Railway Couplings
Around 1994, new standards for the electrical couplings between carriages of United Kingdom passenger trains introduced the requirement for separate earth wires for critical functions such as brakes and doors. Common earths can cause interference between circuits that are otherwise independent, with unpredictable effects.
A similar crosstalk problem occurred when using phantom circuits to increase the number of telegraph or telephone circuits.
Read more about this topic: Double Switching
Famous quotes containing the words railway and/or couplings:
“Her personality had an architectonic quality; I think of her when I see some of the great London railway termini, especially St. Pancras, with its soot and turrets, and she overshadowed her own daughters, whom she did not understand—my mother, who liked things to be nice; my dotty aunt. But my mother had not the strength to put even some physical distance between them, let alone keep the old monster at emotional arm’s length.”
—Angela Carter (1940–1992)
“Just as the sentence contains one idea in all its fullness, so the paragraph should embrace a distinct episode; and as sentences should follow one another in harmonious sequence, so paragraphs must fit into another like the automatic couplings of railway carriages.”
—Winston Churchill (1874–1965)