2乘600MW火電站電氣設(shè)計(jì)

1、一、畢業(yè)設(shè)計(jì)（論文）任務(wù)課題內(nèi)容600MW 火電機(jī)組目前已經(jīng)是我國(guó)電力系統(tǒng)中的主力機(jī)組，由 600MW 機(jī)組為主的火力發(fā)電廠也屬于我國(guó)電力系統(tǒng)的大型主力發(fā)電廠。大型火電廠的電氣主接線設(shè)計(jì)，包括方案擬定、設(shè)備選型和裝置布置，在不同的前提下都有不同的要求，從而得到不同的結(jié)果。本課題的設(shè)計(jì)內(nèi)容主要完成 2×600MW 機(jī)組火力發(fā)電廠的電氣主接線方案擬定、設(shè)備選型和裝置布置的初步設(shè)計(jì)，同時(shí)還應(yīng)考慮今后擴(kuò)建的可能性，并采用 CAD 繪制指定的圖紙。課題任務(wù)要求1熟悉發(fā)電廠電氣一次部分初步設(shè)計(jì)的范圍和步驟，掌握設(shè)計(jì)方法，樹立工程觀點(diǎn)；2熟練掌握 AutoCAD 繪圖軟件；3根據(jù)原始資料，通過相應(yīng)

2、的分析、計(jì)算和比較，確定電氣主接線方案，選擇主變壓器的臺(tái)數(shù)、容量和型式，選擇各電壓級(jí)各主要電氣設(shè)備，進(jìn)行電壓互感器和電流互感器的配置，確定各電壓級(jí)的配電裝置型式，完成設(shè)備的整體布置設(shè)計(jì)；4與廠用電部分配合，完成畢業(yè)設(shè)計(jì)論文的寫作和圖紙繪制；5總結(jié)課題，并通過畢業(yè)論文答辯。課題完成后應(yīng)提交的資料（或圖表、設(shè)計(jì)圖紙）1畢業(yè)設(shè)計(jì)論文及相關(guān)圖紙；2英文翻譯內(nèi)容：原文和譯文；3學(xué)校要求提交的其他設(shè)計(jì)文件和材料。主要參考文獻(xiàn)與外文翻譯文件（由指導(dǎo)教師選定）1 范錫普. 發(fā)電廠電氣部分M，中國(guó)電力出版社，1992，102-129，168-206.2 西北電力設(shè)計(jì)院.電力工程設(shè)計(jì)手冊(cè)M，上?？茖W(xué)技術(shù)出版社，1

3、972,53-88,255-279.3 西北電力設(shè)計(jì)院. 電力工程電氣設(shè)計(jì)手冊(cè)（電氣一次部分）M，中國(guó)電力出版社，1987,45-62,119-123,214-260.4 西北電力設(shè)計(jì)院. 電力工程電氣設(shè)備手冊(cè)M，中國(guó)電力出版社，1990.5 黃純?nèi)A. 發(fā)電廠電氣部分課程設(shè)計(jì)參考資料M，中國(guó)電力出版社，1987.6 胡志光. 火電廠電氣設(shè)備及運(yùn)行M，中國(guó)電力出版社，2001.7 郭啟全. AutoCAD2000 基礎(chǔ)教程M，北京理工大學(xué)，2000.8 鄭忠. 新編工廠電氣設(shè)備手冊(cè)M,兵器工業(yè)出版社,1994.9 涂光瑜. 汽輪發(fā)電機(jī)及電氣設(shè)備M,中國(guó)電力出版社,1998,179-288.10

4、陳尚發(fā). 大型發(fā)電廠電氣主接線探討J，中國(guó)電力，2003 年 36 卷 7 期，起止頁碼：64-66.11 蘇志楊. 大型電廠 500KV 電氣主接線研究J，電力技術(shù)經(jīng)濟(jì)，2003 年 4 期，起止頁碼：34-35.12 楊民，寇正華. 電站電氣一次設(shè)計(jì)J，海河水利，1997 年 3 期，起止頁碼：3536.13 Srdjan Skok ph.D. Transient Analysis of Auxiliary DC Installations in Power Plantsand SubstationsJ,IEEE CHF,8-11 Nov. 2004Page(s):277 280.14 I

