第2章1 樓宇供配電系統(tǒng)(英文)

1、Chapter 2Chapter 2 Power supply and distribution system Power supply and distribution system2.1 Introduction2.1 Introduction2.2 Typical system inside the building2.2 Typical system inside the building2.3 system diagram reading2.3 system diagram reading2.4 monitoring system2.4 monitoring system2.5 Ex

2、amples2.5 ExamplesHydropower plant Thermal power plant Nuclear powerplant Larger userLarger userSubstation Power lineTransmission and distribution User User分配分配distributing distributing 產(chǎn)生產(chǎn)生Generating Generating 傳輸傳輸transmittingtransmitting2.1 Introduction2.1 IntroductionOthersPower supply system 11

3、0kV220kV500kV2.1 Introduction2.1 Introduction2.1 Introduction2.1 Introduction110kV 50-150km110kV 50-150km220kV 200-400km220kV 200-400km500kV 500km500kV 500km35kV10kV380V500kV2.1 Introduction2.1 Introduction10kV0.4kV110kV 10kV 10kV 110kV Power stationTransformerDistribution substations User 2.1 Intro

4、duction2.1 Introduction2.2 Typical system inside the building2.2 Typical system inside the building(a) One main + one spare single busMain Electrical Connection10kV Bus10kV BusS1S2Main Main Spare Spare 主供主供備用備用（a) Two inputs Single bus bar Save (area and finance ) Service interruption or blackout (

5、bus failure ) Building with low reliability requirement or low loadMain Electrical Connection（b) b) Two inputs Sectionalizing bus with tie switch Additional bus tie cabinet and voltage transformer cabinet High reliability Building with high reliability requirement or high load(b) Two inputs single b

6、us with tie switch 10kV Bus10kV BusS1S2Main Main Spare Spare 主主 備備 10kV Bus10kV BusS1S2Power1 Power1 Power2 Power2 Tie switchTie switch2.2 Typical system inside the building2.2 Typical system inside the building(a) One main + one spareTwo 10kV independent power inputsTwo 10kV independent power input

7、s、self-supplied generator, self-supplied generator, Sectionalizing Single bus bar on low sideSingle bus bar on low side。10kV bus10kV busS1S1S2S2Power1 Power1 Power2 Power2 400V bus 400V bus 10kV/400V10kV/400VtransformertransformerSelf-providedSelf-providedgeneratorgeneratoremergency emergency Bus Bu

8、s10kV bus10kV bus(c) Two inputs with generator (c) Two inputs with generator 2.2 Typical system inside the building2.2 Typical system inside the buildingGenerator operation diagram3S3S 10S10S5min5min10min10minMains市電市電generatorgeneratorMain Main switchdisappearrestore Self-startstopMain switch shut

9、down 自備發(fā)電機(jī)組要選擇有自啟動(dòng)裝置的機(jī)組，市電停電后延時(shí)自備發(fā)電機(jī)組要選擇有自啟動(dòng)裝置的機(jī)組，市電停電后延時(shí)3s后開始后開始啟動(dòng)，啟動(dòng)時(shí)間約啟動(dòng)，啟動(dòng)時(shí)間約10s，發(fā)電機(jī)主開關(guān)合閘供電，當(dāng)市電恢復(fù)后，機(jī)組延，發(fā)電機(jī)主開關(guān)合閘供電，當(dāng)市電恢復(fù)后，機(jī)組延時(shí)約時(shí)約5分鐘（帶載運(yùn)行），再空載冷卻運(yùn)行約分鐘（帶載運(yùn)行），再空載冷卻運(yùn)行約10分鐘后自動(dòng)停車。分鐘后自動(dòng)停車。2.2 Typical system inside the building2.2 Typical system inside the building兩路市電與自備電源兩路市電與自備電源 Fire liftFire protec

10、tionEmergency lightingHall lightinggeneratorMain I Main II EmergencybusUPS computerImportant loadinterlockG 一級負(fù)荷單獨(dú)分組方案，一級負(fù)荷單獨(dú)分組方案， 將消防用電等一級負(fù)荷單獨(dú)分出，并集中一將消防用電等一級負(fù)荷單獨(dú)分出，并集中一段母線供電，備用發(fā)電機(jī)組僅對此段母線提供備用電源。段母線供電，備用發(fā)電機(jī)組僅對此段母線提供備用電源。2.2 Typical system inside the building2.2 Typical system inside the building 正常情況

