POST MODULE ASSIGNMENT OF

POWER CABLES

HAIDAR ISMAIL

STUDENT ID: 140154861

EXECUTIVE SUMMARY

This report present the analysis of the power cable when The Lime St. Station requires a new electricity infeed. This report contain four parts:Part 1 identify the possible sources for supplying 60MVA peak to Lime St. StationPart 2 the analysis of the power cable if Paradise St. Substation is chosen as the sourcePart 3 the analysis of alternative option, connect to 132 kV cable Lister Drive-Paradise St. Substation.Part 4 further work required, conclusion, and suggestion.In this report, connection to existing 132 kV cable Lister Drive- Paradise St. Substation is chosen as the best option as provide lower cost, fewer problems, and simple installation.

PART 1BackgroundLiverpool Lime Street Rail Station requires a new electricity infeed. The new load of the station is cyclic, peaking at 60 MVA. The load is cyclic because there are fewer trains at night. The station require the minimum 20 MVA firm capacity so the train still can get start although the main supply is out of service. The load curve of the Lime Street Station is depicted in the graph below

Figure 1 Load Curce of Lime Street Station ( taken from the assignment paper)It is clearly seen that the load is peaking around 60 MVA for 6 hours start from 13.00 to 19.00.Sustained or peak rating of the load basis is used to determine the size of the cable. The considerations why it is better to use peak rating than cyclic rating are because: There is not enough data to calculate cyclic rating. There are lot of uncertainty in cyclic rating calculation itself. Because there are more uncertainty factor when selecting the cable size using cyclic rating rather than using peak rating, hence it is safer to use peak load rating.To specify cable rating, there are some assumption used in this report:ItemValue

Thermal Resistivity ( using stabilise backfill - sand-gravelmixture consisting of a 1 : 1 mixture of selected sand and gravel [1] page 480)1.2 Km/W

Depth of laying900 mm

Ground temperature150 C on summer50 C on winter

Table 1 List of AssumptionThe locations of the rail station and the existing substation and line are shown in the map below:

Figure 2 Map ( from google map)

Figure 3 Lime St. Station - taken from google maps

Connection OptionsNoPossible SourceCapacity (MVA)Load (MVA)Spare Capacity (MVA)Remark

Connect to Substation

1Lister Drive

132 kV3x270 MVA50 %= 3x137.5 3x137.5 Possible

66 kVUnknownUnknownunknownPossible if additional transformer is provided

33 kVUnknownUnknownUnknownPossible if additional transformer is provided

11 kVUnknownUnknownUnknownPossible if additional transformer is provided

2Paradise St. Substation

132 kV150+135=285142.5142.5 142.5 MVA available

33 kV 60 45 15 15 MVA available

3Burlington St. Substation

132 kV150+135=285142.5142.5 142.5 MVA available

33 kV 60 40 20 20 MVA available

4Greek St. Sub.

33kV403.7536.2536.25 MVA available

11 kV7.5 3.75 3.753.75 MVA available

5Copperas Hill Sub

33kV403.7536.2536.25 MVA available

11 kV7.53.75 3.753.75 MVA available

6Oldham Place Sub

33kV403.7536.2536.25 MVA available

11 kV 7.53.75 3.753.75 MVA available

7Bolton St. Sub

33kV403.7536.2536.25 MVA available

11 kV 7.5 3.75 3.753.75 MVA available

8Lime St. Sub

33kV403.7536.2536.25 MVA available

11 kV7.5 3.75 3.753.75 MVA available

Tapping to existing cable

1132 kV

Lister Drive Paradise St150 75 75 Possible

Paradise St. Burlington St.

135 67.5 67.5 Possible

Lister Drive Burlington St.

150 75 75 Possible

233 kV

Paradise St Lister Drive4x20 3x3.75 =11.2568.75Possible

Burlington St-Paradise St4x20 3x3.75 =11.2568.75Possible

Table 2 Source ListFrom the above map, there are several possible source for supplying 60 MVA peak and 20 MVA firm capacity to the Lime St. Station:1) Both 60 MVA peak load and 20 MVA firm capacity are supplied from the same source :a) Both are supplied from Lister Drive Substation 132kV/66kV/33kV/11 kV.i) 132 kVThere is 3x137.5 total spare capacity from 275/132 kV transformers.ii) 66 kVThere is no data about existing transformer capacity. However, it is still possible to connect from 66 kV Lister Drive if a new transformer is provided as worst case scenario.iii) 33 kVThere is no data about existing transformer capacity. However, it is still possible to connect from 33 kV Lister Drive if a new transformer is provided as worst case scenario.iv) 11 kVThere is no data about existing transformer capacity. However, it is still possible to connect from 33 kV Lister Drive if a new transformer is provided as worst case scenario.All of above options need to provide additional switchgears, build a new switchroom, or extend the existing switchroom.b) Both 60 MVA peak load and 20 MVA firm capacity are supplied from Paradise Street Substation. i) 132 kV The total possible capacity of this substation is when it receive full cable capacity current from Lister Drive and Burlington St. Substation:150 MVA + 135 MVA = 285 MVA.These cables are not loaded above 50% of their ratings, hence the spare capacity from this substation is:285 MVA - 150 MVA/2 +135 MVA/2= 142.5 MVA There is no information about the rating of the busbar. Then, the worst case scenario is to assume that the minimum capacity of the 132 kV busbar is the same as the capacity of the 132 kV/33 kV transformer (assume there is no 132 kV load near from this substation). Hence capacity of 132 kV busbar in this substation is 60 MVA. Therefore, it is required to reinforce the substation by providing additional 132 kV switchgear, reinforcing the busbar, extending the switchroom building or building a new switchroom, or use outdoor switchgear.ii) 33 kVBecause 132/33 kV transformer in this substation only has 15 MVA spare capacity, it is required to reinforce the substation by providing additional minimum 65 MVA 132/33 transformer, additional 33 kV switchgear (connected to the new transformer), extending the switchroom building or build a new switchroom, or use outdoor switchgear.

