why neutral and earth should not be connected on 3 phase
440v/50c/s supply at consumer side. where as on
25kv/ac/50c/s railway traction substation neutral and earth
will be connected and track at substation. and track will
act as neutral and earth. Reasons for this is needed
Answers were Sorted based on User's Feedback
Answer / nmr
IF ALL CONSUMERS EARTH ARE CONNECTED TO NEUTRAL AT EACH
CONSUMER POINT, ALL THE EARTH ELECTRODES RESISTANCES ARE
BECOMES PARALLEL ALONG WITH TRANSFORMER SECONDARY NEUTRAL-
EARTH ELECTRODES. HENCE 1/R= 1/R1+1/R2+1/R3+1/R4 ETC.,
THERE EFFECTIVE RESISTANCE IS BECOMES VERY VERY LOW. IF A
30 KVA TRANSFORMER IS THERE. THE CURRENT IL/IPHSE =
30,000/440*1.732 = 40.0 AMPS (WITH UNITY PF) THIS CCURRENT
WILL PASS THROUGH EARTHS ELECTRODES(BECAUSE ALL EARTH
RESISTANCES ARE PARALLEL AND NET RESISTANCE WILL BECOME
LESSER THAN THAT OF NEUTRAL)SO STEP POTNTIAL WILL RAISE
CAUSES ELECTRIC SHOCK TO THE PEOPLE WALKING AT NEAR
TFP/PANNEL BOARDS. IN TRACTION SUBSTATION A EARTH MAT WILL
BE PROVIDED IN THE YARD TO REDUCE THE STEP VOLTAGE NOT TO
GET SHOCK BY THE PEOPLE. OK
NMR/email; firstname.lastname@example.org electrical engineer
|Is This Answer Correct ?||3 Yes||0 No|
Answer / k.prakashchandra
Consumers earth is for connecting to metal bodies to prevent
shock . The neutral is already earthed at the TC and another
earth means extra expenditure.During earth fault ,there will
be temporary rise in voltage resulting in burning out of
potential coils of the energy meter.And if earth is
connected to neutral wire of supply after the RCCB, it will
trip as a portion of neutral current will be bypassed.
|Is This Answer Correct ?||1 Yes||1 No|
Answer / jicks patel
voltage level at consumer side is generally kept low (230v
or 440v),any shocking moment should face fuse sensually.so
no more cost required like earthing.
|Is This Answer Correct ?||1 Yes||2 No|
Answer / shivababa_1812
|Is This Answer Correct ?||1 Yes||12 No|
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