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  1. eejacky

    HVAC pressure test

    As advised by our testing department, HVAC pressure test was not recommended for a 132kV cable circuit. The circuit included a 1km underground cable and a long OHL. The reason for this was that the OHL has a high resistance due to the presence of lightning arrestors and insulators. My question...
  2. eejacky

    Digital multimeter and Meggar

    Hi skogsgurra, Thank you for your reply. Do you mean if I use handheld anlogue multimeter, it will not have such false indication? Also, can you explain more why some digital multimeters are more sensitive to induced AC voltage? Thanks again.
  3. eejacky

    Digital multimeter and Meggar

    I encountered the following problem during our work. I hope the experts can help to solve this problem. I work in 132kV transmission cables. At one time, I tried to use the digital multimeter to identify the correct cable from one end to the remote end. The cable is about 3km long. In one end...
  4. eejacky

    Materials with less effected by eddy current

    Basically, we want to look for a material of a clamping ring/adpater used in the HV side of transformer cable termination. We don't want to have the effect of the eddy current arising from the cable in the ring after energizing the circuit.
  5. eejacky

    Materials with less effected by eddy current

    I have a question on the materials used in power system. If a unmovable metallic ring passed via a phase of cable which carry a current, it was known that an eddy current will be generated in the ring. Any expert know what materials (i.e., stainless steel, copper, etc) will be less effected by...
  6. eejacky

    132kV HVAC test for oil-filled cable

    I heard that 132kV HVAC test is NOT preferable to oil-filled cable. Any expert know the background on this.
  7. eejacky

    Frequent burn out of light bulbs

    My friend had a problem that the lighting system of his home always burn out every two months. The lighting system include six light bulbs (I think it is in parallel arrangement) of which two light bulbs always burned out even after replacing a new one. It is the same case when using either...
  8. eejacky

    132/11kV transformer neutral cable

    Dear all, Why the neutral cable gland shall be insulated from the cable box on the 11kV side of 132/11kV transformer? Also, why the 11kV neutral cable sheath shall be insulated? Is it related to the neutral current transfomer. Thank you!!
  9. eejacky

    HV underground cable - double circuits configuration

    Hi cuky2000, Thank you for your reply. Could you elaborate more about how to devise these equations. Also, how about the case of Y1R1B1(Left) and B1R1Y1(Right)? Jacky
  10. eejacky

    HV underground cable - double circuits configuration

    For 132kV double circuits, the configuration of the two circuits as laid in the same trench would likely be mirror image. That is YRB:BRY either in trefoil or flat formation. Why the configuration should be like this? Is it related to the reduction of energy loss due to inductance?
  11. eejacky

    Impedance of power cable

    In the electrical specification of power cable, I found that the positive sequence impedance and zero impedance of 500 mm sq 132kV cable is lower than 500 mm sq 11kV cable. Is the impadance depends on conductor size or other parameters? Any expert can give me advise on this?
  12. eejacky

    Transposition of transmission line

    Does any expert remember how to prove transposition of three equal length transmission line can minimise the mutual inductance and capacitance? Thank you!!
  13. eejacky

    Cable insulation

    Dear all experts, Is the thickness of the insulation for xlpe cable important to cable design? In other words, whether thick insulation is better than thin insulation? Thank you!!
  14. eejacky

    AC testing

    Dear all experts, I heard that the present equipment used to perform AC testing for power cable (132kV or 400kV) have a specified capacitance tolerance such as 40pF. Why AC testing is not preferable for LONG cable length? Thank you!
  15. eejacky

    Fault level of cable

    Dear all, Which part of the 132kV XLPE cable will determine the fault level of cable? In other words, when there is a short circuit, which part of the cable (i.e conductor shield, insulation, insulation shield or metallic sheath)will be the most electric stress one. Thank you!
  16. eejacky

    Cable arrangement

    Dear all experts, I have a question regarding the 132kV underground cable arrangement. In commom practice, trefoil and flat formation are usually adopted in cable laying, but which one is better? What is their advantages and disadvantages? Also, I have read a page talking about cable...
  17. eejacky

    Testing of LV switchboard

    Dielectric test, Meggar test and ductor test are to be carried out for every new installed LV switchboard assemblies. However, I don't know the basic principle behind these. For meggar test, 1000Vdc is applied with one end to one phase (say R Phase) of busbars while the other end to shorted...
  18. eejacky

    Earthing systems

    I know there are a number of earthing systems including TT system, TN system and IT system. However, I wonder why different countries use different systems. Is there any reasons for that or each system has its own advantages or disadvantages? I hope experts can give me information on these.
  19. eejacky

    HV Underground cable sizing

    If there is any guideline or calculation method that I can refer to in sizing HV underground cable (11kV).

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