Figure 4 Paradise St. Substation - taken from google maps

c) Both 60 MVA peak load and 20 MVA firm capacity are supplied from Burlington Street Substation. i) 132 kVThe total possible capacity of this substation is when it receive full cable capacity current from Lister Drive and Burlington St. Substation:150 MVA + 135 MVA = 285 MVA.These cables are not loaded above 50% of their ratings, hence the spare capacity from this substation is:285 MVA- 150 MVA/2 +135 MVA/2= 142.5 MVAThere is no information about the rating of the busbar. Then, the worst case scenario is to assume that the minimum capacity of the 132 kV busbar is the same as the capacity of the 132 kV/33 kV transformer (assume there is no 132kV load near from this substation). Hence capacity of 132 kV busbar in this substation is 60 MVA. Therefore, it is required to reinforce the substation by providing additional 132 kV switchgears, reinforcing the busbar, extending the switchroom building or building a new switchroom, or use outdoor switchgear.ii) 33 kVBecause Transformer in this substation only has 20 MVA capacity, it is required to reinforce the substation by providing additional minimum 60 MVA 132/33 transformer, additional 33 kV switchgears (connected to the new transformer), extending the switchroom building or build a new switchroom, or just use outdoor switchgears.

Figure 5 Burlington St. Substation- taken from google maps

2) Both 60 MVA peak load and 20 MVA firm capacity are supplied from the different source:a) 132 kVThe peak load is supplied from either one of three 132kV substation (Lister Drive, Paradise St, Burlington St) or tapping to existing 132 kV cable. The firm capacity is supplied from either one of three 132 substation (Lister Drive, Paradise St, Burlington St) or tapping to 132 kV cable but with different location with peak load source.b) 33 kV Capacity of 33/11 kV substationThe total possible capacity of this substation is when it receive full cable capacity current from two 20 MVA cable :2x20 MVA = 40 MVAThe load of each substation is 7.5/2= 3.75 MVA.Hence the spare capacity from this substation is:40 MVA 3.75 MVA = 36.25 MVA There is no information about the rating of the busbar. Then, the worst case scenario is to assume that the minimum capacity of the 33 kV busbar is the same as the capacity of the 33 kV/11 kV transformer (assume there is no 33 kV load near from this substation). Hence capacity of 33 kV busbar in this substation is 7.5 MVA. Therefore, it is required to reinforce the substation by providing additional 33 kV switchgear, reinforcing the busbar, extending the switchroom building or building a new switchroom, or use outdoor switchgear.

The peak load is supplied from either 33 kV substation near the Lime Station or tapping the 33 kV cable. The firm capacity is supplied from either 33 kV substation near the Lime Station or tapping the 33 kV cable but with different location with peak load source.c) Combination of above alternatives.In this report, the 11 kV is not used as the source because the spare capacity is too small.Cable Ampacity Rating at Each of Level VoltageIn this section will be discussed the cable current carry capacity rating. But this rating just for illustration only and detailed calculation will be discussed further in the specific case (alternative connection). In current calculation, the ground temperature in summer is used as worst case scenario. The reason is because the rating cable in summer will be lower than the rating in the winter. The cable should be able to carry the full load current either in summer and winter.1) 132 kVa. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: three coree. Rated Voltage: 132 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Ampacity :

