Transformer Phasing
and why it is important
Operating with separate transformers powering adjacent blocks can create a new difficulty. Namely a Voltage discrepancy between the blocks that is not readily apparent.
When both transformers are set to the same Voltage and their respective power is applied to the 2 adjacent blocks it is possible to read a large Voltage across the one center rail to the other center rail.
When this happens, the two transformers are out of phase.
Rotate the power plug of just one of the transformers and the track Voltage will then be in phase.
A simple indicator is to make a test lamp with wires and clip leads attached; one to the center post and one to the base.
Clip a lead to each center rail.
Adjust the Voltage(s) to make the lamp go out.
Any glowing of the lamp will show an out of phase condition.
Now, with normal house wiring there won't be any minimum glow. The lamp will go out.
In a modern commercial building there is another trap waiting, called 3 Phase.
This will happen with different plugs around a large room being connected to different phases.
With any transformer 120 degrees out with another, there will be no way to get the light to go out.
Now what is the concern with transformers being out of phase?
When a loco's rollers short the two independently powered center rails together, there will be a short circuit current for any Voltage mismatch. This jump up and fall back of current creates very large strong spikes which are almost always detrimental to any loco's electronics.
Also any sustained short will cause overheating, and transformer's circuit breakers are not always responsive to this type of short.
|
|