| 摘要 |
A DC termination circuit is provided for keeping a sealing current on a subscriber line during normal operation in order to prevent an oxidation of contacts in said line. The termination circuit is coupled across the line in response to the normal relatively high line voltage. In order to test the line, especially for its electrostatic capacitance, the line voltage is switched off and a relatively low voltage is applied through test equipment to the line. Responsive thereto, the termination circuit is removed from the line to terminate the sealing current.
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