For 60 MVA cableThe current for the 60 MVA load is = x = x = 262.44 A(rf = rating factor)(From the Fluid Filled Cable Handbook, the cable rating is for cable laid direct at 900 mm to cable top. Hence the rating factor is 1) If 60 MVA load and 20 MVA firm capacity are supplied from different substation/source =Only one circuit is in the trench.No rating factor for circuit spacing. Hence I = 262.4 A.From the handbook, choose 120 mm2 cable, rating 335 A in the summer. If 60 MVA load and 20 MVA firm capacity are supplied from same substation/source =Two circuits are in the trench. It is better if both two cable use the same rating.Rating factor for circuit spacing 450 mm is 0.83. Hence I = = 316.15 A.From the handbook, choose 120 mm2 cable, rating 335 A in the summer.For 20 MVA cableThe current for the 20 MVA load is = x = x = 87.48 A(rf = rating factor)(From the Fluid Filled Cable Handbook, the cable rating is for cable laid direct at 900 mm to cable top. Hence the rating factor is 1) If 60 MVA load and 20 MVA firm capacity are supplied from different substation/source =Only one circuit is in the trench.No rating factor for circuit spacing. Hence I = 87.48 A.From the handbook, choose 120 mm2 cable, rating 335 A in the summer. If 60 MVA load and 20 MVA firm capacity are supplied from same substation/source =Two circuits are in the trench. Hence it is better if use the same cable with other circuit. Two cable use the same rating.From the handbook, choose 120 mm2 cable, rating 335A in the summer.2) 66 kVa. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: three coree. Rated Voltage: 66 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Ampacity :For 60 MVA cableThe current for the 60 MVA load is = x = x = 524.88 A(From the Fluid Filled Cable Handbook, the cable rating is for cable laid direct at 900 mm to cable top. Hence the rating factor is 1) If 60 MVA load and 20 MVA firm capacity are supplied from different substation/source =Only one circuits is in the trench.No rating factor for circuit spacing. Hence I = 524.88A.From the handbook, choose 300 mm2 cable, rating 568 A in the summer. If 60 MVA load and 20 MVA firm capacity are supplied from same substation/source =Two circuits are in the trench. Two cable use the same rating.Rating factor for circuit spacing 450 mm is 0.83. Hence I = = 632.39 A.From the handbook, choose 400 mm2 cable, rating 648 A in the summer.

Figure 6 Data of 66 kV cable 3 core copper, lead sheath - take from Fluid Filled Cable Handbook

For 20 MVA cableThe current for the 20 MVA load is = x = x = 175 A If 60 MVA load and 20 MVA firm capacity are supplied from different substation/source =Only one circuits is in the trench.No rating factor for circuit spacing. Hence I = 175 A.From the handbook, choose 120 mm2 cable, rating 342 A in the summer. If 60 MVA load and 20 MVA firm capacity are supplied from same substation/source =Two circuits are in the trench.Hence it is better if use the same cable with other circuit From the handbook, choose 120 mm2 cable, rating 342 A in the summer.

Figure 7 Cable data for 66 kV 3 core copper lead sheath cable - taken from Fluid Filled Cable Handbook3) 33 kVa. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: three coree. Rated Voltage: 33 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Ampacity :For 60 MVA cableThe current for the 60 MVA load is = x = x = 1049.76 ABecause typical 33kV (3 core solid cable) have typical capacity of 25 MVA 437.40 A, it is required to use 3 cable at minimum (total capacity = 3x25 MVA =75 MVA). Hence rating factor for 3 circuit with 450mm circuit spacing is Rating factor = 0.78Hence cable capacity become = = 560.77 AFrom the handbook, choose 300 mm2 cable, rating 574 A in the summer.(Rating factor for laying depth is 1) If 60 MVA load and 20 MVA firm capacity are supplied from different substation/source =Choose 300 mm2 cable, rating 574 A in the summer. If 60 MVA load and 20 MVA firm capacity are supplied from same substation/source =There are 4 cables used and lied in the same trench, 3 cables for 60 MVA load and 1 cable for 20 MVA load.Rating factor for 4 circuit with 450 mm spacing is 0.71. Hence I = = 616.06 A.From the handbook, choose 350 mm2 cable, rating 619 A in the summer.

For 20 MVA cable If 60 MVA load and 20 MVA firm capacity are supplied from different substation/source , There is only one 20 MVA cable in the trench. The current for the 20 MVA load is = x = x = 349.91 AThere is only one 20 MVA 3 core cable in the trench. So I = 349.91 AChoose 150 mm2 cable, rating 388 A in the summer. If 60 MVA load and 20 MVA firm capacity are supplied from same substation/source =There are 4 cables used and lied in the same trench, 3 cables for 60 MVA load and 1 cable for 20 MVA load.Rating factor for 4 circuit with 450 mm spacing is 0.71. Hence I = = 616.06 A.From the handbook, choose 350 mm2 cable, rating 619 A in the summer.Options ExplanationThis report will discuss three of the possible sources. However there are many options this part. The given options is carefully chosen to represent the possible sources from various places and voltage level.1. Alternative 1: Connection to 132 kV on 132/33 kV substation. 60 MVA cable from Paradise Street Substation, 20 MVA cable from Burlington Street Substation. In this alternatives, the load will be supplied from two different sources: Paradise Street for 60 MVA load. Burlington Street for 20 MVA firm capacity.20 MVA firm capacity is achieved by provide 60 MVA cable from Paradise Street and 20 MVA cable from Burlington Street. Hence if something going wrong with the Burlington Street, the Paradise Street still can cope 60 MVA load (> minimum firm capacity). On the other hand, if something going wrong with Paradise Street, Burlington still can cope 20 MVA load (minimum firm capacity)60 MVA peak load cable from Paradise Street Substationa. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: Three coree. Rated Voltage: 132 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Ampacity :For 60 MVA cableThe current for the 60 MVA load is = x = x = 262.44 AFrom the Fluid Filled Cable Handbook, choose 120 mm2 cable with ampacity 335 A in the summer. i. Quantity: 1 x 120 mm2 three core cable

