[EL] [Renew./Inno.] 問﹕Lift / Elevator 响設計上有啲乜要留意？

答﹕

首先係揀 lift, 主要有三種

有機房Lift (Traction, 拖帶，平時最常見)

無機房Lift (Traction, 慳返間Lift機房，則師最鐘意，但要留意唔係完全冇晒，個頂一樣有啲嘢；而且慳電)

油壓Lift (Hydraulic, 特點係慢，真係好慢，高度有限制，極限幾層樓； 同時可負好重既重量，地鐵站經常見到有用到，或停車場載車)

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之後就根據Rule of thumb 大概預四、五層樓就要一部Lift

再之後就要根據CIBSE Guide D 入機進行精確啲既估算

有兩個重要概念一定要知﹕

5 mins handling capacity 五分鐘裡面，可以載走整棟大樓幾多人。如成棟樓800人, 5 mins handling capacity is 15%, 即係可載走120人。大概預 11-15%
Interval
Travelling Time=Round Trip Time/電梯數量，大概預30s

*Round Trip Time: 一部lift 由地下行完棟樓一圈再返落樓下開門既時間

仲有啲林審嘢要留意，如Car fill factor: 一部16 人Lift未必裝得滿16人，可能得14人；Builder related e.g. lift core requirements, overhead / lift pit size, travel distance etc.

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Innovative 啲既設計﹕

Hall Call Allocation - 即係電腦系統會自動派部LIFT比你

Double Deck - 一個lift car 裡面有兩層

Energy reclaim (EMSD) - Regenerate 返啲電比其他Lift, 重load向下及輕Load Counter Weight 向下個效果會明顯啲

Variable Voltage Variable Frequency VVVF - 通過同時調整Voltage & Frequency, 可以响加速及減速期間降低個Current從而達至Energy Saving.

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Lift T&C and Inspection

Safety Related:
- Over speed governors test; - Safety Break;
- Overload Test;
- Lift door mechnical interlock;

Electrical Related:
- Apparent Power, Total Harmonic Distortion 量度; - Reverse phase, Phase loss (反相，缺相) Test;

Builder Related: - 部LIFT停响最頂嗰層既時候，度 over run 距離； 記咗堆safety components, 因為實要Inspection呢堆嘢

做好晒，行完慢車(比正常慢既速度)嚟試行部LIFT，一切準備就緒，就可以入Form 5 叫EMSD班人嚟驗LIFT
成功驗LIFT後，EMSD 會出一張叫"Use Permit", 你部LIFT就可以正式使用

Fireman Lift係用FSI Genset backup; Non-fireman lift sequential homing用Non FSI Genset backup. 當然一樣可以用FSI Genset嚟backup, 咁就要比FSD批，詳見 https://elvissharing.blogspot.com/2020/03/el-fs-genset.html
Lift Supervisory System都有機會用UPS嚟頂一陣， Say 15mins.

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無機房Lift嘅Lift Shaft 風扇計算﹕

把扇有四個條件係要滿足﹕

1. 足夠MRL 個摩打嘅散熱量；

2. 把扇有兩段控速或以上；

3. 把扇可維持五度至四十度；

4. 把扇做到10ACH for machine room or machinery space at the top of the well and its associated working space for machine room-less lift;

要求1.係要滿足Lift佬；而要求2., 3., 4.係要滿足EMSD嘅Code of Practice on the Design and Construction of Lifts and Escalators, 要留意，呢本嘢係冇得免費下載，以下係部份內容嘅截圖﹕

假設Lift佬嘅摩打散熱要求係1580kcal/h, 我地首先要搵返究竟係幾多個kW, 其實只要用一啲簡單嘅字眼响google search, e.g."kcal to kW online convertor", 就可以搵到點轉，如呢個 huansuan-danwei.info , 即時知道1580kcal/h=1.84kW:

之後我地就用中學會考物理嘅E=mc△T嚟計，為咗易計啲，將條公式兩邊同時除second, 咁就變成 Q = airflow rate * specific heat of air * △T;

而density of air = mass flow rate / volume flow rate, 我地最終目的係要搵個volume flow rate出嚟，成條式reform完就變成﹕

V = Q/ (cp)(△T)(d)

V = airflow rate; (m3/s)

Q = Total heat emitted; (kW)

cp = Specific heat of Air; (1.01 kJ/kg/oK)

