Gunrunner-- Sorry to be so long in reply... I see that late Saturday night seems to be the only time I have to spend on the computer except for chores like taxes and today my wife cannot renew her car registration on line (our DMV requires reservation) because in 1967 she did not obtain a passcode.
So I see a certain time parallel in this to the two Lionel "brick" transformers, 135 va and 180 va. You are quite right that the 180-watt unit has an elaborate control circuit, while the earlier 135-w unit did not have anything near this elaborate. However, it did have a rudimentary circuit to open its 10 A (rated) relay (not a breaker).
This circuit required a short length of ni-chrome resistance wire in one of the low voltage output legs. Reaching the rated 7 A output (apparently somewhat more as built and reported here) caused a sufficient voltage drop across this wire to cause the relay contacts to be opened. A detection trace on a small board (1-inch square?} was run to the far end of the ni-chrome. Measuring this time delay is not easy, but delay must occur when a downstream breaker needs open.
The contemporary downstream TMCC-optional "Power Controller" had similar ni-chrome wires. (But some had mis-wiring which negated the protection needed by the triac pairs used to create the partial waveforms for speed control, much discussed on an earlier board.) I had one of these unit open to verify withstand over 1 cycle.
I have to correct my measurement of maximum possible short-circuit amperage output (105 A) as being that of the 135-w "brick". I now remember it was measured on the 180-w unit much later. By proration. max s/c would be about 75 A for the 135-w. I believe you had a figure of about 100 A for the 180-w.
For other readers, the postwar ZW had deliberate leakage reactance and resistive coil rollers, so its volt-amperes (va) ran rather higher than its useful watts output, and max s/c was about 45 A. That is not the case with the current "brick" transformers, and faster short interruption is necessary but must be time-delayed for the first device in the Lionel cascade protection arrangement.
I did not open the Lionel 180-w "brick" as I already had the circuit diagram for its control wiring. I'll have to find that again, and see if Lionel has revised instructions on-line to show delay time as for GW.
I made an assumption that the two circuits I saw in the older 180-w were both timers, one on the plus phase and one on the negative phase. Now I think I should look more carefully at them--possibly only one was a timer, and revise the previous post. --Frank M
