HUARUI 
Isolation Transformer
An isolation transformer is a power device that transmits electrical energy through electromagnetic induction while simultaneously establishing electrical isolation between the input winding (primary side) and the output winding (secondary side). Its core function is to cut off the direct current path between the power grid and the load, causing the secondary circuit to float to ground, thereby effectively preventing electric shock accidents and suppressing various interference signals in the power grid.
The turns ratio of an isolation transformer can be 1:1 (equal voltage isolation) or other ratios (simultaneous step-up and step-down isolation). Products are divided into two main types: dry-type isolation transformers and oil-immersed isolation transformers. They are widely used in medical equipment, precision instruments, industrial control systems, new energy systems, and various applications with high requirements for safety and power quality.
There is no direct electrical connection between the primary and secondary windings, and there is no potential difference between any wire on the secondary side and the ground. Contact with a single wire will not result in electric shock, effectively ensuring the safety of operators and equipment.
Effectively isolates unstable factors such as harmonics, surge voltages, and spike pulses in the power grid, filtering common-mode and differential-mode interference signals to provide a clean power supply for precision loads. An optional electrostatic shielding layer further reduces inter-winding capacitive coupling, resulting in superior anti-interference performance.
Converts the input voltage to an output voltage suitable for the load according to actual needs, simultaneously achieving the dual functions of electrical isolation and voltage transformation.
When using specific connection groups (such as Dyn11), it can effectively remove third and odd-order harmonic interference, purifying the power grid.
Using an isolation transformer can generate a new neutral line (N line), avoiding equipment malfunctions caused by a faulty original neutral line in the power grid.
The product is available in two types: dry-type (epoxy resin casting/open type) and oil-immersed (mineral oil cooling), suitable for indoor/high-fire-resistance applications and outdoor/high-power applications, respectively.
| Item | Parameter Range / Description |
| Rated Capacity | 5 kVA ~ 2,000 kVA |
| Input Voltage | Single-phase 220V / Three-phase 380V / 440V / 420V / 400V, etc. |
| Output Voltage | Single-phase 110V / 100V / 36V / 24V / Three-phase 220V / 200V / 120V / 110V, etc. |
| Number of Phases | Single-phase / Three-phase |
| Rated Frequency | 50 Hz / 60 Hz |
| Isolation Voltage (Withstand Voltage) | 3 kV / 5 kV / 10 kV (standard); customizable up to 1,000 kV for special products |
| Insulation Class | Class F (155℃) / Class H (180℃) for dry-type; Class A (105℃) for oil-immersed type |
| Protection Class | IP20 ~ IP54 (dry-type); IP54 and above (oil-immersed outdoor type) |
| Efficiency | ≥95% ~ 98.5% (depending on capacity and design) |
| Voltage Regulation | ≤2% (under full load conditions) |
| Impedance Voltage | <7% (standard) |
| No-Load Current | <5% (standard) |
| Insulation Resistance | ≥50 MΩ ~ 500 MΩ |
| Temperature Rise Limit | ≤100 K (dry-type) / ≤65 K (oil-immersed, top oil temperature) |
| Ambient Temperature Range | -5℃ ~ +40℃ (standard); expandable to -40℃ ~ +45℃ (customized) |
| Standards | IEC 60076 / GB 1094 / UL 5085 / CSA / CE / GB 20052 energy efficiency standards, etc. |
Dry-type isolation transformer
1. Core: Utilizes high-permeability grain-oriented silicon steel sheets laminated together or a ferrite toroidal core, effectively reducing losses.
2. High and Low Voltage Windings: Winded with high-quality copper or aluminum wire using a de-fiber winding method. Insulation is achieved through vacuum impregnation, ensuring insulation class F or H.
3. Insulation System: Epoxy resin cast or open insulation structure, fireproof and moisture-proof, suitable for indoor and high-safety environments.
4. Electrostatic Shielding Layer (Optional): A metallic shielding layer placed between the primary and secondary windings, effectively suppressing common-mode interference.
