| 摘要 |
PROBLEM TO BE SOLVED: To acquire accurate loop impedance between L-E without tripping a ground-fault interrupter, even if the ground-fault interrupter is provided in a power line including an active line L, a neutral line N, and a grounding conductor E. SOLUTION: The voltage V<SB>LN1</SB>between L-N and the voltage V<SB>LE1</SB>between L-E in a no-load state are measured under the control of a measurement control means 15. A switch 11 is short-circuited, with an electric power source 13 turned off, to make a current I<SB>LN</SB>flow through an L-N circuit connected to a load resistor R, by impressing a voltage of a main power source 2. Then a voltage V<SB>LN2</SB>between L-N and a voltage V<SB>LE2</SB>between L-E are measured. By opening the switch 11 and turning on the electric power source 13, a known AC current I<SB>NE</SB>is made to flow between N-E to measure a voltage V<SB>NE</SB>between N-E. At reception of measurement value, converted from analog into digital form from an A/C converting means 14, the measurement control means 15 determines and makes a loop impedance Z<SB>LE</SB>between L-E displayed on a display 16. COPYRIGHT: (C)2005,JPO&NCIPI
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