三相220V , delta接法電壓一問

👨🏻‍🏫 學術台工程學

[匿名]

2013-04-23 4:57 pm

請問:
三相三線220V delta接法的電壓量測
相對地標準值各是多少?

相1對相2 220V
相2對相3 220V
相3對相1 220V
相1對地 220 V
相2對地 0 V
相3對地 220 V

這樣是不是異常呢?

更新1:

我記得以前讀過相2對地是190V??? 如果相2接地不會造成短路嗎? 所以相2就是接地,可以這麼說嗎?

回答 (5)

用戶39453

2013-04-23 7:33 pm

✔ 最佳答案

電力系統接地是為了避免電壓浮動對人員或設備產生損傷,

三相四線式通常以N相作為系統接地點.

而三相三線式因為沒有N相, 但為了前述原因通常會以S相接地. 所以S相對地電壓才會是0V.

所以你量到的數值是沒問題的.

參考: 很久很久以前學校老師教的東西

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jose

2013-04-24 7:26 pm

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

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