Interested to Buy Any Domain ? << Click Here >> for more details...
How do we measure earth fault current in Generator
Transformer(20/420kv),Station Transformer(20/11 kv) and Unit
Transformers(20/11kv) for our plant system, since these
don't have any Neutral earth Fault relay connected to their
Neutral Earth?
But for Unit Service transformers(11/.433 Kv) we have an
Earth Fault Relay connected to its neutral earth.Why is such so?
- 1 Answers
- 4825 Views
- NTPC, I also Faced
- E-Mail Answers
Answer Posted / a.p.nanjappa
I assume your generator rating is around 250-315MW.
GENERATOR TRANSFORMER IS YN-d1 or d11, 420kv power
transformer is provided with neutral bushing and solidly
grounded to earth system (U,V,W-N). YOU CAN MEASURE THE
EARTH CURRENT WITH CLAMP ON METER.
GENERATOR 20KV OUTPUT IS CONNECTED WITH lv side of
generator transformer by bus duct. there is a voltage
transformer, 2 winding y/y or three winding VT Y/y-
opendelts. This open delts voltage indicate the fault in
20kv system.
Genrator is provided with 90% and 100 % earth fault
ptortection.
Generator neutral is connected with generator neutral
grounding transformer. Generator neutral transformer
primary is connected to genrator neutral point and other N
is connected to earth. at this point ,You can measure earth
current by clamp on meter.
I assume you have a Generator circuit breaker.
Generator bus is 20kv. This sw.gr feed stn tranformer -
20/11kv system.This station 11kv feed the auxilary
transformers. Vector group of this stn transformer is D/d.
Also unit transformer is 20/11kv. this 11kv bus feed motor
and auxiliayr transformers. vector group is also D/d.
your medium voltage operates as isolated ground system
Unit service transformer is 11/.433 , thereforn vector
group is D/yn. your low voltage feeder need a nuetral.
therefore neutral is brought out. three phase 4 wire, and
230v-n .
please send the rating of transformer. we can explain you
more.
| Is This Answer Correct ? | 0 Yes | 1 No |
Post New Answer View All Answers
Explain the operation principle, advantages and disadvantages of the following converters: a) A 12 pulse converter b) A Switch-mode inverter c) A thyristor inverter
What is resonant peak?
What is the method to solve circuit using source transformation?
Metal covered multiconductor cables shall employ a marker tape located within the cable running for its complete length in lieu of cable surface marking. Is it true or false?
In electrical what is earth(ground)connection, wht is the importance of it, why it is recomended to maitain below 3VAC between Neutral and earthspecially in PLC used machines?
What are the two types of compensation?
What is the general power consumption rating of CPU CRT type and Flat type, Monitor,Printer, projector, Scanner?
Can we use BS 6651 and BS EN 62305 standards for computer room lightning ptotection in substation?
why industry prefer ht motor instead of lt motor.
how a flip flop can be used as a latch?
oil cooled transformer
what r PID controllers?why they r used?what is there purpose?plz Explain in detail
What is a diode?
A generating system will have a total capacity of 300 MW. Find the probable forced outage when the capacity is supplied by two 150 MW units. The operating probability of all units is P=0.98 and forced outage probability rate Q =0.02 .
High speed earth switch operation with diagram
