What is defference between earthed and unearthed cable(HT)?
Which is better for under ground cabling?
- 1 Answers
- 7019 Views
- I also Faced
- E-Mail Answers
Answer Posted / abhinav yadava
Earthed System
 Earlier the generators and transformers were of
small capacities and hence the fault current was less. The
star point was solidly grounded. This is called earthed
system.
Unearthed System
 Today generators of 500MVA capacities are used
and therefore the fault level has increased. In case of an
earth fault, heavy current flows into the fault and this
lead to damage of generators and transformers. To reduce
the fault current, the star point is connected to earth
through a resistance. If an earth fault occurs on one
phase, the voltage of the faulty phase with respect to
earth appears across the resistance. Therefore, the voltage
of the other two healthy phases with respect to earth rises
by 1.7 times. If the insulation of these phases is not
designed for these increased voltages, they may develop
earth fault. This is called unearthed system.
| Is This Answer Correct ? | 16 Yes | 8 No |
Post New Answer View All Answers
explain the what is a drive ? 0 4 which type motor r use in the celling fan..... PCB plannet 2 13 If stator & rotor of a 3-phase induction motor have different no. of poles, will the motor run or not?? types of drives Why dc supply is used for closing and tripping coil of ht breakers. What happen if we use only ups ac supply only. ACC 1 41 how the 3phase induction motor is running in 2phase supply with help of capacitor? 1 33 what is the actual difference betwen constructional details and constructional features? 1 20 how does commutator convert a.c to d.c?
state working of halogen lamp?
A 10 MVA, 66KV, 50Hz, Y-connected 3-phase alternator has synchronous reactance of 0.635 Ù. It is working at full load at 0.8 lagging p.f. condition. Find torque angle, neglect armature resistance.
What is the meaning of floating point earthing in battery backed systems ?
Why there are some equipment(i.e:TV) that using 2-pin plug instead of three? What happen if there is current leakage? Are we going to get electric shock??
What is the basic principal, by which DC voltage level is increased more than the supplied AC voltage during conversion. As upto AC level it is contorrled by firing anlge but after maximum level how is it possible.Please clear picture. OR we have to supply the higher level AC?
I have a drawing of a wound rotor induction motor for a crane. This crane motor has 5 forward speeds & 5 reverse speed implemented of course with different amount of resistance for each speed setting selected. What has got me scratching around is the fact that 8 of the 10 speed selections switch in uneven (unbalanced) amounts of resistances on each of the 3 connections to the motor's rotor.Can this be possible? I would have assumed this would produce unbalanced rotor currents and therefore vibration in the motor. I would greatly appreciate anyone's comments on this. Many thanks, Confused.
Match the following a)(X'+Y') b)X'Y' C)XY 1)NAND 2)NOR 3)Carry
what is star delta starter? how it works? give its control and power diagram.
what happens when dc generator coupled with cycle shaft.also explain what happens when its loaded
there is an alternator 480 k.w, 400v,50hz, 4-wire running on load having leakage alternator body earthed current 38 A. is it within acceptable limit? if yes then give reference if no then how to bring within specified limit
what are the protecyion of transformer & generators
What is resonant peak?
how to find number of run cable laying[LT side] for transformer & alternator secondary side? [above condition for getting output power transformer to main panel side] give the example.
What is servo motor and what are different types of servo motor
