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Cable selection project

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Cable selection project Factory office installation maximum demand sub- mains cable Each factory/warehouse consists of the following loads 8- 250W mercury vapour ... – PowerPoint PPT presentation

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Title: Cable selection project


1
Cable selection project
  • Factory office installation

2
maximum demand sub- mains cable
  • Each factory/warehouse consists of the
    following loads
  • 8- 250W mercury vapour lamps
  • 4-60watt incandescent lamps
  • 3-18watt fluorescent. External
  • 1-500watt sodium vapour lamp. External
  • 6-10A double single phase outlets
  • 3-20A 3 phase outlets
  • 1- 15A three phase storage hot water

3
Office
  • Lighting
  • 8-double 36 watt fluorescent lights
  • Power
  • 8- double10A single phase outlets
  • 1- single 10A single phase outlet

4
Step 1
  • Divide the installation into circuits and
    distribute these circuits across the three phases
  • Calculate the maximum demand of the installation
  • The maximum demand of the sub- mains is the load
    on the heaviest loaded phase

5
Arrange into circuits
  • Factory
  • Circuit 1 (4-250W) lamps (R )
  • Circuit 2 (4-250W) lamps (W)
  • Circuit 3 (4-60watt) 2 EF 60W (B)
  • Circuit 4 (3-18watt) F/lamps (W)
  • Circuit 5 (1x500watt SV lamps) (B)
  • Circuit 6 (2 double 10A) outlets (R)
  • Circuit 7 (2 double 10A) outlets (W)
  • Circuit 8 (2 double 10A) outlets (B)
  • Circuit 9 (20A 3 phase) outlet
  • Circuit 10 (20A 3 phase) outlet
  • Circuit 11(20A 3 phase) outlet
  • Circuit 12 (15A 3 phase) HWS
  • Office
  • Circuit13 (8 double36 watt fluorescent) (B)
  • Circuit14 (3 double 10A outlets)
    (R)
  • Circuit15 (3 double 10A outlets)
    (W)
  • Circuit16 (2 double 1 single 10A outlet) (B)

6
MD Sub-mainsusing table C2
Factory
Circuit no Load group Load calculation R W B
1 A (4-250W)MV lamps 1.5A each 4 x 1.5 6 6
2 A (4-250W) MV lamps 1.5A each 4 x 1.5 6 6
3 A (4-18W) energy saver 0. 05A each 2x60w exhaust fans at 0.3A each 0.8
4 A (3-18W) fluorescent 0.12A each 0.36
5 A 1-500w sodium vapour lamps 0.8 pf 2.72
6 B i 2-10A double 1Phase outlets 4 14.14
7 B i 2-10A double 1Phase outlets 4 14.14
8 B i 2-10A double 1Phase outlets 4 14.14



7
Maximum demand Sub-mains
Circuit no Load group Load calculation R W B
9 B (iii) 20A three phase outlet Full load 20 20 20
10 B (iii) 20A three phase outlet 75 Full load 15 15 15
11 B (iii) 20A three phase outlet 75 Full load 15 15 15
12 G 15A three phase HWS Full load 15 15 15
office
13 A 8-twin 36w fluorescent 6.24
14 B (i) 3-10A double outlets single phase 19.56
15 B (i) 3-10A double outlets single phase 19.56
16 B (i) 2-10A double 1-10A single Outlets single phase 16.3
Maximum D 104.7 104.7 105.6
8
Cable size for sub-main to factory/warehouse unit1
  • The Maximum demand is 106A

Mains
Sub-mains
X90 SDI Cables double insulated buried in
separate U/G conduit Current carrying capacity
T7/18 25mm² 135A Voltage drop T41 Vc
1.62mV/Am So 25mm² X90 SDI Cables in separate
conduits will satisfy both current and voltage
drop requirements. Unit 1 has the longest run
(38 metres) so 25mm² will satisfy units 2 and
3
9
Installation load
  • The installation consists of the following loads.
  • Lighting
  • 24 250W mercury vapour Lamps
  • 24 2x36W Fluorescent Luminaires 0.78A each
  • 12 18W fluorescent to replace 60W
  • 8 18W Fluorescent
  • 6 60W exhaust fans 0.3A each
  • 3 500W

10
Installation load
  • Power
  • 42 double 10A single phase outlets
  • 3 single 10A single phase outlets
  • 9 20A three phase outlets
  • 3 3 phase HWS

