PowerTALK: CABLES Version 3.3x

LV RETICULATION DESIGN:

PowerTALK: CABLES is used for design of LV reticulation networks in towns, suburbs, townships and industry is already used by more than 25 organisations, enabling them to reduce both material and reticulation design costs.

You should seriously consider this package to save you some time and money with your next reticulation project. Below the salient features of the package, and on the following pages a worked example is shown:

User Friendly

User friendly menu driven application program

Overview

All required information on screen, print-outs and disk for future reference

Easy to Use

Easy entry of data; Normal settings saved as defaults

Flexible

Easy to design a single cable; Easy to design a multi substation suburb

Cable types

Default types Aluminium, Copper, Bundle, Line; Also user defined cables

Immediate Results

Settings and cable data can be changed and the effect there-of seen immediately on screen, i.e. voltage drops, cost, cable sizes, etc.

IBM PC Compatible

Works on all PC´s with a minimum of a 80286 and 1MB RAM. It runs under MSDOS, Windows, Windows 95; Supports Dbase III format

Personnel Effective

Lesser qualified technical personnel can now do more using the PC package

Time Effective

Instead of doing the laborious calculations, the engineer now only have to inspect the CABLES results prepared by his planning department

Cost Effective

Better, more cost effective networks can be designed in less time

To User Needs

Many inputs from users since developments have started in 1987

Features

Interactive, immediate results, automatic and manual cable selection; Diversity formulas including „Guidelines"; Voltage drop, diversity, maximum cable current, fault level, ADMD calculations, etc.

Worked example: To design the LV electrical reticulation for Gnudale Extention 7:

The designs illustrated below are chosen to illustrate the flexibility of the CABLES software package. This implies that the print-outs in the examples do not necessarily show the optimum designs.

Gnudale Ext. 7 (previously classified as semi-industrial area) had been re-zoned to a residential area. Gnudale City Council has already planned the streets and services of this area and the electrical department is to submit final designs and cost of the development.

The following facts and constraints come from the typical South African City Council´s minutes of meetings and apply to the map below:

1. Spare capacity must be used on both existing 11kV/400V transformer mini substations (MS01, MS02).
2. The services department requires two off 400V 50kVA 3 phase motors for water pumping as indicated. The voltage drop due to starting current should be observed.
3. Equipment already installed in Ext. 6 are as follows, and should be used where possible:
   

   MS01

   Minisub

   200 kVA

   BCDEFGHI

   Copper cable

   50 mm²

   MS02

   Minisub

   630 kVA

   B

   Copper cable

   35 mm²

   HIJ

   Copper cable

   50 mm²

4. Because of standardisation at the municipal stores, all new main cables should be of the Aluminium types and only of the sizes 50, 95, 120, 185 or 240 mm².
   
5. Gnudale uses 16 mm² Copper service cables connecting all residential properties.
   
6. Street lights are all to be of the Mercury Vapour type, having a starting VA rating of 600W each. A street lamp must be installed every 25-30m in all streets and the cable type to be used is 25 mm² Copper.
   
7. The Electrical Engineer must report on the condition and capacity of existing equipment in Ext. 6, as well as on the cost effectiveness o SRC="Resources/img00137.gif" HEIGHT="135" NATURALSIZEFLAG="3" ALIGN="BOTTOM">

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   edit constants 495x135

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   Major settings
   

   2. The spare capacity of the existing Ext. 6 network is checked by entering MS01 and MS02 into CABLES. The input screens for MS01 are shown below:
   

   ---

   ---

   

   ---

   ---

   cable length & cons number cable type & existing data

   ---

   ---

   ---

   

   ---

   ---

   service connections cable routes

   ---

   ---

   

   ---

   ---

   street lights

   ---

   MS01 Input screens
   

   MS02 result sheet (Dbase III format, imported into Excel)
   

