UG Vs OH CABLES

ACTIVITY ON 8/4/10

discussion with Mr. MOH (external mentor for Cable Unit @ TNBR)

what is UG Vs OH ???

UG is abbreviation of UNDERGROUND Cable
OH is abbreviation of OVERHEAD Cable
both cables are used to distribute electric to consumer or we also can call it as conductor.

Underground Cable

do you know what type of conductor widely used in Malaysia??

- most area in Malaysia use Underground Cable as the conductor


there are Pro n Cons between UG and OH

UG Vs OH

Advantages of UG Cables

- Environmental

- Minimal Visual Impact

- Low EMF

- No corona discharge, RI and TVI

- No bush fire problem

- Minimal lightning problems

- High level of personnel and public safety

- Good working condition

Disadvantages of Ug Cables

- Cost, must consider life time costs not just initial
- Cost differential decreasing with time
- Cost losses (30-60% less than OH), maintenance and repaire
- Undergrounding 25% of the existing EHV and HV lines in Italy and UK will increase the price of electricity by 3-5%
- Undergrounding all of the lines in Italy would increase the cost of electricity by 16%

Biggest contributor supply interuption is Underground Cable Failure


Problems :

- Susceptible for water to enter the cable
- There are a lots of vibration
- Need to dig for further maintenances


At Putrajaya, the underground cables installed was different from other place. they used an advances technology to lay the underground cable. the technology came from Japan which known as Duct Bank. actually at Putrajaya any digging activity are not allowed at all. that is why they used Duct Bank.


Duct Bank : many PVC pipe buried underground was with and without cables inside it. if they need to do the cable maintenances or change the cables they just need to duct the cable from one end until another end. no digging required.. pictures below shows the Duct Bank







Duct Bank



Problems with Duct Bank :

- all the cables (11kV, 30kV,..etc) gathered in one place..since all the cables generate heat, therefore the temperature inside Duct Bank will increase. when the temperature high, resistance will high and I^2R losses will increase..when the area inside is too hot, the cables tend to melt and cause damage to the cable. to implement this technology pic should make sure the insulation material can withstand with the heat produced and use superconductor to carry infinite current with low temperature.

* weather in Malaysia is absaloutely different with Japan... temperature factor are not really considered before implement the system.