Question { 13278 }

To measure insulation resistance of 11KV cable between core
& armour, what should be the test voltage & duration?

Answer

11 kv cable resistance we can measure

Test voltage is 10 kv to 20 kv (RMS Value)
And time is depend on which voltage you are selected.
if 10 kv then time should be 120 sec..........
And resistance valu also going opposit to voltage..
if suppose volt is 10 kv then megger valu 2gomh, And if volt
20 kv and valu 1gomh then cable is ok both are same valu....

Question { Siemens, 7379 }

What is purpose to use relay after digital output module?
Why normally we don't use relay for digital input module?

Answer

Because digital output module out put lode capacity is low
and use relay then we can incrise the output lode & lode
short ckt proctaction also....
in input module pts not need more current and voltage just
a on-off pules

Question { MPSEB, 6508 }

what is skin effect?

Answer

SKIN EFFECT: when we connected supply to a connector then
electron flow, then internal resistance generate in the
center of wire, so then current increase high that time
electrons going fastly then conductor center produce hi
resistance,then electrons going on surface of conductor (its
celled SKIN EFFECT)and conductor can damage

Question { Lanco, 21200 }

WHICH TYPE OF TRANSFORMER USED IN SWITCHYARD IN POWER PLANT?

Answer

STEP UP transformer because they transfer the supply through
long distance cables

Question { MacLellan, 7307 }

IN star -delta motors normally first operated in star
mode {absulated given (r-y-b) phases after one miute change
in delta mode in this case i am change phase sequience for
example R -PHASE TO CHANGE Y-PHASE ;Y-PHASE TO CHANGE
R-PHASE SO THIS TIME MOTOR WILL HAPPEN RUNNIG MODE
EIGHTER(OR) STOP MODE(TRIP MODE)

Answer

motor will stop and triped because motor will try to run in
opposite direction