11、，消防設(shè)備等用電設(shè)備為兩路市電同時(shí)供電，應(yīng)急母線電源正常情況，消防設(shè)備等用電設(shè)備為兩路市電同時(shí)供電，應(yīng)急母線電源由其中一路市電供給。當(dāng)兩路市電失去一路，可以通過兩路市電中間的由其中一路市電供給。當(dāng)兩路市電失去一路，可以通過兩路市電中間的聯(lián)絡(luò)開關(guān)合閘恢復(fù)大部分供電，當(dāng)兩路市電全部失去時(shí)，自動(dòng)啟動(dòng)機(jī)組聯(lián)絡(luò)開關(guān)合閘恢復(fù)大部分供電，當(dāng)兩路市電全部失去時(shí)，自動(dòng)啟動(dòng)機(jī)組ATS開關(guān)轉(zhuǎn)換，應(yīng)急母線由機(jī)組供電，保證消防設(shè)備等重要負(fù)荷的供電。開關(guān)轉(zhuǎn)換，應(yīng)急母線由機(jī)組供電，保證消防設(shè)備等重要負(fù)荷的供電。Fire liftFire protectionEmergency lightingHall lightingge

12、neratorMain I Main II EmergencybusUPS computerImportant loadInter G2.2 Typical system inside the building2.2 Typical system inside the building 對大廳照明等稍為重要的負(fù)荷，由于配電開關(guān)上裝有失壓脫扣器，在對大廳照明等稍為重要的負(fù)荷，由于配電開關(guān)上裝有失壓脫扣器，在市電故障時(shí)已全部分閘，然后可根據(jù)機(jī)組負(fù)荷情況手動(dòng)合閘。例如此時(shí)市電故障時(shí)已全部分閘，然后可根據(jù)機(jī)組負(fù)荷情況手動(dòng)合閘。例如此時(shí)無火災(zāi)可全部合閘，如一旦發(fā)生火災(zāi)，則根據(jù)消防發(fā)出的指令自動(dòng)跳閘。無火

13、災(zāi)可全部合閘，如一旦發(fā)生火災(zāi)，則根據(jù)消防發(fā)出的指令自動(dòng)跳閘。方案適用于電網(wǎng)穩(wěn)定、大樓重要負(fù)荷較多的工程。方案適用于電網(wǎng)穩(wěn)定、大樓重要負(fù)荷較多的工程。Fire liftFire protectionEmergency lightingHall lightinggeneratorMain I Main II EmergencybusUPS computerImportant loadinterlockG2.2 Typical system inside the building2.2 Typical system inside the building ATS (Automatic transfe

14、r switching equipment)ATS (Automatic transfer switching equipment) 自動(dòng)轉(zhuǎn)換開關(guān)電器自動(dòng)轉(zhuǎn)換開關(guān)電器 ATS: ATS: safely switching from utility power to emergency safely switching from utility power to emergency generator power generator power主要用在緊急供電系統(tǒng)主要用在緊急供電系統(tǒng) ATS: ATS: switching from a primary source to a secondary

15、 switching from a primary source to a secondary 將負(fù)載從一個(gè)電源自動(dòng)換接至另一個(gè)（備用）電源將負(fù)載從一個(gè)電源自動(dòng)換接至另一個(gè)（備用）電源 ATS: ATS: 常常應(yīng)用在重要用電場所，其產(chǎn)品可靠性尤為重要。常常應(yīng)用在重要用電場所，其產(chǎn)品可靠性尤為重要。2.2 Typical system inside the building2.2 Typical system inside the building2.2 Typical system inside the building2.2 Typical system inside the buildin

16、g ATS (Automatic transfer switching equipment)ATS (Automatic transfer switching equipment) 自動(dòng)轉(zhuǎn)換開關(guān)電器自動(dòng)轉(zhuǎn)換開關(guān)電器ATS 雙電源切換箱雙電源切換箱 HQQ8-100/4P 20A PC Structure:(1) Power panel (開關(guān)本體開關(guān)本體)(2) CP (控制器控制器)(3) CPS (控制器電源控制器電源)(4) Wiring Harness (連接線連接線) main supply main supply380V/220V bus bar 380V/220V bus bar