5、EEE Recommended Practice for the Design of DC Auxiliary Power Systems forGenerating StationsJ,IEEE STD 946-1992,Decemeber,2nd 1992.注：1. 此任務(wù)書由指導(dǎo)教師填寫。如不夠填寫，可另加頁。2. 此任務(wù)書最遲必須在畢業(yè)設(shè)計(jì)（論文）開始前一周下達(dá)給學(xué)生。3. 此任務(wù)書可從教務(wù)處網(wǎng)頁 2×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)摘要本設(shè)計(jì)討論的是 2×600MW 火電廠電氣主接線方案與設(shè)備布置，火電廠電氣一次部分設(shè)計(jì)是電力工程設(shè)計(jì)的主要工作之一，

6、設(shè)計(jì)的合理與否對(duì)于提高電力系統(tǒng)運(yùn)行的可靠性、經(jīng)濟(jì)性具有重要意義。它對(duì)發(fā)電廠內(nèi)電氣設(shè)備選擇和布置，繼電保護(hù)和自動(dòng)裝置的設(shè)計(jì)起到?jīng)Q定性作用。設(shè)計(jì)詳細(xì)說明了各種設(shè)備選擇的基本的要求和依據(jù)。在分析原始資料，確保供電可靠，調(diào)度靈活，滿足各項(xiàng)技術(shù)要求的基礎(chǔ)上，選擇出一種與發(fā)電廠在系統(tǒng)中的地位和作用相適應(yīng)的接線方式，接下來選擇了主變壓器，進(jìn)行了短路計(jì)算，設(shè)備選擇，設(shè)備校驗(yàn)，然后進(jìn)行了設(shè)備布置方案的設(shè)計(jì),繪制了主接線圖、配電裝置平面布置圖、配電裝置進(jìn)（出）線斷面圖和配電裝置配置圖。本設(shè)計(jì)注意了新技術(shù)和新型設(shè)備的應(yīng)用，把握了當(dāng)代設(shè)計(jì)新趨勢(shì)。關(guān)鍵詞：發(fā)電廠；電氣主接線；短路計(jì)算；設(shè)備選擇 2×600MW

7、 火電廠電氣主接線方案與設(shè)備布置設(shè)計(jì)THE DESIGN OF MAIN ELECTRICAL WIRING ANDLAYOUTIN THERMAL POWER PLANT OF 2× 600MWABSTRACTThe design is refered to the part of 2×600MW thermal power plant mainelectricity wiring and equipment layout.The design of substation electrical first part isone of the key tasks in th

8、e power engineering design. Whether it is reasonable or notis of great significance to raise reliability and economy of power system running . Itplays a decisive role in choice and arrangement of electrical equipment in substation,in design of relay protective and automatic.The paper detail the choi

9、ce of various equipment basic requirements and basis.On the analysis of the original material, and ensuring reliable power supply,scheduling, meet the technical requirements for fle xible and choose the right mainelectrical wiring design,in the system and the status and suited to the role of theconn

10、ection mode,and then choose the main transformer and make short circuitcalculation,choose and calibrate equipment, then design the the equipment layout. Inaddition, the final of the thesis added main electrical wiring, equipment layout ofpower distribution , distribution device cut(out) into line an

11、d configuration diagram ofdistribution device .The new technology and new equipment are applied in the design, and itaccommodates to the new trends in contemporary design.Key words: Thermal power plant ； The main electrical wiring ； short circuitcalculation；equipment selection2×600MW 火電廠電氣主接線與設(shè)

12、備布置方案設(shè)計(jì)目錄第一篇 設(shè)計(jì)說明書1 電氣主接線設(shè)計(jì)·············································

13、83;·················································

14、83;········ 11.1 電氣主接線·······································

15、3;·················································

16、3;············ 11.1.1 電氣主接線的基本要求··································

17、3;···································· 11.1.2 電氣主接線的設(shè)計(jì)原則··········

18、3;·················································

19、3;·········· 11.2 發(fā)電機(jī)電壓級(jí)接線·····································&#

20、183;·················································&#

21、183;·· 21.3 220 kV 電氣主接線············································&#

22、183;·············································21.3.1 單母線分段帶旁路接線·

23、83;·················································

24、83;··················· 21.3.2 雙母線接線····························&#

25、183;·················································&#

26、183;············ 31.4 6 kV 廠用電接線··································

27、3;·················································

28、3;·········42 負(fù)荷計(jì)算及變壓器選擇······································

29、83;·················································

30、83;··· 62.1 廠用負(fù)荷計(jì)算············································

31、83;·················································

32、83;·· 62.2 主變臺(tái)數(shù)、容量和型式的確定············································&#

