We know phase resistance of an electric motor can change drastically with temperature. As temperature rises the resistance rises as a result of copper having a positive temperature coefficient. However, on a three phase motor even though the phase resistance values change with temperature the balance of resistance between the three phases should not change. For your medium and high voltage motors (> 4kV) the balance of resistance is often very low (<1%).  In fact, it is quite common to see values of imbalance in the one-hundredths of a percent (ex. .03%).  The standard MCEGold balance of resistance setpoints for a medium voltage motor is 1% (caution) and 2% (alarm) so a baseline balance of resistance of .03% would have to increase ~3000% to reach the 1% alarm setpoint. Therefore, it is important for you to consider establishing a change from baseline alarm setpoint for your balance of resistance in these situations to alert you to large changes in the circuit condition.