Incandescent light bulbs have an internal fuse-one of the lead in wires that burn as the arc should form from a just opened filament.This is to protect the fixture if anything else.
Distribution transformer secondaries the center tap neutral is grounded inside the transformer case.So if a fault from a shorted sec winding,primay winding short to the secondary-the primary transformer fuse would blow immediately.Linemen test the transformer before replacing the fuse.The voltage at the customer is mostly adjusted at the customers transformer-its primary taps.At work our line voltage is high--supposed to be nominal 4160V but is often over 4200V or even 4300V.The equipment here is designed to "take it"Out 208/120V is often 215,218V.The taps on the 4160V-208/120V can be adjusted at our transformer.500Kka 208/120V.There are two of these transformers on an auto chageover-like on a generator.So if one transformer fails-switches over to the other.These are dry transformers.The origianl were 3 167Kva Westinghouse oil filled(PCB).When these were replaced-2 failed--pretty good after 60+ years.Any of the old transformers were sent to a place in Georga and incinerated.They have an incinerator that can take on large transformers.All that would be left is the copper and iron that would be salvaged.Transformers from three older transmitters went thru that fate.Slowly oil filled transformers out here are being replaced with dry.
Distribution transformer secondaries the center tap neutral is grounded inside the transformer case.So if a fault from a shorted sec winding,primay winding short to the secondary-the primary transformer fuse would blow immediately.Linemen test the transformer before replacing the fuse.The voltage at the customer is mostly adjusted at the customers transformer-its primary taps.At work our line voltage is high--supposed to be nominal 4160V but is often over 4200V or even 4300V.The equipment here is designed to "take it"Out 208/120V is often 215,218V.The taps on the 4160V-208/120V can be adjusted at our transformer.500Kka 208/120V.There are two of these transformers on an auto chageover-like on a generator.So if one transformer fails-switches over to the other.These are dry transformers.The origianl were 3 167Kva Westinghouse oil filled(PCB).When these were replaced-2 failed--pretty good after 60+ years.Any of the old transformers were sent to a place in Georga and incinerated.They have an incinerator that can take on large transformers.All that would be left is the copper and iron that would be salvaged.Transformers from three older transmitters went thru that fate.Slowly oil filled transformers out here are being replaced with dry.