Install it across the track or transformer leads, on each loop. On a KW that would be from A to U (I think) for example, If A powers a track loop, connect it between A and U, just as if you are trying to short it out with a wire. Instead of shorting it out,it conducts voltage spikes over a threshold to the track common. Here is one I made for someone who had 6 loops. It also has added thermal breakers.
LINK
If you use the barrier strip,you can easily remove it if there is a problem of it shorting out. This is rare,normally it would fail open. I have seen the factory TVS units in MTH TIUs burnt to a crisp.
All the TVS does is conduct voltage spikes,harmful to devices with PC chips to common. Voltage spikes are brief but harmful,and can be 80 volts or more. PC chips generally are low voltage devices. Modern engines and equipment have solid state electronics with PC chips. Voltage spikes over 35 can damage solid state electronics over time.
Across the hot and common,the TVS does not conduct operating track voltage and short out. It just conducts the brief voltage spikes. You can not put too many on a loop. One or two maybe enough. They can burn out over time, but if they do, it means it is doing it's job. There really is no downside of putting on multiple TVS units. They do have a small amount of capacitance. If you put a lot on a loop and ran DCS I suppose it could degrade the signal.
You dont need all the technical stuff. Just install one or two on each loop across the common and hot. You can place it most anywhere,across the transformer or track,center rail to outer rail. Technically some places are better than others,but having one anywhere is a lot better than not having one at all. You can also put one on an accessory line. Some accessories have LEDs and other solid state electronics. For example the MTH scale crossing gates have LEDs and a 555 timing circuit for the flashers. If a PW type accessory,such as a Lionel gateman shares the circuit,it could generate harmful spikes. It is best to put such accessories on their own circuit. If you share a circuit,at least add a TVS. Most any device with some inductance can generate a spike. Solenoids are a big culprit,as well as motors. The PW type gateman mentioned has a solenoid which can generate a large spike. A log loader,gantry crane,etc has a motor for example
If you want technical stuff,look up posts by Dale Manquen, I have learned a lot from reading his posts. There are other knowledgeable people,but if you try to follow technical discussions like you mention, it is like trying to watch 5 cooks at once in a kitchen. Too many cooks spoil the broth and you will get confused.
BTW if EVERYTHING you run is post war,you dont need a TVS.
Dale H
