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I am running two loops each on a separate variable output. Each is set up as a Track in the TIU. When I power up the TIU, both tracks in the DCS app show 22 volts. But the voltage to the tracks is zero. I have throttle the track voltage down in each track to zero and then back up again to get power to the physical tracks. Do I have something set wrong or is this the way the TIU is supposed to behave?


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Well, I have settled the issue with the voltage. I now have a new problem. My outer loop is on one VAR output and the inner loop is on the second VAR. They are interconnected by two pairs of switches. When an engine crosses the switches to go from one loop to the other, the power to the estimation loop dies. Between each pair of switches is a short track section which has the cut center rail and I have removed the jumper between the two outer rails. Am I trying to do something that just isn’t possible? 


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Connect the transformer wires that go to the black input terminals of the two TIU channels together with a jumper.  Measure the voltage between the two transformer wires that go to the red input terminals of the same channels.  You should get minimal voltage there.  If you see 25-35 volts, you have a phasing issue.  Some of the PH180 bricks were phased wrong from the factory, so it depends on the vintage of transformers you have if this is an issue.  Also, if the two transformers are plugged into different outlets that are on opposite sides of the 220V main power phases, they'll also be out of phase.  I'm presuming you were mindful of the polarized plugs.

I’m reading 37 volts between the positive connections. I’m ashamed to say that I’m not mindful of polarized plugs. The bricks are plugged into an power strip that has polarized outlets. One slot larger than the other. I made the connecting wire (from the brick to the TIU myself. There was no indication of polarity with the bricks.

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