   3. Firstly, the existing spare capacity must be considered. From the CABLES results can be seen (MS02 shown above):
   

   Mini substation MS01 (200kVA, 39.7kVA spare)

   kVA

   37 consumers and 32 street lights

   160.3

   Mini substation MS02 (630kVA, 177.5kVA spare)

   kVA

   6 consumers and 400kVA bulk load

   452.5

   From the geography of the area, it is not possible to utilize the 39.7 kVA spare capacity of MS01. To MS02 with 177.5 kVA of spare capacity, the 100 kVA townhouse complex is to be connected. From the remaining 77.5 kVA, 77.5 / 3.48 (ADMD) = 22.2 consumers can be fed. However, slightly more than 22.2 can be connected, because of the higher diversity factor (from 6 to 28 consumers). From the street layout, 28 consumers can be connected.
   

   4. The number and location of the new minisubs are decided by looking at the consumer load distribution, street light loads and 3 phase motor loads. Cable routes are always chosen intuitively, depending on the street layout.
   

   Requirements (by studying the reticulation map)
   

   Further new loads (total 423 kVA)

   kVA

   A 2 x motor loads at 50 kVA each

   100

   B 74 street lamps at 600 VA starting

   44.4

   C 80 consumers at 11.5/3.3 kVA ADMD each

   278.8

   D 150 kVA townhouse complex

   150

    

   The required total of 423 kVA can be provided with one 315 kVA and one 200 kVA transformer.
   

   MS03 is chosen to be 315 kVA. From this the motors are fed. From the remaining 215 kVA, 215/3.48 (ADMD) = 61.7 consumers can be fed. Geographically 46 consumers can be connected. The balance has to be fed from MS04.
   

   Mini substation MS03 (315kVA, 55kVA spare)

   kVA

   2x pump motors

   100

   46 consumers at 11.5 kVA BDMD each

   160

   Mini substation MS04 (200kVA, 30.1kVA spare)

   kVA

   34 consumers

   125.5

   74 street lamps

   44.4

   5. After finalising the cable routes, the resulting networks are entered into CABLES, and the results analysed.
   

   

   map of street light layout - new street lights all feeding from MS04
   

   6. The TOTALS program gives an overview as follows:
   

   

   All minisubs included in the project shown
   

   7. Total cable cost for the designed networks, based on the settings as shown on the screen prints, 130.00

   Voltage drop to 5.5%

   68 415.00

   One size per cable section

   80 300.00

   All cables per feeder of one size Aluminium

   98 320.00

   All cables per feeder of one size Copper

   120 542.00

   Total costs for setting variations:

   Please note that above prices are based on user defined costs per meter of installed cable and is independent of the local currency. This specified cost per meter of cable may include labour costs, average overhead, etc.

   8. The complete TOTALS standard results print-out with standard settings to item 1 above, follows:
   

   ---

   ---

   ---

   filename: "MSUB0111.fdr"

   ---

   CABLES licensed to DEMO FULL FUNCTION by J & A MOSTERT

   CABLES v3.32 Aug 3, 1996 14h22

   MSUB0111.fdr SUBSTATION: MSUB01 FDR: 1 TRY: 1 Max phase VD=5.000 %

   Factor:MOSTERT DF=(1.3m+5.49)/(.22m+8.798) ,BDMD kVA= 11.5

   -------------------------------------------------------------------------------

   -----A-----B-----C

   ||

   ||

   |+----D-----E-----F-----G

   |

   |

   +-----H-----I
   

   Single phase distributed load:A Cu4c PVC 25mm~

   A|----------3-----3-----B-----R-----W-----B-----R-----W-----B-----R-----

   W-----B-----R-----W-----B-----R-----W-----B-----R-----W-----B

   Dist m: 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.

