36kV Voltage Transformer (Outdoor type)

36kV Voltage Transformer

36kV Outdoor Voltage Transformer (VT), also known as an Outdoor Potential Transformer (PT), is an instrument transformer designed to accurately transform medium-voltage system voltages up to 36 kV into standardized low-voltage signals for metering, protection, monitoring, and automation systems. It is designed for outdoor installation in substations, switchyards, and distribution networks with exposure to environmental conditions.

Main Functions
Voltage Measurement: Steps down 36kV primary voltage to standard secondary voltages (typically 100 V or 110 V) for measurement equipment.
Protection: Provides accurate voltage inputs to protection relays for:
·Overvoltage protection
·Undervoltage protection
·Directional protection
·Synchronizing
·Frequency protection
·Power system monitoring
Electrical Isolation: Provides insulation and isolation between the high-voltage network and secondary control circuits.

Typical Applications
·Outdoor medium-voltage substations
·Utility switchyards
·33kV distribution networks
·Industrial substations
·Renewable energy collector systems
·Solar and wind power plants
·Mining and heavy industrial facilities
·Railway traction substations

Typical Technical Specifications
·Rated Voltage: 36 kV
·Highest System Voltage: 36 kV or 40.5 kV
·Rated Frequency: 50 Hz / 60 Hz
·Rated Primary Voltage: 33 kV, 35 kV, 36 kV, or 33/√3 kV
·Rated Secondary Voltage: 100 V, 110 V, 100/√3 V, 110/√3 V
·Accuracy Class: 0.1, 0.2, 0.5, 1.0, 3P, 6P
·Rated Burden: 10 VA, 15 VA, 30 VA, 50 VA, 100 VA
·Insulation Type: Porcelain, polymer, or epoxy resin
·Installation: Outdoor
·Cooling Method: Natural Air (AN)

Construction
A typical 36kV outdoor voltage transformer consists of:
·High-voltage primary winding
·Secondary measuring/protection windings
·Laminated silicon steel core
·Epoxy resin insulation system
·Porcelain or composite polymer insulator
·Weatherproof terminal enclosure
·High-voltage terminals
·Secondary terminal box
·Mounting structure
·Grounding terminal

The outdoor insulation system is designed to withstand:
·Rain and moisture
·Solar radiation and UV exposure
·Dust and industrial pollution
·Salt contamination in coastal areas
·Temperature variations
·Outdoor electrical stresses

Common Types
1. Inductive Voltage Transformer (IVT)
·Uses electromagnetic induction principle
·Suitable for metering and protection applications
·Common in 33/36kV substations
2. Phase-to-Ground Voltage Transformer
·Primary connected between phase and earth
·Commonly used in grounded distribution systems
3. Phase-to-Phase Voltage Transformer
·Primary connected between two phases
·Used for line voltage measurement
4. Dual Secondary Voltage Transformer
·Separate windings for:
·Metering accuracy
·Protection accuracy

Advantages
·High voltage measurement accuracy
·Excellent outdoor insulation performance
·Long service life
·Weather-resistant construction
·Low maintenance requirements
·High mechanical strength
·Suitable for harsh environments
·Reliable operation in utility and industrial networks

Applicable Standards
·IEC 61869-1 – Instrument Transformers – General Requirements
·IEC 61869-3 – Additional Requirements for Inductive Voltage Transformers
·IEEE C57.13 – IEEE Standard Requirements for Instrument Transformers

Typical Wiring
Primary Side
·Connected phase-to-phase or phase-to-earth on a 33–36kV medium-voltage system.
Secondary Side
Connected to:
·Energy meters
·Voltage meters
·Protection relays
·Power quality monitoring devices
·SCADA systems
·Remote terminal units (RTUs)
·Synchronizing equipment

Typical Applications by Industry
·Electric Utilities: Distribution substation voltage measurement
·Renewable Energy: Wind and solar collector systems
·Industrial Plants: Medium-voltage feeder and transformer protection
·Mining: Outdoor power distribution networks
·Oil & Gas: Process power substations
·Railway: Traction power measurement
·Infrastructure: Large commercial and public utility systems

Key Features
·Rated voltage up to 36 kV
·Suitable for systems with 40.5 kV maximum voltage
·Outdoor weather-resistant design
·Porcelain/polymer or epoxy insulation
·High dielectric strength
·Accurate metering and protection performance
·Multiple secondary winding configurations
·Low partial discharge characteristics
·Maintenance-free operation
·Designed according to IEC 61869 and IEEE C57.13 requirements