2. A CO-8 relay with a current tap setting of 5 amperes is used with the 100:5 CT. The CTsecondary current I' is the input to the relay operating coil. The CO-8 relay burden is shown in thefollowing table for various relay input currents.CO-8 relay input current I', ACO-8 relay burden ZB, QSecondary exciting volts-E'The following figure depicts the E' versus le of the CT.50010010600:5500:5||||450:5300:5400:5JUN50.5I100:5150:5Til200:5250:5t80.850:5I101.0131.3CTratio50:5100:5150:5200:5250:5300:5400:5450:5500:5600:515Secondaryresistance0.0610.0820.1040.1250.1460.1680.2111.50.2300.2420.296 Se0.10.0010.01150:5Tu200:5250:50.11Secondary exciting amps-le10100600:50.296Compute the primary current for (a) I' = 10 A and Zß = 1 №2, for (b) I' = 13 A and Zß = 1.3 №.(c) Plot I' versus I for five values of I' which are displayed in the table. Note that we alreadycalculated the primary currents for I' of 5, 8, and 15-A in Example solved in Session 12 (Oct. 2nd).When plotting I' versus I by connecting different points, do your best to clearly show the saturationregion of the curve.(d) For reliable relay operation, the fault-to-pickup current ratio with minimum fault current shouldbe greater than two. Determine the minimum fault current for application of this CT and relay with5-A tap setting. In other words, calculate the minimum fault current for which the relay will tripreliably.

The type CO relay consists of an over current unit (CO), an indicating contactor switch (ICS), and…

Compute the primary current for (a) I' = 10 A and ZB = 1 , for (b) I' = 13 A and Z³ = 1.3 №. (c) Plot I' versus I for five values of I' which are displayed in the table. Note that we already calculated the primary currents for I' of 5, 8, and 15-A in Example solved in Session 12 (Oct. 2nd). When plotting I' versus I by connecting different points, do your best to clearly show the saturation region of the curve. (d) For reliable relay operation, the fault-to-pickup current ratio with minimum fault current should be greater than two. Determine the minimum fault current for application of this CT and relay with 5-A tap setting. In other words, calculate the minimum fault current for which the relay will trip reliably.

Compute the primary current for (a) I' = 10 A and ZB = 1 , for (b) I' = 13 A and Z³ = 1.3 №. (c) Plot I' versus I for five values of I' which are displayed in the table. Note that we already calculated the primary currents for I' of 5, 8, and 15-A in Example solved in Session 12 (Oct. 2nd). When plotting I' versus I by connecting different points, do your best to clearly show the saturation region of the curve. (d) For reliable relay operation, the fault-to-pickup current ratio with minimum fault current should be greater than two. Determine the minimum fault current for application of this CT and relay with 5-A tap setting. In other words, calculate the minimum fault current for which the relay will trip reliably.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter12: Power System Controls

Section: Chapter Questions

Problem 12.4P

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