Purpose of transformer
Transformers are designed to do one of the following:
- Step-up voltage; consequently step-down current – enables long-distance transmission by reducing I^2\times R copper losses. Step-ups are found near generating stations.
- Step-down voltage; consequently step-up current – enables distribution of power to customers at a safe voltage magnitude. Step-downs are found near load centers and in sub-transmission systems.
- On distribution transformers, when equipped, the load tap changer keeps the secondary voltage constant as the load increases or decreases.
- The transformer is also designed for special applications such as
- phase-shifting transformer (pushes more power on the transmission line by varying power-angle \sin\delta – learn more)
- HVDC converter transformer
- Static Var Compensator (SVC) transformer (VARs generated by capacitive and inductive elements at medium voltage, you still need a transformer to step-up when tying these elements to the high-voltage grid)
- grounding zig-zag transformer (provide a path for zero-sequence current in an ungrounded system)
Cost of transformer
The cost of a power transformer varies significantly based on BIL rating, MVA rating, core design, guaranteed losses requirement, tank design, etc. The prices listed below are for a standard design transformer (i.e., standard sound – core type transformer).
- Small power transformer with LTC – 10MVA or lower: ~ $600,000
- Medium power transformer with LTC – 10MVA to 50MVA: ~$800,000
- Large power transformer with LTC – 50MVA to 100MVA: ~$1,500,000
- Large power transformer – 100MVA or larger: ~ $2,500,000
- Specialty phase shifting transformer – 100MVA+: ~$4,000,000
Lead time to procure transformer
~ 1 year, regardless of MVA rating.
Information on cost and lead-time are rough estimates — contact vendor with your equipment specifications for actual figures.
I have a 20 megawatt substation to sell. 2-10 megawatt transformers plus the circuit breaker.