q測(cè)量?jī)x器與技術(shù)基礎(chǔ)(已修改)
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【正文】 Luis Introduction to 3 Phase Power Company Confidential 1 3Phase Power Systems 三相電力系統(tǒng) Luis Introduction to 3 Phase Power Company Confidential 2 5 0 0 . 0 0 4 0 0 . 0 0 3 0 0 . 0 0 2 0 0 . 0 0 1 0 0 . 0 00 . 0 01 0 0 . 0 02 0 0 . 0 03 0 0 . 0 04 0 0 . 0 05 0 0 . 0 00 50 1 0 0 1 5 0 200 2 5 0 300 3 5 0 4000 . 0 05 0 . 0 01 0 0 . 0 01 5 0 . 0 02 0 0 . 0 02 5 0 . 0 03 0 0 . 0 03 5 0 . 0 04 0 0 . 0 04 5 0 . 0 00 10 20 30 40 50 60 70 80 90Electricity is generated by conductors rotating though a magic field 電是由在磁場(chǎng)中旋轉(zhuǎn)的導(dǎo)體產(chǎn)生的 Pick a point on a circle, rotating counterclockwise at a fixed speed. When the angle is small the change in height is rapid. As the angle increases towards 90176。 the change in height slows. The distance from the “the horizon” sweeps out a sine wave. 在圓周上選一個(gè)點(diǎn)，該點(diǎn)以固定速率在圓周上向逆時(shí)針?lè)较蛐D(zhuǎn)。當(dāng)旋轉(zhuǎn)的角度比較小時(shí)，高度的變化就比較明顯；當(dāng)旋轉(zhuǎn)角度向 90176。 方向增長(zhǎng)時(shí)， 高度的變化也組件減緩。偏離“水平”方向的高度即形成了一個(gè)正弦波。 Why Sine Waves ? 為什么會(huì)是正弦波？ Luis Introduction to 3 Phase Power Company Confidential 3 Why 3Phase? 為什么為三相？ 700 .00 600 .00 500 .00 400 .00 300 .00 200 .00 100 .000 45 90 135 180 225 270 315 360D e g r e e sV (phase to phase)ABACT hr ee Phase G r ounded 500 .00 400 .00 300 .00 200 .00 100 .000 45 90 135 180 225 270 315 360V (ref to earth)A B C? At any instant the current on the neutral is zero. Try it! 在任何情況下，零線上的凈電流為零。試試看！ ? Three phase motors have better starting torque, run more quietly, are more efficient and are smaller than single—phase motors of similar hp rating 三相馬達(dá)具有更好的起動(dòng)扭矩、運(yùn)行更平順、更有效率，并且體積比相同馬力的單相馬達(dá)更小。 ? If you add more than three phases it adds more cost but doesn’t deliver significant performance improvements 如果相數(shù)多余三個(gè)，會(huì)增加很多費(fèi)用，但是性能并沒(méi)有明顯改善。 ? Three individual voltage phases typically 120 degrees out of phase of each other. 三個(gè)獨(dú)立的電壓相位彼此之間一般相差 120度。 ? Three individual current phases typically 120 degrees out of phase of each other. 三個(gè)獨(dú)立的電流相位彼此之間一般相差 120度。 ? Voltage and current will typically be shifted from each other resulting in ―power factor‖ 電壓和電流的相位一般不一致，所以就有了“功率因數(shù)” Luis Introduction to 3 Phase Power Company Confidential 4 Vector Representation 矢量表示 ? Note that the vectors go in the counterclockwise direction, like the circle in the previous slide 注意：矢量呈逆時(shí)針運(yùn)動(dòng)，類似前面例子中的圓周。 Luis Introduction to 3 Phase Power Company Confidential 5 From the Dam to Your Load 從發(fā)電站到負(fù)載 Luis Introduction to 3 Phase Power Company Confidential 6 From the Dam to Your Load 從發(fā)電站到負(fù)載 High Voltage (over 100kV) is used for transmission. All 3phase 用于電力傳輸?shù)母邏壕€路（ 100kV以上）。全為三相系統(tǒng) Substations use transformers to step down the voltage to medium voltage (4160 to 14kV). PT’s are used to measure voltage levels. 變電站利用變壓器將電壓變?yōu)橹袎海?4160到 12kV）。 使用 PT來(lái)測(cè)量電壓。 Medium voltage is used for distribution. Mostly 3phase. 使用中壓進(jìn)行配電。大多數(shù)為三相系統(tǒng)。 Medium Voltage is stepped down to 240 or 480 for delivery to customers. 中壓又被變?yōu)?240或480伏
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