Faults in underground cable may cause loss of supply to customers and loss of revenue for suppliers so it is imperative that the fault location process is efficient and accurate to minimise excavation time, which results in reducing inconvenience to all concerned. For fault locating to be efficient and accurate technical staff need to have expert knowledge accompanied with experience in order to attain service reliability. This workshop is designed to ensure that those responsible for the selection, laying, operation, maintenance and monitoring of power cables understands the technical issues involved and comply with relevant specifications and requirements. WHO SHOULD ATTEND? Anyone associated with power cable operation, maintenance, location and fault detection techniques. The workshop will also benefit those working in system design as well as site commissioning, maintenance and troubleshooting. Typical personnel who would benefit are: Electrical maintenance technicians and supervisors Maintenance personnel Operations personnel Process control engineers Service technicians MORE INFORMATION: http://www.idc-online.com/content/power-cables-operation-maintenance-location-and-fault-detection-39

1. Power cables: Operation, Maintenance,
Location and Fault Detection
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2. Topics
• Need for high voltage cables
• Advantages of using cables over overhead
transmission lines
• Disadvantages of cables
• Various types of high voltage cables
• Need for cable jointing
• Need for termination
• Various types of jointing kits and termination
kits
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3. What is a CABLE?
• Cable: Denotes a bundle of wires
– e.g: A wire rope is a type of cable
• Electrical cable is a bundle of electrical conductors
used for carrying electricity
– Bare conductors
– Insulated conductors
• In electro-technology, cable means an insulated
electrical conductor used for transmitting electrical
energy
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4. Function of electrical lines
• Transmitting power from generating source to
load centers
• Distributing power from main substations to
individual consumers
• Lines can be overhead conductors or underground
cables
• Long transmission lines and rural distribution by
overhead lines
• Shorter/urban feeders by cables
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5. Typical overhead line
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6. Section of typical HV cable
A l u m i n u m c o n d u c t o r
S e m i c o n X L P E
( C o n d u c t o r s h i e l d )
X L P E i n s u l a t i o n
S e m i c o n X L P E
( I n s u l a t i o n s c r e e n )
C o p p e r t a p e
P V C S t 2
O u t e r s h e a t h
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7. Why high voltage?
• Higher the voltage, lower the current for a given
value of power
• More energy transmitted for a given conductor
section
• Lower conductor losses
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8. Relation between voltage and load
rating
Motor rating in kw Operating voltages in Volts
Up to 200kw 415V
Between 200 to 500kw 3300V
Between 500kw to
2500kw
6600V
Above 2500kw 11000V
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9. Cables-Advantages
• Less space compared to overhead lines
• No visual intrusion (also called visual
pollution)
• Not susceptible to atmospheric activity
(wind/lightning)
• Higher surge impedance reduces severity of
switching overvoltages
• Ideal way to transmit power across a water
body (Ex: supply to an island)
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10. Cable-drawbacks
• Fault location is difficult and time taking
• Expensive
• More monitoring (for certain types of cables)
• Jointing/termination require persons with high
skill levels
• Joints/terminations become weak points
• Testing is difficult and time-consuming
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11. Common types of cables
• PVC insulated cables
• VIR insulated cables
• Low pressure oil filled cables
• High pressure oil filled cables
• Paper insulated cables
• Polyethylene (PE) insulated cables
• Cross linked polyethylene (XLPE) cables
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12. Need for jointing (Splicing)
• Cables are heavy and difficult to transport
• Fixed drum lengths (ex: 500m) are typical
packaging norm
• Longer feeder lengths need joints
• Joints are needed for partial replacement
(in case of a cable fault)
• Joints are also needed for specific purposes
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13. Types of joints
• Straight through
– Long routes and repaired sections
• Branch Y joints
– For branching of a feeder
• T joints
– For branching of a feeder
• Transition joints
– Special joints between two different types of
cables (Oil filled/XLPE)
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14. Straight-through joint
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15. Making of a T-Joint
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16. A typical Y-branch joint
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17. Need for termination
• A cable needs to be connected to an equipment or
another cable
• A connection between two cables is called a joint
• A connection to an equipment is called a termination
• Termination can be indoor type or outdoor type
• End sealing kits are used to cover the cut end of a cable
against moisture entry
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18. Typical outdoor termination
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19. Installation steps
• Preparation of installation site
• Arranging cable supports
• Unwinding of cable from the cable drum
• Laying along the supports and clamping to
prevent dislocation
• Threading through pipes where a cable duct is
used
• Jointing/Termination
• Testing
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20. DO YOU WANT TO KNOW MORE?
If you are interested in further training or information,
please visit:
http://idc-online.com/slideshare
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