Power Testing Medium/High Voltage Motors

When performing power analysis testing on medium or high voltage motors, many companies have installed some form of test access panel for efficiency and safety purposes in compliance with the NFPA 70E. They commonly acquire volt¬age from the secondary of the power transformer (PT) and use that same voltage signal for all tests taken on each of the motor starters connected to that MCC. However, the acquired current signals are taken independent from each starter. A frequently asked question is whether or not the single access point for voltage is sufficient for all the starters on the MCC. Although there are potential problem locations between the PT access point and the motor, the indepen¬dent current acquired per starter will alert that a problem exists. Offline testing may be required to confirm a power cir¬cuit anomaly resulting in a voltage drop in one of the phases.

Tip provided by PdMA Corporation
Phone: 813-621-6463

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