j. Route: Figure 8 Route of Paradise Street Substation - Lime Street StationRoute length : around 920 m.k. Cost : The cost of the cable920 m x 400 = 368,000 The cost of the trench To calculate the trench cost, illustration of the trench is required. The width of the trench for laying 3 x 120mm2 cable is =2x50 mm (space from cable to the trench wall) + 1x 93.4 mm (diameter of cable) = 193.4 mm.To make it simple, set the width to 200 mmThe depth of the trench is 900 mm. The cost of the trench for per metre cable = x 100 = 60Hence the cost of the trench is 920 m x 60 = 55,200.20 MVA firm capacity cable from Burlington Street Substationa. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Core: three cored. Rated Voltage: 132 kVe. Formation: -f. Depth of laying: 900 mm. inside the trench.g. Bonding: cross bondingh. Rating Amps:= x = x = 87.48 AFrom the Fluid Filled Cable Handbook, choose 120 mm2 cable with ampacity 335 A in the summer. i. Quantity: 1 x 120 mm2 three core cablej. Route:

Figure 9 Route of Burlington Street Substation - Lime Street StationIn this route, cable across the top of Kingsway Tunnel is shown in the circle.Route length around 2.2 km

k. Cost : The cost of the cable2200 m x 400 = 880,000 The cost of the trench For laying 1 x 120mm2 cable is2x50 mm + 1x 93.4 mm = 193.4 mm.To make it simple, set the width to 2200 mmThe depth of the trench is 900 mm. The cost of the trench for per metre cable = x 100 = 60Hence the cost of the trench is 2200 m x 60 = 132,000.2. Alternative 2: Connection to 66 kV on Lister Drive Substation. In this alternatives, both 60 MVA load and 20 MVA firm capacity will be supplied from the same source: Lister Drive Substation.For 60 MVA Peak Load cablea. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: Three coree. Rated Voltage: 66 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Ampacity :

The current for the 60 MVA load is = x = x = 524.88 ABecause 60 MVA cable and 20 MVA cable will be laid in the same trench = Two circuits are in the trench. Rating factor for 2 circuit spacing 450 mm for 3 core cable is 0.83.

Figure 10 Pic of table of rating factor of distance spacing - taken from Fluid FIlled Cable HandbookHence I = = 632.39 A.From the handbook, choose 400 mm2 cable, rating 648 A in the summer.

Figure 11 Pic from table 5- taken from Fluid Filled Cable Handbooki. Quantity:1 x 400 mm2 three core cablej. Route:

Figure 12 Route of Lister Drive-Lime Street StationRoute length : around 4750 m.k. Cost :The cost of the cable per metre = 400/300 x 250 = 333Hence the cost of the cable = 4750 m x 333= 1,581,750

For 20 MVA firm capacity cablea. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: Three coree. Rated Voltage: 66 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Bonding: cross bondingi. Ampacity : choose same with 60 MVA peak load cable, 400 mm2 cable, rating 648 A in the summer

j. Quantity: 1 x 400 mm2 three core cablek. Route: Same as 60 MVA cablel. Cost The cost of the cableThe cost of the cable per metre = 400/300 x 250 = 333Hence the cost of the cable = 4750 m x 333= 1,581,750 The cost of the trench The width of the trench for laying 2 x 400mm2 cable with 450 mm spacing is =1 x 450 mm + 2x50 mm + 2x 90.4 mm = 730.8 mm.

Figure 13 Picture from table 5- cable diameter- taken from Fluid Filled Cable HandbookTo make it simple, set the width to 750 mmThe depth of the trench is 900 mm. The cost of the trench for per metre cable = x 100 = 225Hence the cost of the trench is 4750 m x 225 = 1,068,750.3. Alternative 3: Connection to 132 kV of Lister Drive Substation for 60 MVA load and connection to 33 kV of Burlington for 20 MVA load. In this alternatives, the load will be supplied from two different sources: Lister Drive Substation for 60 MVA load. Burlington St Substation for 20 MVA firm capacity.For 60 MVA peak load cable from Lister Drivea. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: Three coree. Rated Voltage: 132 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Bonding: cross bondingi. Ampacity :

The current for the 60 MVA load is = x = x = 262.44 AFrom the Fluid Filled Cable Handbook, choose 120 mm2 cable with ampacity 335 A in the summer. j. Quantity: 1 x 120 mm2 three core cable

k. Route:

Figure 14 Route of Lister Drive-Lime Street StationRoute length: around 4750 m.l. Cost : The cost of the cable4750 m x 400 = 1,900,000 The cost of the trench To calculate the cost of the cable, illustration of the trench is required. The width of the trench for laying 1 x 120mm2 cable is =2x 50 mm + 1x 93.4 mm = 193.4 mm.To make it simple, set the width to 200 mmThe depth of the trench is 900 mm. The cost of the trench for per metre cable = x 100 = 60Hence the cost of the trench is 4750 m x 60 = 285,000.For 20 MVA cable from Burlingtona. Type of Cable : Fluid Filled Cableb. Conductor: copperc. Insulation, components: Paper insulation, lead sheath, PE oversheathd. Core: three coree. Rated Voltage: 33 kVf. Formation: -g. Depth of laying: 900 mm. inside the trench.h. Bonding: cross bonding

i. Ampacity :

