Voltage Ratio = Primary Turns / Secondary Turns
For example:
Trasformatore step-down
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
Elevata sicurezza antincendio
Nessun rischio di perdite d'olio
Requisiti di manutenzione ridotti
Adatto all'installazione in ambienti interni
Rispettoso dell'ambiente
Common Applications
Three phase dry type transformers are commonly installed in:
Edifici commerciali
Ospedali
Aeroporti
Centri dati
Impianti industriali
Shopping centers
Typical ratings:
| Capacità | Applicazione |
|---|---|
| 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.
Vantaggi
- High power capacity
- Excellent cooling performance
- Lunga durata
- Suitable for outdoor applications
Applicazioni
Tra le applicazioni più comuni figurano:
- Sottostazioni di utilità
- Fattorie solari
- Fattorie eoliche
- Impianti industriali
- 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
Applicazioni:
- Zone residenziali
- Commercial facilities
- Fabbriche industriali
4. Three Phase Power Transformer
A trasformatore di potenza trifase is used in high voltage transmission and substations.
Applicazioni:
- Power plants
- Grid substations
- Progetti di energia rinnovabile
Gamma di potenza:
From several MVA to hundreds of MVA.

Three Phase Transformer Applications
Sistemi di alimentazione industriali
Factories rely on three phase transformers to supply power for:
- Motori
- Compressors
- Pumps
- CNC machines
- Production lines
- Automation equipment
Industrial transformers usually require:
- High efficiency
- Funzionamento continuo
- Strong overload capability
Edifici commerciali
Three phase transformers are commonly used in:
- Edifici adibiti a uffici
- Hotels
- Centri commerciali
- Aeroporti
A common North American system:
480V → 208Y/120V
This voltage system is widely used for:
- Lighting
- Impianti di climatizzazione
- Building equipment
Progetti di energia rinnovabile
Solar and wind projects require transformers to increase voltage before grid connection.
Esempio:
Solar inverter:
800V
↓
Transformer:
0.8kV / 35kV
↓
Grid connection
Three Phase Transformer Voltage Ratings
Different countries use different voltage standards.
Nord America
Common voltages:
| Tensione primaria | Tensione secondaria |
|---|---|
| 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:
- CEI
- 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
Esempio:
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:
Trasformatore a secco
Outdoor:
Trasformatore a bagno d'olio
5. Transformer Standards
I progetti internazionali potrebbero richiedere:
- UL certification
- CSA certification
- DOE efficiency
- Norme IEC
- Standard IEEE

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
Perché scegliere il trasformatore EverNew?
EverNew Transformer is a professional transformer manufacturer in China with more than 30 years of experience.
Le nostre capacità produttive comprendono:
Product Range
- Trasformatore di distribuzione
- Trasformatore a secco
- Trasformatore a bagno d'olio
- Trasformatore montato su pad
- Trasformatore di potenza
Technical Capability
Capacità:
15 kVA – 500 MVA
Tensione:
6kV – 500kV
Certificazioni
- UL
- CSA
- CE
- GOST
- ISO
We supply transformers for:
- STATI UNITI D'AMERICA
- Canada
- Sud America
- Europa
- Asia
- Africa
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?
Il prezzo dipende da:
- Transformer capacity
- Voltage rating
- Copper or aluminum winding
- Metodo di raffreddamento
- Standard richiesti
- 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
Conclusione
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
- Metodo di raffreddamento
- Installation environment
- Standard internazionali
Come professionista 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.


