Leakage current or resistance measurement method, and monitoring apparatus and monitoring system of the same

A leakage current measurement method comprising the steps of:

• obtaining a leakage current signal of a three-phase AC target measurement circuit;
• obtaining a voltage signal of said target measurement circuit;
• sampling the waveform of said leakage current signal and said voltage signal for one cycle and for storing said voltage signal;
• and
• calculating the resistance component current by dividing the average of integrated value of instantaneous values of the leakage current and instantaneous values of said stored voltage signal at the phase angle of 30 degrees advance by the square root of average of squared instantaneous values of said voltage signal.

A leakage current measurement method comprising the steps of:

• obtaining a leakage current signal of a three-phase AC target measurement circuit;
• obtaining a voltage signal of said target measurement circuit;
• sampling the waveform of said leakage current signal and said voltage signal for one cycle and for storing said voltage signal;
• and
• calculating the resistance component current by dividing the average of integrated value of instantaneous values of the leakage current and instantaneous values of said stored voltage signal at the phase angle of 30 degrees advance by the square root of average of squared instantaneous values of said voltage signal for the respective phases.

A leakage current measurement method comprising the steps of:

• obtaining a leakage current signal of an AC target measurement circuit;
• obtaining a voltage signal of said target measurement circuit;
• sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle;
• expanding said leakage current signal and said voltage signal to N-th higher harmonic wave component respectively;
• and
• calculating the resistance component that relates to the leakage current according to the simultaneous equations based on the assumption that the value obtained by dividing the leakage current component of the second or higher order by the voltage component of the same order is regarded to be equal to the admittance composed of the resistance component of the same order and the electrostatic capacity component.

A leakage current measurement method comprising the steps of:

• obtaining a leakage current signal of an AC target measurement circuit;
• obtaining a voltage signal of said target measurement circuit;
• sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle;
• expanding said leakage current signal and said voltage signal to N-th higher harmonic wave component respectively;
• and
• calculating the resistance component that relates to the leakage current from the phase angle difference between the leakage current component of at least one order obtained from the expansion arithmetic and the voltage component of the same order.

A leakage current measurement method comprising the steps of:

• obtaining a leakage current signal of an AC target measurement circuit;
• obtaining a voltage signal of said target measurement circuit;
• sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle;
• expanding said leakage current signal and said voltage signal to the DC component and N-th higher harmonic wave component respectively;
• and
• calculating the resistance component that relates to the leakage current by dividing said voltage signal DC component obtained from the expansion arithmetic by said leakage current signal DC component obtained in the same manner.

A monitoring apparatus comprising:

• an input unit for receiving the output of a current transformer for detecting the leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating said leakage current and for conducting the arithmetic processing;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit,
• wherein said arithmetic processing unit includes:
• a means for obtaining a leakage current signal of a target measurement circuit;
• a means for obtaining a voltage signal of said target measurement circuit;
• and
• a means for conducting the processing in which the waveform of said leakage current signal and said voltage signal for one AC cycle is sampled, and the resistance component current is calculated from the result obtained by dividing the average of integrated value of instantaneous values of said voltage signal and instantaneous values of said leakage current signal by the square root of average of instantaneous values of said voltage signal.

A monitoring apparatus comprising:

• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating said leakage current and for conducting the arithmetic processing;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit,
• wherein said arithmetic processing unit includes:
• a means for obtaining a leakage current signal of a three-phase AC target measurement circuit;
• a means for obtaining a voltage signal of said target measurement circuit;
• a means for sampling the waveform of said leakage current signal and said voltage signal for one cycle and for storing said voltage signal;
• and
• a means for calculating the resistance component current by dividing the average of integrated value of instantaneous values of said leakage current and instantaneous values of said stored voltage signal at the phase angle of 30 degrees advance by the square root of average of squared instantaneous values of said voltage signal.

