Traction Transformer

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Product Overview

Traction Transformer

High-voltage rated voltage	110kV / 220kV, other voltages customizable
Low-voltage rated voltage	27.5kV / 2 x 27.5kV
Rated capacity	10MVA - 63MVA, larger capacities customizable
Power Supply Mode	Traction power supply system, 27.5kV / 2 x 27.5kV
Frequency	50Hz, 60Hz customizable for overseas projects
Cooling Type	ONAN / ONAF / OFAF forced-oil-forced-air cooling

Technical Specifications

High-voltage rated voltage	110kV / 220kV, other voltages customizable	Low-voltage rated voltage	27.5kV / 2 x 27.5kV
Rated capacity	10MVA – 63MVA, larger capacities customizable	Power Supply Mode	Traction power supply system, 27.5kV / 2 x 27.5kV
Frequency	50Hz, 60Hz customizable for overseas projects	Cooling Type	ONAN / ONAF / OFAF forced-oil-forced-air cooling
Transformer Type	Oil-immersed traction transformer	Connection Schemes	Single-phase / V-v / Scott-T / AT auto-transformer
Vector Group	V-v / Scott-T / Single-phase / AT auto-transformer and other custom configurations	Short-circuit Impedance	Custom-set according to traction power system tuning requirements
No-load Current	<0.3% – 0.6%, measured at rated voltage	Tap-changer	Off-circuit tap-changer, on-load tap-changer optional
Insulation Level	Compliant with IEC 62695 and GB/T 25120 standards	Ambient Conditions	-40°C to +40°C, high-altitude, coastal anti-corrosion and extreme-cold versions customizable
Traction-side Voltage	27.5kV / 2 x 27.5kV	Grid-side High-voltage Class	110kV / 220kV typical, other voltages customizable
Typical Model	25MVA, 110kV / 2 x 27.5kV V-v connected oil-immersed traction transformer	Typical Configuration	V-v connection, ONAF cooling, gas-relay protection, winding temperature measurement, oil-level and pressure-relief protection
Primary Grid-side Voltage	110kV	Secondary Traction-side Voltage	2 x 27.5kV
Cooling Arrangement	ONAF oil-natural-air-forced cooling	Anti-corrosion Grade	C3, C4, C5, CX-H
Special Monitoring	DGA dissolved-gas-in-oil online monitoring module optional	Partial-discharge Level	<100pC at 1.5 x rated voltage
Noise Level	Typical <=68dB(A) at 1m, low-noise version available	Short-circuit Withstand	Designed according to IEC 60076-5, winding dynamic-force safety margin >1.3 x calculated values
Thermal Performance	Temperature rise compliant with IEC / GB railway traction standards, short-time overload thermal margin reserved	Load Adaptability	Frequent impact loads, regenerative braking feedback, harmonic conditions and frequent short-time overload
Design Life	>=30 years under normal traction substation operating conditions	Insulation & Fluid	Mineral insulating oil, high-fire-point biodegradable ester fluid optional
Core Material	High-permeability low-loss grain-oriented silicon steel, M-4 / M-5 grade or equivalent	Core Joint Technology	Five-step stepped-lap fully-mitered-joint construction
Core Clamping	Reinforced core-clamping structure for vibration and harmonic magnetic flux control	Magnetic Density Control	Strict magnetic-density control for traction-system DC-bias risk
Winding Structure	V-v / Scott-T / single-phase / AT auto-transformer structures available	Winding Mechanical Strength	Reinforced mechanical fastening for frequent traction-side short-circuit shocks
Conductor Transposition	Optimized conductor transposition to reduce harmonic eddy-current and circulating-current losses	Drying Process	Complete vacuum drying process
Impregnation Process	Vacuum oil impregnation	Partial-discharge Control	Strict partial-discharge-level control during manufacturing
Tank Construction	Fully-sealed or conservator-equipped construction	Tank Weld Inspection	Weld inspection with positive-pressure and negative-pressure tightness testing
Pressure Relief	Pressure-relief valve	Oil-level Monitoring	Oil-level indicator
Gas Protection	Gas relay	Winding Temperature Monitoring	PT100 winding temperature sensors
DGA Monitoring	Dissolved-gas-in-oil online monitoring system optional	Cooling Options	ONAN / ONAF / OFAF, OFAF preferred for high-power AT traction transformers
Electromagnetic Design	3D finite-element modelling, harmonic additional-loss calculation and electric-field verification	Load Profile Simulation	Loss simulation under different traction-load profiles
Mechanical Simulation	ANSYS structural simulation for winding electromagnetic forces and transportation loads	Seismic Design	IEEE 693 compliance optional for high-seismic-intensity traction substations
Short-circuit Simulation	Transient magnetic-field simulation for winding stress and deformation	Tank Stray-loss Analysis	Assessment of tank stray heating caused by harmonic magnetic flux
Insulation Coordination	Electric-field-distribution simulation, lightning-impulse and switching-impulse verification	Over-voltage Adaptation	Insulation margin optimized for frequent over-voltage conditions in traction systems
Thermal-flow Simulation	CFD oil-flow simulation and dynamic hot-spot temperature-rise prediction	Overload Thermal Margin	Thermal-margin calculation for short-time overload under traction-load curves
Operating Modes	Steady-state load, impact load and regenerative-braking feedback operating modes	Harmonic Adaptability	Designed to reduce additional losses and overheating caused by harmonic currents
Traction-side Short-circuit Adaptability	Reinforced winding structure for sudden traction-side short-circuit impact	Regenerative Braking Adaptability	Designed for regenerative-braking energy feedback conditions
IEC Standard	IEC 62695	Power Transformer Standards	IEC 60076-1 / 2 / 3 / 5
Chinese Traction Standard	GB/T 25120-2023	Chinese Transformer Standard	GB 1094 series
Railway Environmental Standard	TB/T 3571	North American Standard	IEEE C57.12.00, optional for export projects
Seismic Standard	IEEE 693, optional for high-seismic-intensity traction substations	Environmental Compliance	RoHS / REACH
Dielectric Fluid Compliance	EPA 40 CFR Part 761, PCB-free dielectric fluid	Dielectric Fluid Options	Mineral oil / high-fire-point biodegradable ester fluid
High-altitude Adaptation	Custom design available for high-altitude traction substations	Extreme-cold Adaptation	Custom design available for extreme-cold environments
Coastal Adaptation	C5-M heavy-duty anti-corrosion coating available for coastal salt-spray environments	Chemical-industrial Adaptation	Heavy-duty anti-corrosion protection available for chemical-industrial substations
Factory Acceptance Testing	Insulation test, partial-discharge test, temperature-rise test, noise test, ratio test and impedance measurement	Type Testing	Routine tests and type tests available
Short-circuit Test	Specialized third-party destructive type test, not performed in-house	Witness Testing	Client or third-party witnessed testing available
Test Documentation	Traction-load simulation reports, type-test reports, component certificates and material traceability documents	Carbon Footprint Documentation	LCA life-cycle-assessment documentation available for ESG reporting
Installation Support	Installation guidance and commissioning supervision	Commissioning Support	Post-commissioning performance verification under actual traction-load conditions
Warranty	Comprehensive product warranty, extended service agreement optional	Spare Parts Supply	Minimum 25-year spare-parts supply for key components
Training	On-site or remote operation and maintenance training	Quality Management	ISO 9001 / ISO 14001 / ISO 45001 certified manufacturing facilities
Typical Application	High-speed rail traction substations	Conventional Railway Application	Existing and new electrified railway traction substations
Urban Rail Application	Suburban rail, intercity rail and urban rail transit traction substations	AT Traction Application	AT auto-transformer traction systems for long-distance railway sections
Overseas EPC Application	Overseas electrified railway EPC projects	Railway System Compatibility	27.5kV / 2 x 27.5kV traction power supply systems
Quality Assurance	IEC / GB compliant supply chain with full material traceability	Technical Cooperation	Early-stage cooperation with traction power system design institutes