The current for the 20 MVA load is = x = x = 349.91 AThere is only one 20 MVA 3 core cable in the trench. So I = 349.91 AChoose 150 mm2 cable, rating 388 A in the summer.

j. Quantity: 1 x 150 mm2 three core cablek. Route:

Figure 15 Route of Burlington Street Substation - Lime Street StationRoute length around 2200 m.In this route, cable across the top of Kingsway Tunnel is shown in the circle.l. Cost : The cost of the cable =The cost of the 3 core 150 mm2 33 kV cable per metre = 150/240 x 150 = 93.75Hence the cost of the cable =2200 m x 93.75 = 206,250 The cost of the trench To calculate the cost of the cable, illustration of the trench is required. The width of the trench for laying 1 x 150mm2 three core cable is50 mm x 2 + 1x 62.6 mm = 162.6 mm.To make it simple, set the width to 200 mmThe depth of the trench is 900 mm. The cost of the trench for per metre cable = x 100 = 60Hence the cost of the trench is 2200 m x 60 = 132,000.

PART 2There are many ways to get the cable from Paradise Street Substation to Lime St. In this report, two alternatives is discussed. In this alternative, the Lime St. Station will connect to 132 kV Paradise St. Substation. It is also possible to connect to its 33 kV if additional 132/33 kV transformer with minimum capacity of 65 MVA is provided. 1. Alternative 1 : Figure 16 Route of Paradise St - Lime St alt. 1The length of this route is around 880 m. The advantages of this route are: This route is short, only 880 m Only need to cross one major road (red circle-when crossing lime street toward the station) and cross one minor road (orange circle-when cable come out from the substation toward the left side of the paradise street and when cable). Because the route is short, the working hours needed for this route is small. The route only cross one major road. It means that the route maybe only need to use special excavation one times.The disadvantages of this route are: The route need to cross the lime street, which is the main entrance to the station. The construction work may dissatisfied the passengers. Hence the construction and installation of the cables should be consider the visual nuisance impact to the passenger. This route is in vicinity of the existing 132 kV line. If the spacing between new route and existing line is not calculated carefully, the rating of the new and existing line will reduce significantly. Working HoursAssume for one man: Working hours per metre cable is 4 hours Working hours per crossing minor road work is 10 hours Working hours per crossing major road is 72 hoursHence the total working hours for this route is =880 x 4 hours + 1 x 10 hours + 1x72 hours = 3602 hours per employee.Excavation MethodThe following actions is need to be carried out before excavation work: Acquisition of legal permit Obtain permission from local authorities, police forces, and others.

During excavation work, it is important to provide: Signing and guarding of the work Fulfil technical requirement for backfilling and reinstatement of the excavation.

Because this route need to cross one possibly busy road (lime street station-beige colour), the special treatment need to be taken. The excavation work in the lime street can use several methods: Guided boring Thrust boring Micro tunnelling Auger boring Deep tunnelling

Effect of adjacent cables on the new circuit(s) and effect of the new circuit(s) on adjacent cables This route is in vicinity of the existing 132 kV line. If the spacing between new route and existing line is not calculated carefully, the rating of the new and existing line will reduce significantly. To reduce the effect from existing line, several actions can be taken: Obtain the existing route map to demonstrate the exact location of the existing 132 kV line. To reduce the effect of the existing 132 kV cable to the new line, place the new cable with enough distance to the existing 132 kV cable. For example if the existing cable is located on the left side of the road, the new line should be placed in the right side of the road. However sometimes the map is not accurate and the exact position of the existing cable sometimes can be known after digging up the road during construction. This will waste time and money.

