The Upgradabilty of
Conventional Three Phase
Delta/Star Networks
WHY NEW STANDARDS?
• CAPITAL COSTS
– Initial
– Final
• OPERATIONAL COSTS
• UPGRADABILITY
• SAFETY
• MAINTAINANCE
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
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
Diagrammatic Demonstration-STAR
Losses under imbalanced conditions
Ph Red
Ph Blue
Ph Yellow
Ph Neutr.
1
1
1
1
Amp
35
52
17
26
Loss
1200
2700
300
675
Resistance
Loss W
4875
Diagrammatic Demonstration-DELTA
Losses under imbalanced conditions
Ph Red
Ph Blue
Ph Yellow
Ph Neutr.
1
1
1
1
Amp
20
20
20
0
Loss
400
400
400
0
Resistance
Loss W
1200
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
Delta 2.5MVA Cap Bank - Losses 353 kW (3 000 kW )
DELTA System with 2.5 Mvar Cap Bank
Star 2.5MVA Cap Bank - Losses 591 kW (3000kW )
STAR System with 3.5 Mvar Cap Bank
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
Single phase
transformers pole
mounted, surge arresters
mounted on transformer
Neutral to be earthed,
every first and last
pole from transformer.
No LV earthing at
Transformer Stations
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.
Single Phase General Arrangement Drawing
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)
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.
Thank You!
Connectivity of Pole Mounted Split Meters and Ready Boards
M
M
M
M
Pole Mounted Meter
Box, containing split
meter & circuit breaker,
20A
M
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
123
456
789
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
REVISED STANDARDS
• WHY NEW STANDARDS
• MEDIUM VOLTAGE
• LOW VOLTAGE
• SERVICE LINES
• TRANSFORMERS
• COST SAVING
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%
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
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
ACCELERATED ELECRIFICATION
• Procurement process (Material,
Contractors)
• Labour Contracts (Material by Utility)
• Turnkey Contracts
• Readyboards
• Increase distance 30m > 50m
REVISED STANDARDS
• WHY NEW STANDARDS
• MEDIUM VOLTAGE
• LOW VOLTAGE
• SERVICE LINES
• TRANSFORMERS
• COST SAVING
WHY NEW STANDARDS?
• ECONOMY
• TECHNOLOGY
• SAFETY
• OPERATION
• MAINTAINANCE
MEDIUM VOLTAGE
• VERTICAL CONFIGURATION
LOW VOLATGE
• REFURBISHMENT PROJECTS
– Use existing standards
• NEW PROJECTS
– Use ABC technology
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%
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
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
ACCELERATED ELECRIFICATION
• Procurement process (Material,
Contractors)
• Labour Contracts (Material by ELGZ)
• Turnkey Contracts
• Readyboards
• Increase distance 30m > 50m