Continuously Transposed Conductors
are used in Large Power Transformers, generally more than 50 MVA, Furnace Transformers, and Traction Locomotive Transformers. The current production range of CTC is between 5 to 72 strands with a variety of different insulating materials.
What is CTC?
CTC consists of a group of enamelled rectangular wires, which are connected up parallel to the ends. In the group each strand (enamelled rectangular wire) successively and repetitively takes up every possible position in the whole cross section. The bunch is wrapped with oil compatible pure cellulose paper.
WHAT IS TRANSPOSING?
The enamelled wire
conductors within CTC are arranged in two parallel stacks. One stack having one more conductor that the other. The conductors are continuously transposed by machine action moving them from position to position in discrete steps:
Step1: Conductor 1 is moved from the top of the left hand stack to the top of right hand stack.
Step2: The right hand stack is moved down one conductor thickness in relation to the left hand stack.
Step3: Conductor 3 is moved from bottom of right hand stack to the bottom of left hand stack.
Step4: The left hand stack is moved up one conductor thickness in relation to the right hand stack.
At the end of four transposing step, as shown in the figure, the CTC conductors have returned to the original geometry, but each conductor advanced one position clock-wise.