(11-07-2016, 11:11 AM)onestrangeday Wrote: Hi Signalling Professionals:
Can anyone explain the function of UCR Route Check Relay and USR Route Stick Relay, and the purpose of those 2 circuits?
and the meaning of these 2 relays when they are in the "pick up" state or "drop off" state? (i.e. route checked, or not checked etc.)
Thank you
Bill
There are different types of route relay interlocking and naming and exact use do vary.
Certainly the "USR" Route Stick Relay is a route locking element that would normally be energized but would drop when a route is set to reserves the track section in the direction needed for that route and impose locking on directly and indirectly opposing routes as well as any points contained within that track section; in general there is one USR for the Up Direction over the track section and one for the Down Direction so you might expect them to be named;
XYZ (Up)USR and XYZ (Dn) USR for track section XYZ
The "UCR" Route Checking Relay would certainly pick when the route is established, but it might depend on details of the system quite how much it is proving. My initial assumption would be that it contains almost all the controls that are necessary for signal clearance for that specific route (i.e. class and destination) from the entrance signal; it may perhaps not contain approach release conditions and almost certainly wouldn't contain the proof of the signal's own route indicator (if applicable) is alight but I think would at least have all tracks clear to the overlap beyond the next signal, that signal proved alight and TPWS active if signal at red, foul tracks, flank tracks, point detection etc. Might perhaps contain relevant level crossing controls, but might not have them all. So the UCR is a step on the way to getting the signal to show a proceed aspect, but there will be things it excludes and is probably created to impose approach locking and initiate something else that, once it has done its job, then gets any outstanding items to be proved in the required state which then allows the signal to clear.
So in brief I think it is likely to be a ummation of many, but not all, aspect level controls.
