6.5. Transformers
Transformers
A transformer is the simplest type of a converter. It steps up or down voltages in the system.
The transformer consists of two frames that are not interconnected with windings coiled around them. The voltage is transferred from primary winding to the secondary one through the electromagnetic field that forms around the frames with windings when current is supplied to them. The primary winding creates electromagnetic field around and induces current in the secondary one. Depending on the ratio of coils in the primary and secondary winding, the voltage can be stepped up or down.
The induced current and voltage has reactive power, which creates counter-current in the steel cores of the transformer. This forces them to heat up, therefore all transformers require a good cooling system. Less powerful ones can be cooled by air, the more powerful ones will be cooled by oil. Also, the construction of steel cores prevents the formation of eddy currents which are another reason for the temperature rise in the transformer. Eddy currents form in any piece of a conductor, they resemble a whirl and cause heating and power loss. The larger a solid piece of the conductor is, the more powerful eddy currents are. Therefore, transformer cores consist of thin laminated sheets that are insulated but not of solid frames, thus reducing the losses.
References:
Borstlap, R., Ten Katen, H. (2021) Ship Electrical Systems. 2nd Ed. Dokmar.