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mapj1:
. . . Assuming only one NE bond and one point of earthing for the LV side, it can be treated as TNS, just with the NE link outside the transformer tank. . .
Is there a separate HV earth ?
If not you must assume HV and LV earthing is shared and never interrupt the common CPC while the HV side is connected, even if the LV is off, or the transformer core and all the metalwork attached to it, will be driven to some nasty high voltage by the capacitance between the HV windings and the core and tank.
mapj1:
. . . Assuming only one NE bond and one point of earthing for the LV side, it can be treated as TNS, just with the NE link outside the transformer tank. . .
Is there a separate HV earth ?
If not you must assume HV and LV earthing is shared and never interrupt the common CPC while the HV side is connected, even if the LV is off, or the transformer core and all the metalwork attached to it, will be driven to some nasty high voltage by the capacitance between the HV windings and the core and tank.
We're making some changes behind the scenes to deliver a better experience for our members and customers. Posting and interactions are paused. Thank you for your patience and see you soon!
For more information, please read this announcement