Subsea substation system with one enclosure having separate thermal zones

A power collection system for subsea collection of power from at least one power generation unit, the system comprising:

• at least one power generation unit;
• and
• at least one subsea substation system having an oil-filled water impermeable enclosure;
• an AC-transformer, and
• at least one overcurrent device electrically connected to the AC-transformer, the at least one overcurrent device, the AC-transformer, and the electrical connections between them are accommodated in the oil-filled water impermeable enclosure, wherein
• the enclosure comprises thermal zones within the enclosure, wherein the AC-transformer is arranged in a first thermal zone and the overcurrent devices are arranged in a second thermal zone of the enclosure, wherein a mechanical barrier made from at least one sheet of wood or pressboard form a thermal layer that separates the first thermal zone and the second thermal zone, the mechanical barrier is not sealed against walls of the enclosure, wherein the at least one thermal layer is configured to allow oil flow between the thermal zones in areas between the walls of the enclosure and the mechanical barrier that is sufficiently low such that the first thermal zone differs from the second thermal zone with respect to temperature, arranged subsea connected with the at least one power generation unit to collect electrical power from the at least one power generation unit, the at least one subsea substation system being electrically connected with the power generation unit and to a power consumer by at least one subsea cable of the power collection system.