△T = Genset room temperature rise; (oK), 跟據EMSD CoP, 最高溫度係40, 假設吹入lift shaft散熱嘅風係由室外吹入去，跟據BEEO 2018, outdoor design temperature 係35度，即係(40-35)=5

d = Density of air (1.20 kg/m3)

V = 1.84/(1.01*1.2*5) = 0.304m^3/s

之後就要先搵個static出嚟，搵風扇也好，泵也好，Static+Flow Rate係必備。假設Lift shaft 係2.9m x 5.2m x 53.2m(H), 頂同底有兩個0.3 meter square嘅louver, 咁個static應該點計？

首先假設咗成條lift shaft係一條石屎風喉；由於條shaft太大以致唔可能由CIBSE Guide C搵到送風嘅有效面積，所以一般會以橫切面嘅方形畫到最大嘅圓形直徑嚟估算，即係2.9m. 之後我地再用google大神search "concrete duct friction loss calculator"類似字眼，就會搵到大量嘅online calculator, 就以 Good Calculators 為例子，輸入晒數據就可以發現，原來呢個風量嘅情況下，個pressure drop (or say friction loss) 係可以ignore:

再之後估算一個louver個pressure drop有幾多，一般顧問會say落去如10-50Pa; 又或者可以大概計下，都係可以用google大神search "louver pressure drop calculator" or "louver pressure catalogue": 

Air volume flow rate, louvre area等數都有(留意係入個有效面積，即係如果係一個0.3m x 1m = 0.3meter square嘅builder窿，一般係會take返0.5 efficiency, 即係0.15 meter square); 而個discharge loss coefficient 可以搵啲類似嘅catalogue攞返個數。計完之後，見到個pressure大概係17Pa, 一上一下兩個louvre即係34Pa.

最後要check埋把扇達唔達到"10ACH for machine room or machinery space at the top of the well and its associated working space for machine room-less lift"要求，一般係lift shaft overrun嘅volume除一個鐘頭嘅秒數3600, 設overrun為5m

2.9m x 5.2m x 5m x 10 / 3600 = 0.209m^3/s

0.304m^3/s > 0.209m^3/s，所以係滿足得埋條件4.所要求嘅10ACH.

之後就可以去catalogue揀風扇﹕

為咗滿足條件2.嘅要求，當然係要搵啲有兩段速以上嘅風扇。

(Source: 香港電梯資料網 hkelev.com)

[AC] 問﹕Chilled Water Distribution Loop 有幾多種類？各有乜特點？

答﹕
Type 1: Single loop, constant flow,
Pressure sensor (installed in critical part) control bypass modulating valve, temperature sensor detect changing zone load and control 2 way valve.

For old or small building, 最舊式。

隨住時代既進步，VSD 同 Chiller技術都進步咗，以前舊樓冇用VSD, 個Chiller Evaporator 又唔可以Handle variable flow, 但上述問題都隨住時代進步而解決咗。而家一loop過搞掂，用嚟改裝Type 1, 即係Type 2 係 Type 1既升級版。
Type 2: Single loop with VSD,
Variable flow, pressure sensor (installed in critical part) control VSD, temperature sensor detect changing zone load and control 2 way valve. 條bypass 同埋個modulating valve唔洗再用。

For small building

Type 3, EMSD當年出過書仔叫大家用

Type 3: Primary & Secondary Loop, primary loop constant 可以令部chiller行得更穩定，secondary loop 行VSD. Keep primary loop constant flow, only need to consider primiary loop resistance (呢個講法可能有啲舊，我見Primary Loop都有VSD, 盡量令條by-pass flow rate 同Secondary 同步，但primary side 個flow點都大過secondary, 如果唔係return chilled water就會响條by-pass度同supply chilled water mix埋。Chiller evaporator 有個最低Limit, 大機50% 細機70%); Secondary loop use VSD to achieve variable flow with 2 way modulating valve, Primary loop 唔會受Secondary loop 既 arrangement 影响。
Primary Loop Size 大過或等於Secondary Loop, 原因為如果大唔過的話有機會條decoupler反流，到時相對高溫既水又流返入個coil度個2 way valve又會開盡，做成out of control (https://www.youtube.com/watch?v=9WeRclR1X_c)

而家可以再响Secondary Loop 度加一樣叫 "Predictive System Curve Controller" 既嘢，配合VSD使用。
原理 - Air terminal 駁住個2 way valve, 如果冇用呢舊嘢，當Air terminal 冷水需求降低時，個Valve就會收緊，同時多咗水經 by-pass. 用呢舊嘢目的係要同VSD配合，儘量開大個2 way valve從而降低系統既壓力，以達到節能效果。要做pricise commisioning.