17、 TransformerTransformer10kV/400V10kV/400V380V/220V spare 380V/220V spare difficult to get two inputs， 400V power supply nearby main input 10kV， 400V spare small building ,low power consumption.(d) Two inputs ( main and spare )(d) Two inputs ( main and spare )2.2 Typical system inside the building2.2

18、 Typical system inside the building進(jìn)進(jìn)線線柜柜計(jì)計(jì)量量柜柜保護(hù)柜保護(hù)柜互感器柜互感器柜變壓器柜變壓器柜變壓器柜變壓器柜其他變電其他變電所所電容器柜電容器柜保護(hù)柜保護(hù)柜進(jìn)進(jìn)線線柜柜metering cabinet power incoming cabinet otherotherstationsstationsProtectionProtectioncabinetcabinetVoltageVoltagetransformertransformercabinetcabinettransformertransformercabinetcabinetcapacit

19、orcapacitorcabinetcabinetProtectionProtectioncabinetcabinetpower incoming cabinet 進(jìn)進(jìn)線線柜柜計(jì)計(jì)量量柜柜保護(hù)柜保護(hù)柜互感器柜互感器柜變壓器柜變壓器柜變壓器柜變壓器柜其他變電其他變電所所電容器柜電容器柜保護(hù)柜保護(hù)柜進(jìn)進(jìn)線線柜柜metering cabinet power incoming cabinet otherotherstationsstationsProtectionProtectioncabinetcabinetVoltageVoltagetransformertransformercabinetcab

20、inettransformertransformercabinetcabinetcapacitorcapacitorcabinetcabinetProtectionProtectioncabinetcabinetpower incoming cabinet 1 兩路兩路10KV 進(jìn)線進(jìn)線 一路由市網(wǎng)供給，電纜引入，（裝有專用計(jì)量柜和進(jìn)線開關(guān)）一路由市網(wǎng)供給，電纜引入，（裝有專用計(jì)量柜和進(jìn)線開關(guān)）2 另一電源為備用電源，架空引入，由本企業(yè)引入。無計(jì)量柜另一電源為備用電源，架空引入，由本企業(yè)引入。無計(jì)量柜,有進(jìn)線保護(hù)柜。有進(jìn)線保護(hù)柜。進(jìn)進(jìn)線線柜柜計(jì)計(jì)量量柜柜保護(hù)柜保護(hù)柜互感器柜互感器柜變壓器柜變壓

21、器柜變壓器柜變壓器柜其他變電其他變電所所電容器柜電容器柜保護(hù)柜保護(hù)柜進(jìn)進(jìn)線線柜柜metering cabinet power incoming cabinet otherotherstationsstationsProtectionProtectioncabinetcabinetVoltageVoltagetransformertransformercabinetcabinettransformertransformercabinetcabinetcapacitorcapacitorcabinetcabinetProtectionProtectioncabinetcabinetpower in

22、coming cabinet 3 Incoming line protection cabinet: 進(jìn)線保護(hù)柜，當(dāng)變配電系統(tǒng)或母線出現(xiàn)短進(jìn)線保護(hù)柜，當(dāng)變配電系統(tǒng)或母線出現(xiàn)短路和過載時(shí)斷路器自動(dòng)跳閘。路和過載時(shí)斷路器自動(dòng)跳閘。circuit breaker operate automatically進(jìn)進(jìn)線線柜柜計(jì)計(jì)量量柜柜保護(hù)柜保護(hù)柜互感器柜互感器柜變壓器柜變壓器柜變壓器柜變壓器柜其他變電其他變電所所電容器柜電容器柜保護(hù)柜保護(hù)柜進(jìn)進(jìn)線線柜柜metering cabinet power incoming cabinet otherotherstationsstationsProtectionPr

23、otectioncabinetcabinetVoltageVoltagetransformertransformercabinetcabinettransformertransformercabinetcabinetcapacitorcapacitorcabinetcabinetProtectionProtectioncabinetcabinetpower incoming cabinet 4 Voltage transformer cabinet: metering and protection進(jìn)進(jìn)線線柜柜計(jì)計(jì)量量柜柜保護(hù)柜保護(hù)柜互感器柜互感器柜變壓器柜變壓器柜變壓器柜變壓器柜其他變電其他變

