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DEE-24116 Distribution Automation Examination, September 11, 2017
Pekka Verho (Calculator allowed)

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4)

Explain shortly the following terms dealing with distribution automation:
a) DMS
b) PLC
c) 1EC61850
d) AMR
e) SCADA

Explain typical feeder protection solution, which can be applied in radially operated
and neutral isolated medium voltage network. Which protection functions are used,
what are the principles in definition of relay settings?

Describe briefly, how the development of distribution automation has changed the
following operationa! processes:

a) Location of short circuit faults in medium voltage network

b) Handling of low voltage network faults

c) Customer service during fault situations

Calculate the reliability indices SAIFI, SAIDI and MAIFI in the following simple
feeder: Calculate the indices also in case when the disconnector is remote controlled
(switching time is 5 minutes) and in the case when the disconnector is replaced by a
circuit breaker. What else method could be used to evaluate reliability?

Failure rate = 5 faults / 100 km, a
Temporary failure rate = 40 faults / 100 km, a
Switching time of disconnector 1 h, repair time 3 h
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Area 1 Area 2

 

Line length 20 km Line length 40 km

Number of customers 400 Number of customers 200