RATING OF LIGHTENING ARRESTER FOR 11 KV LINE IS 9 KV BUT WE
KNOW THAT LIGHTENING ARRESTER IS USED FOR OVER VOLTAGE
PROTECTION SO WHY NOT THE RATING OF LIGHTENING ARRESTER BE
MORE THAN 11KV ???????????????//
Answers were Sorted based on User's Feedback
Answer / elangovan t
Lightning arrester is to protect the system from any high
voltages such as lightning.
If the system voltage is 11kv, then the phase voltage will
be 11/sqrt(3)=6.35kv. It means the RMS voltage of the phase.
The maximum voltage or the peak voltage across the arrester
and earth will be 6.35*sqrt(2)=8.98kv.i.e 9kv.
Therefore, for 11kv line it is rated for 9kv.
Is This Answer Correct ? | 135 Yes | 10 No |
Answer / h r jadhav
when we use ac line having system line voltage 11kv,in
this case phase voltage [phase to neutral which is earthed}
is 6.351 kv. lightening arrester is connected between phase
and neutral. lightening arester are nothing but the voltage
dependant resistors which act as insulator up to not only
the phase volatage ie 6.351 kv rms but ac peak voltage
reaches to 6.351 rms x root of 2 ie 1.414=8.98 kv. for
normal operation of system. thus the L A s are rated for
normal voltages 9 kv and discharge current generaly 10 kamp.
when ever voltage surges occures due to lightenig or either
by system abnormabilty,L A becomes for a instance as a
conductor provides path to surge voltages and prevents
failure of insulation leveles of equipment of system
Is This Answer Correct ? | 32 Yes | 5 No |
Answer / nageshwar
FOR A 11KV LINE LINE TO GROUND VOLTAGE IS 11KV/SQRT(3). IT
GIVES OF THE ORDER OF 6KV ONLY. AS ARRESTER IS USED FOR
LINE TO GROUND TO DISCHARGE THE FAULT CURRENT TO GROUND ITS
RATING SHOULD BE MORE THAN 6KV. GENERALLY WE USE 9KV.
Is This Answer Correct ? | 32 Yes | 16 No |
11kv is line voltage,but we put the lighting arrester in
phase so phase voltage of 11kv line is 6.351kv,now we can
not put rating of lighting arrester to 6.351kv because it is
normal phase voltage,so we put it 1.414(square root of
2)times more than phase voltage 6.6kv means 9kv.
Is This Answer Correct ? | 13 Yes | 4 No |
Answer / gunasekaran
for solid grounding maximum voltage build up at earth faul
condition it self is not more than 80% of line voltage so
11*.8=8.8KV so we r using 9KV
Is This Answer Correct ? | 8 Yes | 9 No |
Why the Transformer Nuetral is grounded?
10 Answers Infosys, Khartoum Refinery,
What will happened. if we feed 3phase supplay to the stater with out insert the rotor. How much current will flow through the stater winnding?
Is current shock due to voltage or current? pls answer
why use generator Earthing/Graunding.
Can we use a window type neutral CT instead of a bar type neutral CT. We have an issue with a neutral bar type CT of 800/1 ratio with a Circuit breaker NS800L shneider type, and we want to change it with a window type. Pls advise. Thanks
IS there any mechanical connection between the field winding and armature winding of a dc generator?
75 kw motor take 45 amp in no load delta in star 10 amp but in load it will take 160 amp but IR velue of winding above 500 at 1kw ph to earth and ph to ph. what problem it should be?
why transformer rated in KVA not in KW ? we know that W= v*i
Befor synchronissation of Generator what test to be carried out.pl.specify with reason.
how does directional relay work incase of ac ?
what is the difference between ac and dc?which one is more efficient?and what r their advantages
what is the basis for selection of Protection CT class ? How anyone can decide whether to go for 5P10 or 5P20 ?