current trasnsformer, Electrical Engineering

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 ?
Posted Date: 10/7/2012 3:31:06 PM | Location : United States







Related Discussions:- current trasnsformer, Assignment Help, Ask Question on current trasnsformer, Get Answer, Expert's Help, current trasnsformer Discussions

Write discussion on current trasnsformer
Your posts are moderated
Related Questions

3) A sine wave oscillator, in effect, converts

Define Gray Code - bcd to decimal conversion? The Gray Code is a variation on binary code in which only 1 bit is changed from the preceding number. The bit so as to changes is

LT Metering or Low Tension Metering The subsequent types of meters are generally used for LT consumers: Whole Current Meters i)   Single phase meters ii)   3-phase

how do you get better at school

Explain the meaning of Ring Counters? A ring counter is fundamentally a circulating shift register in which the output of the most significant stage is fed back to the input of


Classification of Feedback Control Systems by Control Action A more common means of describing industrial and process controllers is by the way in which the error signal E(s) i

Q. Explain the working of LEDs OPTOELECTRONIC devices either produce light or use light in their operation. The first of these, the light-emitting diode (LED), was developed to

Give the operating modes of 8259a? (a) Automatic Rotation (b) End of Interrupt (EOI) (c) Fully Nested Mode  (d) Automatic EOI Mode (e) Specific Rotation (f) Edge