Answer / cnu

Basically a device is earthed to avoid any stray
circulating current that appear on the body of the device
operating with an AC supply.

since AC creates an alternating flux. this changes in flux
induces stray currents in the metallic body of the devices.

When coming to DC, since it is a constant voltage it does
not produce flux change to induce any currents so earthing
is not required for a DC battery.

Answer / prasoon

In a HV Sub station, 220 Volt system is not earthed to
avoid mal operation of DC controlled electrical elemnets in
case of a earth fault.

50 Volt system is earthed (-ve). This is done as 50 volt
system is used for electronic circuits where -ve voltage is
required to opearate npn transistors.

Answer / aamod tripathi

To avoid circulating current in DC system.

Answer / owais chaudhri

b/c there is already availabe zero potential in batry
(ie -ve terminal).

Answer / kanth

there is no need of earthing fo Dc systems
and in AC only earthing is needed
bcoz power generated from generators and ttransfer from
transformers ,so transrormers neutral's earthing has done
(in star-star or delta-star trafo)so phase currents goes
directly though earth or in neutral as a returned path to
transformer.
so we r using neutral for return path and earthing for
safety

What is Partial Discharge test .Please specify that this test can be test on 11/0.433 KV,630 KVA Transformer.

1 Answers   NBCC,

---

What is the difference between MCB and Earth MCB? What is the working principal of MCB?

2 Answers  

---

how can get electrical "c" licence.i am complited in DEEE.PASSING YEAR OF 1993.WORKING IN PVT COCERN LT LINE.PLEASE ADVISE ME .CELL NO 9994786021

0 Answers  

---

why Power transmssion voltages are as 11kV,33kV,66kV,220kV and so on only?

2 Answers  

---

why the iron chains were hanged at the back or front of the trucks earlier which were touching the earth?

2 Answers  

---

---

what is the maximum load in MDB,SMDB and DB

1 Answers  

---

why is neccessary Tap changing of power transformer with in a certain time

1 Answers  

---

explain with the help of loading capability curve,reactive power generation and absorption from synchronous generator?

0 Answers  

---

How to calculate the efficiency of Turbo Generator(Alternator) in general....?

0 Answers   Thermax,

---

what is the difference between power transformer & distribution transformer and what are their ratings respectively?

4 Answers  

---

Upto what extend the powerfactor of a supply system can be improved to be cost effective?

1 Answers  

---

In a circuit a capacitor (paper capacitor ) was burned due to over voltage in this case can we replace that type cappacitor with other tye capacitor ?

1 Answers  

---