A monitoring apparatus comprising:

• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating said leakage current and for conducting the arithmetic processing;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit,
• wherein said arithmetic processing unit includes:
• a means for obtaining a leakage current signal of a three-phase AC target measurement circuit;
• a means for obtaining a voltage signal of said target measurement circuit;
• a means for sampling the waveform of said leakage current signal and said voltage signal for one cycle and for storing said voltage signal;
• and
• a means for calculating the resistance component current by dividing the average of integrated value of instantaneous values of said leakage current and instantaneous values of said stored voltage signal at the phase angle of 30 degrees advance by the square root of average of squared instantaneous values of said voltage signal for the respective phases.

A monitoring apparatus comprising:

• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating said leakage current and for conducting the arithmetic processing;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit,
• wherein said arithmetic processing unit includes:
• a means for obtaining a leakage current signal of an AC target measurement circuit;
• a means for obtaining a voltage signal of said target measurement circuit;
• a means for sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle;
• a means for expanding said leakage current signal and said voltage signal to N-th higher harmonic wave component respectively;
• and
• a means for calculating the resistance component that relates to said leakage current according to the simultaneous equations based on the assumption that the value obtained by dividing said leakage current component of the second or higher order by the voltage component of the same order is regarded to be equal to the admittance composed of the resistance component of the same order and the electrostatic capacity component.

A monitoring apparatus comprising:

• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating said leakage current and for conducting the arithmetic processing;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit,
• wherein said arithmetic processing unit includes:
• a means for obtaining a leakage current signal of an AC target measurement circuit;
• a means for obtaining a voltage signal of said target measurement circuit;
• a means for sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle;
• a means for expanding said leakage current signal and said voltage signal to N-th higher harmonic wave component respectively;
• and
• a means for calculating the resistance component that relates to said leakage current from the phase angle difference between said leakage current component of at least one order obtained from the expansion arithmetic and the voltage component of the same order.

A monitoring apparatus comprising:

• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating said leakage current and for conducting the arithmetic processing;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit,
• wherein said arithmetic processing unit includes:
• a means for obtaining a leakage current signal of an AC target measurement circuit;
• a means for obtaining a voltage signal of said target measurement circuit;
• a means for sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle;
• a means for expanding said leakage current signal and said voltage signal to the DC component and N-th higher harmonic wave component respectively;
• and
• a means for calculating the resistance component that relates to said leakage current by dividing said voltage signal DC component obtained from the expansion arithmetic by said leakage current signal DC component obtained in the same manner.

A monitoring system for monitoring said leakage current comprising:

• a monitoring apparatus including:
• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating and operating said leakage current having a means for obtaining a leakage current signal of a target measurement circuit, a means for obtaining a voltage signal of said target measurement circuit, and a means for conducting the processing in which the waveform of said leakage current signal and said voltage signal for one AC cycle is sampled, and the resistance component current is calculated from the result obtained by dividing the average of integrated value of instantaneous values of said voltage signal and instantaneous values of said leakage current signal by the square root of average of instantaneous values of said voltage signal;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit, and
• a host apparatus for storing and displaying the information obtained from said monitoring apparatus.

A monitoring system for monitoring said leakage current comprising:

• a monitoring apparatus including:
• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating and operating said leakage current having a means for obtaining a leakage current signal of a three-phase AC target measurement circuit, a means for obtaining a voltage signal of said target measurement circuit, a means for sampling the waveform of said leakage current signal and said voltage signal for one cycle and for storing said voltage signal, and a means for calculating the resistance component current by dividing the average of integrated value of instantaneous values of said leakage current and instantaneous values of said stored voltage signal at the phase angle of 30 degrees advance by the square root of average of squared instantaneous values of said voltage signal;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit, and
• a host apparatus for storing and displaying the information obtained from said monitoring apparatus.

