مقتطفات فى التصميم والتنفيذ الكهربى
(، يمكنك تحميل بعض الملفات الهامة آخر المقال.)
(Lighting)
What are the types of lamps?
Filament: Incandescent, Halogen (tungsten), Reflector
Gas discharge Fluorescent, High pressure sodium, Low pressure sodium, High pressure
mercury, Metal halide, Led
Tube: TL-D (T8) % TL-5
Compact: Integrated & Non integrated
What are the types of fluorescent lamps?
How can you calculate No of luminaires
N = (Lux * a * b)/ (Lumen * UF * MF * n)
Lux: From codes
a: length of room
b:
Width of room
Lumen:
from
MF:
maintenance factor indoor = 0.8 Outdoor = 0.6
n:
No of lamps in luminaire
UF:
utility factor
N:
No. of luminaire
How can you get UF
Via
two factors
Room index
K = (L * W) / {(L + W)*h}
L: Length
of Room
W:
Width of Room
h: distance between luminaire to work place
Knowing color of ceiling, wall and work place, then use catalog table
How can you get No of luminaires in length and width?
In
length = √ (L*N/W)
In
width = √ (W*N/L)
L:
Length of room
W:
Width of room
VA for one light circuit
VA for one lighting circuit as standard is 1200 VA
حساب عدد وحدات الاضاءة وتوزيعها يدويا
من المعلوم انه يوجد برامج رائعة لحساب عدد وحدات الاضاءة وتوزيعها مثل برنامج الديلكس والاصدرات الحديثة منه، وبادخال البيانات صحيحة واستخدام الوحدة المناسبة الصحيحة ستحصل على نتائج صحيحة، ولكن هنا سنشرح الطريقة الدوية حيث يمكن اللجوء اليها عند الرغبة فى الحصول على نتائج سريعا او فى عدم توفر برامج الديلكس.
ولحساب وحدات الاضاءة نستخدم المعادلة التالية:
N=(LUX*a*b)/(LUMEN*n*UF*MF)
N: عدد وحدات الاضاءة، الوحدة يمكن ان تحتوى على اكثر من لمبة
LUX: شدة الاضاءة المطلوبة للمكان ونحصل عليها من الاكواد IEC, EC, NEC
a: طول الغرفة بالمتر
b: عرض الغرفة بالمتر
LUMEN: ليومن للمبة الواحدة ونحصل عليه من كتالوج وحدات الاضاءة
n: عدد اللمبات فى وحدة الاضاءة
MF: معامل الصيانة، يكون 0.8 للوحدات التى تركب داخل المبنى، وتكون من 0.4 الى 0.6 للوحدات التى تركب خارج المبنى
UF: معامل الاستخدام، وللحصول عليه يجب حساب Room Index (K)
K = (a*b) / {(a+b) * hb}
hb: المسافة بين سطح العمل و وحدة الاضاءة
ومن الكتالوج وبمعرفة K و معاملات انعكاس الجدران والسقف والارضيات ومن الجدول نحصل على UF
وبالتعويض فى المعادلة نحصل على عدد الوحدات المطلوبة للغرفة.
ولتوزيع الوحدات نستخدم المعادلات التالية:
(N in length = √(b*N)/a
N in width = √(a*N)/b)
وبذلك تحصل على عدد الوحدات فى الطول و العرض
(Power Sockets)
VA
for one socket
180
VA in IEC code & NEC code
250
VA in EC code EC: Egyptian code
Weather proof socket location
Corridors, Kitchen, Bathroom, Outdoor, Store, Factories
VA for one socket power circuit
VA
for one socket power circuit as standard=
2000 VA
AMPERE OF LOAD
Ampere
per one KVA for single phase I= 4.5 * KVA
Ampere per one KVA for three phase I= 1.5 * KVA
(CIRCUIT BREAKER)
Ampere for CB = safety factor * I L
Safety factor=25% over load AS EC EC: Egyptian code
20%
over load AS IEC European code
10% over load AS NEC American code
Suitable C.B for load 100 KVA is 100*1.5*1.25 = 187.5 We select 200 A as EC
What are standard rate of C.B
10,
16, 20, 25, 32, 40, 50, 60, 80, 100, 125, 160, 200, 250, 400, 630, 800, 1000,
1250, 1600, 2000, 2500, 3200, 4000
CIRCUIT BREAKER TYPES & RATE
*MCB
(miniature C.B) RATE FROM 10 A TO 125 A
*MCCB
(molded case C.B) RATE FROM 16 A TO 1600 A
*ACB
(air C.B) RATE FROM 630 A TO 6300 A
(Cables)
Cable voltage rate:
Low
voltage cable from 1 volt to 1000 volt
Medium
voltage cable from 1 KV to 66 KV
High
voltage cable from 66 KV to 500 KV
What are differences between PVC and XLPE
MAX.
