The overvoltage can cause excessive current to flow as well as creating excessive voltage stresses. In both cases, the electrical insulation system inside the motor or equipment can be degraded reducing life or causing damage.

What is the effect of overvoltage?

EFFECTS OF OVER VOLTAGES ON POWER SYSTEMS

damage to them when it frequently occurs. Over voltage caused by surges can result in spark over and flash over between phase and ground at the weakest point in the network, breakdown of gaseous/solid/ liquid insulation, failure of transformers and rotating machines.

Is over voltage dangerous?

cannot cope with any additional current and voltage peaks. Without effective protection, the overvoltages destroy sensitive electronic components in the circuits of the connected appliances. ... The most dangerous causes are very high voltage peaks caused by indirect lightning strikes.