Oil-immersed and cast-resin transformers do the same job – but in very different ways. Which design is the better choice depends above all on where the transformer will be installed.
Oil-immersed transformers: proven for high power
Insulating oil cools and insulates the windings very effectively. Oil-immersed transformers are therefore the first choice for high power ratings and outdoor installation, for example in substations or at wind farms.
Cast-resin transformers: safe indoors
In cast-resin transformers the windings are embedded in epoxy resin. Without oil there is no risk of leaks and a much lower fire load. This makes them ideal for buildings, hospitals, data centres and tunnels.
Comparison at a glance
- Location: oil-immersed mostly outdoors, cast-resin mostly indoors
- Maintenance: oil analyses for oil-immersed units, visual inspections for cast-resin units
- Fire protection: cast-resin transformers are flame-retardant and self-extinguishing
- Power range: oil-immersed up to several hundred MVA, cast-resin typically up to around 25 MVA
Not sure which design suits your project? Talk to us – we will find the right solution together.