the electrostatic induction on the iron core and other metal artifacts have suspended potential cause of discharge, so the iron core and its metal components in addition to wear heart screw, must be reliable grounding. Iron core is laminated to allow only a little ground, if there are two above ground, the ground loop can be formed between each point. When the main track through this and closed loop, in which will produce loop current, internal overheating caused by accidents. Core if not grounding can produce higher suspended potential at run time, lead to internal discharge, etc. , against the normal operation of the transformer; Each part of the core as the location of the electric and magnetic field is different, can produce is not exactly the same potential, the formation of the batteries is poor, only allow one-point earthing is to ensure that each part of the core of the potential is consistent, otherwise the core internal circulation form, cause core fever.