33、183;························· 62.2.1 主變壓器臺(tái)數(shù)的確定·····················

34、83;·················································

35、83;··· 72.2.2 主變壓器容量的確定···········································

36、3;······························· 72.2.3 主變壓器型式的選擇················

37、;··················································

38、;········· 72.3 廠用變臺(tái)數(shù)、容量和型式的確定·····································

39、83;··························· 92.3.1 工作變壓器的臺(tái)數(shù)和型式的確定···················

40、;···································· 92.3.2 廠用變壓器的容量的確定··········

41、3;·················································

42、3;······ 93 最大持續(xù)工作電流及短路計(jì)算·········································

43、;····································· 113.1 各回路最大持續(xù)工作電流··········

44、;··················································

45、;················ 113.2 短路電流計(jì)算點(diǎn)的確定和短路電流計(jì)算結(jié)果·····························

46、83;············· 113.2.1 短路電流計(jì)算的目的·································

47、83;······································· 113.2.2 電氣設(shè)備基本假定·······

48、3;·················································

49、3;··················· 113.2.3 短路電流計(jì)算的一般規(guī)定···························&#

50、183;····································· 124 主要電氣設(shè)備選擇··········&

51、#183;·················································&

52、#183;····································· 142×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)4.1 高壓斷路器的選擇說明····&#

53、183;·················································&#

54、183;························ 144.2 隔離開關(guān)的選擇·······················

55、··················································

56、·················· 164.3 母線的選擇······························

57、··················································

58、··················· 174.3.1 220kV 母線的選擇···························

59、3;················································· 174

60、.3.2 發(fā)電機(jī)出口封閉母線的選擇···············································&

61、#183;············· 184.4 絕緣子和穿墻套管的選擇說明·································

62、;·································· 184.4.1 型式選擇·············

63、3;·················································

64、3;····························· 184.4.2 額定電壓選擇··················&

65、#183;·················································&

66、#183;················ 194.4.3 穿墻套管的額定電流選擇與窗口尺寸的配合····························

67、83;···· 194.4.4 穿墻套管的熱穩(wěn)定校驗(yàn)··········································&#

68、183;·························· 194.4.5 動(dòng)穩(wěn)定校驗(yàn)·····················

69、··················································

70、·················· 194.5 電流互感器的配置和選擇·····························

71、·············································· 204.5.1 電流互感器的配置·&

72、#183;·················································&

73、#183;························· 204.5.2 技術(shù)條件······················

74、··················································

75、····················· 214.5.3 動(dòng)穩(wěn)定校驗(yàn)··························

76、3;·················································

77、3;············ 214.6 電壓互感器的配置和選擇說明··································&#

78、183;································ 214.6.1 互感器的配置···············

79、;··················································

80、;···················· 224.6.2 技術(shù)條件···························

81、3;·················································

82、3;··············· 224.7 各主要電氣設(shè)備選擇結(jié)果一覽表·······························&

83、#183;································ 224.8 電氣總平面布置及配電裝置的選擇·············

84、83;············································· 234.8.1 配電裝置應(yīng)滿足的基本要求·

85、··················································

86、·········· 234.8.2 配電裝置的設(shè)計(jì)原則·····································

87、···································· 234.8.3 高壓配電裝置的選擇···········

88、··················································

89、············ 231 短路電流計(jì)算書····································

90、··················································

91、················· 251.1 各元件電抗標(biāo)幺值的計(jì)算······························

92、·············································· 251.2 220 kV 母線短路電流的計(jì)算&

93、#183;·················································&

94、#183;·····················261.3 600MW 發(fā)電機(jī)出口的短路電流························

95、83;·········································282 主要電氣設(shè)備選擇計(jì)算書······

96、··················································

97、······························· 312.1 高壓斷路器的選擇計(jì)算················&

98、#183;·················································&

99、#183;············· 312.2 高壓隔離開關(guān)的選擇計(jì)算·································&

