【正文】 The first part consists of specifications, putation book and Electrical engineering drawings about the design. The specifications has several parts which are General analysis of the station, Load analysis, The selection of the main transformer, Layout of configuration, Computation of short circuit。線路保護(hù)的整定計(jì)算 。負(fù)荷分析與主變選擇 。電氣主接線設(shè)計(jì) 。主變壓器的保護(hù)整定計(jì)算 。 Select of electric 鄭州大學(xué)電氣工程學(xué)院畢業(yè)論文 2 devices, Power distribution devices, General design of substation plane and the design of thunderbolt protection. The second part also consists of specifications, putation book and electrical drawings about the design。變壓器能使電力系統(tǒng)各個(gè)部分運(yùn)行在電壓不同的等級(jí)。它在鐵圈中建立了磁通 φ，它的幅值和方向都會(huì)發(fā)生周期性的變化。這兩種相關(guān)的損耗被稱為鐵芯損耗。這種情況是非線性鐵芯材料造成的。一次側(cè)空載電流很小，僅為滿載電流的百分之幾。用字母 a 來(lái)表示這個(gè)比率，如下式 a = psEE = psNN 假設(shè)變壓器輸出電能等于其輸入電能 —— 這個(gè)假設(shè)適用于高效率的變壓 器。 當(dāng)副邊電壓 Vs 相對(duì)于原邊電壓減小時(shí)，這個(gè)變壓器就叫做降壓變壓器。 從電源側(cè)來(lái)看變壓器，其阻抗可認(rèn)為等于 Vp / Ip。換句話說(shuō)，極性的標(biāo)注可以表明當(dāng)電流流過(guò)兩側(cè)的線圈時(shí)，線圈中的磁動(dòng)勢(shì)會(huì)增加。感應(yīng)電壓的減小將使外施電壓和感應(yīng)電動(dòng)勢(shì)之間的差值更大，它將使初級(jí)線圈中流過(guò)更大的電流。故一次側(cè)電流 Ip 是電流 Ip’與 I0’的和。一次側(cè)漏磁也一樣。 譯自 科技英語(yǔ) XXX： XF110KV 變電所設(shè)計(jì) 7 原文 TRANSFORMER 1. INTRODUCTION The highvoltage transmission was need for the case electrical power is to be provided at considerable distance from a generating station. At some point this high voltage must be reduced, because ultimately is must supply a load. The transformer makes it possible for various parts of a power system to operate at different voltage levels. In this paper we discuss power transformer principles and applications. 2. TOWWINDING TRANSFORMERS A transformer in its simplest form consists of two stationary coils coupled by a mutual magic flux. The coils are said to be mutually coupled because they link a mon flux. In power applications, laminated steel core transformers (to which this paper is restricted) are used. Transformers are efficient because the rotational losses normally associated with rotating machine are absent, so relatively little power is lost when transforming power from one voltage level to another. Typical efficiencies are in the range 92 to 99%, the higher values applying to the larger power transformers. The current flowing in the coil connected to the ac source is called the primary winding or simply the primary. It sets up the flux φ in the core, which varies periodically both in magnitude and direction. The flux links the second coil, called the secondary winding or simply secondary. The flux is changing。 thus the induced quantities Ep and Es vary as a sine function. The average value of the induced voltage given by Eavg = turns c h a n g e in flu x in a g iv e n tim eg iv e n tim e which is Faraday’s law applied to a finite time interval. It follows that Eavg = N 21/(2 )mf? = 4fNφm which N is the number of turns on the winding. Form ac circuit theory, the effective or rootmeansquare (rms) voltage for a sine wave is times the average voltage。 that is, it has no losses. Thus Pm = Pout or VpIp primary PF = VsIs secondary PF where PF is the power factor. For the abovestated assumption it means that the power factor on primary and secondary sides are equal。 and (2) it provides a ponent to account for the hysteresis and eddy current losses in the core. There bined losses are 鄭州大學(xué)電氣工程學(xué)院畢業(yè)論文 8 normally referred to as the core losses. The noload current Iθ is usually few percent of the rated fullload current of the transformer (about 2 to 5%). Since at noload the primary winding acts as a large reactance due to the iron core, the noload current will lag the primary voltage by nearly 90186。另外，兩側(cè)繞組同樣具有阻抗，這也將產(chǎn)生一個(gè)電阻壓降。因?yàn)樵谶@種狀況下鐵芯的磁通是恒定的。 總的來(lái)說(shuō)，變 壓器為了保持磁通是