If a three phase running motor looses a phase then what would happen
It would refuse to take the load, sudden loss of rpm. Voltage protection relay trip the contractor, overload relay trip the contactor. Due to phase losses, if the motor gets overload, MCB would trip for balance over load. The motor will burn if it continues to run in phase failure condition so this problem must be solved quickly.
Motor will absorb a huge amount of negative sequence current which will create a dangerous overheating which can damage it. that is why it’s highly recommended to activate and set the 46 protection element in the relay protecting the motor