Three-phase Dry-type Isolation Transformer

Product Introduction

Three phase dry type isolation transformers are designed for voltage conversion, electrical isolation and reliable power interfaces in industrial applications. The primary and secondary windings are electrically separated, so the equipment side operates on an independent circuit instead of being directly connected to the supply line. The dry type construction uses air as the cooling and insulating medium and adopts an oil-free design, which simplifies indoor installation close to the equipment it serves. Industrial isolation transformers of this type are commonly used where machinery requires a different voltage level from the local supply, or where an isolated power interface is needed for stable operation.

Typical applications include semiconductor equipment, CNC machine tools, medical equipment and industrial automation systems, as well as imported equipment that requires voltage compatibility with local supply standards. The transformer is also commonly installed in front of UPS units to provide an isolated input interface. For real installations, the Winzele project cases in the section below include semiconductor manufacturing equipment powered through three phase dry type isolation transformers.

Product Functions and Features

1. Voltage Conversion and Electrical Isolation

The transformer converts AC voltage levels between the primary and secondary sides while keeping the two windings electrically isolated. It is suitable for equipment that requires an independent power interface.

2. F/H Insulation and Dry Type Construction

The windings are vacuum impregnated as a whole and use insulation class F or H. The dry type construction is suitable for indoor industrial installation.

3. Customized Electrical Configuration

Input voltage, output voltage, frequency, connection group, winding configuration and grounding requirements can be engineered to match the application.

4. Shielding and Grounding Design

Optional electrostatic shielding and neutral grounding configurations are available. When properly designed and grounded, these configurations reduce common-mode disturbances.

Transformer Design & Working Principle

Understanding transformer electrical isolation, winding structure and mechanical design.

01 Electrical Isolation Principle

A three-phase isolation transformer uses separated primary and secondary windings to provide galvanic isolation between input and output circuits.

• Primary winding
• Secondary winding
• Magnetic core
• Electrical isolation

02 Transformer Winding and Insulation Structure

The transformer design includes primary winding, secondary winding, insulation layers and shielding components to improve electrical safety and reduce electrical interference.

• Primary winding
• Secondary winding
• Copper foil shielding
• Insulation materials
• Transformer core

Featured Project Cases

Selected installations using Winzele three-phase isolation transformers for voltage adaptation and equipment protection.

1500kW 380V to 200V Transformer System for Semiconductor Manufacturing Equipment

1500kW 380V to 200V Transformer System for Semiconductor Manufacturing Equipment

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100KVA 380V to 220V Three Phase Dry Type Isolation Transformer for Industrial Equipment Voltage Adaptation

100KVA 380V to 220V Three Phase Dry Type Isolation Transformer for Industrial Equipment Voltage Adaptation

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Technical Specifications

01 General Specifications

02 Electrical Characteristics

03 Loss & Performance

04 Mechanical & Installation

05 Standards & Environmental Requirements

Transformer Manufacturing Process & Testing Procedure

Transformer manufacturing involves multiple controlled processes, including material preparation, core assembly, winding, insulation treatment, final assembly and electrical testing.

Raw Material Preparation

Transformer production starts with controlled raw materials including silicon steel and copper winding conductors. Silicon steel sheets are precisely processed before core assembly.

Core Manufacturing

Transformer cores are assembled with controlled lamination stacking to achieve proper magnetic performance.

Winding Process

Different winding technologies including wire winding and copper foil winding are applied according to transformer design requirements.

Vacuum Pressure Impregnation (VPI) Process

Vacuum pressure impregnation is an important insulation treatment process for dry-type isolation transformers. The process removes air and moisture from winding insulation structures, improves insulation strength, mechanical stability and long-term operating reliability.

Transformer Assembly Process

The transformer assembly process integrates completed windings, magnetic cores, insulation components and mechanical structures into a complete dry-type isolation transformer. Each assembly step is controlled to ensure proper electrical performance, mechanical strength and long-term reliability.

Transformer Testing Procedure & Quality Control

Each transformer undergoes electrical testing to verify winding performance, insulation strength and thermal reliability before shipment.

