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?

Answers were Sorted based on User's Feedback



We use ungrounded DC system (220V/110V) for control and protection system in substations etc. Supp..

Answer / krishna

Usage of differential relay for 220V/110V is not an
economical idea. Differential protection is the costlier
protection. DC Cables should be protected from earthleakage
bacause of which voltage differences occurs and trips the
circuits due to large variations. I suggest to go for
MCCB/MCB of required rating which trips the circuit when
earth leakage occurs.

Is This Answer Correct ?    5 Yes 1 No

We use ungrounded DC system (220V/110V) for control and protection system in substations etc. Supp..

Answer / ch.shankar

use dc differential relay or poles insulation monitor which
will help u to measure leakage

Is This Answer Correct ?    5 Yes 3 No

We use ungrounded DC system (220V/110V) for control and protection system in substations etc. Supp..

Answer / k.prakashchandra

Normally dc earth fault locater is employed. If one polarity
shows earth fault there is nothing to panic.Heavy fault
current occurs if the other polarity also develops fault. If
tripping is provided ,the protection may get lost.

Is This Answer Correct ?    1 Yes 0 No

We use ungrounded DC system (220V/110V) for control and protection system in substations etc. Supp..

Answer / sanjay choubey aditya electron

You can use online Insulation Monitor Bender Germany make
products for above requirement you can also see website for
more details: www.bender.org many Steel Plant, Substation
are using Bender products same applicaton.

Is This Answer Correct ?    1 Yes 0 No

We use ungrounded DC system (220V/110V) for control and protection system in substations etc. Supp..

Answer / sanjay

You can use online Insulation Monitor Bender Germany make
products for above requirement you can also see website for
more details: www.bender.org many Steel Plant, Substation
are using Bender products same applicaton.

Is This Answer Correct ?    0 Yes 0 No

Post New Answer

More Electrical Engineering Interview Questions

calculation of knee point voltage of current transformer?

2 Answers   TATA,


Is it advisable to buy a plot for house construction near High Tension Power lines? If it so how much distance it should be away from power line? Iam residing at Chennai, Tamilnadu, India.

2 Answers  


what is the purpose of fuse?

7 Answers  


our company have 750 kva oil transformer.still we have facing a problem that is when voltage is 11.5 kv coming from HT side then LT-side voltage is 420v or above at tape 1.please give me best solution to decrease the voltage.

3 Answers  


single phase voltage 230 and Three phase voltage 450 why 690 voltage

1 Answers   XYZ,






I've heard that most of the substations are rated in multiples of 1.11 because of form factor.What is form factor?

3 Answers  


Electronic circuit

0 Answers  


why using carbun bresh in dc motor

3 Answers  


why CFL lamp requires less electricity than a normal lamp?/

3 Answers  


what is polarity in ac system? and how do identified?

1 Answers  


What is TR of AC?

11 Answers   Carrier, Reliance,


What is a DC series motor?

0 Answers   Ericsson,


Categories
  • Civil Engineering Interview Questions Civil Engineering (5085)
  • Mechanical Engineering Interview Questions Mechanical Engineering (4452)
  • Electrical Engineering Interview Questions Electrical Engineering (16632)
  • Electronics Communications Interview Questions Electronics Communications (3918)
  • Chemical Engineering Interview Questions Chemical Engineering (1095)
  • Aeronautical Engineering Interview Questions Aeronautical Engineering (239)
  • Bio Engineering Interview Questions Bio Engineering (96)
  • Metallurgy Interview Questions Metallurgy (361)
  • Industrial Engineering Interview Questions Industrial Engineering (259)
  • Instrumentation Interview Questions Instrumentation (3014)
  • Automobile Engineering Interview Questions Automobile Engineering (332)
  • Mechatronics Engineering Interview Questions Mechatronics Engineering (97)
  • Marine Engineering Interview Questions Marine Engineering (124)
  • Power Plant Engineering Interview Questions Power Plant Engineering (172)
  • Textile Engineering Interview Questions Textile Engineering (575)
  • Production Engineering Interview Questions Production Engineering (25)
  • Satellite Systems Engineering Interview Questions Satellite Systems Engineering (106)
  • Engineering AllOther Interview Questions Engineering AllOther (1379)