Transformer Basics: Complete Guide
What is a Transformer?
A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It converts voltage levels while maintaining the same frequency, enabling efficient long-distance power transmission and distribution.
Types of Transformers
Dry-Type Transformer
- • Uses air cooling (AN)
- • Fire-resistant, safe for indoor use
- • Low maintenance
- • Suitable for hospitals, data centers
- • IEC 60076-11 compliant
Oil-Immersed Transformer
- • Uses oil cooling (ONAN/ONAF)
- • Higher efficiency
- • Better heat dissipation
- • Outdoor installation
- • IEC 60076 compliant
Key Parameters
| Parameter | Description | Typical Range |
|---|---|---|
| Rated Power (kVA) | Apparent power capacity | 30 - 2500 kVA |
| Primary Voltage | Input voltage | 10kV, 12kV, 33kV |
| Secondary Voltage | Output voltage | 400V, 415V |
| Frequency | Operating frequency | 50Hz or 60Hz |
| Impedance | Short-circuit voltage % | 4% - 6% |
Cooling Methods
- AN (Air Natural): Natural air circulation cooling for dry-type transformers
- ONAN (Oil Natural Air Natural): Oil circulation with natural air cooling
- ONAF (Oil Natural Air Forced): Oil circulation with forced air fans
- OFAN (Oil Forced Air Natural): Forced oil circulation with natural air cooling
IEC Standards
- IEC 60076: Power transformers - general requirements
- IEC 60076-11: Dry-type transformers
- IEC 60214: Tap-changers
- IEC 60076-2: Temperature rise