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 the need for a controller?

0 Answers  

how a vibration switch's high signal will going to trip the motor? can u explain with some examplesand wiring diagrams?

1 Answers   Bhel, Wartsila,

how to calculate a cable size while load is given in amp or kw and length is also define.?

1 Answers  

is it possible to step down voltage of single phase from a three phase sysem? explain

2 Answers  

What is mean by single phasing used in distribution of electricity in rural area of maharashtra state?

3 Answers  

How addressable fire systems work? Pl. send details with architect.(Loop), also send details regarding Gas system. Pl. help me.Thanks

1 Answers   Siemens,

What is differance between Slip ring motor and Squirrel cage Motor ?

2 Answers  

expansion of rccb

3 Answers  

Magnetizing current for induction motor compared to transformer is= A equal B more C less D depends on load

1 Answers  

why synchronous motor is not self starting

5 Answers   Cenored,

How to test REF relay testing for LV panel as per Kahramaa standard?

0 Answers  

What is the formula to find maximum load of a DG (Single phase and Three phase)?

1 Answers