100、#183;·········································· 312×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)2.3 母線的選擇計(jì)

101、算··················································

102、;·········································· 322.3.1 220kV 母線的選擇····

103、83;·················································

104、83;······················ 322.3.2 發(fā)電機(jī)出口封閉母線的選擇························

105、····································· 332.4 高壓絕緣子和穿墻套管的選擇計(jì)算·········&#

106、183;·················································&#

107、183; 342.5 電流互感器的選擇計(jì)算··············································

108、83;································· 342.5.1 220kV 側(cè)電流互感器的選擇············

109、83;················································ 342.5.2

110、21kV 側(cè)電流互感器的選擇···············································

111、3;··············· 352.6 電壓互感器的選擇計(jì)算································

112、;················································ 362.6.2 22

113、0kV 電壓互感器的選擇················································

114、················· 36結(jié) 論································

115、··················································

116、·········································· 37參 考 文 獻(xiàn)······&#

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123、3;········································ 41附錄 1：電氣主接線圖附錄 2：220 kV 總平面布置圖附錄 3：220 kV 出線、主變間隔斷面圖附錄 4

124、：220 kV 母聯(lián)、3#廠用變間隔斷面圖附錄 5：220 kV PT/I 母聯(lián)接線橋間隔斷面圖2×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)第一篇 設(shè)計(jì)說明書1 電氣主接線設(shè)計(jì)1.1 電氣主接線電氣主接線既是電氣設(shè)計(jì)的首要部分，又是構(gòu)成電氣系統(tǒng)的主要環(huán)節(jié)。電氣主接線是由電氣設(shè)備通過連接線，按其功能要求組成接受和分配電能的電路，成為傳輸強(qiáng)電流、高電壓的網(wǎng)絡(luò)，故又稱之電氣主系統(tǒng)或一次接線。主接線代表了發(fā)電廠電氣部分的主體結(jié)構(gòu)，是電力系統(tǒng)網(wǎng)絡(luò)結(jié)構(gòu)的重要組成部分，直接影響運(yùn)行的可靠性、靈活性并對(duì)電器選擇、配電裝置布置、繼電保護(hù)、自動(dòng)裝置和控制方式的擬定都有決定性的關(guān)系。因此，主接線的正

125、確合理設(shè)計(jì)，必須綜合處理各個(gè)方面的因素，經(jīng)過技術(shù)、經(jīng)濟(jì)論證比較后方可確定5。1.1.1 電氣主接線的基本要求1）運(yùn)行的可靠性：主接線系統(tǒng)應(yīng)保證對(duì)用戶供電的可靠性，特別是保證對(duì)重要負(fù)荷的供電。2）運(yùn)行的靈活性：主接線系統(tǒng)應(yīng)能靈活地適應(yīng)各種工作情況，特別是當(dāng)一部分設(shè)備檢修或工作情況發(fā)生變化時(shí)，能夠通過倒換開關(guān)的運(yùn)行方式，做到調(diào)度靈活，不中斷向用戶的供電。在擴(kuò)建時(shí)應(yīng)能很方便的從初期建設(shè)到最終接線。3）主接線系統(tǒng)還應(yīng)保證運(yùn)行操作的方便以及在保證滿足技術(shù)條件的要求下，做到經(jīng)濟(jì)合理，盡量減少占地面積，節(jié)省投資1。1.1.2 電氣主接線的設(shè)計(jì)原則以設(shè)計(jì)任務(wù)書為依據(jù)，以國(guó)家經(jīng)濟(jì)建設(shè)的方針、政策、技術(shù)規(guī)定、標(biāo)準(zhǔn)

126、為準(zhǔn)繩，結(jié)合工程實(shí)際情況，在保證供電可靠、調(diào)度靈活、滿足各項(xiàng)技術(shù)要求的前提下，兼顧運(yùn)行、維護(hù)方便，盡可能地節(jié)省投資，就近取材，力爭(zhēng)設(shè)備元件和設(shè)計(jì)的先進(jìn)性與可靠性，堅(jiān)持可靠、先進(jìn)、適用、經(jīng)濟(jì)、美觀的原則4。本設(shè)計(jì)發(fā)電廠為設(shè)計(jì)規(guī)模如下：1）發(fā)電機(jī)和變壓器采用單元接線。2）220kV 線路 4 回，另預(yù)留 2 回備用。第 1 頁 共 40 頁2×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)3）高壓廠用電采用 6kV。4）低壓廠用采用 380/220V 的三相四線。1.2 發(fā)電機(jī)電壓級(jí)接線發(fā)電機(jī)和變壓器采用單元接線。單元接線是大型機(jī)組廣泛采用的接線形式。發(fā)電機(jī)出口不裝斷路器，為調(diào)試方便可裝

