1. Experiences on location of earth faults and short circuits
in rural medium voltage networks
Hans Roman, Hans Hylla,
envia Mitteldeutsche Energie AG (enviaM) , Germany

2. Liberalization of electricity market
forces the reduction of costs for
networks
personell
leads to a decrease of
supply reliability
service quality

3. Strategy to compensate the negative influences
Faster location of faults in MV- networks,
because faults in MV- networks have the greatest influence on supply reliability and service level for most of customers.

4. Conditions in MV-networks of enviaM
normal open-operated rings
earth fault neutralization
mainly rural areas

5. Technical concept of short circuit location
fault information
network
control center
(reactance)
digital distance protection relay
topology
switching states
location (spot) of fault for display
network data
location
module
Network
data base

6. Visualization of fault location

7. Accuracy of fault location
2, 3 - phase-fault
mean deviation 236 / 229 m
maximum deviation 1900 / 1208 m
in 90% of cases faulty or neighbouring line section have been located !!
Double-earth- fault
mean deviation 965 m
maximum deviation 3769 m
Earth-fault
mean deviation m
maximum deviation 2383 m

8. Results :
Service staff is “in sight” of fault spot (short searching route, reduction of local switching operations)
Reduction of fault-location time on min
faster supply-restoration