For large building and variable load


仲有種叫做Variable Primary Flow, Primary loop 有個Flow meter control bypass valve (其實同Type 2有啲乜本質上分別？除咗一個係Pressure Sensor control primary pump; 另一個係Flow Meter control bypass)

相對於Primary - Secondary, 好處包括裝少set Secondary Pump, lower initial cost; all pumps are VSD installed (P - S 組 Primary pump 係constant, 如果用量低的話就直接開泵又關泵， low load嗰陣optimize唔到pump energy). 壞處最主要係個Control複雜咗，同埋Chiller前要加isolation valve




Also reference: https://www.youtube.com/watch?v=-ahb6g3mrnE ; https://www.youtube.com/watch?v=41jRD61MW1o

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此外仲可以配合埋响個Return Water 度加個Differential Pressure Control Valve做Total Hydronic Balancing.

先講一般既water balancing. 每條Branch前都有隻Manual Balancing Valve 較水，由於chilled water去得遠啲，pressure head就會細啲，即係越近pump既branch就要較得實啲。

之後講Total Hydronic Balancing. 如果响某啲Branch度忽然個load好細，就會引致其他Branch個flow好大，咁隻控制Zone load既Modulating Control Valve就要較到好好好細，但細極有個極限，有啲類似VAV個Damper, 太細就會non linear characteristic out of control. 隻Differential Pressure Control Valve 就响呢個時候發揮作用，幫補隻Modulating Control Valve 收細個Flow, 從而比信號隻VSD令Motor減流速節能。

(鳴謝﹕Kelvin Mak)

[PD] [FS] [AC] 問﹕一組Water Pump 前後都有好多部件，分別係啲乜嚟，有乜用？

答﹕

Globe Valve: 

- 因舊嘢個樣成個波咁而得名。可用嚟調較水量，同埋由於裡面成隻碟向下座，更低leakage; 但重，Pressure Drop大，

Check Valve:

- 阻止水倒流，同二極管原理類似；上面有個鏍絲開蓋換裡面塊Disc

Pressure Guage:

- 顧名思義，攞嚟度Pressure. 原理係少量水隊上去頂住裡面隻碟再調個指針

Y-Strainer

- 啲水流過隔垃圾

Gate Valve

- 因個閘成個Gate咁款而得名。只能用嚟做開關，難以較水量。好處係平、簡單設計、Low pressure drop；但如果關唔實會有Vibration, 同埋由於塊disc插入方向，冇Globe Valve關得咁實。

Gate Valve (駁住Pressure Guage嗰個)，又叫Plug Valve, 同Ball Valve好似，外形上唔易分

- 細件，可經常開關，Low Pressure Drop. 呢類轉九十度開關既Valve相對反應快；用於相對細flow

仲有啲係上面張圖冇但係又經常用既Valve:

Butterfly Valve

- 反應快，Low Pressure Drop, 用响High flow low pressure, 

Pressure Reducing Valve

- 顧名思義，降壓用

(鳴謝﹕K; Source: https://www.youtube.com/watch?v=DVd0TW7HffU)

[Renew./Inno.] 問﹕有邊啲Solar Related system? With explain

答﹕

1. Solar hot water system

Two Types: Flat-plate Collector, Evacuated Tube Collector

Flat-plate Collector - 成本低，但重，只能提供中等熱量；
Evacuated Tube Collector - 相對貴，但較輕盈，可以供相對高熱量(60℃-80℃)
安裝時要留意唔好比第二塊個影遮到，同埋反起22度

連埋熱水爐配合使用

Solar Cooling for Absorption Chiller - 得個知字UP下，不太實用，因為要用好大面積去收集熱力嚟餵個Chiller

2. Photovoltaic

Three types: Monocrystalline, Polycrystalline, Thin-film

Monocrystalline 個efficiency 比Polycrystalline 稍高啲，大概係15%；Thin-film 最低，得7%；
當然價錢同效率係成正比。

