TMS bus bar trunking systems for rated current up to 11,000 A are used for electrical connections in power plants and substations, residential buildings, malls and shopping centers, other industrial applications and installed in the threephase AC circuits with frequency of 50 and 60 Hz with rated voltage up to 1 kV, and direct current circuits with rated voltage up to 1.5 kV and rated current up to 22,800 A.


  • Compact dimensions and any turning angles,
  • Small weight of elements,
  • High resistance to short-circuit currents,
  • High mechanical strength,
  • Low electrical losses,
  • Effective natural cooling,
  • Not requiring welding during bus duct installation,
  • Designed for operation at seismic loads of division 9 by EMS-98 scale at the elevations of up to 70 m,
  • Operation temperature of -45° to +60°С.


TMS bus duct consists of elements in various designs. Bus duct elements as per fig. 1, consists of parallel copper or aluminium insulated buses of rectangular section enclosed in the extruded aluminium enclosure featuring the cooling ribs. The absence of air gaps between buses favours the decrease of inductive resistance and improves heat dissipation of the system. The bus duct elements are manufactured in length not exceeding 4 m.
All the current conductors of the TMS bus duct are insulated with mylar film. The insulation possesses high chemical strength, is flame-retardant and has excellent electrical insulating properties and protects the conductor s against contact with moisture and air. The design of bus bar element joints allows to compensate construction tolerances.



Fig. 1. TMS bus duct trunking system elements

The elements are connected between each other according to fig.2 using a special set of connection and insulating plates tightened between each other with bolts

Fig. 2. Connection of TMS bus duct trunking system elements

For connection to different electrical equipment, terminal elements are used (see fig. 3) Terminal elements can be produced in different designs depending on the project requirements. The contact flags of the terminal elements have the openings for bolted connection of the terminal elements with the electrical equipment (for more detailed description of terminal elements see our catalogue's page 48-50). For connecting of the bus duct elements between each other, no openings in connection flags are required.


Fig. 3. TMS bus duct terminal elements

For compensation of the bus duct thermal dilatations, special expansion elements are applied (see fig. 4). The average installation interval is 40 m for copper bus ducts with and 35 m for aluminium bus ducts. A more precise interval is determined based on the route design for a particular project (for ordering information please use our questionnaire our special online form).

Fig. 4. TMS bus duct trunking system expansion element

Additional accessories include current and voltage transformers, branching devices for cable connection and protective enclosures for the bus duct connection with transformers and LV switchgears. The list of bus duct components is defined in the route assembly drawing developed for a particular project.
On customer request, bus duct conductors can be tin plated, nickel plated or silver plated.
RTC-ELECTRO-M provides services for installation supervision and installation of bus ducts at the customer’s site. RTC-ELECTRO-M experts regularly visit the sites after installation to inspect the bus duct systems (operational check of busducts and itsoperating conditions).


Bus ducts shall be mounted on loadbearing building structures (supports, floor, walls, ceiling) according to a engineering drawings using special steel or aluminium elements, seat angles, steel studs of various lengths and metalware supplied in set with the bus ducts.


The bus duct scope of supply includes:
  • Bus bar elements
  • A set of connecting plates for joints
  • Flexibles for connecting the equipment
  • Bus duct mounting system for fixing to building structures and metalware
  • Grounding system for supports, plates, protective enclosures etc.