Type of the cableIn this alternatives, The 60 MVA load will connect to 132 kV line of Paradise St. Substation. The 132 kV, 2 x 30 MVA cable will be used.20 MVA firm capacity is achieved by provide 2x 30 MVA cables from Paradise Street. Hence if something going wrong with the one group of cables, the other cable still can cope 30 MVA load (more than 20 MVA minimum firm capacity).30 MVA cable from Paradise Street Substationa. Type of Cable : Fluid Filled Cableb. Conductor: CopperBecause in this assignment the cost of 132 kV cable is 400 irrespective of the conductor material, hence it is better to use copper.c. Insulation, components: Paper insulation, lead sheath, PE oversheath.d. Rated Voltage: 132 kVe. Depth of laying: 900 mm. inside the trench.f. Ampacity :The current for the 30 MVA load is = x= x = 158.09 A If choose single core copper cable =From the Fluid Filled Cable Handbook, choose 120 mm2 cable with ampacity 364 A in the summer with diameter 51.6 mm. If choose 3 core copper cable =From the Fluid Filled Cable Handbook, choose 120 mm2 cable with ampacity 335 A in the summer with diameter 98.4 mm.It may be better to choose 3 core conductor. Although it is not common to use 3 core 132 kV in Europe, it is common in the UK and the diameter of the conductor still reasonable (not very large). Use 3 core cable in this assignment will also: Save more money from cost of cable. If the project use 3 core cable, the project only need to purchase 1/3 length of single core cable. For example: if the route length is 100 m, the project need to purchase 100 m of 3 core cable. If the project use single core cable, the project need to purchase 300 m single core cable. (It only apply to this assignment because the cost of 132 kV cable, either single core or 3 core, is 400 per metre). Provide narrower trench width. Narrow trench will reduce cost of trench construction and allow less disturbance to the traffic.Hence choose 120 mm2 cable, with rating 335 A in the summer.g. Core: three coreh. Quantity: 2 x 120 mm2, three core cables.i. Formation: -j. Cable length: 880 m per groupIn fact, each of these cable used in this project has capacity of:335 A x 132 kV x 1.732 = 76.59 MVA.Hence total capacity of the cable in this alternative is 76.59 MVA x 2 = 153.18 MVA. It is more than enough to supply 60 MVA with 20 MVA firm capacity. Costa. Cable Cost. There are 2 cables in this route :2x880 m x 400 = 704,000b. Trench costThe width of the trench needed is:450 mm + 2x50 mm + 2x 98.4 mm = 746.850mm50mm450mm

To make it simple, set the width to 750 mm.The depth of the trench is 900 mm.Trench cost per metre cable is: x 100 = 225Hence the cost of the trench is 880 m x 225 = 198,000.Pulling Tension and Pulling PositionThe allowable load limit is shown in the table 3 below

Table 3 Pulling load for conductor metal - taken from distance learning material chapter 5Because the cable use 3 core coper conductor, hence the calculations must consider only two conductor instead of three.

Hence the maximum allowable pulling load for this option is 1200 kg.

Assumption: The load needed to pull the cable from the drum is 150 kg.Cable rollers are used so friction factor = 0.2Weight is obtained from the table 13 Fluid Filled Cable Handbook : 18.7 kg

Figure 17 Weight of cable data - taken from Fluid Filled Cable Handbooka. Pulling from Paradise St. SubstationThe tension pulling calculations are present below:

Therefore, the pulling tension from Paradise St to Lime St in this route is kgb. Pulling from Lime St. stationThe tension pulling calculations are present below:

Therefore, the pulling tension from Paradise St to Lime St in this route is kg.It is obvious for this option the best initial position to pull the cable is from Lime St. Station. Also because the pulling tension is exceed the allowable pulling load limit, it is required to divide the route into multiple pulling position.

2. Alternative 2 : Figure 18 Route of Paradise St - Lime St alt.2The length of this route is approximately 910 m. The advantages of this route are: This route is short, only 910 m, but slightly longer than alternative 1. Only need to cross one major road (red circle) and cross two minor road (orange circle). Because the route is short, the working hours needed for this route is small. The route only cross one major road. It means that the route maybe only need to use special excavation one times.The disadvantages of this route are: The route need to cross the lime street, which is the main entrance to the station. The construction work may dissatisfied the passengers. Hence the construction and installation of the cables should be consider the visual nuisance impact to the passenger. This route is in vicinity of the existing 132 kV line. If the spacing between new route and existing line is not calculated carefully, the rating of the new and existing line will reduce significantly. Working HoursAssume for one man: Working hours per metre cable is 4 hours Working hours per crossing minor road work is 10 hours Working hours per crossing major road is 72 hoursHence the total working hours for this route is =910 x 4 hours + 2 x 10 hours + 1x72 hours = 3732 hours per employee.Excavation MethodSame as alternative 1 Effect of adjacent cables on the new circuit(s) and effect of the new circuit(s) on adjacent cables Unlike the first alternative, this route is far from existing 132 kV line. Because of this, the rating of the new and existing line will not reduce. It is safe to suggest that this route will not violate the existing 132 kV line. Type of the cableIn this alternatives, The 60 MVA load will connect to 132 kV line of Paradise St. Substation. The 132 kV, 2 x 30 MVA cable will be used.20 MVA firm capacity is achieved by provide 2x 30 MVA cables from Paradise Street. Hence if something going wrong with the one group of cables, the other cable still can cope 20 MVA load (minimum firm capacity).30 MVA cable from Paradise Street Substationa. Type of Cable : Fluid Filled Cableb. Conductor: Copperc. Insulation, components: Paper insulation, lead sheath, PE oversheath.d. Rated Voltage: 132 kVe. Depth of laying: 900 mm. inside the trench.f. Ampacity : 120 mm2 cable, with rating 335 A in the summer.g. Core: three coreh. Quantity: 2 x 120 mm2, three core cables.i. Formation: -j. Cable length: 910 m per group.In fact, each of these cable used in this project has capacity of:335 A x 132 kV x 1.732 = 76.59 MVA.Hence total capacity of the cable in this alternative is 76.59 MVA x 2 = 153.18 MVA.It is more than enough to supply 60 MVA with 20 MVA firm capacityCosta. Cable Cost, there are 2 cables in this route :2x910 m x 400 = 728,000b. Trench costThe width of the trench needed is:450 mm + 2x50 mm + 2x 98.4 mm = 746.850mm50mm450mm

To make it simple, set the width to 750 mm.The depth of the trench is 900 mm.Trench cost per metre cable is: x 100 = 225Hence the cost of the trench is 910 m x 225 = 204,750.Pulling Tension and Pulling PositionUse the allowable load limit that is shown in the table 2, the allowable pulling load is :

Hence the maximum allowable pulling load for this option is 1200 kg.

