RJR posted:Gentlemen, I would appreciate it if you could answer a couple of simple questions.
On page 3 of the Service Bulletin, what is the ID number(s) for the ACT244s?
Did pre-Rev-L TIUs use the ACT 244?
Since the surges that damage the ACT244s (unless they just "wear out") originate in derailments, would it make sense to install a heavy duty TVS in each block, near the single centerrail drop called for by DCS, to snub the surge before heading to the TIU. I do recognize that TVSs should be near to the device they protect, but seems to me that snubbing the surge can take place anywhere between origin and victim. ????
The transient events are actually pretty high bandwidths up to 100s of MHz so nulling the voltage at the track doesn’t necessarily mean you’ve nulled it at the TIU because you’re in the “telegrapher’s” regime where the wavelength and wire length are comparable.
The only way to guarantee a null at a particular position along the line is to impose the null at that position:
Vtotal(z)=VP e^Yz + Vn e^-Yz