Protection & Accessories

Reliable Protection System and Flexible Accessories

Our Pad Mounted Transformers are equipped with reliable protection devices and accessories to ensure safe operation in underground distribution systems and utility applications.

Standard Accessories

HV/LV Bushings

Reliable medium voltage connection with excellent insulation performance.

Oil Level Gauge

Easy monitoring of insulating oil level for maintenance.

Pressure Relief Device

Improves transformer safety under abnormal conditions.

Drain Valve

Convenient oil draining and maintenance operation.

Tap Changer

Off-circuit Tap Changer (OCTC), ±2 × 2.5%

Nameplate

Provides complete transformer rating and technical information.

Optional Accessories

Temperature Indicator

Monitors transformer operating temperature for reliability.

Remote Monitoring System

Supports smart grid and remote transformer condition monitoring.

Surge Arrester

Protects pad mounted transformers against lightning and voltage surges.

Key Features of Transformers

Key Benefits:

Enhanced operator and public safety
No exposed high-voltage components
Suitable for underground distribution systems
Reliable operation in outdoor environments

Key Benefits:

Weather-resistant construction
Corrosion-resistant surface treatment
Secure locking compartment
Suitable for public and utility applications

Key Benefits:

Space-saving installation
Low-profile outdoor design
Easy inspection and maintenance
Ideal alternative to overhead distribution systems

Available Configurations:

Loop feed distribution system
Radial feed distribution system
Dead-front cable connection
Customized MV and LV connection arrangements

Available protection and accessories include:

High voltage fuses
Current limiting fuses
Load break switches
Surge arresters
Pressure relief devices
Temperature monitoring systems

These protection solutions help ensure safe operation under different load and fault conditions.

Key Benefits:

Low no-load losses
High energy efficiency
Excellent thermal performance
Long operational lifetime

Manufacturing & Testing

Strict Quality Control and Transformer Testing

Every Pad Mounted Transformer undergoes comprehensive testing to ensure high reliability, safety and long service life according to international standards.

Routine Tests

Transformer Ratio Test

Ensures accurate voltage transformation performance.

Winding Resistance Test

Verifies winding quality and electrical performance.

No-Load Loss Test

Checks transformer core efficiency and energy performance.

No-Load Loss Test

Confirms transformer rated efficiency under operating conditions.

Impedance Test

Ensures correct electrical characteristics and system compatibility.

Dielectric Test

Verifies insulation strength and operational safety.

Special Tests

Temperature Rise Test

Validates thermal performance and cooling capability.

Lightning Impulse Test

Tests insulation capability against surge conditions.

Partial Discharge Test

Ensures insulation quality and long-term reliability.

Everything We Do Is At A High Standard

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WHAT WE DO

CTSS Transformer Applications and Solutions

We design and manufacture liquid-filled power transformers and distribution transformers for a wide range of applications, including solar power, data centers, industrial facilities, and utility systems. With experienced engineers and advanced manufacturing capabilities, we provide customized transformer solutions and complex winding designs to meet the specific electrical and performance requirements of each project.