Applications

Medical Equipment

PDU applications (CT / DR / MRI): Isolation transformers are commonly used in power distribution units (PDUs) for CT, DR and MRI systems to provide electrical separation and a reliable power interface for medical imaging equipment..
Electrical isolation purpose: The transformer helps separate the equipment circuit from the upstream power supply and supports stable operation of sensitive medical imaging systems. The final safety performance depends on the complete power distribution design, protective grounding, safety devices and the requirements of the equipment manufacturer.

CNC Machine Tools and Precision Equipment

Machining centers and CNC lathes: serves as an isolated power interface at the rectification front end of precision servo control equipment such as machining centers and CNC lathes.
Precision equipment: effectively suppresses interference signals on the power supply of the precision equipment.

Imported and Exported Equipment Voltage Adaptation

Imported equipment: converts the local 380V supply to the voltage standards of imported equipment — Japanese 200V/220V, US 480V and European 400V — to meet the domestic operation needs of the equipment.
Exported equipment: converts foreign 200V/220V, 480V and 400V supplies to 380V, providing voltage compatibility for exported equipment operating at the local supply standard.

Analytical Instruments and Industrial Bypass Isolation

Analytical instruments and laboratory equipment: Safety isolation provides electrical separation between the equipment and the supply system, helping improve operator protection when combined with proper grounding and protective devices..
Industrial bypass isolation cabinets: The isolation transformer can help reduce neutral-to-ground voltage issues and common-mode disturbances depending on the grounding system, shielding design and installation conditions.

Isolation Transformer with UPS Systems

Neutral Grounding and Zero-Sequence Voltage Control

△/Y connection creating a new neutral point: the three-phase dry-type isolation transformer uses a △/Y connection and generates a new neutral line (zero line), making the equipment independent of the neutral line of the power grid.
Avoiding abnormal operation caused by poor grid neutral conditions: because the equipment no longer depends on the neutral line of the power grid, abnormal operation caused by a poor grid neutral is avoided.
Reducing zero-ground voltage problems: The isolation transformer output can help reduce excessive neutral-to-ground voltage issues when the secondary neutral and grounding system are properly designed.

Disturbance Isolation and Harmonic Separation

Third harmonic isolation: When significant third harmonic components are present in the power system, a Delta/Wye connected isolation transformer can provide a path for triplen harmonic currents and help reduce their propagation to the upstream power system when properly designed.
Interference and common-mode disturbance reduction: the isolation transformer reduces interference signals between the power grid and the connected equipment.
Nonlinear load harmonic isolation: can help limit the propagation of certain harmonic currents from nonlinear loads, depending on transformer impedance, connection method and system design.
Control system sampling interference: nonlinear load current distortion can affect sampling accuracy; sampling at the input end of the Yo/△ isolation transformer provides a control signal that reflects the actual situation, so the voltage-stabilized power supply can be controlled normally.

UPS Bypass Isolation

UPS input isolation transformer (△/Yo): connect an isolation transformer to the input end of the UPS and its power supply.
Bypass safety isolation: After the isolation transformer is connected, the secondary winding is magnetically coupled with the primary winding while remaining electrically separated. This configuration provides an isolated power interface and improves system safety when combined with proper grounding and protection measures.
UPS output isolation transformer (Yo/△): Connect an isolation transformer to the output end of the UPS and the power supply:
The output isolation transformer can help reduce the influence of nonlinear load current distortion on the operation of the voltage-stabilized power supply and limit the propagation of certain disturbances to the upstream power system when properly designed and applied.
For unbalanced loads, a Yo/△ connection can help maintain stable operation of the voltage-stabilized power supply when the transformer capacity, connection method and system design are properly selected.

Mechanical Structure & Dimensions

Mechanical drawings provide installation reference dimensions for three-phase isolation transformer integration.

Three-Phase Dry-Type Isolation Transformer Model Selection

Available capacities, dimensions and enclosure options for three-phase dry-type isolation transformers.

Small Capacity Isolation Transformer Models (3–10 kVA)

Standard Industrial Isolation Transformer Models (15–250 kVA)

High Capacity Isolation Transformer Models (350–1250 kVA)

Standard models are available up to 1250 kVA. For higher capacity requirements, including projects above this range, please contact Winzele engineering team for customized transformer design and evaluation.