Measurement Equipment

The instrument used to monitor power quality conditions for this project is the BMI (Basic Measuring Instruments) 7100 PQNode. It has the capability to measure rms variations (sags/swells), high speed transients (switching impulse), waveshape faults (capacitor switching), and harmonic distortions (FTT). Any disturbance on a voltage channel automatically cross-triggers all current and voltage measurement channels for a complete three-phase analysis. Voltage sag and swell (rms) disturbance recording is controlled by the following settings: threshold, hysteresis, cycles to trigger (pickup time), cycles to end (dropout time), time interval for Min/Avg/Max computations, and number of time intervals for each record. Voltage impulse disturbance in the 5kHz to 1MHz frequency range are sensed by peak detector circuits. Sub-cycle voltage disturbances are detected by waveshape fault detection circuits. Voltage waveshape fault event data files contain two cycles of captured waveform data, including one cycle of pre-triggered and one cycle of post-triggered waveform. The instrument uses a patented Floating Window Algorithm that captures any distortion on the voltage waveform including sub-cycle events. All disturbance events and steady state data are time and date stamped. Data collected from the instrument can be correlated to operations in the City of Santa Clara's power system grid or operational changes inside the plant

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