current trasnsformer, Electrical Engineering

Assignment Help:
A 13.8 kV feed er circui t breaker has a 600:5 multira tio curr ent
transform er with charact eristics as show n in Figure 5.11. Th e max -
imum load on the feed er is 80 A pri mary. Phase time inve rse overcurrent
relays are connec ted to the CT secon daries. The relay burden
is 3.2 VA at the tap values selected, and the lead burden is 0.38 V.
a. If the 100:5 CT ratio is used, then a relay tap of 5 A is required in order
for the relay pickup to be 125% above the maximum load. With these,
determine the minimum primary current to just operate the relays.
b. For the select ion of part a what is the appro ximate maximu m
symme trical fault curr ent for whi ch the CTs will not saturate
(use the ANS I=IEEE knee point)?
c. If the 200:5 CT ratio is used so that the 2.5 A relay tap can be used,
determine the minimum primary current to just operate the relays.
13.8 kV
Bus Load bus
Equivalent
source
MVASC = 312.5
Z0 = 11.93 ?8 pu
On 100 MVA base
On 100 MVA base
X1 = X2 = j 0.42 pu
X0 = j 1.26 pu
X2 = 0.15 pu
X0 = 8
4 MVA load
@ 0.9 pf
@ 4 MVA
FIGURE P4.3
 2006 by Taylor & Francis Group, LLC.
d. Repeat part b for the selection of part c.
e. Which of thes e two CT and relay select ions would you recommend ?

Related Discussions:- current trasnsformer

Technical loss in electrical systems, Technical Loss in Electrical Systems ...

Technical Loss in Electrical Systems Technical loss is inherent in electrical systems, as all electrical devices have a few resistances and the flow of currents causes a power

Illustrate computer-controlled routing, Q. Illustrate Computer-controlled r...

Q. Illustrate Computer-controlled routing? Computers are employed in network with common channel signaling (CCS) features. In CCS, there is a separate computer-controlled signa

Calculate rotor copper losses, A 20 h.p. , 3 phase, 400 volt, 60 hertz, 4 p...

A 20 h.p. , 3 phase, 400 volt, 60 hertz, 4 pole induction motor delivers full load at 5% slip. The mechanical rotational losses are 400W. Calculate (a) The electromagnetic torqu

Find the impedance of the series combination, Q. An RL series circuit carri...

Q. An RL series circuit carries a current of 0.02 cos 5000t A. For R = 100  and L = 20 mH, find the impedance of the series combination and determine the voltage across the series

Working of r-2r ladder converter, R-2R LADDER CONVERTER Figure shows a ...

R-2R LADDER CONVERTER Figure shows a 4-bit R-2R ladderD/Aconverter,which contains a reference voltage source, a set of four switches, two resistors per bit, and an op amp. The

Explain demodulation of dsb, Q. Explain Demodulation of DSB? Demodulati...

Q. Explain Demodulation of DSB? Demodulation of DSB SC AM signals requires a synchronous demodulator, which is also known as coherent or synchronous detector. That is, the demo

Zener Diode, #question ...THE APPLICATION AND OPERATION OF ZENER DIODES

#question ...THE APPLICATION AND OPERATION OF ZENER DIODES

Discuss important properties and uses of ceramics, Discuss important proper...

Discuss important properties and uses of Ceramics. Ceramics - These are materials made by high temperature firing treatment of natural clay and specific inorganic matters. The

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd