Rectifier Transformer

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Product Overview

Rectifier Transformer

High-voltage rated voltage	3kV - 110kV; higher voltage available upon custom request
Low-voltage rated voltage	0.4kV - 3.5kV valve-side voltage; customized for rectifier bridge applications
Rated capacity	500kVA - 50MVA; larger capacity available upon custom design
Power Supply Mode	AC grid input to rectifier stack for high-current DC power supply
Frequency	50Hz / 60Hz; dual-frequency design available
Cooling Type	ONAN / ONAF / OFAF for oil-immersed type; AN / AF for dry-type

Technical Specifications

Parameter	Value	Parameter	Value
High-voltage rated voltage	3kV – 110kV; higher voltage available upon custom request	Low-voltage rated voltage	0.4kV – 3.5kV valve-side voltage; customized for rectifier bridge applications
Rated capacity	500kVA – 50MVA; larger capacity available upon custom design	Power Supply Mode	AC grid input to rectifier stack for high-current DC power supply
Frequency	50Hz / 60Hz; dual-frequency design available	Cooling Type	ONAN / ONAF / OFAF for oil-immersed type; AN / AF for dry-type
Transformer Type	Rectifier transformer; oil-immersed or dry-type	Application Type	Industrial rectification and high-current DC power supply
Pulse Configuration	6-pulse / 12-pulse / 24-pulse / 36-pulse multi-phase shift	Short-circuit Impedance	6% – 20%; adjustable according to rectifier-system short-circuit-current-limiting requirements
No-load Current	<0.20% – 0.35% measured at rated voltage	Tap-changer	Off-circuit tap changer standard; on-load OLTC vacuum tap changer optional
Insulation Level	According to IEC 60076-3 and GB 1094 series based on voltage grade	Primary Grid-side Voltage	35kV ±2 x 2.5% in the reference application; custom tap range available
Valve-side Voltage	0.4kV – 3.5kV in the reference application; customized according to rectifier bridge requirements	Typical Model	25MVA / 35kV 12-pulse oil-immersed rectifier transformer
Configuration	3-phase, multi-secondary split-winding, phase-shift structure	Cooling Arrangement	OFAF forced oil forced air for oil-immersed type; AF forced air cooling for dry-type
Phase-shift Accuracy	Multi-pulse winding phase-angle deviation within ±0.5°	Harmonic Adaptability	Designed for non-sinusoidal current and harmonic additional loss conditions
Short-circuit Withstand	Designed and validated according to IEC 60076-5 and GB/T 18494; dynamic-force safety margin >1.3 x calculated value	Thermal Performance	Hot-spot temperature rise complies with IEC / GB limits; ≥20% thermal margin for short-time overload
Overload Capability	150% overload for 2 hours; 200% overload for 1 minute; application-specific	Life Expectancy	≥30 years under normal service conditions and rated rectifier working conditions
Partial Discharge Level	Oil-immersed: <100pC at 1.5 x rated voltage; dry-type: compliant with GB 1094.11 requirements	Noise Level	Typical ≤68dB(A) at 1m; low-noise design available down to 60dB(A)
Energy Efficiency	No-load and load losses independently verified; harmonic additional loss calculated according to IEC 61378-1	Harmonic Loss	Additional harmonic loss considered in electromagnetic and thermal design
Insulation and Fluid Option	Mineral oil or biodegradable ester fluid for oil-immersed type; F/H-class epoxy casting for dry-type	Insulation Type	Oil-immersed insulation or dry-type epoxy insulation
Core Material	High-permeability low-loss grain-oriented silicon steel, M-4 / M-5 grade or equivalent	Core Construction	Five-step stepped-lap construction with fully mitered joints
Core Clamping	Optimized clamping structure designed to restrain harmonic magnetic-flux vibration	Core Gap Control	Strict gap control to suppress DC-bias magnetic risk under rectifier operation
Winding Structure	Multi-winding / split-winding / phase-shift winding structure customized for 6-, 12-, 24- and 36-pulse systems	Conductor Transposition	Optimized transposition to reduce harmonic eddy-current and circulating-current losses
Winding Cooling Design	Oil-duct / air-duct layout optimized for non-uniform harmonic heating	Winding Mechanical Strength	Enhanced mechanical fastening to withstand repeated rectifier-side commutation short-circuit forces
Oil-immersed Manufacturing	Full vacuum drying and oil impregnation to control partial-discharge risk	Dry-type Manufacturing	Epoxy vacuum casting with high mechanical strength and resistance to moisture and pollution
