Monitoring system

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Monitoring System

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  • Suitable for medium and large power transformers with OLTC
  • Simple cost effective design thanks to a decentralized modular architecture with central and local units
  • Safe, reliable and easy to use


Measurement and Monitoring

  • OLTC tap position
  • Oil temperature in the diverter switch
  • Air temperature in MDU cabinet
  • Ambient temperature
  • MDU motor surface temperature
  • Top oil temperature in the transformer tank
  • Bottom Oil temperature in the transformer tank
  • Oil level in OLTC
  • Transformer tank oil level
  • Power supply voltage of the OLTC motor
  • OLTC motor load current
  • Transformer load current at the HV side (through the OLTC contacts)
  • Busbar voltage at the HV side
  • OLTC technological limits monitoring – logical equations
  • BIs, BOs status monitoring


Calculation and statistics

  • Date/time when OLTC position has been changed
  • Number of OLTC switching operations for revision and inspection
  • OLTC torque monitoring
  • OLTC Working hours for revision and inspection
  • Winding hot-spot temperature
  • Transformer loss of life
  • OLTC Switching operation as a function of load current
  • OLTC Oil operational period


Visualization, control blocking and signalization

  • Visualization on the CU Graphical display
  • Ability to switch over between Local(from the MCS) and Remote (from SAS)
  • OLTC control
  • OLTC local control – via CU front panel
  • OLTC remote control – via BI or upper level of SAS/SCADA
  • Raise/lower control commands to MDU
  • Control of heating
  • Emergency stop of MDU
  • MDU control prohibition
  • OLTC blocking in case of availability of definite conditions - OLTC oil overtemperature, thermal overcurrent, GOOSE mеssages,
  • OLTC Warning signalization
  • Tap changer does not execute raise/lower output command
  • Tap changer in intermediate position
  • Tap changer reach the upper/lower limit position


Event recorder

  • Last stored event
  • The events stored during the last hour/24 hours/month
  • Fault filter



  • RS 485
  • 100BASE FX ST/LC optical Ethernet
  • 100BASE TX RJ45 electrical Ethernet
  • Communication with the PC based MMI program through a dedicated FO cable
  • SNTP/PTP time synchronization through the substation LAN and GPS