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FABT 6-35 kV
Fast automatic
bus transfer

Short circuit in external and internal power supply systems remain major cause of power supply failures. The number of short circuits rises every year because of high level of equipment deterioration.

If this is the case, power consumers have to handle the problems of power supply by themselves. It is especially about enterprises with complex manufacturing process or highly automatized enterprises. Such as companies of oil and gas production and processing, metallurgical, water supply, and many others. 

Short voltage sags act negatively on the high- and low-voltage motor drives, control elements of electrical power systems and automatic devices. 

Even if the duration of a sag is several hundred milliseconds, voltage sags cause considerable economic loss because of high failure rate during a year.  To prevent damage of electrical equipment and provide continuity of manufacturing process we improved conventional ABT system. FABT_10_APS is technically advanced fast automatic bus transfer system.

Scheme of a two-section switchgear with two input and one section switch. 

Operating procedure of FABT APS starts with acting of fault detectors interacting together according with the specific algorithm. These algorithms identify emergency conditions which require fast switch to next (spare) incoming feeder (К1, К2, К5 short circuits) or do not require FABT operations (К3, К4 short circuits).  It takes minimum time to prevent damages; time matching with RPEA devices of adjacent elements of the grid is not required. The time of fault detectors' response to emergency conditions does not exceed 10-15 ms. Starting elements of FABT_10_APS use unique operating algorithm, providing very short response time (about 5-20 ms, depending on the type of fault). Full cycle of load transfer takes 27-40 ms in case of using fast power vacuum ВВ/TEL switches.


To adjust FABT settings we use a reliable, time proved software. It provides high accuracy of voltage, current, active and reactive power measurement for all units of power grid. FABT settings calculations are based on parameters of existing power supply scheme of the plant, external power grid structure and operational electrical load.

FABT APS is designed for substations with the following switchgear:

  • two busbar sections with two main incoming feeders and busbar coupler;

  • one busbar section with one main incoming and one standby feeder.


FABT_10_APS system works with fast power switches such as Sion M by Siemens, NM1T by ABB, Shell FT2 by TAVRIDA Electric.

When using FABT with switches of other types it is essential to ensure tolerability of supply interruption time in order to maintain work process.

FABT APS implementation provides significant positive results:


  • Secure and uninterruptible (continuous) power supply of the customer in case of faults in supply network;


  • Higher level of residual voltage (6(10)/0,4 kV), minimized quantity of accidents of automatic cutoffs by magnetic starters and contactors, control equipment failures are prevented; 

  • Self-starting of motors after supply restoration;

  • Prevention of expensive downtime;

  • Reduced self-starting currents resulting in  extension of equipment lifetime, such as motors, pumps and transformers because there is no need to restart the machines;


  • Reduced risks of environmental accidents;


  • Advanced manufacturing automation, increased productivity.

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