Best 208 to 400V 3-Phase Transformer Guide for Industrial Power
When working with industrial electrical systems, selecting the right 208 to 400V three-phase transformer is essential for stable power distribution and machine performance. This guide highlights five reputable models designed to convert between 400V three-phase inputs and 208V outputs (or vice versa), covering dry-type, isolation, and step-up/step-down configurations. Each option balances efficiency, durability, and practical features for CNCs, HVAC, and other industrial loads. Use the quick-reference table below to compare key specs at a glance.
| Product | Capacity | Primary/Secondary | Type | Key Benefit |
|---|---|---|---|---|
| 1 pcs New 10 kVA Isolation Transformer (IYFDDKI) | 10 kVA | 400V → 208V | Isolation Transformer | One-year warranty; sealed, reliable industrial unit |
| GoHz 4 kVA 3 Phase Isolation Transformer | 4 kVA | 400V → 208V | Dry-Type Copper | Low noise; durable copper winding |
| WTTTOOLS 10KW 3-Phase Converter | 10 kW | 220V → 380V | Power Converter | Electronic display; user-friendly |
| 15 kVA WYE 240Y/208Y Transformer (American Rotary) | 15 kVA | 240Y/208Y | Wye Auto Transformer | Flexible wiring for step-up/step-down |
| GoHz 8 kVA 3 Phase Isolation Transformer | 8 kVA | 400V → 208V | Dry-Type Copper | High efficiency; robust industrial use |
1 pcs New 10 kVA Isolation Transformer, 3 Phase, 400V to 208V

Model: 10 kVA; Type: Industrial Product; Condition: Brand New. Comes with a one-year warranty and services experience in industrial automation. Designed for converting 400V three-phase input to 208V output while providing isolation to protect downstream equipment. Suitable for CNC machines, controlled power applications, and equipment that requires a separate ground reference.
GoHz 4 kVA 3 Phase Isolation Transformer (400V to 208V)

Specifications: 3 phase; 4 kVA; Primary/Secondary Voltage: 120V–480V optional. Copper winding (default) with a dry-type, air-cooled design. This transformer provides reliable 3-phase isolation and stable voltage conversion for industrial power systems, reducing noise and improving protection for sensitive equipment.
10KW Transformer 3-Phase AC 220V to 380V Power Converter

Power: 10 kW; 3-phase AC 220V to 380V; Input 220V; Output 380V. Features an ergonomic electronic display for easy operation and monitoring, with dimensions around 470mm x 370mm x 360mm and a weight around 50kg. This unit is designed for stable, efficient voltage transformation in industrial settings, offering a compact footprint for service walls or equipment cabinets.
1 pcs New 10 kVA Isolation Transformer, 3 Phase, 400V to 208V (Second Listing)

Model: 10 kVA; Type: Industrial Product; Condition: Brand New; One-Year Warranty. This listing mirrors a reliable 3-phase isolation solution, confirming suitability for 400V to 208V conversions with protective isolation to safeguard downstream equipment in automation and manufacturing environments.
15 kVA WYE 240Y/208Y Volt Primary to 208Y/240Y Volt Secondary Transformer

Brand: American Rotary. 3-Phase Auto Transformer, Dry Type with copper coils. KVA: 15; Primary: 240V Y; Secondary: 208V or 240V depending on wiring. This transformer supports either step-up or step-down configurations, with 60Hz operation. Insulation class and temperature rise details indicate robust performance in demanding environments requiring flexible phase-to-phase voltage management.
3 Phase Buck and Boost Transformer (208V to 240V)

Brand: Larson Electronics. 3 Phase Buck and Boost Transformer with 208V primary and 240V secondary, offering 50/60Hz operation and multiple amperage options on the secondary (31.3, 46.9, or 62.5 Amps). Note: This product includes safety and policy restrictions on returns and emphasizes handling and disposal considerations for certain transformer configurations. Suitable for precise voltage balancing in mixed-load environments.
GoHz 8 kVA 3 Phase Isolation Transformer (400V to 208V)

Specifications & Industrial Use: 3 phase; 8 kVA; Primary/Secondary voltage 120V–480V optional. Copper winding (default) with a dry-type cooling system. Designed for stable 3-phase power delivery in CNC machines, HVAC systems, and manufacturing equipment. Features a high-efficiency core and Dyn11 wiring for reliable, long-term operation in demanding settings.
Buying Guide: Key Considerations For 208V/400V 3-Phase Transformers
- Voltage configuration and flexibility: Confirm whether you need 400V to 208V, 208V to 400V, or bidirectional capability. Some units support multiple primary/secondary voltages or auto-transforming options (Y-D configurations) for versatile deployments.
- Power rating and load type: Match the transformer’s kVA/kW rating to the connected equipment’s continuous load, surge requirements, and inrush behavior. Industrial automation often benefits from isolation transformers to protect sensitive drives and CNCs from line disturbances.
- Isolation vs. autotransformers: Isolation transformers provide galvanic isolation to reduce common-mode noise and improve safety, while autotransformers can be more compact and cost-effective for simple step-up/step-down tasks. Choose based on protection needs and load stability.
- Construction and cooling: Dry-type copper-wound transformers with air cooling offer durability and low maintenance in indoor environments. Liquid-filled or special insulation classes may be required for harsh or high-temperature settings.
- Efficiency and core design: Look for low-loss silicon steel cores and designs such as Dyn11 windings to maximize efficiency and reduce heat. This matters for continuous operation and energy costs in manufacturing lines.
- Physical footprint and mounting: Consider dimensions, weight, and mounting provisions to fit within electrical cabinets or service bays, especially for retrofit projects where space is limited.
- Warranty, service, and support: A robust warranty (e.g., one year or longer) and access to vendor support are important for industrial deployments where downtime is costly.
- Safety and compliance: Ensure the unit complies with applicable electrical standards and installation codes. Be mindful of safety notes, especially around returns, disposal, and factory-tested integrity for some transformer configurations.
- Installation considerations: Verify wiring practices, grounding requirements, and protective devices. Improper installation can affect performance and safety, so consult a qualified electrician or engineer for complex setups.