127、隔離開關(guān)。對(duì) 220MW 以上機(jī)組，發(fā)電機(jī)出口采用分相封閉母線，為減少開斷點(diǎn)，亦可不裝隔離開關(guān)，但應(yīng)留可拆點(diǎn)。以利于機(jī)組調(diào)試。這種單元接線，避免了由于額定電流或短路電流過大，使得選擇出口斷路器時(shí)受到制造條件或價(jià)格高等原因造成的困難。接線圖如下圖 1.1 所示。圖 1.1 發(fā)電機(jī)-雙繞組變壓器單元接線(采用封母閉線）1.3 220kV 電氣主接線由于此發(fā)電廠為地區(qū)大型發(fā)電廠,考慮到為 220kV 高壓配電裝置接線且出線為 4回，按發(fā)電廠技術(shù)標(biāo)準(zhǔn)及規(guī)程規(guī)范，首先要滿足可靠性準(zhǔn)則的要求，有兩種可能接線方式：?jiǎn)文妇€分段帶旁路接線和雙母線接線。1.3.1 單母線分段帶旁路接線其可靠性比單母線分段高，斷路

128、器經(jīng)過長(zhǎng)期運(yùn)行或者開斷一定次的短路電流之后，其機(jī)械性能和滅弧性能都會(huì)下降，必須進(jìn)行檢修以恢復(fù)其性能。一般情況下，該回路必須停電才能檢修。設(shè)置旁路母線的唯一目的，就是可以不停電的檢修任一臺(tái)出線斷路器，但旁路母線不能代替母線工作。其極大的提高了可靠性，但這增加了一臺(tái)旁路斷路器的投資。但旁路母線系統(tǒng)增加了許多設(shè)備，造價(jià)昂貴，運(yùn)行復(fù)雜，只有在出線斷路器不允許的情況下，才應(yīng)設(shè)置旁路母線。凡采用許多年內(nèi)不需檢修的 SF6 斷路器時(shí)，可不裝設(shè)旁路母線6。接線圖如下圖 1.2 所示。第 2 頁 共 40 頁2×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)圖 1.2 單母線分段帶有專用旁路母線接線1

129、.3.2 雙母線接線此接線有兩組母線，并且互為備用。每一電源和出線的回路，都裝有一臺(tái)斷路器，有兩組母線隔離開關(guān)，可分別與兩組母線連接。兩組母線之間的聯(lián)絡(luò)，通過母線聯(lián)絡(luò)斷路器來實(shí)現(xiàn)。此接線停電的機(jī)會(huì)減小了，必需的停電時(shí)間縮短了，供電可靠、調(diào)度靈活、擴(kuò)建方便、便于實(shí)驗(yàn)。但當(dāng)母線故障時(shí)，隔離開關(guān)作為倒換操作電器，使操作的及時(shí)性、快速性受到一定影響。接線圖如下圖 1.3 所示。圖 1.3 雙母線接線綜述：從技術(shù)、經(jīng)濟(jì)及供電可靠性等多方面進(jìn)行比較，此發(fā)電廠 220kV 電氣主接線選擇雙母線接線方式。第 3 頁 共 40 頁2×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)1.4 6kV 廠用電

