The Upgradabilty of Conventional Three Phase Delta/Star Networks

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Jasmine Lawson
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1 The Upgradabilty of Conventional Three Phase Delta/Star Networks

2 WHY NEW STANDARDS? CAPITAL COSTS Initial Final OPERATIONAL COSTS UPGRADABILITY SAFETY MAINTAINANCE

3 CONVENTIONAL CONFIGURATION Electrification Area 1-ph. MV/LV transformer HV/MV Substation SEF Protection MV 3-Wire line Single Phase MV Lines Single Phase LV Lines Electrification Area

4 Losses under Imbalanced Conditions The Delta Systems balances the loads and no losses are accumulated in the neutral conductor The following is a comparison for equal loading on the LV side Losses are displayed for a 1 km section of MV line only

5 Diagrammatic Demonstration-STAR Losses under imbalanced conditions Ph Red Ph Blue Ph Yellow Ph Neutr. Loss W Resistance Amp Loss

6 Diagrammatic Demonstration-DELTA Losses under imbalanced conditions Ph Red Ph Blue Ph Yellow Ph Neutr. Loss W Resistance Amp Loss

7 Comparison of Voltage drop and Losses for two system using same conductors sizes The system simulates six villages 30km apart & 30km away from the 3 ph lines. Saturation load is 1000W per household A 2.5 MVar Cap Bank is needed for the Delta System A 3.5 MVar Cap Bank is needed for the Star System

8 Delta 2.5MVA Cap Bank - Losses 353 kw (3 000 kw )

9 DELTA System with 2.5 Mvar Cap Bank

10 Star 2.5MVA Cap Bank - Losses 591 kw (3000kW )

11 STAR System with 3.5 Mvar Cap Bank

Conductor fixing position Stay assembly, complete with pre-form, stay

Three phase transformers mounted on transformer platform, surge arresters

12 Conductor fixing position Stay assembly, complete with pre-form, stay insulator, turn-buckle and base plate. Three phase transformers mounted on transformer platform, surge arresters mounted on transformer Transformer surge arresters and tank earthed at transformer stations. Min 10 ohm earth resistance to be obtained Neutral to be earthed, every first and last pole from transformer. No LV earthing at Transformer Stations Three Phase General Arrangement Drawing

No LV earthing at Transformer Stations Single phase transformers pole mounted, surge arresters mounted on

13 Single Phase General Arrangement Drawing Neutral to be earthed, every first and last pole from transformer. No LV earthing at Transformer Stations Single phase transformers pole mounted, surge arresters mounted on transformer Transformer surge arresters and tank earthed at transformer stations. Min 10 ohm earth resistance to be obtained Stay assembly, complete with pre-form, stay insulator, turn-buckle and base plate.

14 IDENTIFIED ISSUES Connectivity of 3 ph plant Existing MV lines conversion Substations revamp The MV 73% less capacity lighter poles, insulators and conductors earth fault protection (safer)

15 CONTINUED. Low voltage reticulation upgradable System imbalances and harmonics transfers Earth wires vulnerable to theft Compatibility with regional standards Alternative systems offer no visible cost savings Proper comparisons should be made.

16 Thank You!

17 Connectivity of Pole Mounted Split Meters and Ready Boards M M M M M Pole Mounted Meter Box, containing split meter & circuit breaker, 20A Service cable, two core copper conductor 6-10 sq mm, with integrated twin comms. meter cable, 1 sq mm. Poles to be earthed, every first and last pole from transformer. No LV earthing at Transformer Stations All customers to be provided with earthed installations No neutral to be earthed after the E/L unit to ensure save operation of E/L breakers Ready Board, containing circuit breakers, light fitting, SSO s, meter key pad, neutral and earth terminals

19 REVISED STANDARDS WHY NEW STANDARDS MEDIUM VOLTAGE LOW VOLTAGE SERVICE LINES TRANSFORMERS COST SAVING

20 SERVICE LINE 6 sq mm SINGLE CORE CONDUCTOR Lower cost Lighter weight on structure CONDUCTOR FROM POLE TO METER Anchor to pole with pole lug No joints required No D-Irons & isolators required on pole ANCHOR SERVICE LINE TO HOUSE ROOF STRUCTURE No Service Bracket required FLY FUSE Protect network from service cable faults Cut-off position INSTALLATION TIME 50%

21 TRANSFORMERS GALVANIZED DISTRIBUTION BOX MAIN LV CIRCUIT BREAKER TO PROTECT TRANSFORMER No fuse to bypass with wire Transformer is protected against overload Phase balance can be checked if breaker trips Transformer can be replaced with bigger one RATED CIRCUIT BREAKERS ON CABLE CIRCUITS

22 POTENTIAL SAVINGS Time, cost, maintenance MEDIUM VOLTAGE Less components, less failure, less maintenance LOW VOLTAGE 40 % saving on material cost Saving per km LV line (average) Time saving easier construction SERVICE CONNECTION LINE 23% Saving on material cost 50% saving on installation time 50% less components to procure, transport & manage

23 ACCELERATED ELECRIFICATION Procurement process (Material, Contractors) Labour Contracts (Material by Utility) Turnkey Contracts Readyboards Increase distance 30m > 50m

24 REVISED STANDARDS WHY NEW STANDARDS MEDIUM VOLTAGE LOW VOLTAGE SERVICE LINES TRANSFORMERS COST SAVING

25 WHY NEW STANDARDS? ECONOMY TECHNOLOGY SAFETY OPERATION MAINTAINANCE

26 MEDIUM VOLTAGE VERTICAL CONFIGURATION

27 LOW VOLATGE REFURBISHMENT PROJECTS Use existing standards NEW PROJECTS Use ABC technology

28 SERVICE LINE 6 sq mm SINGLE CORE CONDUCTOR Lower cost Lighter weight on structure CONDUCTOR FROM POLE TO METER Anchor to pole with pole lug No joints required No D-Irons & isolators required on pole ANCHOR SERVICE LINE TO HOUSE ROOF STRUCTURE No Service Bracket required FLY FUSE Protect network from service cable faults Cut-off position INSTALLATION TIME 50%

29 TRANSFORMERS GALVANIZED DISTRIBUTION BOX MAIN LV CIRCUIT BREAKER TO PROTECT TRANSFORMER No fuse to bypass with wire Transformer is protected against overload Phase balance can be checked if breaker trips Transformer can be replaced with bigger one RATED CIRCUIT BREAKERS ON CABLE CIRCUITS

30 POTENTIAL SAVINGS Time, cost, maintenance MEDIUM VOLTAGE Less components, less failure, less maintenance LOW VOLTAGE 40 % saving on material cost Saving per km LV line (average) Time saving easier construction SERVICE CONNECTION LINE 23% Saving on material cost 50% saving on installation time 50% less components to procure, transport & manage

31 ACCELERATED ELECRIFICATION Procurement process (Material, Contractors) Labour Contracts (Material by ELGZ) Turnkey Contracts Readyboards Increase distance 30m > 50m

MV network design & devices selection EXERCISE BOOK

MV network design & devices selection EXERCISE BOOK EXERCISES 01 - MV substation architectures 02 - MV substation architectures 03 - Industrial C13-200 MV substation 04 - Max. distance between surge arrester