We have proposed a novel planar lightwave circuit (PLC) optical sensor to monitor the contamination in a flow-cell where water is continuously supplied through a water quality measurement system. We designed a PLC chip with a V-shape waveguide and the simulated its function as a sensor for monitoring contamination in a flow-cell using a numerical the FDTD (finite-difference time-domain) analysis. A novel cross type of waveguide was introduced to make the PLC chip of the V-shaped waveguide. The fabricated PLC was cut into the cross waveguide. A change in the optical propagation loss of the PLC sensor was observed after immersing the PLC sensor into city water. It was determined that the propagation loss of the PLC sensor was 3 dB at a wavelength of 1.55 μm in the city water for 15 days.

Diagnostic tests were performed on two high voltage (HV) motor stator windings. These tests included the measurement of insulation resistance, polarization index, AC current, dissipation factor (tanδ) and partial discharge (PD) magnitude. Surface contamination of HV motor stator windings has an effect on the AC current and tanδ. When the stator windings were finished cleaning and insulation reinforcement, the increase rate of AC current (ΔI) and dissipation factor (Δtanδ) were very small compared to those before cleaning. However, the PD magnitude remained the same. These tests show that cleaning and insulation reinforcement of HV motor stator windings can reduce the insulation failure.

A bushing is very important because it must supply the high voltage to the power equipment. Generally, the surface of bushing is contaminated with rain, dust, salt and others. A bushing with contaminations at air are serious problem in insulation. Therefore, it is important to understand the inspection and diagnoses of the safety. The ultra-violet rays(UV) camera has attracted interest from the view point of easy judgement. In this paper, we will report on the corona discharge characteristics on bushing model with contaminations. Also, UV images of discharge in air are analyzed using prototype UV camera of Korea. These results are studied at both AC and DC voltage under a non-uniform field.