"B" phase to ground power source
"B" phase to ground power source
(OP)
Can incoming power as "B" phase to ground cause problems with 110 v circuits, used for computers. How does "B" phase to ground actually work for 480 (3 phase) and 220. Why was this a method of providing power to a production facility.






RE: "B" phase to ground power source
http://www.patchn.com/deltasys.htm
RE: "B" phase to ground power source
RE: "B" phase to ground power source
A brief explanation:
A brief explanation:
The center-tapped delta giving 120V single phase is only possible and available in a system with 240V line-to-line secondary voltage. In a 3-phase system, three 240V single-phase transformers are arranged in delta connection. You get 240V (3 phase) between line to line. One of the transformers is center-tapped and the center tap is also grounded. Voltage between the center-tap and the two lines connected to this unit will be 120V. Convention is to keep this two as A and C phases. The voltage between the center-tap (or the ground) and the B phase will then be 208V (not 120 or 240). That’s why it’s not good for 120V equipment.
Such system is not possible with 480V system (to provide 120V) or any other voltage.
The reason such system is used for a production facility is that it is very convenient and economical way for a utility co to provide both 3 phase and single phase (120V) power with one set of transformers. They have to inventory one type of single-phase transformers and group them to provide 3-phase service. Also in production facilities single phase loads are a very small percentage of the overall 3 phase loads such as motors. Such a system also does not require a intervening step-down transformer for 120V as it will be required in a 480V system. This is all assuming 240V, 3-phase service is adequate for the facility.