Electric Power Supply for the “Munjino brdo” Tunnel on Highway E-763 (Section Preljina – Požega)
Location: MB Tunnel, Highway E-763, Preljina – Požega section
Tunnel Length: Right tube – 2,740 m; Left tube – 2,755 m
Elektrovat successfully implemented the project for the electric power supply of the MB tunnel complex, ensuring the reliability and safety of all electromechanical systems in accordance with the highest standards.
Power Supply to Transformer Stations
The power supply to the tunnel’s electromechanical equipment is provided through four transformer stations (TS1, TS2, TS3, and TS4):
- TS1 and TS4: Installed outside the tunnel, in close proximity to the entrance and exit portals.
- TS2 and TS3: Located within the tunnel’s vehicular passages.
The main grid power supply is provided from the 35/10 kV Krstac transformer station, while the backup supply is provided from the 35/10 kV Milićevo selo transformer station.
Backup Power Supply
The backup power supply is provided by a 2,500 kVA diesel generator (DEA) and a 10/0.4 kV, 3,150 kVA transformer. The transformer steps up the voltage to 10 kV, which is then distributed via 3 x (N)A2XS(F)H 1×150 RM/25 mm² cable lines to the medium-voltage (MV) busbar section designated for powering the transformer stations from the diesel generator.
Cable Systems and Interlocks
The transformer stations are interconnected as follows:
- Grid supply: Via 3 x (N)A2XS(F)H 1×150 RM/25 mm² cables.
- Backup generator supply: Via separate cables of the same type.
The MV switchgear sections for grid and generator supply are separated by coupling fields with electrical interlocks preventing improper source connection.
Automation
The power supply system for the transformer stations is automated, enabling efficient management and control.
Transformer Specifications
- TS1 and TS4: Each equipped with two oil-immersed transformers rated at 630 kVA. In the event of a failure of one transformer, the other automatically takes over the load by activating the coupling field on the low-voltage (LV) switchboard.
- TS2 and TS3: Each equipped with two dry-type transformers rated at 800 kVA, with the same functionality for load takeover in the event of a failure.
UPS Systems and Critical Infrastructure
All transformer stations (TS1–TS4) are equipped with UPS devices ensuring continuous power supply for the following systems:
- Base lighting of MB tunnel
- Ventilation systems at TS2 and TS3
- Fire detection and intrusion detection panels
- Access control systems
- Emergency (evacuation) lighting
- LED markers
- Electric door drives for vehicular and pedestrian passages
- Lighting for vehicular and pedestrian passages
- OA-SOS automation cabinets
Specialized Power Supply Systems
The project also includes power supply for:
- MB tunnel ventilation system
- Overpressure ventilation in pedestrian and vehicular passages
- Adaptive lighting system
- Fire hydrant installations
Cables Used
- All systems except for the adaptive lighting are powered by fire-resistant cables of type FE180/E90, which maintain power supply for 90 minutes in case of fire.
- The adaptive lighting system uses halogen-free cables of type N2XH-J.
Total Installed Power
The total installed power of all consumers in the MB tunnel is 1,997.045 kW.
This project confirms Elektrovat’s capability to implement complex, high-performance electrical power systems, guaranteeing the safety and reliability of the infrastructure.
