We use ungrounded DC system (220V/110V) for control and protection system in substations etc. Suppose we have long 2 core DC cables running from our DCDB in control room to the load (length of around 2 to 3 km). Do we need to protect these long DC cables from earth leakages or not? If yes how?

5 Answers   Siemens,

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how can we detect that which is receiving side and which is sendind end of a trnasmmison line by just seiing it?i.e its which end is coming from genertaing and distribution side?

5 Answers  

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how to conduct dc resistance test for rotor of an alternator and how to measure the rotor dc resistance value theoritically?

0 Answers  

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What is the need of earthing transformer for delta side of a transformer. (Think of a line section between a star/delta transformer at a grid substation and delta/star transformer at a village. An earthing transformer is there at the delta side of the star/delta transformer at grid substation). As there are no ground reference there will not be fault current if a one phase is grounded. Further L-L phase will be sensed by the primary side of star/delta transformer as a L-G fault. So why an earthing transformer is required at delta side

0 Answers   CEB,

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If Neutral Grounding Resistor (GR) failed/shorted. Is it repairable.

0 Answers  

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what is difference between isolation and ultra isolation transformer?, what is the method of testing ?

0 Answers  

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what is power factor when in view of a lineman

3 Answers   KSEB,

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Difference between shunt, PMG and AREP excitation. Which is the most reliable between PMG and AREP.

0 Answers   ABB,

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what is difference b/w CFL and Ordinary lamps? which one is useful for power saving?

5 Answers  

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Define average demand?

0 Answers  

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What is the ratio of Booster transformer?

0 Answers  

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From stability point of view,What(higher/lower) should be the value of inertia constant of rotating machines?

1 Answers  

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