Improving existing motor protection for medium voltage motors

摘要

The authors analyze motor failures and the associated costs. The abilities and limitations of older forms of motor protection utilizing induction type over current relays are contrasted with the desired protection. The features of several different types of current microprocessor-based relays are reviewed as eligible candidates for motor protection upgrades. An example of work performed as part of a comprehensive field retrofit is presented, as well as the associated economic considerations.