設計﹕
D.C.輸出，要配合Inverter轉返做A.C.嚟用；有舊後備電池，有找就充電，唔夠太陽能就放電；

用呢啲再生能源，太陽能也好，風能也好，最終都要接入自己棟樓個電網Grid
EMSD出過個指引，大致如下
- 1500kVA牛只可以揹200kW 再生電源；
- 再生能源都係發電，會同供電端(即CLP/HEC)連接；
- 見下圖，如果有人打咗個ACB，諗住同電力公司切斷後就冇電到，但個再生電源端會繼續供電過嚟，咁就會好危險；
- 所以就要有個叫"Anti Islanding" 既概念，即係不論任何情況電力公司嗰邊冇電到，再生能源端都要切斷停止供電；用指示牌提示電工要兩邊電都同時切斷先可以開始做嘢；
- 响Inverter方裝isolation transformer, 避免D.C. current進入供電端 (直流電過唔到個Transformer)；
- 同時可用Power Analyzer, 只要再生電源端電源質量ok(有機有Harmonic)先接入電網；

吹水嘢﹕
可掛facade/roof, 即BIPV；
塊嘢唔乾淨會降低效率；
單塊做下樣既可配合Tracking devices (single or two axis) 使用

(鳴謝﹕紅豆; Source: EMSD, BSRIA)

[FS] 問﹕幾時需要Intermediate Booster Pump? Jockey Pump又攞嚟做乜？

答﹕

Fire Hydrant & Drencher System會用到Intermediate Booster Pump, 要one duty one standby

由個 FS inlet 至最高嗰個Drencher head / Fire Hydrant 超過60m就要用。
消防車比8bar入嚟，個Outlet要比返3.1bar出去。

Jockey Pump用嚟做乜？

JockeY pump 係比Duty pump細一級既pump, 用嚟減少隻大pump既運行。如果有人開消防嘢用水/偷水，就會用jockey pump補壓，但如果兩分鐘都補唔到壓，就會開大pump。簡單嚟講就係用隻細泵嚟保護隻大泵，等隻大泵唔洗咁容易就開。

(鳴謝﹕Jakcy Chan; Source: FSD)

[EL] 問﹕燈有啲乜種類及特點？有啲乜節能方式？

答﹕

首先搞清楚以下幾點基本概念

LED:
如果問你Lighting方面有啲乜節能方式，可以答

Luminous Flux: (光通量)

單位(Lumen)  ，描述一個光源既發光能力

 [1 lux=1lm/m2, 概念同 Density=mass/volume 一樣]

Efficacy: (發光效率)

發光效率, 單位 (lm/W)

燈膽 8-18lm/W; 光管 37-100lm/W, 明顯地光管發光效率較高

Colour Temperature: (色溫)

顏色描述，低過3300K屬暖色，3300-5300K屬中間色，5300K屬冷色

Colour Rendering: (顯色性)

用Ra, 0-100, 數值越高，越能令物件體現出其真實顏色, 鎢絲燈及卥鎢燈可去到95

Design 上，Lighting Power Density 跟EMSD BEEO; 用幾多Lux就跟CIBSE Code
for Interior Lighting

Incandescent Lamp:

即係普通鎢絲燈膽，由25W-200W。

特徵﹕Low installation and replacement cost, Excellent colour rendering, Instantanouos
on/off, Short life, Low efficacy, high heat output

Tubular Fluorescent Lamp:

原理係加熱燈絲，電子撞擊Hg蒸氣，Hg蒸氣令其發紫外線，紫外線射到管內壁螢
光物質，從而發可見光。

分T12/T10/T8/T5

Good efficacy, Broad range of colour rendering & temperature, With control gear

Compact Fluorescent Lamp:

原理同 fluorescent lamp 一樣，只不過個型狀係燈膽型燈膽頭

特徵﹕Direct replacement for incandescent lamp, Control gear integral in the lamp,
relative high initial cost, less efficiency than tubular

Sodium Lamp:
External lighting, Highest efficacy, Long Lift, Poor colour rendering

High Pressure Mercury Lamp:
Replaced by high pressure sodium and metal halide lamp, 冇乜點用，得個知字

Metal Halide Lamp:
Good efficacy, Good colour rendering, Long life, floodlight, long start up and
restrike time, 由於colour rendering好，所以响啲精緻裝飾地方會用