11
Consumers Mains maximum demand
Load Group load Calculation R W B
24 250W mercury vapour Lamps (8 per phase) 8 x 1.5 12 12 12 12
24 2x36W Fluorescent Luminaires (8 per phase) 6.24 6.24 6.24
12 18W fluorescent (0.05A) to replace 60W 4 x 0.05 0.2 0.2 0.2 0.2
6 60W exhaust fans (0.3A each) 2 x 0.3 0.6 0.6 0.6 0.6
8 18W Fluorescent (0.12A) 3,3,2 per phase 0.12 x 3 .36 0.12 x 2 .24 0.36 0.36 0.24
3 500W 2.71 2.71 2.71
14 Double 1 single 10A single outlets per phase (29 per phase) 87 outlets total 95.65 95.65 95.65
9 20A three phase outlets 20 8 x 15 140 140 140 140
3 - 15A 3phase HWS 3 x 15 45 45 45 45
MD 302.8 302.8 302.7
12
Cable Size consumers mains
  • The consumer mains are X90 SDI cables installed
    in conduit U/G for a length of 40 metres
  • Determine the cable size to suit current and
    voltage drop requirements
  • Table 2.4 item 2 refers to Table 7/16
  • 150mm² 330A The cable can carry the MD current
  • Check for voltage drop.
    Table
    41 Vc for 150mm² conductors 0.309mV/Am (60ºC)
    The cable is rated at 90ºC and by choosing a Vc
    value at 60ºC this allows for temperature rise
    under Short circuit conditions

13
Progressive Voltage drop
Consumers main Volt drop 3.745 volts
DB unit3
10 metres
40 metres
MSB
Turret
20 metres
DB Unit 2
38 metres
DB Unit 1
Sub-main voltage drop 6.52 volts
3.745 Volts
6.52 Volts
14
Progressive Voltage drop distribution board unit 1
Consumers mains
Final sub-circuits
Sub-main
5.57 volts allowed in all single phase circuits

9.735 Volts allowed in all 3 phase circuits
3.745 volts 3 phase Value
6.52 volts 3 phase value
3.7456.52 10.265 volts 3 phase Therefore the 3
phase voltage drop allowed in all 3 phase
circuits supplied from the DB Unit1 is 20
10.265 9.735 V To determine the single phase
voltage allowed in final sub circuits
Therefore the single phase Voltage drop allowed
in all single phase circuits supplied from
distribution board Unit 1 is 11.5 5.93 5.57
Volts
15
(No Transcript)
16
Circuit arrangements
Cable Designation Maximum demand Installation Parameters AZ/NZS 3008/1/1 Table No column
Consumers mains 302 A XLPE (X90) SDI enclosed UG Table 2.4 Table 7 4 16
Sub-mains 106 A X90 SDI enclosed U/G Table 2.4 Table 7 4 18
4x250W MV Lamp Factory 2 circuits 6A TPS V90 installed with 3 other circuits De rate 0.78 Table 2.1 Table 9 Table 24 4 2 8
10A outlets Factory 16A TPS V90 installed with 3 other circuits spaced De rate 0.87 item22 Table 2.1 Table 9 Table 24 4 2 8

17
Cable designation Maximum demand Installation parameters AS/NZS 3008 Table no Column no
3 phase outlets 20A TPS V90 installed with 2 other circuits On cable De rate 0.82 Table 2.1 Table 12 Table 24 4 2 8
EF Battens In Toilets 0.8A TPS unenclosed 3 other circuits on cable tray up wall from switchboard Table 2.1 Table 9 Table 24 De-rate 0.88 4 2 8
HWS 15 TPS unenclosed 3 other circuits on cable tray up wall with 3 other circuits Table 2.1 Table 12 Table 24 De-rate 0.88 4 2 8
500W SV 2.8A TPS installed enclosed U/G Table 2.4 Table 9 4 16
18
Cable Size 20A 3Ø outlets Distribution board Unit
1
Sub-main
Mains
MSB
Unit 1 DB
U/G turret
Determine the cable size for the 20A 3 phase
outlets 1 per circuit, longest run 38 metres The
cable is 3core TPS V 90 installed enclosed in
air. No de-rating for this section. Unenclosed in
air spaced on perforated tray up wall above
switchboard 4 circuits
20A 3Ø outlet
To satisfy voltage drop requirements Table 42 a 4
mm² Cable with a Vc value of 9.71 mV/Am value is
required
19
Cable Size 20A 3Ø outlets Distribution board Unit
1
Sub-main
Mains
MSB
Unit 1 DB
U/G turret
Determine the cable size for the 20A 3 phase
outlets 1 per circuit, Route length 25
metres Current carrying capacity is the limiting
factor in this circuit
20A 3Ø outlet
To satisfy Current carrying capacity, a 4mm² TPS
cable is required
20
Cable Size 20A 3Ø outlets
Sub-main
Mains
MSB
Unit 1 DB
U/G turret
Determine the cable size for the 20A 3 phase
outlets 1 per circuit, Route length 15 metres
20A 3Ø outlet
In this instance Voltage drop is not the
governing factor. A 4mm² cable is required for CCC
21
10A single phase outlets
  • 6 outlets in warehouse 2 per phase, (3 circuits).
  • Circuit 1 (38m route length) The outlet is at the
    end of the run therefore use MD 10A
  • Therefore from Table 42, 4mm² cable is required
    for volt drop
  • Cable enclosed in conduit on wall with 3 0ther
    circuits spaced
  • ( 4 circuits )
  • Table 9/6 4mm² cable 26A
  • De-rating Table 22 (0.9) 26 x 0.87 23.4A

