Interested to Buy Any Domain ? << Click Here >> for more details...
Dear All,
In a 400V power system, ratio of three current transformers
installed incoming switchgear is 4000/1. Maximum three
phases short circuit current of this system is 48kA. One CT
is installed on neutral of upstream transformer (6/0.42kV,
solidly earthed) for 51G protection. Would you please inform
me about the correct CT ratio of this current transformer
(on neutral)??
Thanks a million
- 2 Answers
- 4716 Views
- I also Faced
- E-Mail Answers
Answer Posted / k.prakashchandra
The maximum earth fault current occurs when the phase comes
in contact with the earthed metal part.That will be about
230/0.5 i.e. about 500 A ,ignoring impedance of tr and
taking ER as 0.5 ohms.It is the usual practice to set EFR at
20% of OCR setting.For REFR the CT ratio should be the same
as that of phases.You can have a 2 core 4000:1 NCT and set
the 51G at 0.1 to 0.2 In ,using one of the two secondaries.
| Is This Answer Correct ? | 0 Yes | 0 No |
Post New Answer View All Answers
Define the overload capacity of the motor?
What is the effect of pi controller on the system performance?
How to determine the breaking capacity such as break down current and break down voltage for VCB and CT's.
Hello Guys !! i want to rrb section engineer electrical(signal) previous model papers? any body help me?
what are all types of cross section in AC cables?
what is mean by parallel operation of permanent magnet generators
what is difference between 5A and 100A CT constructional wise and operation?
How many sprinklers should be in one pipe line?
Explain how you intend to work under pressure to meet up with deadline target?
What is the meaning of Insulation H for transformers????
Transmission through a short line depends on
What is PQA???Applications........
How to reduce -234126219.6403 MVAr generation and by what?
why power not passes in plastic and rubber material
in shunt clippers why a resistor is used in sereis with the input