Assumption: The load needed to pull the cable from the drum is 150 kg.Cable rollers are used so friction factor = 0.2Weight is obtained from the table 13 Fluid Filled Cable Handbook : 18.7 kgc. Pulling from Paradise St. SubstationThe tension pulling calculations are present below:

Therefore, the pulling tension from Paradise St to Lime St in this route is d. Pulling from Lime St. stationThe tension pulling calculations are present below:

Therefore, the pulling tension from Paradise St to Lime St in this route is kg.It is obvious for this option the best initial position to pull the cable for this route is from Lime St. Station. Also because the pulling tension is exceed the allowable pulling load limit, it is required to divide the route into multiple pulling position.

PART 3

The several options of the source for the new 60 MVA Lime St. Station have been discussed in Part 1 and Part 2. In this part, another alternative that may provide more advantages, fewer problems, and might be cheaper is suggested.

There is existing cable in vicinity of the Lime St. Station that can become a new power source for 60 MVA load. This part propose to connect the 60 MVA load to existing cable line that near from Lime St. Station.

There are several existing line in the vicinity of the Lime St. Station that can become potential sources:a. Tapping to existing 132 kV cable Lister Drive-Paradise St.The cable has spare capacity of 75 MVA, enough to cope additional 60 MVA load. The cable is in good condition, can be operated at 900, and is installed around 12 years ago. Hence, it is safe to add 60 MVA load to this cable and no need to reinforce the cable. b. Tapping to existing 33 kV cable.If this option is chosen, it is required to connect to several cable because each cable dont have 60 MVA spare capacity. c. Connect to existing 33 kV substation.Each 33/11 kV substation has 36.25 MVA spare capacity available. The company only required to provide additional switchgear, building a new substation, or extending substation.d. Combination of above options.It is better to choose the option that is not required to provide additional equipment ( transformer, switchgears) or the option that is not required to reinforce the existing substation or cable.

Figure 19 Position of the cables in vicinity of the Lime St. Station taken from the assignmentAlternative RouteThis part propose to connect the 60 MVA peak load and 20 MVA firm capacity to existing 132 kV load near from Lime St. Station ( existing 132 kV cable Paradise St Lister Drive Substation).There are several advantages if the power distribution company choose this option:a. The route for this option is short, compare with if the source is taken from Paradise St. Substation (Part 2).b. From Table 2 Source list, spare capacity of this 132 kV cable is 75 MVA. Hence it is enough to supply 60 MVA peak load and 20 MVA firm capacity. c. The cable is in good condition, can be operated at 900, and is installed around 12 years ago. Hence, it is safe to add 60 MVA peak load to this cable and no need to reinforce the cable.d. The route will dig up white road. It means that the construction and installation work in this route is provide less disturbance for the road user. e. Because this option will dig up along the non-busy traffic, the work can be carried out at any time. Therefore the duration of the project will be short. f. The route is straight forward, hence the pulling tension is very low.g. No need to cross any road.h. No special excavation method is required.However, this options has disadvantage:a. It is required to cut existing 132 kV cable. Therefore large area will experience a black out (loss of supply) during jointing work. Precaution should be taken during the jointing work to minimise risk and further impact.b. The loss of supply can be minimised by finishing cable laying work before jointing work. This allow 2 or 3 hours for jointing work, provide only short duration for black out.c. The jointing work should be carried out at midnight to minimise the negative impact to customer.

132 kV new cable132 kV existing cable

Figure 20 Alternative route - road map-taken from google maps

132 kV new cable132 kV existing cable

Figure 21 Alternative route - earth map- taken from google mapsThe length of this route is around 105 m.

Working HoursAssume for one man: Working hours per metre cable is 4 hours Working hours per crossing minor road work is 10 hours Working hours per crossing major road is 72 hoursHence the total working hours for this route is =2x 105 x 4 hours = 420 hours per employee.The working hours is lower than the working hours if the load connect to Paradise St. substation.Excavation MethodThe following actions is need to be carried out before excavation work: Acquisition of legal permit Obtain permission from local authorities, police forces, and others.During excavation work, it is important to provide: Signing and guarding of the work Fulfil technical requirement for backfilling and reinstatement of the excavation.

Because this route ne does not need to cross any road, no special excavation method is needed:Effect of adjacent cables on the new circuit(s) and effect of the new circuit(s) on adjacent cables There is no adjacent cable if this route is chosen. The only adjacent cable is the 132 kV existing cable that the new cable connect into. Hence there is no significant effect either to new circuit or the existing cable.

