Advanced thermal overload protection for high tension motors using digital protection relays

The modern multiphase Medium Voltage motors are generally very robust and reliable, but advanced and intelligent protection devices are required to give adequate protection, as the modern designs operate very close to their thermal limits. The age of protecting the rotating equipments using electromechanical devices has now diminished. The present day scenario is that motor protection is now accomplished with digital protection relays. These motor protection relays are capable to monitor and diagnose long-term failure, based on the information collected and processed by powerful data acquisition systems. The world of motor protection sets up inimitable challenges, the most vital being the thermal protection. This paper presents an advanced thermal overload protection technique using smart digital relays to protect High Tension motors, along with the basic protection functions.