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Page 276

| Figure 14-8 (cont.) (C) scheme using CA percentage differential relays; (D) directional comparison scheme using direct current over a pair of wires (a-c connection omitted for simplicity). (Courtesy, Westinghouse Electric Co.) |

| mission lines. The leasing adds to the cost of such systems. The greatest disadvantage, however, is the practical limitsome ten milesfor the positive and effective operation of such systems that is imposed by the burden limitations of the associated current transformers. |

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