Transformer Model
Magnetic Flux
Voltage Waveforms
Power Analysis
Transformer Parameters
Primary Winding
Secondary Winding
Core Parameters
Display Options
Quick Presets
Transformer Equations
Transformer Losses Analysis
Copper Loss (I²R)
Iron Loss (Core)
What is a Transformer?
A transformer is a static electrical device that transfers electrical energy between circuits through electromagnetic induction. It consists of two or more coils of wire (windings) wound around a common magnetic core. When alternating current flows through the primary winding, it creates a changing magnetic field in the core, which induces a voltage in the secondary winding. Transformers are essential for voltage transformation in power transmission and distribution systems, allowing efficient long-distance power transfer at high voltages and safe utilization at lower voltages.
Working Principle
Electromagnetic Induction: Based on Faraday's law of electromagnetic induction, a changing magnetic field induces an electromotive force (EMF) in a conductor. The primary winding's AC current creates a time-varying magnetic flux in the core, which induces voltage in the secondary winding.
Turns Ratio: The voltage ratio is determined by the turns ratio: V₁/V₂ = N₁/N₂. More turns on secondary = step-up transformer. Fewer turns on secondary = step-down transformer.
Current Inverse: Current is inversely proportional to voltage (ideal): I₁/I₂ = N₂/N₁. Higher voltage side has lower current.
Power Conservation: In an ideal transformer, input power equals output power. Real transformers have losses due to resistance and magnetic effects.
Transformer Losses Analysis
Copper Loss (I²R Loss): Power dissipated as heat in the winding resistances. P_cu = I₁²R₁ + I₂²R₂. Varies with load current squared. Can be reduced by using thicker wires and good conductivity materials.
Iron Loss (Core Loss): Consists of hysteresis loss (energy to reverse magnetic domains) and eddy current loss (circulating currents in core). P_fe = P_hysteresis + P_eddy. Nearly constant at all loads. Can be reduced by using laminated cores and high-grade silicon steel.
Stray Loss: Leakage flux causing eddy currents in nearby metal parts. Minimized by proper winding design and magnetic shielding.
Dielectric Loss: Loss in insulation materials, especially at high voltages. Depends on insulation quality and voltage stress.
Applications of Transformers
Power Transmission: Step-up transformers increase voltage for efficient long-distance transmission (lower I²R losses). Step-down transformers reduce voltage for safe distribution and use.
Voltage Conversion: Convert between different voltage levels (120V to 240V, etc.) for appliance compatibility and regional power standards.
Impedance Matching: Match impedance between source and load for maximum power transfer in audio and RF circuits.
Isolation: Provide electrical isolation between circuits for safety and noise reduction. Isolation transformers protect equipment and personnel.
Measurement: Instrument transformers (potential and current transformers) step down high voltages/currents for safe metering and protection.
Electronics: Power supplies use transformers for voltage conversion and isolation in chargers, adapters, and electronic devices.
Transformer Efficiency
Transformer efficiency is typically very high (95-99%) because there are no moving parts. Efficiency = (Output Power / Input Power) × 100%. Losses are minimized by: using low-resistance windings (copper or aluminum), laminated core construction to reduce eddy currents, high-grade core materials with low hysteresis loss, proper core design to minimize leakage flux, and optimal cooling systems. Large power transformers can achieve efficiencies above 99%, making them one of the most efficient electrical machines available.