http://static.schneider-electric.us/docs/Electrical%20Distribution/Switchboards/QED-S/2700DB0202.pdf
google "grounded delta" 這是排在第一的,新的installation 大都不採用此法,過去用的多,但是還是有電力公司選用此法.
Corner-grounded delta systems are not recommended for new installations.
However, some utilities still provide this system, and many old installations
still exist. Schneider Electric has tested equipment for use on
corner-grounded delta systems to provide Underwriters Laboratories Inc.
(UL®) listed products for this application
by -?-
這是三年前英文yahoo的一個發問的答案
http://answers.yahoo.com/question/index?qid=20100911180858AALarMRBest Answer - Chosen by AskerA corner-grounded delta system has the following characteristics:
* Grounding one phase stabilizes the voltage of the other two phases
to ground.
* High fault currents may flow on the first ground fault, requiring the
immediate clearance of this first fault.
* The voltage to ground in this system will be the system voltage, usually
240 or 480 volts.
Corner-grounded delta systems are not recommended for new installations because more suitable and reliable systems are available today.
Corner grounded delta distribution systems is not recommended, for several reasons:
Nearly all low voltage systems in the past were supplied from transformers with delta-connected secondaries. Grounding one of the phases provided a means of obtaining a grounded system. In this way, a grounded system could be obtained at a minimum of expense where existing delta transformer connections did not provide access to the system neutral.
Possibly, customers wanted to avoid installing equipment ground fault protection as required by the NEC on solidly grounded wye electrical services.
This system could result in the use of less expensive equipment, since two-pole switches and a neutral could be used for three-pole applications.
Corner-grounded delta systems have several advantages and
disadvantages, as listed below.
2013-04-24 11:32:47 補充：
http://answers.yahoo.com/question/index?qid=20100911180858AALarMR
還有優缺點,已無法再上傳
