what is the difference between earthed system and unearthed
system.. where do we use unearthed system because in
electrical catalogues always cable for earthed and unearthed
system is given..pls elaborate
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Answer Posted / bikash chandra pal
WAHT IS EARTHED SYSTEM??
when the source(it may be feeding generator neutral point
or feeding transforme neutral or a bus through a zig-zag
transformer etc)neutral point of a perticular voltage level
of a system is earthed(may be solidly or through a
resistance/inductance), then that perticular voltage level
of the system is called as earthed system.
WAHT IS UNEARTHED SYSTEM??
When the above said neutral point is not earthed then that
perticular voltage level of the system is called as
unearthed system.
ADVANTAGES OF EARTHED SYSTEM
The system eathing(solidly or through a resistance or
impedance) is done to provide a returne path of earth fault
current, which in turne helps
1)To isolate the faulty part of the system due to earth
fault by sensing earth fault current.
2)To Reduce the insulation requirement of phase elements of
equipments connected in that voltage level & cost of the
equipment/s in turn. VIZ: Earthed grade cables are less
costlier than unearthed grade cables.
3)Fenomennon like ARCHING GROUND can be avoided.
So,
System with lesser Equipment cost(refer SL.NO.(2)above),
health of the concern part of the system(Refer sl no.(1) &
(3)above) remain protected.
DISADVANTAGES OF EARTHED SYSTEM
Possibility of interruption of power supply due to earth
fault,is more in EARTHED SYSTEM than UNEARTHED SYSTEM.
ADVANTAGES OF UNEARTHED SYSTEM
1)Possibility of continuation of power supply is more in
UNEARTHED SYSTEM, as tripping of system due to first earth
fault is not happens.
2)sensing of presence of earth fault through sensing of
concern system's neutral displacement is possible & planned
maintenance/earth fault clearence of the system is
possible,which supports better availity of the system &
lesser interruption of process.
DISADVANTAGES OF UNEARTHED SYSTEM
1)Isolation of the faulty part of the system due to earth
fault by sensing earth fault current is not possibele due
to first earth fault.
2)Insulation requirement of phase elements of equipments
connected is higher Hence cost of the equipment/s is
higher. VIZ: unearthed grade cables are costlier than
earthed grade cables.
3)Fenomennon like ARCHING GROUND is there.
So,
Capital investment is higher for unearthed System, But
availability of system is better.
| Is This Answer Correct ? | 41 Yes | 1 No |
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