On your CW-80, there are two "U" post, which are the common connection. These would be connected to the outside rail and the common post on the signal. The "A" post is the variable voltage supply, controllered by the lever on the CW-80, and would be connected to the center rail of the track. The "B" post is a fixed output voltage which is you preset. This "B" post is connected to the #3 contact on the 153C contactor. This will supply power to the signal lamps and the center rail in the insulated section. Using the 153C as Lionel describes it, there is no variable voltage control for trains in the insulated section. The trains are going to get the same voltage you have set for the lamps for this short section of track.
If your "B" post is already used for something else, or you want to have variable voltage to the locomotive in the insulated section, the "A" post can be connected to the #3 contact on the 153C contactor. Using this arrangement the signal lamp brightness will vary with the track voltage.
