How to choose a 380V to 220V transformer

This is a very practical question 👍. To choose a 380V → 220V transformer (also known as a voltage converter or step-down transformer), you need to consider the following factors:

🛠️ 1. Identify the correct input and output voltage

• Input voltage: 380V three-phase or 380V single-phase (must be accurately identified).

  • In industrial settings, it’s usually 380V three-phase.

  • Some places use 380V by taking only one phase (between two phase lines).

• Output voltage: 220V single-phase or 220V three-phase (depending on the equipment you use).

  • For household appliances or small machines → usually need 220V single-phase.

  • For industrial equipment → may require 220V three-phase.

⚡ 2. Calculate the required capacity

• Calculate the total power of the devices you plan to use (W or VA).

• Choose a transformer with a capacity at least 20–30% higher than the actual demand.

  • Example: If devices consume 5 kW → choose a transformer around 6–7 kVA.

🔌 3. Select the appropriate transformer type

• Isolation transformer: Safer, reduces interference, isolates the grid → commonly used for sensitive equipment.

• Autotransformer: Cheaper, more compact, high efficiency but does not isolate the grid → less safe in case of faults.

🏗️ 4. Check standards and safety

• Choose a unit with overload and overvoltage protection, fuse, or circuit breaker.

• Prefer reputable brands that meet ISO, IEC, or CE standards if available.

• Ensure clear labeling: voltage, current, capacity, wiring diagram.

📦 5. Installation environment

• If installed in factories with humidity, dust, or vibration → choose a model with dustproof and moisture-proof casing (IP54 or higher).

• If installed outdoors → use a protective cabinet or specialized outdoor transformer.

💰 6. Brand and service

• Choose a reputable supplier with warranty and technical support.

• Trusted Vietnamese brands: Lioa, Robot, Đông Anh, Thibidi…

• Imported options: Schneider, ABB, Siemens, Mitsubishi, Omron…

🔎 Summary:

• Identify phase (single-phase or three-phase).

• Calculate device power.

• Select type (isolation or autotransformer).

• Prefer reputable brands with safety protection.

• Choose a transformer with 20–30% spare capacity.

Would you like me to suggest a few specific models (with reference prices, brands, places to buy) based on your needs? (For example: how many devices, how many kW?)