Type of the cableIn this alternatives, The 60 MVA load will connect to the existing 132 kV cable. The 132 kV, 2 x 30 MVA cable will be used.20 MVA firm capacity is achieved by provide 2x 30 MVA cables from existing 132 kV cable. Hence if something going wrong with the one group of cables, the other cable still can cope 30 MVA load (more than 20 MVA minimum firm capacity).Same type of cable is used for connection to 132 kV existing cable line. The reason is because to prevent negative impact during fault location process if choose different type of cable30 MVA cable connect to existing 132 kV cablea. Type of Cable : Fluid Filled Cableb. Conductor: CopperBecause in this assignment the cost of 132 kV cable is 400 irrespective of the conductor material, hence it is better to use copper.c. Insulation, components: Paper insulation, lead sheath, PE oversheath.d. Rated Voltage: 132 kVe. Depth of laying: 900 mm. inside the trench.f. Ampacity :The current for the 30 MVA load is = x= x = 158.09 Achoose 3 core copper cable =From the Fluid Filled Cable Handbook, choose 120 mm2 cable with ampacity 335 A in the summer with diameter 98.4 mm.Hence choose 120 mm2 cable, with rating 335 A in the summer.g. Core: three coreh. Quantity: 2 x 120 mm2, three core cables.i. Formation: -j. Cable length: 105 m per groupIn fact, each of these cable used in this project has capacity of:335 A x 132 kV x 1.732 = 76.59 MVA.Hence total capacity of the cable in this alternative is 76.59 MVA x 2 = 153.18 MVA. It is more than enough to supply 60 MVA with 20 MVA firm capacity. Costa. Cable Cost. There are 2 cables in this route :2x105 m x 400 = 84,000The cable cost is cheaper than if the power is taken from Paradise St. Substation.b. Trench costThe width of the trench needed is:450 mm + 2x50 mm + 2x 98.4 mm = 746.8To make it simple, set the width to 750 mm.The depth of the trench is 900 mm.Trench cost per metre cable is: x 100 = 225Hence the cost of the trench is 105 m x 225 = 23,625.The trench cost is cheaper than if the power is taken from Paradise St. Substation.Pulling Tension and Pulling PositionUse the allowable load limit that is shown in the table 3, the allowable pulling load is:

Hence the maximum allowable pulling load for this option is 1200 kg.Assumption: The load needed to pull the cable from the drum is 150 kg.Cable rollers are used so friction factor = 0.2Weight is obtained from the table 13 Fluid Filled Cable Handbook : 18.7 kgThe tension pulling calculations are present below:

Therefore, the pulling tension in this route is 524.7kg.The pulling tension does not exceed the maximum allowable pulling load 1200 kg. Hence, it is only has one initial pulling position, allowing the simple project to save money and time. Because the route is straight, there is no difference of tension pulling either if the initial drum position is in existing 132 kV cable or in the Lime St. Station.There is no jointing bay position in this route.

PART 4

This part will present the conclusion, the further works required, and any suggestion and recommendation for the project. Tapping to 132 kV cable line (Lister Drive Paradise St) provide the most cost effective solution, few problems, and short working hours. One advantage of the alternative solution (connect to existing 132 kV cable Lister Drive- Paradise St) is that this route is straight, hence it does not have bend. Provide simple installation and low pulling tension. The cable is in good condition, can be operated at 900, and is installed around 12 years ago. Hence, it is safe to add 60 MVA peak load to this cable and no need to reinforce the cable. Same type of cable is used for connection to 132 kV existing cable line. The reason is because to prevent negative impact during fault location process if choose different type of cable. The route will dig up white road. It means that the construction and installation work in this route is provide less disturbance for the road user. Because this option will dig up along the non-busy traffic, the work can be carried out at any time. Therefore the duration of the project will be short. The route is straight forward, hence the pulling tension is very low. No need to cross any road. No special excavation method is required. It is required to cut existing 132 kV cable. Therefore large area will experience a black out (loss of supply) during jointing work. Precaution should be taken during the jointing work to minimise risk and further impact. Precaution should be taken to prevent oil leakage and other environmental risk during jointing work. The loss of supply can be minimised by finishing cable laying work before jointing work. This allow 2 or 3 hours for jointing work, provide only short duration for black out. The jointing work should be carried out at midnight to minimise the negative impact to customer. For further study, the cost of additional equipment required (transformer, switchgears, reinforcing the substation) is needed to show clear comparison between the options. It is recommended to carry out ground thermal resistivity and ground temperature to improve the accuracy of the calculation. This report could be improved by providing detail jointing work practice, excavation practice, and health and safety guideline. Before starting the construction work, it is important to carry out risk and environmental assessment.

REFERENCES[1] Moore, G. F. et al, Electric Cables Handbook (Third Edition), BICC Cables, London. (1997).[2] C. Xerri, Power Cables, Newcastle : Newcastle Upon Tyne, 2014.[3] http://www.google.co.uk/maps[4] http://www.bing.com/maps/19 | Haidar Ismail PMA Power Cables