| 摘要 |
An insulation detecting system is provided to remotely control insulation resistance for voltage of a commercial AC frequency between a power line and the ground. An analog/digital converting unit(61) converts an analog value into a digital value. A digital/analog converting unit(51a,51b,51c) converts the digital value into the analog value. An analog multiplying unit(52a,52b,52c) multiplies an analog component. A setting unit(63) sets and inputs various data. A display unit(64) displays the various data or alarms. An operation control unit(62) has an operation function. A memory unit(66) stores the various data. A voltage detecting device detects a voltage component of a power line to accurately detect active leakage current. A voltage detecting unit(31a,31b,31c) converts the voltage component into a predetermined voltage size. A voltage filter unit(32a,32b,32c) extracts the voltage component of a commercial frequency component from the voltage component. A 90 degree phase shifting unit(33a,33b,33c) shifts a phase of voltage of the commercial frequency component by 90 degrees. A zero phase current transformer(10) detects zero leakage current flowing between the power line and the ground. A current/voltage converting unit(41) converts a current value of the zero phase leakage current into a voltage value. An amplifying unit(42) amplifies the zero phase leakage current. A current filter unit(43) extracts a zero phase leakage current component of the commercial frequency component through the voltage filter unit. A synchronous detecting unit(44) synchronously detects the zero phase leakage current component of the commercial frequency component, the voltage component of the commercial frequency component, and the 90 degree shifted voltage component. A reactive current compensating winding has an auxiliary winding function. A compensating filter unit(53a,53b,53c) flows current to the reactive current compensating winding of the zero phase current transformer. |
