1. A ground fault detection apparatus for detecting a ground fault of a solar battery in a solar power generation system which causes a non-insulated type inverter to convert DC power generated by the solar battery into AC power and outputs the AC power to a commercial power system, comprising:
differential current detection means for detecting a differential current between output lines of the solar battery;
AC leakage current removing means for removing an AC leakage current component due to a capacitance to ground of the solar battery from the differential current; and
determination means for determining whether a ground fault state has occurred by comparing a current value output from said AC leakage current removing means with a predetermined threshold value.
2. The apparatus according to claim 1, wherein said AC leakage current removing means removes a frequency component twice a frequency of the commercial power system from the differential current.
3. The apparatus according to claim 1, wherein said AC leakage current removing means calculates a prediction value of an AC leakage current from a voltage variation amount of the output line of the solar battery and the capacitance to ground of the solar battery and subtracts the prediction value from a value of the differential current.
4. The apparatus according to claim 1, wherein said AC leakage current removing means calculates a prediction value of an AC leakage current from a voltage variation amount of a booster section of the non-insulated type inverter and the capacitance to ground of the solar battery and subtracts the prediction value from a value of the differential current.
5. The apparatus according to claim 1, wherein said AC leakage current removing means calculates a prediction value of an AC leakage current from an output power amount of the non-insulated type inverter and the capacitance to ground of the solar battery and subtracts the prediction value from a value of the differential current.
6. The apparatus according to claim 1, wherein said AC leakage current removing means includes filter means for removing a PWM component of the non-insulated type inverter from the differential current.
7. A solar power generation system comprising:
a ground fault detection apparatus for detecting a ground fault of a solar battery in a solar power generation system which causes a non-insulated type inverter to convert DC power generated by the solar battery into AC power and outputs the AC power to a commercial power system, including,
differential current detection means for detecting a differential current between output lines of the solar battery,
AC leakage current removing means for removing an AC leakage current component due to a capacitance to ground of the solar battery from the differential current, and
determination means for determining whether a ground fault state has occurred by comparing a current value output from said AC leakage current removing means with a predetermined threshold value; and
control means for controlling operation of said non-insulated type inverter and a state of a system interconnection switch in accordance with a determination result from said ground fault detection apparatus.
8. A ground fault detection method of detecting a ground fault of a solar battery in a solar power generation system which causes a non-insulated type inverter to convert DC power generated by the solar battery into AC power and outputs the AC power to a commercial power system, comprising the steps of:
detecting a differential current between output lines of the solar battery;
removing an AC leakage current component due to a capacitance to ground of the solar battery from the differential current; and
determining whether a ground fault state has occurred by comparing a current value after removal of the AC leakage current component with a predetermined threshold value.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A wrist exerciser comprising:
a casing comprising upper and lower casing members mounted together to form a substantially spherical shape, the upper casing member defining an opening;
a retention ring fixed in the casing substantially corresponding to a great circle of the sphere of the casing, diametrically opposite holes being defined in the retention ring;
a rotor having opposite shafts rotatively received in the holes for rotatively supporting the rotor in the casing;
at least one illumination element mounted on an outside surface of the rotor;
a power source contained in the rotor;
a control circuit contained in the rotor and in electrical connection with the power source and the illumination element, the control circuit selectively lighting the illumination element; and
transmission means comprising:
a transmitter mounted in the rotor and comprising an interface circuit connected to the control circuit and a connection member in connection with the interface circuit, and
a transmission cable having opposite ends forming first and second connectors, the first connector being releasably mateable with the connection member of the transmitter of the rotor and the second connector being adapted to connect an external device for transferring an electrical signal from the external device to the control circuit.
2. The wrist exerciser as claimed in claim 1, wherein the upper and lower casing members are made of light transmitting material.
3. The wrist exerciser as claimed in claim 1, wherein the rotor defines a circumferential groove.
4. The wrist exerciser as claimed in claim 1, wherein the illumination element comprises a light emitting diode.
5. The wrist exerciser as claimed in claim 1, wherein the power source comprises:
a permanent magnet attached to the retention ring;
a winding mounted to the rotor and substantially opposing the permanent magnet whereby when the rotor rotates, the winding cuts though magnetic lines of force of the magnet thereby inducing an electrical current in the winding; and
a rectification and regulation circuit receiving and processing the electrical current to supply electrical power to the illumination element and the control circuit.
6. The wrist exerciser as claimed in claim 5 further comprising a mounting flange formed around one of the holes of the retention ring and wherein the permanent magnet comprises a ring mounted to and supported by the mounting flange with the shaft of the rotor extending through the ring of the magnet.
7. The wrist exerciser as claimed in claim 1, wherein the power source comprises a battery and a switch that selectively connects the battery to the control circuit and the illumination element to power the control circuit and the illumination element.
8. The wrist exerciser as claimed in claim 1, wherein the control circuit comprises programmable means.
9. The wrist exerciser as claimed in claim 1, wherein the control circuit comprises a microprocessor comprising an output terminal connected to the illumination element, the microprocessor comprising a control program for selectively lighting the illumination element by sending an electrical signal at the output terminal.
10. The wrist exerciser as claimed in claim 9, wherein the microprocessor comprises a number of different control programs and a selection switch for selecting one of the control programs with which the microprocessor lights the illumination element.
11. The wrist exerciser as claimed in claim 1, wherein the interface circuit comprises a Universal Serial Bus (USB) based interface.
12. The wrist exerciser as claimed in claim 1, wherein the interface circuit comprises an RS232 interface.
13. The wrist exerciser as claimed in claim 1, wherein the connection member of the rotor comprises a mini USB socket connector while the first connector of the transmission cable is a mini USB plug connector.
14. The wrist exerciser as claimed in claim 1, wherein the connection member of the rotor comprises an RS232 connector.
15. The wrist exerciser as claimed in claim 1, wherein the first connector of the transmission cable comprises a mini USB plug connector.
16. The wrist exerciser as claimed in claim 1, wherein the first connector of the transmission cable comprises a USB plug connector.
17. The wrist exerciser as claimed in claim 1, wherein the first connector of the transmission cable comprises an RS232 connector.
18. The wrist exerciser as claimed in claim 1 further comprising an electronic counter mounted to the casing.