LED:

High efficacy, instant light, fitted into existing lighting fittings, various colour temperature,
low voltage supply, long life, realiable, colour rendering都好
隨住LED起嚟越平，用電少散熱少效率高應用又廣泛，將會對比其他種類既燈有
絕對優勢，會取代幾乎所有燈﹕

Lighting Energy Saving Strategies有下列幾種
- Digital & Addressable Lighting Interface (DALI): 簡單嚟講即係CCMS;
- Occupancy Sensor: 冇人郁就算動熄燈；
- Photocell Sensor: 放近窗邊，夠光就自動關啲燈；

- Task Lighting, 即係大環境放少啲燈，但跟據辦公室佈置每位比啲localized啲既燈；

- T5管或Electronic Ballast, 相對Low既答法，因為都已面臨全面淘汰；
- Astronomical Time Switch - 自動決定某啲燈如Landscape Lighting幾時開，配合埋
Photocell Sensor用

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Emergency Lighting
當冇咗燈嗰陣，照住成條exit route.
紅皮書要求Escape Route 1 Lux, Staircase 1 lux;
一冧Normal電就要五秒之內起動到，發電機冇可能咁快起到，所以要自己揹舊
Central Battery, 呢舊電起碼要頂到30mins直到發電機著

Exit Sign
min. 2 hours

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Lumen Method

N = number of lamps required.

E = illuminance level required (lux)

A = area at working plane height (m2)

F = average luminous flux from each lamp (lm)

UF = utilisation factor, an allowance for the light distribution of the luminaire

          and the room surfaces.

MF = maintenance factor, an allowance for reduced light output because of

deterioration and dirt.

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Also reference: Football Field / Stadium Lighting Design

鳴謝﹕Ir.理查德

[AC] 問﹕Chiller 有邊幾種？有別有啲乜特點？

答﹕

首先講大分類，Water Cooled Chiller & Air Cooled Chiller
最大分別係佢地個Condensor散熱方式，前者係用水散熱(連住Set Cooling Tower)，後者用風散熱。
Water Cooled Chiller好處係COP高，即係Operating Cost低得多；但同時佔地多，initial cost高，Cooling Tower要用水，泵sets等部件多咗意味住可靠性都低咗maintenance都複雜咗。


之後再以Comperssor分類Reciprocating Chiller / Screw Chiller / Centrifugal Chiller，Water Cooled Chiller & Air Cooled Chiller 都可以用呢啲Compressor



用唔同Compressor，以致個Cooling Capacity/COP都唔同

	Reciprocating	Screw	Centrifugal
Air Cool Capacity	Lower than 1500kW
Air Cool COP	Around 3
Water Cool Capacity	35-700kW	100-2100kW	350-4000kW (380V) 20000kW (11kV)
Water Cool COP	Around 5		Around 6
Characteristic	Relatively higher noise & vibration, 小型用	中型至大型	大型

For min. COP requirement, your can refer EMSD BEEO 2018 Edition, 以上都只係個方便記既約數。如果有落VSD的話，Air cooled 加1 咁上下，Water cooled 加1.5-2

Heat Pump refer http://elvissharing.blogspot.com/2020/03/ac-heat-pump.html

 Energy Saving Consideration:
- 加VSD，Air cool 同 Water Cool 都用得，high initial cost for device & control, part load上表現好
- Oil Free Compressor, Air cool 同 Water Cool 都用得，high initial cost for device & control, Integrated Part Load Value IPLV & Full Load 都比傳統Chiller好，有study say 慳電30%
原理﹕
Air Bearing - 個Shaft 轉起上嚟嗰陣有個air gap, 個leaf foil 脹開令到個Shaft 轉起嚟嗰陣掂唔到其他地方

Magnetic Bearing - 用Magnetic keep 個Shaft 响中間

https://www.youtube.com/watch?v=kQtNM72swO0

- Increase chilled water temperature, say 7^oC to 8^oC，但要考慮dehumidification問題，同埋可能會反而開冷氣開耐咗，要做個retro-commissioning先知

仲有種特別啲既Chiller 叫 Absorption Chiller，佢既特點係冇咗Compressor嗰part，用熱，尤其係廢熱取代。COP相對低，say 0.6-2

