Circuit Page 1
Circuit Page 2
Circuit Page 3
| This page (Page 1) was first seen in Plate 231. At that time, only one point-motor circuit was documented, so there were only three entries (one for the common wire, another for the red wire, and another for the green wire). These three entries (the ULML-pt-1 entries) are still on Page 1 of the circuit table. Unlike the operating diagrams shown in previous plates, the circuit table keeps growing, page after page, as new electric circuits are added to the layout.
The next time this page was shown, in Plate 241, all the point motors for the locomotive service yard had been documented, for a total of four circuits. Because each point-motor circuit uses three wires, twelve rows of the circuit table had been used up. Page 1 at that time contained thirteen rows, because the top row of each page must contain column headings. Page 1 now contains thirteen data rows and one heading row. The bottom row on page one contains wiring information for the common circuit of the embankment level main line point number 2, which creates the yard throat for the embankment-level marshalling yard. The number 5 in the last row, under the heading circuit column number informs us that wiring for this new point motor will use the first unused position in the power distribution center's terminal blocks, which happens to be position number 5. Keep in mind that the power distribution center is laid out in indexed sequential form (see Plate 226). Return to main text |  |
| This page (Page 2) is entirely new. The first two rows contain wiring directions for the second and third circuits of embankment level main line point number 2, the common circuit of which was documented in the bottom row of Page 1. Please observe that the circuit table is a continuous, open-ended document, unlike the operating diagrams, each of which can be confined to a single page.
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| Here (Page 3) we see the end of the circuit table at this time. The circuit column number in the table contains a 9, thereby informing us that nine of the ten existing point-motor circuit positions have been allocated.
The builder, studying this table, observed that two more points, both of them in the embankment-level passenger terminal, do not yet appear in this diagram. The inclusion of the two passenger-terminal points will bring the total number of point-motor circuits to eleven, one more than the current capacity of the power distribution center. The builder has thus been warned that it is time to think about ordering more terminal blocks for the distribution center. The circuit table is now revealed to be a valuable planning aid. Return to main text |  |