Overload Protection of Motors---Four Common Questions

The four most commonly asked questions regarding overload protection of small induction motors (up to 200 hp) are discussed. 1) What are the common causes of motor failures? 2) What types of overload protection are available, and what are the advantages and disadvantages of each? 3) When are three overload relays required? 4) Do moderm overload relays protect the new NEMA rerate motors?