   0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0 25.0

   kVA : 1.20 1.80 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.6

   0 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60
   

   |A|---A1 7.2 kVA * 1

   107m

   -------------------------------------------------------------------------------

   Nr Size Length Type N SN Amp F2 F1 Vd SVd Unit Price

   - --- ----- -------- -- -- --- ---- ---- ---- ---- ------ --------

   A BAREx Busbar 0 37 231 3.23 1.00 0.00 0.00 0.00 0.00

   A 25 106.8 Cu4c PVC 7.2 kVA 31 1phase 2.52 2.52

   B 50Ex 10.0 Cu4c PVC 4 9 94 1.59 1.00 0.19 0.19 0.00 0.00

   C 50Ex 60.0 Cu4c PVC 5 5 76 1.31 1.00 0.93 1.12 0.00 0.00

   C 16 25.0 Service 50 1.49 2.61
   

   D 50Ex 60.0 Cu4c PVC 4 20 143 2.44 1.00 1.75 1.75 0.00 0.00

   E 50Ex 20.0 Cu4c PVC 6 16 132 2.26 1.00 0.54 2.29 0.00 0.00

   F 50Ex 40.0 Cu4c PVC 4 10 108 1.84 1.00 0.88 3.17 0.00 0.00

   G 50Ex 50.0 Cu4c PVC 6 6 76 1.31 1.00 0.77 3.94 0.00 0.00

   G 16 15.0 Service 50 0.89 4.84
   

   H 50Ex 50.0 Cu4c PVC 3 8 94 1.59 1.00 0.96 0.96 0.00 0.00

   I 50Ex 75.0 Cu4c PVC 5 5 76 1.31 1.00 1.16 2.12 0.00 0.00

   I 16 25.0 Service 50 1.49 3.61

   mm~ m Amp Div Unb % % Rand/m

   37 consumers 0.00

   ------------------------------------------------------------------------ Rand

   Source level: 250 MVA 0.64m Ohm (all LV level)

   Transformer: 11000:400 200 kVA 4.5% 36.02m Ohm

   3ph fault at transformer terminals HV = 360.75 kA LV = 6.30 kA

   3ph faults at last pillar box of all routes:

   Zc ( ABC) = 33.04m Ohm ==> 4.37kA (Zs+Zt+Zc)

   Zc ( ADEFG) = 80.24m Ohm ==> 2.48kA (Zs+Zt+Zc)

   Zc ( AHI) = 59.00m Ohm ==> 3.12kA (Zs+Zt+Zc)

   Max. current (incl. 3ph & 1ph)=231 A => 17.8 A/cons. => 4.1 kVA per cons. (ADMD)

