TAFT 112

Terminal of Automated Functions of Transformer 110 kV/VN (TAFT 112) is used for automated control of single transformer 110 kV/VN with arc suppression coil and with switching shunt resistor to its disconnection. Each automated function of transformer, coil and shunt resistor can be on/off individually. Each automated algorithm is calculated in 100 ms interval allowing fast enough response for arc suppression coil adjusting even in steep resonance network. TAFT 112 is used in stations with transformers block, arc suppression coils and busbars. See picture below.

Station setup


TAFT 112 has been certified according to the CSN EN 61326:99+A1:99+A305 and CSN EN 61000-6-2 ed.2:02 in Electrotechnical Testing Institute in Prague.

Each TAFT automation parameters are set through Windows application. TAFT is connected with computer using the USB interface. Interface of programming application is user friendly and some functions are fully automatic. During the operation all regulation events are recorded in log in non-volatile memory and can be accessed by the application localy or remotely i.e. through GSM modem.

 TAFT 112

Automated volage regulation of transformer

Regulator issues the command for tap changing (increasing or decreasing) if the displacement voltage on transformer output exceeds selected range and last longer than predefined interval allows. This delay can depend on the size of the displacement (the bigger displacment the shorter dealy) or constant. 

Voltage regulation functions:

• Adjusting the required value to load – required voltage depends on transformer current, compensation of voltage loss on line. Additionally to these to methods, there is an option used to decreasing the transformer load.
• Delay the output command for tap changer – inverted, constant, combined delay.
• Detection of regulation oscillation – successive oscillating tap changing commands in specific time interval.


Automation of arc suppression coil adjustment

The automation uses two basic modes:

• Fine-tuned coil ILnast = IC

• Uncompensated status, splitted on:

        • Under-compensated  ILnast=IC(1-ΔIC-)
        • Over-compensated   ILnast=IC(1+ΔIC+)


Uncompensation is defined either by current margin ±ΔIC from the fine-tuned status or by voltage deviation i.e. relative voltage drop of coil (UL) against voltage of fine-tune situation ULres, in both under-compensated (k-) and over-compensated (k+) situation.

Solutions in networks with big capacitive unbalance 

The big unbalance phase-voltages accure in such networks, thus increasing insulation load. Damping of the MV network through auxiliary resistor automatically disconnected during ground fault is used to solve this issue. This solution is standard function of adjustment coil automation.


Automation of resistor

Automation issues command to resistor connection if ground fault (UL>Urzs) duration exceeds predefined delay Tvzs. Another connection of resistor is blocked if the ground fault (ULrzs) lasts longer than specified blocking delay Tbzs. In case of short-time ground faults, each lasting less than Tvzs, the connection of resistor occures when overall elapsed time exceeds Tvzs. In such case the predefined blocking time is prolonged.

The automation includes heat module alerting if 50 per cent of heat capacity is reached. Would another resistor connection lasts for TZAPR and exceeded heat capacity, the resistor connection is blocked and alarmed.


Title Implementation year Detail
Řízení transformátorů VVN - FVE Ševětín 2010 -
Řízení transformátorů VVN - rozvodny ČEZ (Sušice, Nýrsko, Horažďovice, Přeštice) 2005 -