Oil-Immersed Isolation Transformer
1. Core: Same as dry-type, high-permeability silicon steel sheets laminated together.
2. High and Low Voltage Windings: Winded with high-quality copper or aluminum wire.
3. Insulating Oil: Mineral oil (IEC 60296), providing insulation, heat dissipation, and arc extinguishing functions, suitable for high-power and outdoor applications.
4. Transformer Tank: Steel welded sealed enclosure with an external heat dissipation structure.
1. Core Product Advantages
① Safe and Reliable: Achieves "safe power supply" through electrical isolation, effectively preventing electric shock accidents. In high-safety-requirement applications such as medical equipment and laboratories, leakage current can be controlled at the microampere level.
② Excellent Anti-interference Performance: Isolates grid harmonics, surges, spike pulses, and other interference. With optional electrostatic shielding, common-mode interference immunity can be further enhanced, providing a clean power supply for precision loads.
③ Dual Function (Isolation + Transformation): Can be designed as 1:1 pure isolation or step-up/step-down + isolation, flexibly adapting to different scenario requirements.
④ Flexible Structure and Wide Scenario Coverage: Dry/oil-immersed, single-phase/three-phase, capacity coverage from 0.5kVA to 2000kVA, suitable for both small medical instruments and high-power industrial power distribution.
⑤ Low loss, high efficiency: Utilizing a high-permeability magnetic core and low-loss winding design, efficiency can reach 95%–98.5% or higher, resulting in significant energy savings.
⑥ Long lifespan, low maintenance: Dry-type isolation transformers are designed for maintenance-free operation, while oil-immersed isolation transformers can have a service life of 20–30 years under standardized operation and maintenance conditions.
2. Service Life
Dry-type isolation transformers: Under standard operating conditions and standardized usage, the designed service life can reach 20–25 years. Core components (core, windings) have no easily damaged parts, and the insulation system (epoxy resin/F-class/H-class) ages slowly, requiring no maintenance.
Oil-immersed isolation transformers: The designed service life can reach 20–30 years, comparable to ordinary oil-immersed transformers. Equipment aging mainly stems from the deterioration of insulating oil and the aging of seals; regular oil quality testing and seal replacement can extend the service life.
1. Daily Maintenance
Dry-type Isolation Transformer
① Daily Inspection: Regularly inspect the equipment's appearance, checking for any unusual odors, noises, overheating, discoloration, or signs of insulation damage.
② Cleaning and Dust Removal: Regularly clean the dust from the core and winding surfaces to prevent dust accumulation from causing a decrease in insulation performance or poor heat dissipation.
③ Terminal Inspection: Regularly tighten the terminals and check for overheating or oxidation at the connections.
Oil-Immersed Isolation Transformer
① Daily inspection as with ordinary oil-immersed transformers (oil level, oil temperature, oil leakage check).
② Oil Quality Testing: Take samples every 1-2 years to test the dielectric strength, moisture content, and dissolved gases (DGA) of the insulating oil.
③ Cleaning and Heat Dissipation: Regularly clean dust and debris from the radiator and tank surface.
2. Safety Standards
① Ironclad Rule for Safe Use: The secondary winding of the isolation transformer must remain independent—that is, the secondary winding must not be grounded, connected to a protective conductor, or connected to other electrical circuits. Secondary grounding will compromise the isolation effect and disable the electric shock protection function.
② Live-line work safety: Equipment maintenance must be performed after power is disconnected, voltage is tested, and a grounding wire is connected before any operation. Disassembly and assembly while the equipment is energized are strictly prohibited.
③ Fire prevention and environmental protection: Open flames and flammable and explosive materials are strictly prohibited around the equipment. When changing the insulating oil in an oil-immersed isolation transformer, a dedicated container must be used for recycling; indiscriminate dumping is strictly prohibited.
1. Medical Industry: Safe and isolated power supply for operating room medical equipment, intensive care unit monitors, MRI equipment, and laboratory analytical instruments.