24、電所所電容器柜電容器柜保護(hù)柜保護(hù)柜進(jìn)進(jìn)線線柜柜metering cabinet power incoming cabinet otherotherstationsstationsProtectionProtectioncabinetcabinetVoltageVoltagetransformertransformercabinetcabinettransformertransformercabinetcabinetcapacitorcapacitorcabinetcabinetProtectionProtectioncabinetcabinetpower incoming cabinet 5

25、Power transformer: 兩臺兩臺10/0.4KV電力變壓器電力變壓器Y/Y0，由高壓斷路器進(jìn)行高壓，由高壓斷路器進(jìn)行高壓側(cè)短路保護(hù)和過載保護(hù)。側(cè)短路保護(hù)和過載保護(hù)。進(jìn)進(jìn)線線柜柜計(jì)計(jì)量量柜柜保護(hù)柜保護(hù)柜互感器柜互感器柜變壓器柜變壓器柜變壓器柜變壓器柜其他變電其他變電所所電容器柜電容器柜保護(hù)柜保護(hù)柜進(jìn)進(jìn)線線柜柜metering cabinet power incoming cabinet otherotherstationsstationsProtectionProtectioncabinetcabinetVoltageVoltagetransformertransformercab

26、inetcabinettransformertransformercabinetcabinetcapacitorcapacitorcabinetcabinetProtectionProtectioncabinetcabinetpower incoming cabinet 6 High voltage output to other power station. 高壓引出線：去往其他變電所高壓引出線：去往其他變電所或桿上變壓器，也是由高壓斷路器進(jìn)行短路和過載保護(hù)?；驐U上變壓器，也是由高壓斷路器進(jìn)行短路和過載保護(hù)。進(jìn)進(jìn)線線柜柜計(jì)計(jì)量量柜柜保護(hù)柜保護(hù)柜互感器柜互感器柜變壓器柜變壓器柜變壓器柜變壓器柜

27、其他變電其他變電所所電容器柜電容器柜保護(hù)柜保護(hù)柜進(jìn)進(jìn)線線柜柜metering cabinet power incoming cabinet otherotherstationsstationsProtectionProtectioncabinetcabinetVoltageVoltagetransformertransformercabinetcabinettransformertransformercabinetcabinetcapacitorcapacitorcabinetcabinetProtectionProtectioncabinetcabinetpower incoming cab

28、inet 7 Capacitor cabinet: reactive power compensation. 電容器柜：在高壓側(cè)進(jìn)電容器柜：在高壓側(cè)進(jìn)行無功功率補(bǔ)償，將本系統(tǒng)的功率因數(shù)提高到電業(yè)部門所規(guī)定的數(shù)值。一般在行無功功率補(bǔ)償，將本系統(tǒng)的功率因數(shù)提高到電業(yè)部門所規(guī)定的數(shù)值。一般在0.95左右。左右。power supply bureauB1B22 Two inputs Sectionalizing with tie switch1 low voltage bus4 Power feeder panel 3 Capacitor compensation cabinet 5 Lighting

29、 feeder panel 2.2 Typical system inside the building2.2 Typical system inside the building2.3 Diagram reading 2.3 Diagram reading ( () )1 Diagram type system diagram 什么系統(tǒng)圖？什么系統(tǒng)圖？ 當(dāng)拿到一張圖紙時(shí)當(dāng)拿到一張圖紙時(shí),若看到有若看到有母線母線,就是就是變配電所的主電路圖變配電所的主電路圖。然后看是否有電力變壓器，如然后看是否有電力變壓器，如果有電力變壓器就是果有電力變壓器就是變電所主變電所主電路圖電路圖，如果沒有則是，如果

30、沒有則是配電所配電所的主電路圖的主電路圖。2 single wire diagram元件技術(shù)數(shù)據(jù)采用兩種形式表元件技術(shù)數(shù)據(jù)采用兩種形式表示：示：Datasheet（1）標(biāo)注在圖形符號的旁邊）標(biāo)注在圖形符號的旁邊 （如變壓器、發(fā)電機(jī)等）（如變壓器、發(fā)電機(jī)等）（2）以表格形式給出）以表格形式給出（如開關(guān)設(shè)備等）（如開關(guān)設(shè)備等）Transformation station 變電所變電所Distribution Station 配電所配電所4 Analysis methods 圖的分析方法圖的分析方法從電源進(jìn)線開始，按照電能從電源進(jìn)線開始，按照電能流動(dòng)的方向進(jìn)行。流動(dòng)的方向進(jìn)行。Bus 母線母線 Ma

