Transformer cooling system

A transformer installation comprising:

• a first dry transformer comprising:
• a first core comprising:
• a first leg;
• a first winding body arranged around the first leg;
• a first cooling channel extending in a direction of a longitudinal axis of the first winding body, wherein the first cooling channel is disposed between an inner part of the first winding body and an outer part of the first winding body;
• a first housing for containing the first dry transformer, the first housing having a first inlet portion for receiving air from outside the housing and a first outlet portion for expelling air outside the first housing;
• a flow generating device arranged at the first outlet portion and adapted to generate an under pressure for sucking the air from the first inlet portion towards the flow generating device and to expel the air through the first outlet portion outside the first housing, wherein the flow generating device comprises a first flow generating unit arranged at the first outlet portion to force an air stream to flow from the first inlet portion to the first outlet portion of the first housing through the first cooling channel of the first dry transformer and a second flow generating unit arranged upstream of the first flow generating unit in the direction of the air stream to create a further under pressure in the first cooling channel of the first dry transformer;
• and
• a second dry transformer comprising:
• a second core comprising:
• a second leg;
• a second winding body arranged around the second leg;
• and
• a second cooling channel extending in a direction of a longitudinal axis of the second winding body, wherein the second cooling channel is disposed between an inner part of the second winding body and an outer part of the second winding body;
• a second housing for containing the second dry transformer, the second housing having a second inlet portion for receiving air from outside the housing and a second outlet portion for expelling air outside the second housing;
• and
• the flow generating device further arranged at the second outlet portion and adapted to generate an under pressure for sucking the air from the second inlet portion towards the flow generating device and to expel the air through the second outlet portion outside the second housing, wherein the first flow generating unit is further arranged at the second outlet portion to force an air stream to flow from the second inlet portion to the second outlet portion of the second housing through the second cooling channel of the second dry transformer, and wherein the flow generating device further comprises another second flow generating unit arranged upstream of the first flow generating unit in the direction of the air stream to create a further under pressure in the second cooling channel of the second dry transformer,
• wherein the respective first and second housings of the first and second dry transformers are separate from each other;
• and
• wherein the second flow generating units comprise a respective pressure chamber located within and separate from their respective housings, wherein the pressure chamber is connected at one end of the winding body of the first and second dry transformers and connected to the first flow generating unit through at least an outlet tube.

A dry transformer comprising:

• a housing having an inlet portion for receiving air from outside the housing and an outlet portion for expelling air outside the housing;
• a core arranged within the housing;
• a winding body arranged around the core;
• a cooling channel extending in a direction of a longitudinal axis of the winding body, wherein the cooling channel is disposed within the winding body;
• and
• a flow generating device arranged within the housing at the outlet portion and adapted to generate an under pressure for sucking the air from the inlet portion towards the flow generating device and to expel the air through the outlet portion outside the housing, wherein the flow generating device comprises a first flow generating unit arranged at the outlet portion to force an air stream to flow from the inlet portion to the outlet portion of the housing through the cooling channel of the dry transformer and a second flow generating unit arranged upstream of the first flow generating unit in the direction of the air stream to create a further under pressure in the cooling channel of the dry transformer;
• wherein the second flow generating unit comprises a pressure chamber located within and separate from the housing, wherein the pressure chamber is connected at one end of the winding body of the dry transformer and connected to the first flow generating unit through at least an outlet tube.