Project -
Power System Protection - Differential Protection
Use the CTs provided to design a bus differential scheme for the substation below. Show each 87 relay as a circle and connect the appropriate CTs to the relay. Do not worry about the "unused" relays - they will be used for the line distance relays (designed by another engineer - not by you). Draw dashed arrows from each 87 relay to the breaker or breakers it trips.
Then wire the transformer differential relays in the diagram on the next page. Show the CT connections and label the currents in each power circuit and in each part of the CT secondary circuits. Be sure to "treat" any unused CTs appropriately.
Component Non-Radial System Protection
Start with the transmission line shown below.
First, connect one of the CTs (the correct one) to each of the distance relays. Then treat the unused CT the way unused CTs need to be handled. Then draw a dashed line with an arrow pointing from each of the distance relays to the breaker it trips.
Now, implement a permissive underreaching transfer trip (PUTT) protection scheme for the transmission line. Assume the line is 100 miles long. Specify zone settings in miles (instead of mhos), with positive numbers indicating a distance in front of the relay and negative numbers indicating a distance behind the relay. Complete the following table:
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Relay
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Settings
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Zone 1
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Zone 2
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Zone 3
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21-1
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21-2
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Finally, explain exactly what should happen when faults occur at locations A, B, and C by completing the table below. The "Which zone sees the fault" column should contain a number 1, 2, or 3, and the "Pilot Signal" and "Send breaker trip signal?" columns should contain a "yes" or "no".
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Fault Location
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21-1
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21-2
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Which zone sees the fault?
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Pilot Signal
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Send breaker trip signal?
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Which zone sees the fault?
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Pilot Signal
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Send breaker trip signal?
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Sent
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Received
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Sent
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Received
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A
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B
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C
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Textbook - INDUSTRIAL POWER DISTRIBUTION, SECOND EDITION by RALPH E. FEHR, III.
Attachment:- Project.rar