The medium voltage switchgear is designed for the primary or secondary distribution of the medium voltage electrical energy in transformer stations, industrial substations, transforming posts.

The type CI/CE indoor/outdoor electrical switchgears are designed for rated voltage of 7,2; 12; 24 kV and rated current up to 4000 A.

Medium Voltage SwitchGears


  • Thermal-electrical plants, 
  • Hydro-electrical plants,
  • Nuclear-electrical plants,
  • Mining industry,
  • Naval industry,
  • Oil industry,
  • Chemical industry,
  • Subscriber transformer posts,
  • Airports,
  • Transformer stations and substations.





The indoor medium voltage switchgear is made of metallic elements assembled to form two cabinets with simple/double busbar system, aerial insulation.
In can be manufactured in withdrawable version (with truck) or fixed version (without truck). It can be equipped with vacuum quenching circuit breakers (SIEMENS, ALSTOM, SCHNEIDER, EATON, ABB, TAVRIDA) or SF6 (ABB, ALSTOM, SCHNEIDER) or air disconnectors (SIEMENS, ALSTOM, EATON, ABB) or SF6.


Construction versions:Medium Voltage Enclosure

  • Indoor or outdoor,  
  • Transformer stations or posts,
  • Transformer,
  • Coupling with circuit breaker,
  • Disconnecting,
  • Radial line,
  • Interconnecting line,
  • Motor,
  • Capacitor pile,
  • Busbar voltage measurement,
  • With surge arresters,
  • Internal services (TSI).


Medium Voltage SwitchGearscelula medie tensiune, distributie, distributie primara, celula electrica de interior








celula medie tensiune, distributie, distributie primara, celula electrica de interior, ceule medie tensiune dalkia



The switchgears are built so that all normal usage and maintenance operations including regular checks of the phases' succession, earthing connections, cable’s fault detection, and dielectric tests can be done safely.

Thanks to a high degree of automation the switchgears can be integrated in a remote control SCADA monitoring system.

The switchgear can be equipped with devices from our traditional suppliers SIEMENS, ALSTOM, SCHNEIDER, EATON, A

BB, TAVRIDA or devices from other producers according to our customers’ requirements.


celula cu masura de sosire, medie tensiune



Frontal view for the input measurement switchgear



  1. Truck actuation
  2. Digital protection relay
  3. Door locking mechanism for low voltage compartment
  4. Command buttons
  5. Inspection window for truck position
  6. Door locking mechanism for medium voltage compartment
  7. Mimic diagram
  8. Ampermeter voltage measurement
  9. Command key circuit breaker  


celula cu masura de sosire, medie tensiune, vedere laterala



 Lateral section for input measurement switchgear

  1. Cables voltage measurement transformer
  2. Disconnector PP (CLP)
  3. Withdrawable truck with circuit breaker
  4. Circuit breaker
  5. Secondary circuits compartment
  6. Current transformer support/frame
  7. Insulator support cross-bar
  8. Insulator support
  9. Insulator support cross-bar
  10. Current transformer
  11. Arc fault pressure relief
  12. Metal duct for secondary cable between cells
  13. Power broaches


Frontal view for output switchgear 


  1. Truck actuation
  2. Digital protection relay
  3. Door locking mechanism for low voltage compartment
  4. Push-buttons for opening and shutting switching devices
  5. Inspection window for truck position
  6. Door locking mechanism for medium voltage compartment
  7. Mimic diagram
  8. No voltage signaling lamp

celula medie tensiune, distributie, distributie primara, celula electrica de interior

Lateral section for the output switchgear


  1. Circuit-breaker withdrawable truck
  2. Disconnector PP (CLP)
  3. Insulator support cross-bar var. I
  4. Current transformer cross-bar
  5. Circuit-breaker
  6. Tray back panel
  7. Surge arresters cross-bar
  8. Insulator support
  9. Insulator support cross-bar var. II
  10. Equipment back panel
  11. Insulator support cross-bar var. III
  12. Hatches
  13. Secondary circuits trunk

Switchgear compartments:

  1. Busbar compartment
  2. Cable compartment
  3. Circuit-breaker compartment
  4. Secondary circuits compartment



A. The busbar compartment is located at the rear upper side of the switchgear.



  • The busbars are installed on support or passage insulators made of epoxy resins.
  • The busbars can be insulated or bare.
  • Pressure relief cover for arc fault protection is provided.
  • This compartment can be accessed through the rear-upper side or the switchgear. 
  • The compartment is fitted with single busbar system up to 4000 A.

