Frequently Asked Questions: Motor Protection

What is rise time

The Pulse Width Modulation voltage takes some time to rise from its minimum to its maximum value. This period is often called “rise time”. Due to the great rapidity of switching on the variable frequency drive stage, the growth of the voltage wavefront takes place too fast and, with the power electronics advance, these transition… Read more »

What is Peak Voltage?

Peak voltage is the highest point or highest value of voltage for any voltage waveform. It is a power quality issue that occurs when devices that use Pulse Width Modulation, such as a variable frequency drive, is added to a power system.  The resulting peak voltage is a result of the switching speed and length…

What is common mode current?

The common mode voltage produced by the typical PWM drive induces common mode currents that travel through parasitic capacitances located in the cable and motor. Common mode currents flow through the bearings of the motor itself. This causes an effect known as “fluting” or “bearing currents.” As low common mode current discharges through the bearing,… Read more »