Pursuant to Article 116 of the Energy Law

4.2.11.2.3. For protection of 110 kV overhead lines main and backup protection against faults 
is required. Required protective functions by protection devices should be 
a) for main protection devices: 
- distant protection with at least four time-under impedance stages;
- line differential protection (mandatory for 110 kV cables, and for overhead lines 
in the cases where the calculations show that the selectivity of protection 
devices cannot be achieved by distance protection); 
- automatic reclosure for breaker;
- broken conductors protection; 
- breaker failure protection; 
- switch on to fault protection; 
- multi stage three phase overcurrent protection; 
- multi stage earth fault overcurrent protection. 
- directional earth fault overcurrent protection; 
- overload protection; 
- detection of current reversal for protection of long distance transmission lines 
starting and ending in the same facility; 
- weak end infeed supply protection; 
- power swing blocking; 
- secondary circuits supervision (secondary current and secondary voltage 
circuits); 
- fault locator; 

---

35 
- communication logic between the protection devices at the ends of the 
transmission line (supports communication logic among distance protection 
devices, directional earth fault devices, communication for line differential 
protection);
- pole discordance protection; 
- trip circuit supervision for breaker (as external device for each tripping coil ); 
a) for backup protection devices: 
- multi stage three phase overcurrent protection; 
- multi stage earth fault overcurrent protection; 
- direction earth fault overcurrent protection; supervision of secondary current 
and secondary voltage circuits; 
In plants with auxiliary buss bar system 110 kV, switching of protection trips on bus coupler 
bay breaker should be provided.