Abstract
Municipal water pumps use an induction motor with a Fluke 434-II power quality analyzer to measure inrush current. To pump water from the river to the reserve tank, they use two parallel 120 HP motor pumps and two parallel 180 HP motor pumps to deliver water from the reserve tank to overhead tanks distributed across the municipal areas. Four control panels equipped with soft starters supply the motors. The soft starters’ purpose is to limit the motors’ inrush (starting) current, thereby reducing the electrical and mechanical stresses on the motors and pumps. The supplier is commissioning the entire new system. The measurement revealed that the transformer’s HT fuse tends to blow when a 180 HP motor starts, and a 120 HP motor is running. We also observed that this does not happen when a 180 HP motor runs, and a 120 HP motor starts. According to its nameplate, the transformer can supply the required current. We present the test results that demonstrate these issues.
Keywords: Fluke 434-II Power Quality Analyzer, Induction Motor, Inrush Current.