The 6 winding transformer which i shown in figure is a 1:1:1:1:1:1 transformer.It is a schematic of wurth electronics flex transformer. If I apply voltage at one winding of primary what is the current path in secondary? and what is the applications of this type of 6 winding and equal ratio transformers?
This is meant to be a flexible transformer that can do many things, depending on how you connect the windings. Each winding is magnetically coupled to the others. It is up to you how to connect windings in series or parallel or leave them open to get the ratios you want.
Secondary windings connected in series give you higher voltage at the same current. In parallel, they give you higher current at the same voltage. For primary windings, they have the opposite effect.
The advantage of a device like this is that you can stock one transformer and use it for different purposes in different designs. It also helps the manufacturer in that they don't have to make as many different transformers.
This is not a current transformer, if you apply an AC voltage to one winding, you can measure nearly the same voltage at all other windings. Current flows only through windings connected to a load. You can use only two windings or more. You may connect several windings in series or parallel, but you have to respect the winding direction. The dots are marking the winding direction. For a parallel connection, pin 1 may be connected to pin 2 and pin 4 to pin 5. For a serial connection, pin 4 and 2 are connected. The parallel connection is used for more current and less windings resistance, the serial connection for more voltage and higher resistance. You can use this transformer for a 1:1 ratio, but also 1:2, 1:3, 1:4, 1:5, 2:3.