B. The cable compartment located at the rear-lower side of the switchgear:



  • It’s provided with a pressure relief duct for the gases resulted from an arc fault, by way of a hatch installed on the upper side;
  • The connection to the outgoing terminals can be made through busbars, single-core cable or three-core cable;
  • It contains a neutral bar;
  • Equipped with anti-condensation resistance;
  • It can be equipped, based on demands, with current transformers, earthing disconnector, surge arresters, capacitive dividers with voltage detection system for cables, secondary bars, doughnut-type current transformer;
  • It can be accessed through the back or the front (through the voltage measurement truck compartment);
  • The earthing switchblades (CLP) close or open voluntarily after the extraction of the truck;


  • In case the CLP is closed the insertion of the truck is prevented;
  • The switchgears are equipped with earthing busbars (CLP);
  • The withdrawable truck is automatically earthed starting with the insertion in the “control” position through the help of connected sliding contacts at
  • The earthing disconnector (CLP) provided for the safety of the intervention operations inside the medium voltage compartment.

C. The circuit-breaker compartment located in the frontal-lower side of the switchgear:


  • It contains a truck (in the withdrawable version), on which the medium voltage circuit-breaker is installed;
  • The truck’s connection is done with a special key through an endless screw;
  • The truck’s connecting and disconnecting operations are performed in a pre-determined sequence;
  • When drawing-out the truck from the switchgear, the visible separation of the live circuit (busbars) from the outgoing bars (cables compartment) is achieved;
  • In the back side of the compartment there is a protective shutters system which, when the truck is extracted, isolates the live parts;
  • It is fitted with thermostatic heating;
  • The compartment is fitted with pressure relief covers for arc fault protection;
  • The position of the truck – circuit-breaker set is monitored by the arresters; these send in the secondary circuits compartment blocking electrical contacts, wrongful operation, normal maneuvers allowance, position signaling.
  • The truck has three distinct positions: 1. Working position (drawn-in); 2. Testing position; 3. Drawn-out position (out of the switchgear).




D. Secondary circuits compartment, located in the upper frontal side of the switchgear:


It contains low voltage devices for command, protection, measurement and signaling;

The mimic diagram is applied on the door and it is provided with electronic switch positions indicators;

The protection can be made through electromagnetic and digital relays;

The digital protection relay can be drawn-out of its location without disconnecting the circuits (plug-in system).

The digital protection relay, the measurement devices (ampermeters, voltmeters), signaling devices (lamps, command buttons), command keys that have to be visible or accessible in any moment are applied on the frontal side of the compartment.

The other secondary circuits devices (command and protection) are installed inside the compartment.

The electrical connections (the auxiliary wiring) between the low voltage circuits and the devices installed on the truck are made through a plug-in connector.


At the beneficiary’s request the protection relays can be programmed and parameterized by S.C. Automatica S.A. team of specialists.

Digital protections and parameterization 

The digital relays can be equipped with up to four types of serial interfaces:



  • Frontal interface for the local connection to a PC;
  • Service interface for remote control programming;
  • Interface for SCADA system;
  • Additional interface (communication with RTD modules).
  • In order to supplement the protection functions and to insure an easy faults’ analysis, the relays can have integrated functions for control, measurement and monitoring.
  • For special applications, along-side the main protection, emergency protection is also used.



protectii digitale, scada, parametrizareprotectii digitale, scada, parametrizareprotectii digitale, scada, parametrizare




The secondary circuits compartment can contain digital protection relays for:

  • Overhead lines,
  • Motors,
  • Transformers,
  • Capacitors,
  • Busbars,
  • Generators,
  • Cables.

The parameterization of the digital relays is done using dedicated software that allow the real-time data and signal transfer.

The communication with the digital replay is done electrically or optically through different application protocols (IEC 60870, MODBUS, PROFIBUS, IEC 61850, etc.).



Types of primary switchgears

Truck compartment

In the fixed version, the truck can be replaced by:

  • Disconnector (with or without earthing);
  • Switch disconnector or fuse disconnector;
  • Return busbars.

In the withdrawable version the truck is equipped with:

  • Vacuum or SF6 circuit-breaker;
  • Vacuum contactor (provided or not with fuse holder);
  • Voltage transformers (single or double pole) with protection power fuses incorporated on the primary side in fixed version installation or on the truck;
  • Isolation bars (return).



Cables compartment



It can contain:

  • Current transformers;
  • Earthing disconnector;
  • Surge arresters;
  • Capacitors;
  • Secondary bars (measuring switchgear);
  • Capacitive dividers with voltage detection system for the bars.

Busbar compartment

  • The busbars system is installed on epoxy resins insulators. The insulators are post or bushing type insulators.
  • Upon request, capacitive divider insulators for voltage detection can be installed.




The medium voltage switchgear underwent the following tests according to EN62271-200 and ST 015 AUTOMATICA:

  • Climate actions,
  • Heating,
  • Mechanical,
  • Dielectric,
  • Electrical,
  • Breaking current of the switchgear,
  • Protection degree,
  • Stability on transportation and preservation,
  • Resistance to arc fault,
  • Thermal and dynamic withstand,
  • Protective coating.