| 摘要 |
A remotely controlled switch box 102 reconfigures the connections of the live, neutral and earth terminals 101 in a ring main distribution board 102 so that an electrician using a resistance meter 103 can conduct different resistance tests at sockets 115 on the ring main without returning to the distribution board. In particular the live terminals may be coupled to the neutral terminals and then to the earth terminals so that R1+RN and R1+R2 tests may be made. Reference values for these tests are derived from resistance measurements made on the earth, live and neutral loops (figure 3). The switches in the box 102 (figure 5) are controlled reliably in dependence on coded low frequency signals sent from the meter 103. |
