Generator Transformer

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Product Overview

Generator Transformer

High-voltage rated voltage	110kV / 220kV / 330kV / 500kV, customizable
Low-voltage rated voltage	10.5kV - 27kV, typical; custom voltages available
Rated capacity	30MVA - 800MVA; larger-capacity units customizable
Power Supply Mode	Generator-connected, generator terminal connection
Frequency	50Hz; 60Hz customizable for overseas projects
Cooling Type	ONAF / OFAF / ODAP forced-oil-circulation cooling

Technical Specifications

High-voltage rated voltage	110kV / 220kV / 330kV / 500kV, customizable	Low-voltage rated voltage	10.5kV – 27kV, typical; custom voltages available
Rated capacity	30MVA – 800MVA; larger-capacity units customizable	Power Supply Mode	Generator-connected, generator terminal connection
Frequency	50Hz; 60Hz customizable for overseas projects	Cooling Type	ONAF / OFAF / ODAP forced-oil-circulation cooling
Vector Group	YNd11, YNd and other custom configurations	Short-circuit Impedance	Custom-designed according to power-plant system-protection coordination requirements
No-load Current	<0.25% – 0.50%, measured at rated voltage	Tap-changer	Off-circuit tap-changer standard; OLTC optional
Insulation Level	Compliant with IEC 60076-3 and GB 1094 series	Ambient Conditions	-40°C to +40°C; high-altitude, coastal anti-corrosion and extreme-cold versions customizable
Transformer Type	Generator step-up transformer, oil-immersed power transformer	Typical Model	240MVA, 220kV / 15.75kV generator step-up transformer
Generator-side Voltage	15.75kV in typical application profile	Grid-side Voltage	220kV in typical application profile
Typical Cooling Arrangement	ONAF oil-natural-air-forced cooling	Anti-corrosion Grade	C3, C4, C5, CX-H
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 and structurally reinforced according to IEC 60076-5; winding dynamic-force safety margin >1.3 x calculated values	Thermal Performance	Temperature rise compliant with IEC / GB standards; thermal margin reserved for cyclic variable generator loads
Over-excitation Capability	Enhanced design for generator-unit over-excitation transient events	Design Life	≥30 years under normal power-plant operating conditions
Insulation & Fluid	Mineral insulating oil; high-fire-point biodegradable ester fluid optional	Dielectric Fluid	Mineral oil or high-fire-point biodegradable ester fluid
Tank Construction	Conservator-equipped or fully-sealed tank construction	Tank Tightness Test	Positive-pressure and negative-pressure tightness testing
Tank Weld Inspection	All tank welds inspected and tested	Core Material	High-permeability low-loss grain-oriented silicon steel
Core Joint Technology	Five-step stepped-lap fully-mitered-joint construction	Core Clamping	Reinforced core-clamping structure
Conductor	Advanced conductor transposition scheme	Winding Structure	Optimized winding structure with enhanced mechanical clamping
Winding Insulation	Upgraded main-and-minor insulation system for transient over-voltage conditions	Drying Process	Multi-stage vacuum drying
Impregnation Process	Hot-oil impregnation	Partial-discharge Control	Strict partial-discharge control during manufacturing
Bushing Assembly	High-reliability bushing assembly	Pressure Relief	Pressure-relief valve
Oil-level Monitoring	Oil-level indicator	Gas Protection	Gas-relay protection
Winding Temperature Monitoring	PT100 winding temperature sensors	DGA Monitoring	DGA dissolved-gas-in-oil online monitoring system optional
Electromagnetic Design	3D finite-element modelling with stray-loss and additional-loss analysis	Mechanical Design	ANSYS structural simulation and dynamic-force verification
Short-circuit Simulation	Transient magnetic-field simulation for winding stress, deformation and clamping-system performance	Insulation Coordination	Electric-field-distribution simulation with lightning-impulse and switching-impulse verification
Thermal-flow Simulation	CFD oil-flow simulation and cyclic hot-spot-temperature prediction	Seismic Design	Seismic and mechanical-strength verification; IEEE 693 optional
Over-excitation Design	Magnetic-density control and over-excitation capability verification	Generator-side Adaptability	Designed for frequent load fluctuation, unit start-stop inrush current and over-excitation conditions
Generator-side Short-circuit Adaptability	Enhanced winding mechanical strength for generator-source short-circuit conditions	Harmonic Adaptability	Designed to reduce additional losses caused by harmonic currents and leakage flux
Applicable Standard	IEC 60076-1 / 2 / 3 / 5	Application Guide	IEC 60076-8
Chinese Standard	GB 1094 series	Technical Standard	GB/T 6451
North American Standard	IEEE C57.12.00 / C57.12.90	Seismic Standard	IEEE 693 optional for high-seismic-zone power plants
Environmental Compliance	RoHS / REACH	Dielectric Fluid Compliance	EPA 40 CFR Part 761; PCB-free dielectric fluid
Oil System	Conservator-equipped or fully-sealed configuration	Cooling Configuration	ONAF / OFAF / ODAP for large-capacity GSU units
Tap-changer Configuration	Off-circuit tap-changer or OLTC according to power-plant requirements	Special Options	DGA online monitoring system and high-fire-point dielectric fluid
Coastal Adaptation	C5-M heavy-duty anti-corrosion coating optional	High-altitude Adaptation	Custom design available
Extreme-cold Adaptation	Custom versions available for extreme-cold power-plant sites	High-temperature Adaptation	Thermal margin optimized for cyclic variable generator-load conditions
Factory Acceptance Testing	Insulation test, partial-discharge test, temperature-rise test, noise-level test, ratio test and impedance measurement	Witness Testing	Client or third-party witnessed testing available
Short-circuit Test	Special destructive type test performed by authorized third-party institutions	Test Documentation	Full type-test reports, simulation reports, component certificates and material traceability documents
Installation Support	Installation guidance and commissioning supervision	Commissioning Support	Post-commissioning performance verification under actual generator-loaded 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	Coal-fired power plants and gas combined-cycle power plants	Hydro Application	Hydro-power and pumped-storage power stations
Renewable Energy Application	Large-scale centralized new-energy power-generation bases	EPC Application	Overseas thermal, hydro and combined-cycle power-plant EPC projects

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.