Voltage Ratio = Primary Turns / Secondary Turns
For example:
Step Down Transformer
Input:
13.8kV
Output:
480V
The transformer reduces medium voltage electricity to a usable low voltage level for industrial equipment.
Three Phase Transformer Types
Three phase transformers can be classified according to construction, insulation method, cooling system, and application.
1. Three Phase Dry Type Transformer
A three phase dry type transformer uses air as the cooling and insulation medium instead of transformer oil.
Dry type transformers are widely used where fire safety and environmental protection are important.
Advantages of Dry Type Transformer
Høj brandsikkerhed
Ingen risiko for olielækage
Lavt vedligeholdelsesbehov
Egnet til indendørs montering
Miljøvenlig
Common Applications
Three phase dry type transformers are commonly installed in:
Kommercielle bygninger
Hospitaler
Lufthavne
Datacentre
Industrielle faciliteter
Shopping centers
Typical ratings:
| Kapacitet | Anvendelse |
|---|---|
| 15 kVA | Small commercial loads |
| 45 kVA | Industrial equipment |
| 75 kVA | Building power supply |
| 500 kVA | Factory distribution |
| 2500 kVA | Large industrial systems |
EverNew manufactures dry type transformers with:
- Copper winding
- Aluminum winding
- Cast resin insulation
- UL/CSA compliant designs

2. Three Phase Oil Immersed Transformer
A three phase oil immersed transformer uses insulating oil for cooling and electrical insulation.
Oil immersed transformers are commonly used for outdoor power distribution because they provide excellent heat dissipation and high capacity capability.
Fordele
- High power capacity
- Excellent cooling performance
- Lang levetid
- Suitable for outdoor applications
Anvendelser
Common applications include:
- Forsyningsstationer
- Solcelleparker
- Vindmølleparker
- Industrianlæg
- Power transmission systems
Typical voltage ratings:
- 6kV
- 10kV
- 11kV
- 13.8kV
- 35kV
- 110kV
- 220kV
3. Three Phase Distribution Transformer
A three phase distribution transformer is designed to reduce medium voltage electricity to low voltage for end users.
Typical conversion:
11kV → 400V
13.8kV → 480V
35kV → 400V
Applikationer:
- Boligområder
- Commercial facilities
- Industrielle fabrikker
4. Three Phase Power Transformer
A trefaset strømtransformator is used in high voltage transmission and substations.
Applikationer:
- Power plants
- Grid substations
- Projekter inden for vedvarende energi
Effektområde:
From several MVA to hundreds of MVA.

Three Phase Transformer Applications
Industrielle kraftsystemer
Factories rely on three phase transformers to supply power for:
- Motorer
- Compressors
- Pumps
- CNC machines
- Production lines
- Automation equipment
Industrial transformers usually require:
- High efficiency
- Kontinuerlig drift
- Strong overload capability
Kommercielle bygninger
Three phase transformers are commonly used in:
- Kontorbygninger
- Hotels
- Shoppingcentre
- Lufthavne
A common North American system:
480V → 208Y/120V
This voltage system is widely used for:
- Lighting
- VVS-anlæg
- Building equipment
Projekter med vedvarende energi
Solar and wind projects require transformers to increase voltage before grid connection.
Et eksempel:
Solar inverter:
800V
↓
Transformer:
0.8kV / 35kV
↓
Grid connection
Three Phase Transformer Voltage Ratings
Different countries use different voltage standards.
Nordamerika
Common voltages:
| Primær spænding | Sekundær spænding |
|---|---|
| 480V | 208Y/120V |
| 600V | 347/600V |
| 13.8kV | 480V |
| 34.5kV | 480V |
International Markets
Common systems:
| Primary | Secondary |
|---|---|
| 10kV | 400V |
| 11kV | 415V |
| 20kV | 400V |
| 35kV | 400V |
EverNew transformers can be designed according to:
- IEC
- ANSI
- IEEE
- UL
- CSA
- CE
- GOST

How To Select A Three Phase Transformer?
Choosing the correct transformer requires evaluating several technical parameters.
1. Transformer Capacity (kVA)
The transformer capacity must match the electrical load.
Common sizes:
- 15 kVA
- 30 kVA
- 45 kVA
- 75 kVA
- 112,5 kVA
- 150 kVA
- 500 kVA
- 1000 kVA
- 2500 kVA
2. Input and Output Voltage
Et eksempel:
Commercial building:
Input:
480V Three Phase
Output:
208Y/120V Three Phase
3. Frequency
Common frequencies:
- 50Hz
- 60Hz
4. Transformer Cooling Method
Choose according to installation environment:
Indoor:
Transformer af tør type
Outdoor:
Olieinddækkede transformatorer
5. Transformer Standards
Internationale projekter kan kræve:
- UL certification
- CSA certification
- DOE efficiency
- IEC-standarder
- IEEE-standarder

Three Phase Transformer Manufacturer
Selecting a reliable three phase transformer manufacturer is important for ensuring safety, efficiency, and long service life.
A professional transformer supplier should provide:
✔ Engineering design support
✔ Factory testing
✔ International certifications
✔ Customized voltage solutions
✔ Export experience
Why Choose EverNew Transformer?
EverNew Transformer is a professional transformer manufacturer in China with more than 30 years of experience.
Vores produktionskapacitet omfatter:
Product Range
- Distributionstransformator
- Transformer af tør type
- Olieinddækkede transformatorer
- Pad-monteret transformator
- Strømtransformator
Technical Capability
Kapacitet:
15 kVA – 500 MVA
Spænding:
6kV – 500kV
Certificeringer
- UL
- CSA
- CE
- GOST
- ISO
We supply transformers for:
- USA
- Canada
- Sydamerika
- Europa
- Asien
- Afrika
Three Phase Transformer FAQ
What is the difference between single phase and three phase transformer?
A single phase transformer is normally used for smaller loads, while a three phase transformer is designed for industrial and commercial power systems requiring higher capacity.
What is the most common three phase transformer voltage?
Common systems include:
- 480V
- 208Y/120V
- 400V
- 415V
- 13.8kV
- 35kV
How much does a three phase transformer cost?
Prisen afhænger af:
- Transformer capacity
- Voltage rating
- Copper or aluminum winding
- Afkølingsmetode
- Gældende standarder
- Order quantity
How do I choose a three phase transformer size?
You should consider:
- Total connected load
- Starting current
- Future expansion
- Voltage requirements
- Efficiency requirements
Konklusion
A three phase transformer is an essential component in modern electrical power systems, providing efficient voltage conversion for industrial, commercial, and renewable energy applications.
Choosing the correct transformer requires careful evaluation of:
- Power capacity
- Voltage levels
- Afkølingsmetode
- Installation environment
- Internationale standarder
Som professionel three phase transformer manufacturer, EverNew Transformer provides reliable transformer solutions worldwide with customized designs from low voltage distribution systems to high voltage power networks.
Contact EverNew Transformer today for your three phase transformer project.


