Knowledge Base
Transformer
An electrical device that transfers energy between circuits through electromagnetic induction, changing voltage levels while maintaining frequency.
A transformer is a static electrical device that transfers alternating current (AC) energy between two or more circuits through electromagnetic induction. It consists of two or more coils of wire — called windings — wound around a common magnetic core.
How Transformers Work
When an alternating current flows through the primary winding, it creates a changing magnetic field in the core. This changing field induces a voltage in the secondary winding through Faraday's law of electromagnetic induction. The ratio of primary to secondary turns determines whether the voltage is stepped up or stepped down.
The voltage ratio follows the equation: V₁/V₂ = N₁/N₂, where V represents voltage and N represents the number of turns in each winding.
Types of Transformers
- Step-up transformers — increase voltage from primary to secondary (used in power generation)
- Step-down transformers — decrease voltage (used in distribution and industrial applications)
- Isolation transformers — provide galvanic isolation with a 1:1 turns ratio
- Autotransformers — use a single winding with taps for voltage adjustment
- Toroidal transformers — use a doughnut-shaped core for low profile and low electromagnetic interference
Applications in Industry
Transformers are essential in virtually every electrical system. In industrial settings, they are used for power distribution, motor control, welding equipment, furnace controls, and precision instrumentation. Low-voltage transformers are particularly important in manufacturing environments where equipment requires specific voltage levels different from the mains supply.
At Unitraf JSC, we design and manufacture a wide range of low-voltage transformers for industrial applications, including single-phase and three-phase configurations rated from a few VA to several hundred kVA.
Key Specifications
When selecting a transformer for an application, engineers consider several critical parameters:
- Power rating (VA or kVA) — the maximum apparent power the transformer can handle continuously
- Voltage ratio — primary and secondary voltage levels
- Frequency — typically 50 Hz (Europe) or 60 Hz (North America)
- Insulation class — determines maximum operating temperature (Class B: 130°C, Class F: 155°C, Class H: 180°C)
- Cooling method — dry-type (air-cooled) or oil-immersed
- Efficiency — modern transformers achieve 95–99% efficiency depending on size