31、in wiring diagram主接線圖主接線圖Cabinet Type 配電屏型號配電屏型號Serial number編號編號3 Construction 圖的構(gòu)成圖的構(gòu)成2.3 Diagram reading 2.3 Diagram reading ( () )5 Incoming lines電源進(jìn)線電源進(jìn)線 兩路進(jìn)線兩路進(jìn)線（1）Aluminium strand conductor over-head leading-in ，(LJ-325mm2） QL (load switch)（FN3-10/30-50R） FU (Fuse) （RW4-10-50/30A）into Transfo

32、rmer（SL7-315kVA，10/0.4kV） distribution panel NO.3 Bus2.3 Diagram reading 2.3 Diagram reading ( () )5 Incoming lines電源進(jìn)線電源進(jìn)線 兩路進(jìn)線兩路進(jìn)線（1）采用）采用LJ-325mm23根根25mm2的鋁絞線，架空引入，經(jīng)的鋁絞線，架空引入，經(jīng)過過負(fù)荷開關(guān)負(fù)荷開關(guān)QL (load switch)（FN3-10/30-50R）、熔斷器）、熔斷器FU（RW4-10-50/30A）送入主變壓）送入主變壓器（器（SL7-315kVA，10/0.4kV），），將將10kV的電壓變換為的電壓變

33、換為0.4kV的電的電壓送入壓送入3號配電屏，然后進(jìn)到母號配電屏，然后進(jìn)到母線上。線上。（2）備用發(fā)電機(jī)經(jīng)）備用發(fā)電機(jī)經(jīng)QF（低壓斷（低壓斷路器）和路器）和QS（刀開關(guān)）進(jìn)入（刀開關(guān)）進(jìn)入2號號配電屏，之后到母線配電屏，之后到母線2.3 Diagram reading 2.3 Diagram reading ( () )FN3-10R/400 5 Incoming lines電源進(jìn)線電源進(jìn)線 兩路進(jìn)線兩路進(jìn)線（1）采用）采用LJ-325mm23根根25mm2的鋁絞線，架空引入，經(jīng)的鋁絞線，架空引入，經(jīng)過過負(fù)荷開關(guān)負(fù)荷開關(guān)QL (load switch)（FN3-10/30-50R）、熔斷器）、

34、熔斷器FU（RW4-10-50/30A）送入主變壓）送入主變壓器（器（SL7-315kVA，10/0.4kV），），將將10kV的電壓變換為的電壓變換為0.4kV的電的電壓送入壓送入3號配電屏，然后進(jìn)到母號配電屏，然后進(jìn)到母線上。線上。（2）備用發(fā)電機(jī)經(jīng)）備用發(fā)電機(jī)經(jīng)QF（低壓斷（低壓斷路器）和路器）和QS（刀開關(guān)）進(jìn)入（刀開關(guān)）進(jìn)入2號號配電屏，之后到母線配電屏，之后到母線2.3 Diagram reading 2.3 Diagram reading ( () )FN3-10R/400 Circuit breaker:Circuit breaker: Over current protect

35、ion Over current protection 低壓斷路器對發(fā)動(dòng)機(jī)低壓斷路器對發(fā)動(dòng)機(jī)進(jìn)行過流保護(hù)進(jìn)行過流保護(hù).Knife switch:Knife switch: disconnector for service disconnector for service 刀開關(guān)起隔離帶電母線刀開關(guān)起隔離帶電母線作用，便于檢修發(fā)動(dòng)機(jī)出線的自動(dòng)空氣斷路器。作用，便于檢修發(fā)動(dòng)機(jī)出線的自動(dòng)空氣斷路器。2.3 Diagram reading 2.3 Diagram reading ( () )5 Incoming lines電源進(jìn)線電源進(jìn)線 兩路進(jìn)線兩路進(jìn)線（2）Back up generator (s

