245kV Inductive Voltage Transformer (IVT), also known as a Potential Transformer (PT) or Voltage Transformer (VT), is an extra-high-voltage (EHV) instrument transformer designed to accurately reduce system voltages up to 245 kV to standardized low-voltage values for metering, protection, monitoring, and control. It provides electrical isolation between the high-voltage transmission network and secondary equipment, ensuring safe and reliable operation while maintaining high measurement accuracy.
Working Principle
A 245kV inductive voltage transformer operates on the principle of electromagnetic induction. The primary winding is connected across the high-voltage transmission line or busbar, and the alternating magnetic flux generated in the laminated steel core induces a proportional voltage in the secondary winding according to the transformer turns ratio.
Main Components
·High-voltage primary winding
·Metering and protection secondary windings
·Laminated silicon steel magnetic core
·Oil-paper insulation system
·Porcelain or composite silicone rubber insulator housing
·Oil expansion bellows or conservator
·Primary high-voltage terminal
·Secondary terminal box
·Earthing terminal
·Pressure relief device
·Galvanized steel mounting base
Typical Technical Specifications
·Highest System Voltage: 245 kV
·Rated Primary Voltage: 220 kV or 230 kV
·Rated Secondary Voltage: 100 V, 110 V, 100/√3 V, 110/√3 V
·Frequency: 50 Hz / 60 Hz
·Accuracy Class: 0.1, 0.2, 0.5, 3P, 6P
·Rated Burden: 25–500 VA
·Rated Voltage Factor: 1.2 continuous, 1.5 for 30 s (typical)
·Insulation Level: 460/1050 kV (Typical)
·Cooling: Oil Natural Air Natural (ONAN)
·Installation: Outdoor
Applications
A 245kV inductive voltage transformer is widely used in:
·Extra-high-voltage transmission substations
·Utility transmission switchyards
·Grid interconnection substations
·Thermal, hydroelectric, and nuclear power plants
·Wind farm collector substations
·Large-scale solar power plants
·Industrial EHV substations
·HVDC converter stations (AC side)
Advantages
·High measurement accuracy
·Excellent dielectric insulation performance
·Reliable long-term operation
·High mechanical and short-circuit strength
·Low maintenance requirements
·Suitable for harsh outdoor environments
·Supports both revenue metering and protection functions
Typical Secondary Outputs
Standard secondary voltages include:
·100 V
·110 V
·100/√3 V
·110/√3 V
These outputs are commonly connected to:
·Revenue energy meters
·Protective relays
·Synchronizing relays
·SCADA and energy management systems
·Automatic voltage regulators (AVR)
·Power quality analyzers
·Digital fault recorders
·Disturbance monitoring equipment
Common Standards
A 245kV inductive voltage transformer is typically designed and tested in accordance with:
·IEC 61869-3 – Instrument Transformers – Additional requirements for Inductive Voltage Transformers
·IEC 61869-1 – General requirements
·IEEE C57.13 – IEEE Standard Requirements for Instrument Transformers
·IEC 60044-2 (legacy standard, superseded by IEC 61869)
Typical Applications in a 245kV Substation
·Busbar voltage measurement
·Transmission line voltage monitoring
·Revenue and settlement metering
·Distance, differential, and overvoltage protection
·Synchronizing and auto-reclosing systems
·SCADA and remote terminal unit (RTU) monitoring
·Automatic voltage regulation (AVR)
·Fault recording and disturbance analysis
·Power quality monitoring
Key Features
·Designed for 245 kV extra-high-voltage systems
·High dielectric strength with oil-paper insulation
·Available with single or multiple secondary windings
·Excellent thermal and mechanical stability
·Long service life with minimal maintenance
·Weather-resistant porcelain or composite housing
·Fully compliant with international IEC and IEEE standards
A 245kV Inductive Voltage Transformer is an essential instrument transformer for extra-high-voltage transmission networks. It delivers a precise, isolated, and scaled representation of system voltage to metering, protection, and automation equipment, ensuring dependable operation, accurate billing, and enhanced power system safety in modern transmission substations.