2. Industrial Automation: Anti-interference and isolated power supply for PLC control systems, servo motor drives, CNC machine tools, robot production lines, and sensor detection equipment.
3. Precision Electronics Industry: Purified power supply for chip testing equipment, semiconductor manufacturing production lines, electronic component testing instruments, and high-end audio equipment.
4. New Energy Industry: Photovoltaic inverter testing systems, battery management systems (BMS), charging pile testing platforms, and auxiliary circuits for wind power converters.
5. Building and Security: Fire emergency power supply systems, power supply for surveillance cameras, access control and security equipment, elevator control systems.
6. Rail Transit: Subway signal control systems, train onboard equipment, track testing instruments, platform power supply systems.
7. Testing and Measurement Systems: Purified and anti-interference power supply for precision measurement and testing systems, isolated from the power grid.
1. Environmental Risks (Applicable to both dry-type and oil-immersed types)
1. Heat Dissipation Limitations: Dry-type isolation transformers rely on natural cooling or forced air cooling, requiring good ventilation at the installation location. For enclosed, high-temperature environments, a fan with a casing or increased capacity margin is necessary.
2. Moisture and Corrosion Risks: Epoxy resin cast dry-type isolation transformers offer good moisture resistance, but their open structure is unsuitable for high-humidity environments. Oil-immersed sealed structures offer stronger resistance to moisture and salt spray.
3. Altitude Adaptability Limitations: At altitudes exceeding 1000m, reduced air density leads to decreased external insulation strength, necessitating customized high-altitude insulation-enhanced dry-type or oil-immersed products (increasing creepage distance).
4. Electromagnetic Interference Risk: In industrial environments with strong electromagnetic interference, it is recommended to select isolation transformers with electrostatic shielding layers to effectively suppress common-mode interference.
2. Installation Limitations
1. Spacing Requirements: Dry-type isolation transformers require sufficient ventilation space (typically ≥200mm around the transformer), while oil-immersed transformers require sufficient space for heat dissipation and maintenance operations.
2. Installation Foundation: Dry-type isolation transformers can be floor-mounted or installed in a cabinet, while oil-immersed transformers require a concrete foundation platform or pole support.
3. Fire Safety Compliance: Indoor installation of oil-immersed isolation transformers requires fireproof walls, oil leakage collection tanks, and other facilities. Dry-type isolation transformers are fire-resistant and moisture-proof, with fewer restrictions on indoor installation.
This product supports full-dimensional personalized customization and can be precisely adapted to project conditions, environmental conditions, industry standards, and customer needs. Key dimensions are as follows:
| Customization Dimension | Optional Range / Description |
| Structure Type | Dry-type (epoxy resin cast / open type) / Oil-immersed type (mineral oil cooling) |
| Capacity & Voltage | 5 kVA ~ 2,000 kVA; Input/output voltage customized as needed (standard below 1000V; high-voltage special types customizable) |
| Number of Phases | Single-phase / Three-phase |
| Transformation Ratio | 1:1 (pure isolation) / Step-up / Step-down + Isolation (customizable as needed) |
| Shielding Configuration | Unshielded / Single electrostatic shielding layer / Double electrostatic shielding layer (suppresses common-mode + differential-mode interference) |
| Insulation Class | Class F (155℃) / Class H (180℃) for dry-type; Class A (105℃) for oil-immersed type |
| Protection Class | IP20 ~ IP54 (dry-type); IP54 and above (oil-immersed outdoor type) |
| Corrosion Protection Treatment | Customized C4 / C5 grade anti-corrosion coatings and stainless steel fasteners available for coastal salt spray and chemical corrosion environments |
| Standards | IEC 60076 / GB 1094 / UL 5085 / CSA / CE / GB 20052 energy efficiency standards, etc. |
| Accessories | Thermostat, fans (dry-type forced air cooling), protective housing, terminal protection cover, intelligent monitoring, etc. (optional as needed) |
| Colors & Markings | User-specified color codes (RAL, etc.); nameplates and warning labels in Chinese, English, or bilingual |