   Circuit breaker = 250A CB

   Total load = 160.3 kVA Spare = 39.7 kVA ADMD

   Ex=Existing cable, Te=Size Temporarily chosen, Ec=Size c

   |||+----H

   |||

   |||

   ||+-----I

   ||

   ||

   |+------J

   |

   |

   +-------K
   

   -------------------------------------------------------------------------------

   Nr Size Length Type N SN Amp F2 F1 Vd SVd Unit Price

   - --- ----- -------- -- -- --- ---- ---- ---- ---- ------ --------

   A BAREx Busbar 0 34 913 3.13 1.00 0.00 0.00 0.00 0.00

   B 185 50.0 Al4c PVC 6 34 191 3.13 1.00 0.88 0.88 94.00 4700.00

   C 185 95.0 Al4c PVC 6 28 172 2.89 1.00 1.51 2.39 94.00 8930.00

   D 95 75.0 Al4c PVC 6 6 76 1.31 1.00 0.97 3.36 56.00 4200.00

   D 16 20.0 Service 50 1.19 4.55
   

   E 185 30.0 Al4c PVC 5 16 132 2.26 1.00 0.36 2.75 94.00 2820.00

   F 185 60.0 Al4c PVC 6 11 108 1.84 1.00 0.60 3.35 94.00 5640.00

   G 95 20.0 Al4c PVC 5 5 76 1.31 1.00 0.26 3.61 56.00 1120.00

   G 16 20.0 Service 50 1.19 4.80
   

   H 50Ex 45.0 Cu4c PVC 0 0 144 1.00 1.00 1.33 1.33 0.00 0.00

   H 3ph 100.0 kVA144
   

   I 50HIEx 10.0 Cu4c PVC 0 0 216 1.00 1.00 0.44 0.44 0.00 0.00

   I 3ph 150.0 kVA216
   

   J 50HIEx 10.0 Cu4c PVC 0 0 216 1.00 1.00 0.44 0.44 0.00 0.00

   J 3ph 150.0 kVA216
   

   K 95 45.0 Al4c PVC 0 0 144 1.00 1.00 1.10 1.10 56.00 2520.00

   K 3ph 100.0 kVA144

   mm~ m Amp Div Unb % % Rand/m

   34 consumers 29930.00

   ------------------------------------------------------------------------ Rand

   Source level: 250 MVA 0.64m Ohm (all LV level)

   Transformer: 11000:400 630 kVA 4.5% 11.43m Ohm

   3ph fault at transformer terminals HV = 360.75 kA LV = 19.13 kA

   3ph faults at last pillar box of all routes:

   Zc ( ABCD) = 60.36m Ohm ==> 3.58kA (Zs+Zt+Zc)

   Zc ( ABCEFG) = 57.91m Ohm ==> 3.68kA (Zs+Zt+Zc)

   Zc ( AH) = 21.24m Ohm ==> 8.90kA (Zs+Zt+Zc)

   Zc ( AI) = 4.72m Ohm ==> 16.98kA (Zs+Zt+Zc)

   Zc ( AJ) = 4.72m Ohm ==> 16.98kA (Zs+Zt+Zc)

   Zc ( AK) = 17.68m Ohm ==> 9.99kA (Zs+Zt+Zc)

   Max. current (incl. 3ph & 1ph)=913 A => 76.0 A/cons. =>17.6 kVA per cons. (ADMD)

   Circuit breaker = NoCB CAB<BKR! 999<9999

   Total load = 632.4 kVA Spare = -2.4 kVA ADMD

   HI = WARNING: Cable overload !!!!

   Ex=Existing cable, Te=Size Temporarily chosen, Ec=Size chosen by Economiser

   -------------------------------------------------------------------------------

   -------------------------------------------------------------------------------

   filename: "MSUB0311.fdr"

   CABLES licensed to DEMO FULL FUNCTION by J & A MOSTERT

   CABLES v3.32 Aug 3, 1996 14h22

   MSUB0311.fdr SUBSTATION: MSUB03 FDR: 1 TRY: 1 Max phase VD=5.000 %

   Factor:MOSTERT DF=(1.3m+5.49)/(.22m+8.798) ,BDMD kVA= 11.5

   -------------------------------------------------------------------------------

   -----A-----B-----C

   +++||

   |||||

   ||||+----D

   ||||

   ||||

   |||+-----E-----F-----G

   |||

   |||

   ||+------H

   ||

   ||

   |+-------I

   |

   |

   +--------J-----K-----L
   

   -------------------------------------------------------------------------------

   Nr Size Length Type N SN Amp F2 F1 Vd SVd Unit Price

   - --- ----- -------- -- -- --- ---- ---- ---- ---- 35.00 1575.00

   H 3ph 50.0 kVA 72
   

   I 50 30.0 Al4c PVC 0 0 72 1.00 1.00 0.73 0.73 35.00 1050.00

   I 3ph 50.0 kVA 72
   

   J 95 75.0 Al4c PVC 5 16 132 2.26 1.00 1.68 1.68 56.00 4200.00

   K 95 30.0 Al4c PVC 5 11 108 1.84 1.00 0.55 2.23 56.00 1680.00

   L 50 30.0 Al4c PVC 6 6 76 1.31 1.00 0.76 3.00 35.00 1050.00

   L 16 30.0 Service 50 1.78 4.78

   mm~ m Amp Div Unb % % Rand/m

   46 consumers 26700.00

   ------------------------------------------------------------------------ Rand

   Source level: 250 MVA 0.64m Ohm (all LV level)