Chiller Maintenance
留定啲窿、I-Beam, Eye Bolt可以成部吊走

(Source: TheEngineeringMindset.com, EMSD BEEO)

[PD] 問﹕一單新project由申請供水到完工既流程係點？

答﹕

一開JOB，首先要搵顧問 (或業主自己)，向水記check下該地段有冇Fresh / Flush water supply, 即係WWO132, 大概講下你棟新樓係乜用途、預估水用量等。OK的話WSD會覆張WWO1004比你。
之後則師出到張GBP後，機電顧問就可以預備Vertical Plumbing Line Diagram VPLD，Water meter schedule, 預算水缸大小及種類。
有晒呢堆資料後，就向WSD入WWO542 (係人都入得，有張公司BR就得) 申請供水proposal，之後水記會比返張批準信你同埋要你交按金。
之後就到入WWO46 Part 1, 2, 都係入VPLD同埋Annex等一系列潔具用品，呢部份就真係要搵AP同水喉匠簽名。
跟住水記會覆返張WWO46 Part 3 比你話你聽開得工。

流程如下圖﹕

之後就開工。嗰張嘢叫Paritial Part 4, 類似地渠咁入form, 驗牌子，3M鉛捧。Underground藏喉的話要RPE加簽。
完工後入正式Part 4 驗安裝咗既嘢。

Part 4要入既嘢包括﹕對Annex, Layout, 其實即係你之前Part 1, 2 入嗰啲嘢，驗鉛紀錄。

之後水記會覆張Part 5A 比你話你聽你啲嘢已裝好及驗完，但不等於比水紙。

跟住再填WWO132 Part 2 叫佢嚟駁水，WSD報稱要預早三個月通知。

跟住要比每層樓三次循環沖洗紀錄，約水記夾驗水板，每個ZONE攞三個板，有14個parameters要驗，除大樓外，大喉入水嗰個位都要驗。

OK後，先比埋個張WWO46 PART 5B你。最後比埋張water supply cert.你。

3M驗鉛棒用法﹕攞支嘢响焊接位擦一擦，變紅色即係有鉛。

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設計考慮﹕

系統分zone, 同消防差唔多，最高幾層加Pump, 之後過50m要加減壓制。一般都三Zone, 加泵一Zone, Gravity 一Zone, 減壓制一Zone.
首先講水缸點Size, 最常識都諗到，就係由Daily Consumsion 去估算。
以下數字大概知道就得﹕ 頭十個單位每個單位135L，之後就每個90L；Cleasing and irrigation都係45L per point; 沖廁水就45L一個Point, 理得尿兜也好屎塔也好，都係呢個數。呢堆數據可以由WSD Plumbing Handbook搵到。

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改善鉛水問題及應對方案﹕
Time to time Inspection and checking。WSD有個 Enhanced Water Quality Monitoring Programme. 有六種金屬會進行監測，分別係銻、鎘、鉻、銅、鉛、鎳。

WSD會全港隨機抽樣 (非強制)，由一個WSD Water Sampler + 一個獨立顧問LP上門攞水板。

首先會隨機攞一次水板，如果第一次超標就會試第二次。第二次試法係先放水五分鐘，再等三十分鐘先攞。

如果超標，冇計架，惟有裝濾水器或用蒸餾水煮食。

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WSD而家有啲新嘢係Automatic Meter Reading (AMR) System

(鳴謝﹕K)

[EL] 問﹕ Lift / Elevator 有啲乜Safety Devices?

答﹕

Devices for locking the door:
- 有機械臂等裝置，令到棟LIFT門關好後部LIFT先可以郁；

Over speed governors:
- 過咗一定速度就有機械裝置剎停部LIFT；

Buffer:
- LIFT槽底個彈弓，有Hydraulic 或 Mechanical, 只係防墮幾層；

Safety Break / Safety Gear:
- 失速時/斷纜時夾住條Rail;



Essential Power:
- 冇電嗰陣都仲可以停去最近樓層及開門；

Fire Resistant Cable:
- For lift homing and Fire Services Lift；

優質Youtube參考，睇透成部Lift結構﹕https://www.yotube.om/watch?v=uX9i5YAVhQw


(Source: 香港電梯資料網 hkelev.com, EMSD)

