Eta-com UK - Cast-Resin Insulated Busway Systems

Low / Medium Voltage - Cast Resin Busbar Type - Features & Ratings

betobar-r

The betobar-r busbars have been developed as a modern, all-purpose means of efficient and safe transmission of electrical energy. It has been in manufacture for more than thirty-five years. The betobar-r system complies with all the requirements for current distribution at low and medium voltage.

The busbar consists of copper or aluminium conductors, embedded in an enclosure of a difficult inflammable, selfextinguishing and homogeneous insulation mix based on epoxy cast-resin with mineral fillers ensuring high mechanical strength and chemical withstand. Standard types are available for current ratings up to 6300 A and voltage ratings up to 24kV. Systems for higher current ratings or DC applications are possible. The busbar line consists of a number of prefabricated elements. The electrical joining of the conductors is achieved by means of double fish plates and high tensile steel bolts.

The junctions and the element ends are overcast with the same insulation mix as used for the elements. In this way an integral insulating enclosure to IP68.7 is guaranteed over the full length of the busbar run. Straight junctions and also elbow junctions are available each facilitating installation adjustments of 10-20 mm per standard junction.

betobar-r busbars are suitable for application in large buildings, industrial plants, power stations, sub-stations and large switchrooms, such as :

• factory distribution of low and medium voltage power
• rising mains with tee-offs to sub-distribution boards in highrise buildings
• transformer switchboard connections
• main switchboard feeders to distribution panels
• generator and large motor feeders
• long lines with low voltage drop
• 400 Hz distribution systems

The betobar-r busway system is available in a wide range of standard element shapes, forms, lengths all of which are fabricated to suit the typical project requirements.

• straight elements
• elbow elements, flat-flat and on edge
• thermal expansion compensation elements
• Z (double elbow) and T elements
• flanged terminal elements
• tap-off facilities and phase-transfer elements
• tailor-made terminal elements for transformer or generator & switchboard connection betobar-r

IEC standard – Temperature limits

In accordance with the I.E.C. standard the betobar-r nominal current ratings are all based on a daily average ambient temperature of 35°C a maximum to of 40°C. The conductor temperature rise dt of 60°C at a power frequency of 50 Hz limits the surface temperature at max. 95°C. If the local conditions are different from the design values, the maximum permissible load current has to be corrected by the factors.

Weights

The weights of the betobar-r for the LV-types are the average weight of a 3-phase + neutral type, including the junction and the casting mix per system length of 2 m. For MV-types the supporting insulators and any possible screening is included. If partitions for a full phase segregation are needed, they have to be added as extra weight.

System impedance

The busduct resistance values (A.C. resistance) Ra20 are based on a copper temperature of 20°C and a power frequency of 50Hz in accordance with the I.E.C standard. Ra85 is the more realistic resistance at a copper operating temperature of 85°C. The reactance values (X) of the LB-types are based on the standard phase sequence RSTTSR for a 3-phase system.

For other configurations, frequencies or extreme temperatures, please consult Eta-com B or your betobar-r agent.

All impedances have been calculated with physical values :

- Specific resistance at 20°C for copper : r = 0.0175 W.mm²/m

- Temperature coefficient for copper : a = 0.00392 1/°C

Maximum voltage

PH1- and PH1.2-types are designed for a maximum voltage of 17.5 kV. In areas open to the public and if the type has no screening, the voltage level is limited to 12 kV.