   Transformer: 11000:400 315 kVA 4.5% 22.87m Ohm

   3ph fault at transformer terminals HV = 360.75 kA LV = 9.83 kA

   3ph faults at last pillar box of all routes:

   Zc ( ABC) =104.63m Ohm ==> 2.11kA (Zs+Zt+Zc)

   Zc ( AD) = 31.00m Ohm ==> 5.69kA (Zs+Zt+Zc)

   Zc ( AEFG) = 64.13m Ohm ==> 3.18kA (Zs+Zt+Zc)

   Zc ( AH) = 34.88m Ohm ==> 5.28kA (Zs+Zt+Zc)

   Zc ( AI) = 23.25m Ohm ==> 6.69kA (Zs+Zt+Zc)

   Zc ( AJKL) = 64.52m Ohm ==> 3.22kA (Zs+Zt+Zc)

   Max. current (incl. 3ph & 1ph)=389 A => 24.3 A/cons. => 5.6 kVA per cons. (ADMD)

   Circuit breaker = 400A CB

   Total load = 269.8 kVA Spare = 45.2 kVA ADMD

   Ex=Existing cable, Te=Size Temporarily chosen, Ec=Size chosen by Economiser

   -------------------------------------------------------------------------------

   -------------------------------------------------------------------------------

   filename: "MSUB0411.fdr"

   CABLES licensed to DEMO FULL FUNCTION by J & A MOSTERT

   CABLES v3.32 Aug 3, 1996 14h22

   MSUB0411.fdr SUBSTATION: MSUB04 FDR: 1 TRY: 1 Max phase VD=5.000 %

   Factor:MOSTERT DF=(1.3m+5.49)/(.22m+8.798) ,BDMD kVA= 11.5

   -------------------------------------------------------------------------------

   -----A-----B-----C

   |

   |

   +----D-----E-----F-----G
   

   Single phase distributed load:A Cu4c PVC 25mm~

   A|----------3-----R-----3-----W-----B-----3-----R-----W-----B-----R-----

   W-----B-----R-----W-----B-----R-----W-----B-----R-----W-----B-----R-----

   -----B-----R-----W-----B-----R-----W-----B-----R-----W-----B-----R-----W

   Dist m: 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.

   0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.

   30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0

   kVA : 3.00 0.60 2.40 0.60 0.60 5.40 0.60 0.60 0.60 0.60 0.6

   0 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.6

   0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60 0.60
   

   |A|---A1 17.4 kVA * 1

   146m

   -------------------------------------------------------------------------------

   Nr Size Length Type N SN Amp F2 F1 Vd SVd Unit Price

   - --- ----- -------- -- -- --- ---- ---- ---- ---- ------ --------

   A 185 10.0 Al4c PVC 4 34 266 3.13 1.00 0.25 0.25 94.00 940.00

   A 25 146.4 Cu4c PVC 17.4 kVA 75 1phase 8.35 8.60

   B 50 50.0 Al4c PVC 4 9 94 1.59 1.00 1.57 1.82 35.00 1750.00

   C 50 50.0 Al4c PVC 5 5 76 1.31 1.00 1.27 3.09 35.00 1750.00

   C 16 25.0 Service 50 1.49 4.58
   

   D 185 75.0 Al4c PVC 4 21 143 2.44 1.00 0.99 1.23 94.00 7050.00

   E 185 40.0 Al4c PVC 6 17 132 2.26 1.00 0.49 1.72 94.00 3760.00

   F 120 40.0 Al4c PVC 5 11 108 1.84 1.00 0.59 2.31 62.00 2480.00

   G 120 30.0 Al4c PVC 6 CAB<BKR! 295< 300

   Total load = 184.6 kVA Spare = 15.4 kVA ADMD

   Ex=Existing cable, Te=Size Temporarily chosen, Ec=Size chosen by Economiser

   -------------------------------------------------------------------------------