130、接線按發(fā)電廠技術(shù)標(biāo)準(zhǔn)及規(guī)程規(guī)范，高壓廠用電采用 6kV，高壓廠用電系統(tǒng)應(yīng)采用單母線分段接線。采取可靠的“按爐分段”的接線原則，每臺(tái)鍋爐由兩段母線供電， 兩段母線由同一臺(tái)廠用變壓器供電。低壓廠用母線采用單母線分段接線，即按爐分段。且由于低壓系統(tǒng)負(fù)荷較多，故采用動(dòng)力與照明分開，分組供電。單母線分段的特點(diǎn)如下：?jiǎn)文妇€用分段斷路器進(jìn)行分段，當(dāng)任一段母線或某一臺(tái)母線隔離開關(guān)故障及檢修時(shí)，自動(dòng)或手動(dòng)跳開分段斷路器，僅有一半線路停電，另一段母線上的各回路仍可正常運(yùn)行。重要的負(fù)荷分別從兩段母線上各引出一條供電線路，就保證了足夠的供電可靠性，兩段母線同時(shí)故障的概率較小，此接線還具有良好的靈活性、經(jīng)濟(jì)性，但當(dāng)一段

131、母線或母線隔離開關(guān)故障或檢修時(shí)，該段母線的回路都要在檢修期停電1。接線圖如下圖 1.4 所示。圖 1.4 單母線分段接線低壓廠用采用 380/220V 的三相四線制系統(tǒng)。廠用工作電源從主變壓器的低壓側(cè)引接，供給本機(jī)組廠用負(fù)荷。接線圖如 1.5 所示。圖 1.5 廠用電源變壓器低壓側(cè)引接第 4 頁 共 40 頁2×600MW 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)高壓廠用啟動(dòng)（備用）電源經(jīng)由啟/備變壓器從 220kV 母線上引接。接線圖如 1.6所示。圖 1.6 從發(fā)電機(jī)電壓母線上引接低壓廠用啟動(dòng)（備用）電源引自相應(yīng)的高壓廠用 6kV 母線段。第 5 頁 共 40 頁2×600M

132、W 火電廠電氣主接線與設(shè)備布置方案設(shè)計(jì)2 負(fù)荷計(jì)算及變壓器選擇2.1 廠用負(fù)荷計(jì)算計(jì)算變壓器的容量時(shí)，不但要統(tǒng)計(jì)變壓器連接分段母線上實(shí)際所接電動(dòng)機(jī)的臺(tái)數(shù)和容量，還要考慮它們是經(jīng)常工作的還是備用的，是連續(xù)運(yùn)行的還是斷續(xù)運(yùn)行的。為了計(jì)及這些不同的情況，選出既能滿足負(fù)荷要求又不致容量過大的變壓器，所以又提出按使用時(shí)間對(duì)負(fù)荷運(yùn)行方式進(jìn)行分類。經(jīng)常負(fù)荷是指每天都要使用的電動(dòng)機(jī)；不經(jīng)常負(fù)荷是指只在檢修、事故或機(jī)爐起停期間使用的負(fù)荷；連續(xù)負(fù)荷是指每次連續(xù)運(yùn)轉(zhuǎn) 2 小時(shí)以上的負(fù)荷；短時(shí)負(fù)荷是指每次僅運(yùn)轉(zhuǎn) 10120min 的負(fù)荷；斷續(xù)負(fù)荷是指反復(fù)周期性地工作，其每一周期不超過 10min 的負(fù)荷5。變壓器母線分段上負(fù)荷計(jì)算原則如下：1）經(jīng)常連續(xù)運(yùn)行的負(fù)荷應(yīng)全部計(jì)入。如吸風(fēng)機(jī)、送風(fēng)機(jī)、電動(dòng)給水泵、循環(huán)水泵、凝結(jié)水泵、真空泵等電動(dòng)機(jī)。2）連續(xù)而不經(jīng)常運(yùn)行的負(fù)荷應(yīng)計(jì)入。如充電機(jī)、事故備用油泵、備用電動(dòng)給水泵等電動(dòng)機(jī)。3）經(jīng)常而斷續(xù)運(yùn)行的負(fù)荷亦應(yīng)計(jì)入。如疏水泵、空壓機(jī)等電動(dòng)機(jī)。4）短時(shí)斷續(xù)而又不經(jīng)常運(yùn)行的負(fù)荷一般不予計(jì)算。如行車、電焊機(jī)等。但在選擇變壓器時(shí)，變壓器容量應(yīng)留有適當(dāng)裕度。5）由同一臺(tái)變壓器供電的互為備用的設(shè)備，只計(jì)算同時(shí)運(yùn)行的臺(tái)數(shù)。除了考慮所接的負(fù)荷