A monitoring system for monitoring said leakage current comprising:

• a monitoring apparatus including:
• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating and operating said leakage current having a means for obtaining a leakage current signal of a three-phase AC target measurement circuit, a means for obtaining a voltage signal of said target measurement circuit, a means for sampling the waveform of said leakage current signal and said voltage signal for one cycle and for storing said voltage signal, and a means for calculating the resistance component current by dividing the average of integrated value of instantaneous values of said leakage current and instantaneous values of said stored voltage signal at the phase angle of 30 degrees advance by the square root of average of squared instantaneous values of said voltage signal for the respective phases;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit, and
• a host apparatus for storing and displaying the information obtained from said monitoring apparatus.

A monitoring system for monitoring said leakage current comprising:

• a monitoring apparatus including:
• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating and operating said leakage current having a means for obtaining a leakage current signal of an AC target measurement circuit, a means for obtaining a voltage signal of said target measurement circuit, a means for sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle, a means for expanding said leakage current signal and said voltage signal to N-th higher harmonic wave component respectively, and a means for calculating the resistance component that relates to said leakage current according to the simultaneous equations based on the assumption that the value obtained by dividing said leakage current component of the second or higher order by the voltage component of the same order is regarded to be equal to the admittance composed of the resistance component of the same order and the electrostatic capacity component;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit, and
• a host apparatus for storing and displaying the information obtained from said monitoring apparatus.

A monitoring system for monitoring said leakage current comprising:

• a monitoring apparatus including:
• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating and operating said leakage current having a means for obtaining a leakage current signal of an AC target measurement circuit, a means for obtaining a voltage signal of said target measurement circuit, a means for sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle, a means for expanding said leakage current signal and said voltage signal to N-th higher harmonic wave component respectively, and a means for calculating the resistance component that relates to said leakage current from the phase angle difference between said leakage current component of at least one order obtained from the expansion arithmetic and the voltage component of the same order;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit, and
• a host apparatus for storing and displaying the information obtained from said monitoring apparatus.

A monitoring system for monitoring said leakage current comprising:

• a monitoring apparatus including:
• an input unit for receiving the output of a current transformer for detecting said leakage current of a target measurement circuit;
• an A/D converter unit for converting the output of said input unit to a digital value;
• a memory unit for storing the value that has been converted by said A/D converter unit;
• an arithmetic processing unit for calculating and operating said leakage current having a means for obtaining a leakage current signal of an AC target measurement circuit, a means for obtaining a voltage signal of said target measurement circuit, a means for sampling and storing the waveform of said leakage current signal and said voltage signal for one cycle, a means for expanding said leakage current signal and said voltage signal to the DC component and N-th higher harmonic wave component respectively, and a means for calculating the resistance component that relates to said leakage current by dividing said voltage signal DC component obtained from the expansion arithmetic by said leakage current signal DC component obtained in the same manner;
• and
• an output unit for supplying the arithmetic result of said arithmetic processing unit, and
• a host apparatus for storing and displaying the information obtained from said monitoring apparatus.

A monitoring apparatus having a means for measuring said leakage current or the resistance of a target measurement circuit and for conducting the arithmetic processing, comprising:

• a terminal table for connecting the current signal line and said voltage signal line extending from a current transformer;
• a setting unit for setting the current transforming ratio and selecting a plurality of inputs, and for switching the display type;
• and
• a display unit for displaying the set values and arithmetic processing result,
• wherein said apparatus has one side of about 200 mm and the other side of about 150 to 20 mm in appearance.

A monitoring apparatus having a means for measuring said leakage current or the resistance of a target measurement circuit and for conducting the arithmetic processing, comprising:

• a terminal table for connecting the current signal line and said voltage signal line extending from a current transformer;
• a setting unit for setting the current transforming ratio and selecting a plurality of inputs, and for switching the display type;
• and
• a display unit for displaying the set values and arithmetic processing result,
• wherein the height of the terminal table of said monitoring apparatus is in a range from 60 to 80 mm.