[FS] [PD] 問﹕消防水泵同普通用水泵最大分別係乜？

答﹕

消防水泵要試三點


即係BS EN 12845個Table 16

先講第一點，會响個Control Valve C Gauge度試；
第二點都係响C Gauge度試；
第三點回缸嘔住水模擬緊堅係爆咗頭嘅情況，嚟確定第一、二點都做到呢個Pressure & Flow Rate. 
(我估呢個亦都係點解Control Valve Set要放响地下嘅原因，目的就係為咗可以直接用呢個點嚟簡單Pre Calculation)
(至於點解要試兩點，有一個講法係第一點同第二點分別模擬成個Sprinkler System 最高最遠嗰點同埋最高嗰點；仲有一個講法係用嚟確定你個Pump嘅Charateristic, 睇你會唔會一Drop少少Pressure個Flow就會Drop到唔乎合requirement)

至於消防水泵條Pump Curve一般嚟講應該Flat啲定Steep啲好啲？其實應該係Flat啲好，首先係我地都唔知邊個ZONE方粒頭會爆，即係幾時都唔知道條System Curve係點。如果太Steep個Flow同Pressure比起第二同第三點測試個差會好大唔同。

唔同Zone的話係用Multi Stage Pump再以唔同Outlet嚟供水，唔同Outlet provide到唔同Head

普通水泵只要試一點；

此外消防泵係要以High Rupturing Capacity (HRC) Fuse嚟保護，主係係MCB 同 FUSE 跳制特性有關，say 25A 嘅MCB同25A嘅FUSE, 如果篤50A電流入去，MCB幾秒就跳，但FUSE可能要十幾廿分鐘先跳。咁就就算overloading 都好，個消防泵就可以堅持到最後一刻。<--以前聽過N咁多個版本解釋呢樣嘢，暫時覺得呢個版本較可信。

直到睇到 電氣生涯 Electrical Lift: https://lifelectrical.blogspot.com/2018/04/fuse.html ，發現呢個解釋最清楚，詳見上link留言部份高手嘅解釋。

(鳴謝﹕Aska Chan, 肥喵; Source: BS EN 12845)

[EL] 問﹕How to Plan & Design Electricity Supply System for Building?

答﹕

Supply side:

1. Dual HV feeders from the supply grid for sensitive buildings;
2. Decentralize, if more than 3 Tx, multiple room, ensure Tx room & LV switch room free of water hazard; Transformer room & LV switch room closed to the load centre if possible to reduce copper loss;
   
   
   
   一般1500kVA一隻牛，但可特別申請2000kVA；一間房可放一至三隻牛。
3. Dual supplies and Interconnecting facilities, if multi-transformer installation, backup Tx capable to handle essential load from failure Tx, say 25%;
   Diverse supply routing, main electrical distribution circuits/risers separated into two electrical rooms/risers ;
4. Sufficient capacity reserve for various design considerations, future expansion, power harmonics from electronic ballast for lamps, VSD, IT equipment etc., say 20%;
   Spare switchgears/cable containment between the two electrical rooms/risers;
5. Vertical in-line of risers, avoid material wastage and lower the headroom;
6. Essential and non-essential switchboard seprate compartment;
   
7. CAT5 singal transmission limit
   

Click開就睇到兩隻牛互相backup electrical diagram

Secondary Backup Power Supply

1. Emergency Genset, may consider N+1 and sufficient capacity of fuel tank; https://elvissharing.blogspot.com/2020/03/el-fs-genset.html
2. Plug in point for mobile genset
3. UPS/EPS (香港好似叫Central Battery System CBS;
   
   Genset initial & operating cost最平，UPS最貴，切換最快；EPS切換慢過UPS但平過UPS;

Metering
Electricity kWh Meters --> 計電費用
Separate Check Meters --> Energy Aduit 用
另外，啲Fixed Telecommunication Network Services FTNS Operators, 唔同商戶、停車場等，都用獨立電錶計電。main circuit, sub main circuit, freeder circuit等都會掛。

Voltage Dip Compensator:

電壓忽然發生驟降，可以用舊Voltage Dip Compensator 解決，有Capacitor Type or Battery Type

個人感想﹕商業世界同政府Project都幾唔同，商業世界求Initial cost低，慳到錢先係王道；政府則求穩，無限備份，錢唔係重點。

(鳴謝﹕Raymond Cheng)