Induction motor overvoltage due to power factor improvement capacitor

The problem of damaging overvoltages which result from using an oversized power factor correction capacitor is studied using digital simulation techniques. The overvoltages can occur during disconnection from the sources. The results are compared with results obtained from experiments performed on a 1.5 HP, 208 V, three-phase motor. The computer plots and experimental results indicate that no problem is encountered with the correction up to 100% or less. The major hazardous effect of these capacitors at no load is that the terminal voltage is sustained for several seconds. It is clear from the stimulation results that while the problem of overvoltage may have been significant in the machines constructed 40 or 50 years ago, it is probably no longer a concern in the modern machine design. This can be attributed to the fact that newer machines are constructed with less steel and, hence, operate deep into the saturation region.<>