Abstract: A gas-insulated apparatus is equipped inside with multiple sensors for sensing a partial discharge signal caused by a foreign substance, and a frequency analyzing section for analyzing the frequency of the sensed partial discharge signal. A defect type judging section estimates the defect type of the foreign substance from the signal obtained through the frequency analysis or from the voltage phase distribution of partial discharge synchronized with the frequency of the voltage applied to the gas-insulated apparatus, and a location determining section estimates the defect location and signal intensity from the multiple partial discharge signals. A defect size calculating section estimates the defect size for each defect type from the signal intensity and field distribution at the defect location. Dielectric breakdown risk evaluation is performed based on the defect size and type, and the insulation failure risk is diagnosed from the partial discharge.

Abstract: In the measurement of partial discharge, a voltage detected by an antenna is input to a spectrum analyzer and a phase difference between an operating voltage and a power supply of the spectrum analyzer is obtained by phase domain analysis using the spectrum analyzer. Based on the phase difference and the voltage phase shift associated with the input impedance of a signal converter circuit, the time axis displayed on the screen of the spectrum analyzer is compensated. After the compensation has been carried out, the voltage detected by the antenna is input into the spectrum analyzer and the partial discharge pattern which synchronizes with the operating voltage is measured by phase domain analysis using the spectrum analyzer.

Abstract: Prior to the measurement of partial discharge, a voltage detected by the antenna is inputted into a spectrum analyzer, a phase difference between an operating voltage and a power supply of the spectrum analyzer is obtained by phase domain analysis using the spectrum analyzer. Based on the phase difference and the voltage phase shift associated with input impedance of the signal converter circuit, the time axis displayed on the screen of the spectrum analyzer is compensated. After the compensation has been carried out, the voltage detected by the antenna is inputted into the spectrum analyzer, the partial discharge pattern which synchronizes with the operating voltage is measured by phase domain analysis using the spectrum analyzer.

Abstract: A forklift has a travelling carriage, a straddle arm disposed on the travelling carriage, a mast disposed on the straddle arm to be reciprocally movable in a horizontal direction, a fork disposed on the mast to be movable up and down, and a cover disposed on the travelling carriage. When the mast is in a reach-in operation, the cover covers at least an upper side of an article supported by the fork.

Abstract: A forklift has a travelling carriage, a straddle arm disposed on the travelling carriage, a mast disposed on the straddle arm to be reciprocally movable in a horizontal direction, a fork disposed on the mast to be movable up and downm, and a cover disposed on the travelling carriage. When the mast is in a reach-in operation, the cover covers at least an upper side of an article supported by the fork.