An isolation transformer provides galvanic separation between the power source and the load to improve safety and clean up noisy power. At its simplest — often a 1:1 device — the primary and secondary windings are magnetically coupled but electrically isolated, so hazardous direct connection to the utility neutral/earth is removed. This makes isolation transformers ideal where low leakage, reduced common-mode noise, surge attenuation and human safety matter.
How it works (simple, authoritative)
Transformers obey the turns ratio relationships. U1/U2=N1/N2 and I1/I2=N2/N1. In a 1:1 isolation transformer the nominal voltage and current remain the same while the primary and secondary circuits are electrically decoupled.
Because the secondary is floating relative to earth, there is no fixed line-to-earth potential on either secondary conductor — touching one conductor alone will normally not create a return path through earth and therefore reduces touch-shock risk. Carefully designed isolation transformers can also:
- Attenuate certain harmonic content (e.g., third-order harmonics in specific winding/vector configurations),
- Reduce common-mode interference and noise,
- Limit surge energy through magnetic saturation or selected core design, and
- Provide a new, stable neutral/reference for sensitive control and measurement systems.
Note: transformers do not change frequency and are not a substitute for active harmonic filters when high-order harmonics are present.
Typical applications
- Service and maintenance power (safe working voltage for technicians)
- Test benches, oscilloscope and audio equipment repair (floating secondary for safety)
- Medical and laboratory equipment (use certified medical isolation models)
- Industrial control panels, PLCs and CNC machines (noise suppression and clean sampling signals)
- AV and high-fidelity audio systems (improved S/N)
- Data centers, telecom, UPS input conditioning and lighting where leakage current and EMI must be minimized
Key benefits
- Electrical safety: reduces touch-shock risk and isolates equipment from utility faults.
- Noise & EMI suppression: reduces common-mode noise and helps prevent equipment-generated harmonics from polluting the grid.
- Surge attenuation: core design and winding layout provide some protection from transients.
- Customizable: voltage ratios, impedances, shielding and enclosures tailored to your environment.
Typical technical specifications (example / configurable)
- Power range: 0.5 kVA – 500 kVA (custom sizes available)
- Voltage: single-phase 110/115/120/220/230/240 V; three-phase 380/400/415 V (or to customer spec)
- Frequency: 50 / 60 Hz (special 400 Hz units available)
- Insulation class: Class F / H (or to customer spec)
- Cooling: AN (air natural), AF (air forced), ONAF, or liquid for large units
- Enclosure: IP00 (open), IP21, IP44, IP54, or weatherproof cabinets
- Leakage current: designed to meet low-leakage requirements for sensitive equipment
- Consttion: EI core, toroidal, or wound core; copper windings standard (aluminum on request)
- Tests: routine and type tests per customer requirements; factory test report available

Isolation transformer price — what affects cost
Searching for isolation transformer price? Price varies widely because transformers are highly configuration-dependent. Major cost drivers:
- kVA rating — largest single driver (larger cores, more copper).
- Phase & voltage — three-phase and special voltages cost more.
- Core & winding material — toroidal vs EI core; pure copper windings increase cost vs aluminum.
- Shielding & filtering — electrostatic shields, common-mode chokes add cost.
- Enclosure & IP rating — cabinets, IP/weatherproofing, seismic bracing.
- Standards & certification — medical, UL/EN/IEC testing or custom reports increase lead time and cost.
- Quantity & customization — one-off prototypes cost more per unit than production runs.
- Testing & documentation — factory acceptance testing (FAT), test certificates, and EMI/insulation reports add to price.
Indicative price bands (for planning only): small single-phase units (sub-kVA) can be a few hundred USD; moderate industrial units (5–50 kVA) typically range from low hundreds to a few thousand USD; large three-phase or certified medical units are several thousand USD. For an accurate isolation transformer price tailored to your specs, please request a quote — we provide detailed, itemized offers.
How to select the right isolation transformer (quick guide)
- Define application (safety, EMI reduction, filtering, audio fidelity).
- Confirm load type: linear vs non-linear (harmonics).
- Determine kVA, voltage, phase and allowed short-circuit impedance.
- Decide leakage current limits and required grounding scheme (floating vs grounded secondary).
- Specify environmental and enclosure requirements (IP, vibration, mounting).
- Ask for test reports / certificates if your industry requires them.
- Consider lifecycle costs: efficiency, maintenance, and serviceability.
Why choose ZHENGXI
ZHENGXI supplies custom and standard isolation transformers designed for demanding industrial, audio, medical and laboratory applications. Our manufacturing process includes precision winding, vacuum impregnation, strict QC testing and optional FAT documentation. We offer flexible customization, worldwide logistics and technical support to help you pick the right model — from small service isolation units to large three-phase power conditioners.
FAQs
Q1 — What’s the difference between an isolation transformer and an autotransformer?
A: An isolation transformer has separate primary and secondary windings and provides galvanic isolation between circuits — important for safety and noise reduction. An autotransformer shares a winding for input and output (no galvanic isolation) and is typically smaller and cheaper but does not provide the safety benefits of isolation.
Q2 — Can an isolation transformer remove harmonics and protect against surges?
A: Isolation transformers can attenuate certain harmonic components (especially low-order/common-mode harmonics) and reduce common-mode noise; some core designs also limit surge energy. However, they are not a universal harmonic filter — for severe harmonic distortion or demanding surge protection, combine the transformer with active filters, surge protectors or dedicated EMI filters.
Q3 — How much does an isolation transformer cost?
A: Isolation transformer price depends on kVA, phase, voltage, construction, shielding, enclosure, testing and certification. We provide competitive, detailed quotes — send your required kVA/voltage/installation details and we’ll return a tailored offer with lead time and optional test documentation.
Ready to specify a model or get an exact isolation transformer price? Contact our sales team with your application details (kVA, voltage, phase, environment and any required certifications) and we’ll prepare a no-obligation quote and datasheet.