Tank Stray-loss Suppression	Magnetic shunting and copper shielding composite design	Tank Integrity Test	Full vacuum and positive-pressure integrity testing for oil-immersed tank
Corrosion Protection	Anti-corrosion coating up to C5-M grade optional	Protective Enclosure	Optional IP protective enclosure for dry-type units
Temperature Monitoring	Built-in PT100 temperature sensor for real-time winding hot-spot monitoring	Special Function	Built-in winding temperature monitoring and harmonic-loss optimized design
Electromagnetic Design	3D finite-element modeling with harmonic eddy-current loss and multi-winding phase-shift simulation	Phase-shift Simulation	6-pulse / 12-pulse / 24-pulse / 36-pulse rectification system phase-shift angle simulation
Mechanical / Seismic Design	ANSYS structural analysis for winding dynamic force and mechanical strength	Seismic Standard	IEEE 693 seismic compliance available as an option
Short-circuit Simulation	Transient magnetic-field simulation for winding stress and rectifier commutation peak current	Harmonic Load Simulation	Stray-loss increase caused by harmonic flux evaluated during design
Insulation Coordination	Electric-field distribution simulation with DC-component superposition on valve-side winding insulation	Impulse Withstand	Lightning impulse and switching impulse withstand verification
Thermal-flow Simulation	CFD oil-flow / air-flow simulation with harmonic additional loss included	Hot-spot Control	Hot-spot temperature prediction with reserved overload temperature margin
Applicable Standard	IEC 61378-1 / IEC 61378-3; IEC 60076 series	North America Standard	IEEE C57.18.10 for semiconductor rectifier transformer performance and testing
China Standards	GB/T 18494.1-2014 / GB/T 18494.3-2023; GB 1094 series	Dry-type Standard	GB 1094.11 dry-type power transformer technical requirements
Industrial Standard	JB/T 8636 technical specification for power converter transformers	Environmental Compliance	RoHS / REACH; PCB-free dielectric fluid requirement according to EPA 40 CFR Part 761
Material Traceability	Critical components sourced from IEC / GB compliant supply chains with full material traceability	Quality Management	ISO 9001 / ISO 14001 / ISO 45001 certified manufacturing site
Factory Acceptance Test	Complete routine test, type test and special test	Special Test Items	Harmonic-related assessment and multi-winding phase-shift angle verification
Witness Testing	Client or third-party inspection available	Testing Organizations	KEMA, CESI, DNV and domestic authorized testing institutes available
Site Service	Installation guidance, commissioning supervision and post-commissioning performance verification	Service Condition	Performance verification can be conducted under actual rectifier load
Warranty	Comprehensive product warranty; extended service agreement optional	Spare Parts Supply	Minimum 25-year spare-parts supply support
Training	On-site or remote operator and maintenance training	Training Scope	Special operating-mode precautions for rectifier transformers
Customization Capability	Multi-pulse phase-shift, oil-immersed / dry-type, anti-corrosion, seismic, high-altitude and tropical-humid adaptations	Environmental Adaptability	Customized solutions for coastal, chemical-plant, high-altitude and special industrial environments
Typical Applications	Electrolytic aluminum, electrolytic copper, chlor-alkali, water-electrolysis hydrogen production	Metallurgical Applications	DC electric-arc furnace, rolling mill DC drive and mine hoist rectifier power supply
Rail Transit Applications	Subway traction rectifier power-supply systems and 12-pulse / 24-pulse rectifier units	Mining Applications	Mineral processing, electroplating and surface-treatment production lines
New-energy Applications	Centralized rectification for renewable-energy power stations	Energy-storage Application	Energy-storage converter front-end transformer
Project Experience	Rectifier transformers running in more than 30 countries	Project Scope	Electrolysis, hydrogen production, metallurgy, rail transit and turn-key industrial projects
Technical Support	Early-stage technical co-review with rectifier-system suppliers	Loss Calculation	Open-book loss calculation including harmonic additional loss
Technical Documentation	Full material documentation and complete test-report delivery	Carbon Footprint	LCA environmental life-cycle assessment data available on request

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.