36、tand by or spare) QF（circuit breaker低壓斷路器）低壓斷路器） QS disconnector, isolating switch （knife switch刀開關(guān)）刀開關(guān)）Distribution panel NO 2 Bus6 Distribution cabinet 第第3 3號配電屏號配電屏 Type ：BSL-11-01 低壓配電屏用于電源進(jìn)線。低壓配電屏用于電源進(jìn)線。 Two knife switch for dis connection（一個(gè)隔離變（一個(gè)隔離變壓器供電，一個(gè)隔離母線，壓器供電，一個(gè)隔離母線，防止備用發(fā)動(dòng)機(jī)供電，便防止備用發(fā)動(dòng)機(jī)供電

37、，便于檢修低壓斷路器）于檢修低壓斷路器） One low voltage circuit breaker 萬能型低壓斷路器萬能型低壓斷路器 （型號為（型號為DW10，額定電流，額定電流為為600A，電磁脫扣器的動(dòng)，電磁脫扣器的動(dòng)作整定電流為作整定電流為800A，能對，能對變壓器進(jìn)行過電流保護(hù)）變壓器進(jìn)行過電流保護(hù)）Operation sequence: 配電屏操作順序：配電屏操作順序：斷電時(shí)：先斷開斷路器，后斷開隔離刀開關(guān)斷電時(shí)：先斷開斷路器，后斷開隔離刀開關(guān)送電時(shí)：先合刀開關(guān)，后合斷路器送電時(shí)：先合刀開關(guān)，后合斷路器2.3 Diagram reading 2.3 Diagram readin

38、g ( () )不能小也不能大，小了會(huì)誤動(dòng)作，大了不起保護(hù)，這個(gè)調(diào)整就叫整定 7 Transformer protection 變壓器保護(hù)變壓器保護(hù) lightning rod 避雷器避雷器 型號：型號：FS-10型型 Protection 保護(hù)變壓器，防止雷電襲擊。保護(hù)變壓器，防止雷電襲擊。 A group of three on the high side of the transformer 在變壓器高壓側(cè)進(jìn)線端安裝了在變壓器高壓側(cè)進(jìn)線端安裝了一組（共一組（共3個(gè)）個(gè)）2.3 Diagram reading 2.3 Diagram reading ( () )8 Main electri

39、cal connection 主結(jié)線主結(jié)線 分段分段 單母線單母線 隔離刀開關(guān)聯(lián)絡(luò)隔離刀開關(guān)聯(lián)絡(luò) Radial配電方式為放射式。配電方式為放射式。9 Operation principle 工作原理工作原理當(dāng)電源進(jìn)線正常供電而備用發(fā)當(dāng)電源進(jìn)線正常供電而備用發(fā)電機(jī)不供電時(shí)，聯(lián)絡(luò)開關(guān)閉合，電機(jī)不供電時(shí)，聯(lián)絡(luò)開關(guān)閉合，兩段母線都由主變壓器供電。兩段母線都由主變壓器供電。當(dāng)電源進(jìn)線、變壓器等故障或當(dāng)電源進(jìn)線、變壓器等故障或檢修時(shí)，變壓器的出線開關(guān)斷檢修時(shí)，變壓器的出線開關(guān)斷開，停止供電，聯(lián)絡(luò)開關(guān)斷開，開，停止供電，聯(lián)絡(luò)開關(guān)斷開，備用發(fā)動(dòng)機(jī)供電。備用發(fā)動(dòng)機(jī)供電。 母線的母線的段和段和 段段Section

40、Section段為重要負(fù)荷段為重要負(fù)荷 SectionSection段為一般負(fù)荷段為一般負(fù)荷 2.3 Diagram reading 2.3 Diagram reading ( () )10 Feeder 出線出線從母線經(jīng)配電屏、饋線向電力從母線經(jīng)配電屏、饋線向電力負(fù)荷供電。負(fù)荷供電。 電路圖中都標(biāo)注有：電路圖中都標(biāo)注有：Distribution panel Type (配電屏型號配電屏型號) Feed line Type (饋線型號饋線型號) Cross section area 截面積截面積、 Laying 敷設(shè)方式敷設(shè)方式、 Installed capacity 安裝容量（或功率）安裝容量（或功率）Calculating power 計(jì)算功率計(jì)算功率 Calculating current 計(jì)算電流計(jì)算電流Feed circuit: 該變電所共有該變電所共有1010個(gè)個(gè)饋電回路，其中饋電回路，其中3 3和和9 9為備用為備用2.3 Diagram reading 2.3 Diagram readin