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
- 4919 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
how braking & making capacity of circuit breaker is calculated?
What is the effect of atmospheric pressure & Temp; on efficiency of motor? Why NGR(Neutral Grounding Resistor) is used in 132/11 KV Transformer & how? What is the use of Auto T/F in Grid Station?
hi I have done 3 yrs diploma in electrical engg after 10+2. I have 16 years of work experience into design proposals sales and engg application development in LV/MV swithcgear and sub station automation field. I want to apply for immigration to new zealand but I am not sure whether I qualify or not since I dont have a degree. Can anyone advice? Thanks Riz
What is the Temperature to be set in Thermostat provided in Marshalling box of the Transformer / Motor.
What is the function of the generator exciter?
what is the principle of operation of tungstun bulb ??
explain working principle of earth leakage relay
How many types of protection relays are there based on the characteristic?
from where the self excitrd induction generator get the power?why is the voltage regulation is poor of seig?
define as synchronous generator
in non technical way how can u define POWER FACTOR??
What is a dominant pole?
What is the difference between circuit breaker and isolator
what are the tests comes under the type test, what tests comes under routine tests.
Are Refrigerators & Deep Freezers the Inductive load ? How to calculate the Power Factor & hence the Output Power for them ?