22
10A single phase socket outlets
  • Circuit 2 (30m route length)
  • Therefore from Table 42 2.5mm² with a Vc value
    of 15.6mV/A.m is required
  • Circuit 3 route length 20m route length can also
    be wired in 2.5mm²
  • Table 9 column 6 (2.5mm² cable)20Ax0.9 18A
  • So a 2.5mm² cable will satisfy both CCC and Vd

23
Light Circuits unit 1 Circuit 1 (4x250W mercury
vapour)
  • Route length 38m
    Maximum Demand 4 x 1.5A
    6A.
  • Circuit beaker rating 10A . Determine Cable size
  • So from Table 42 a 2.5mm² cable with a Vc value
    of 15.6mV/A.m three phase 15.6 x 1.155 18mV/A.m
    is required

24
Light Circuits unit 1 Circuit 2 (4x250W mercury
vapour)
  • Route length 44m
    Maximum Demand 4 x 1.5A
    6A. See clause 3.5.2 50 of circuit
    protective device can be used
  • Circuit beaker rating 10A . Determine Cable size
  • So from Table 42 a 2.5mm² cable with a Vc value
    of 15.6mV/A.m three phase 15.6 x 1.155 18mV/A.m
    is required

25
Circuit 3 four battens and 2 EFToilets
  • Route length 28m
  • So from Table 42 1.5mm² cable is required
  • Table 9 column 6 (1.5mm² cable 14A)

26
Circuit 4 (3x 18W) Fluorescent
  • Route length 50m
  • Voltage drop is not a factor for this circuit
  • Either 1mm² or 1.5mm² can be used

27
Circuit 5 (500W) sodium Vapour
  • Route length 16m
  • TPS Cable V90 Installed enclosed U/G

Distribution Board
500W Sodium vapour
  • Voltage drop is not a factor for this circuit
  • Either 1mm² or 1.5mm² can be used

28
Hot Water Cylinder3 phase 15A
  • Route length 28m
  • Cable 3core E enclosed TPS V90
  • Table 12 column 2 (2.5mm² 23A)
  • Check Voltage drop
  • Table 41 (2.5mm² 15.6mm²)Therefore 2.5mm² Cable

29
Office
  • 8-2x36W(0.78A) fluorescent one circuit
  • Route length 40m Use 10A MCB
  • Rule 3.6.2 50. circuit protective device for
    voltage drop

Table 42 1.5mm² 28.6mV/Am. Use 1.5mm² cable
30
Office10A socket outlets
  • Circuit 14 (three double outlets)
  • Route length 22m TPS cable installed unenclosed
    in air Table 9 column 4 (2.5mm² 26A)Use 20MCB
  • Rule 3.6.2 (50. circuit protective device for
    voltage drop)

Table 42 2.5mm² 15.6mV/Am 2.5mm Cable for all
socket outlet circuits in the office.
31
Fault loop impedance
  • The earth fault-loop impedance in an MEN system
    comprises the following parts, starting and
    ending at the point of the fault.
  • a) The protective earthing conductor, (PE),
    including the main earthing terminal/connection
    or bar and MEN.
  • b) The neutral return path, consisting of the
    neutral conductor, (N), between the main neutral
    terminal or bar and the point at the transformer
    (the earth return path RG to RB has a relatively
    high resistance and may be ignored for an
    individual installation in an MEN system)

32
Fault loop impedance
  • c) The path through the neutral point of the
    transformer and the transformer winding.
  • d) The active conductors as far as the point of
    the fault.
  • The earth fault-loop is normally regarded as
    consisting of the following two parts-
  • i) conductors upstream or external to the
    reference point and
  • ii) conductors down stream or internal to the
    reference point.
  • Refer to appendix B for detail

33
Path taken by an earth fault current
34
Earth fault-loop impedance
Distributor's network
Fault current IA
A
H
POS
MEN
NeutralBar
Main Earth
Faulty equipment
Soil resistance high between electrodes
35
Determine maximum route lengthto satisfy fault
loop impedance.
  • The maximum length of a circuit can be determined
    using Table B1
  • (Exceptions include circuits wired in 4mm² cable
    protected by a 16A or 20A Type C MCB)
  • The maximum length for this example will need to
    be calculated

36
Calculation 16A MCB
A 4mm² Cable protected by a 16A MCB can be run
109m and not exceed the earth fault loop
impedance requirements
37
Switchboards Units 1-3
120A Main switch

MCBS
L
L
L
L
L
P
P
P
P
P
P
HW
L
P
P
P
10 10 10 10 10 16 16 16 20 20
20 16 10 16 16 16
38
Main Switch Board
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