Temp at normal operate PVC 70
MAX.
Temp at short circuit PVC 90
MAX.
Temp at normal operate PXLPE 150
MAX.
Temp at short circuit XLPE 9250
What are standard cross section of cables
1.5,
2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400
How
can you check voltage drop and SC of cable
A-Voltage
drop of cable
From
catalogue we get mv/m/A of cable and calculate voltage drop from VD= (mv/m/A) *
I
Or
VD= (1.73*IL*L*R*cosα)/1000
VD%= (dV/380)*100, Must be less than 5%
C-Short circuit test
A=
9.1 * √t * Isc For copper
A= 14.2 * √t * Isc For Aluminum
A:
Cable cross section
t:
Short circuit period
Isc:
short circuit current
(Air Condition)
1
TON = 1.5 HP
12000
BTU = 1 TON
8000
BTU = 1HP
(Distributor)
What are types of distributor?
A-
16 cell
C-14
cell
Loop rate
Max
load of one loop is 5 MVA
What are differences between Load breaker switch, circuit breaker and Isolator Switch
C.B: 1-Auto disconnect, 2-For arc extinguisher, it contains chamber arc, operates at load and short circuit, 3-Used for operation
(RMU)
What is RMU consist of
A-
3 or 4 LBS: (3) 630A for incoming, (1) 400A for Transformer
B-HRCF:
high rupture
capacity fuse to protect TR from SC
C-Medium
cables
(Bus
bar)
Calculate
BB for TR 2MVAI=
1.5 * 2000= 3000
BB
is 3200 A
(Earthing)
What is the standard value of good earth?
Less
than 5 ohm
How can you use earth meter for measuring earth
1-disconnect
main rod from loads
2-fix
one rod of device in ground at distance not less 5m from main rod
3-fix
the second rod of device in ground in distance not less than 5m from first rod
and not less than 10m from main rod
4-press
test bush button
(Transformer)
10.1-What the Suitable C.B for transformer with rate 2000KVA
The
Suitable C.B for transformer with rate 2000KVA is 2000*1.5 = 3000A
What
are differences between oil and dry transformer?
(Generator)
How can you calculate generator rate for any load?
KVA
GEN. = 2*dynamic loads+1*static loads
(Fire System)
What is fire system consist of?
A-FACP:
Fire alarm control panel
B-Detectors
C-Call
points
D-Alarms
alert
E-Control
modules: control another systems
F-Conduits
and cables
What are types of FACP and difference between them?
A-Conventional
FACP:
Less
loops and sensor
Less
cost
Used
in small zones and not important zone
B-Addressable
FACP
More
loops and sensors
Specific
zone alarm
Isolate
fault
Smart
system
What differences between class A & B cable in fire system?
Class
B used for line isolating
What difference between UL & BS in fire system?
UL
(Under writers Laboratory) and it means (according to USA standard)
BS
(Britch Standard) and it means (according to Europe standard)
(IP telephone and data system)
Which cable used in telephone and data system?
UTP:
Un shielded twisted pair
What
types of this cable?
CAT3,
CAT4, CAT5, CAT6, CAT5e, CAT6e
When
No. of cat increased, it will be better
(Sound System)
Watt of power amplifier = Sum of load speaker watt + future extension
(CCTV System)
What means by (camera must be typed power over Ethernet?
It
means that no external power needed
(Shop drawing)
Cross
section area of cable = 40% cross section area of pipe
Light
switch install at height = 120 or 130 cm
General
power socket at height =120 or 130 cm for high level, 30 or 40 cm for low level
Telephone
outlet at height = 40 cm low level, 150 cm high level
Computer
and TV out let at height = 40 cm
Branch
distribution board at height =140 cm from its bottom or 180 cm from top
Fire
panel at height = 180 cm from its bottom
The
suitable conduits type for exposed installation in building is EMT conduits
Max
length of light circuit must not exceed than 30 meter
الرابط التالى لملف مهم يخدم الموضوع:
https://drive.google.com/file/d/1hUUO7skUIqKdfmrK_kNJfcWQ4GHSyb3g/view?usp=drive_link
تعليقات
إرسال تعليق