What is the 2 stage stalling protection for PHT motor?

What is the 2 stage stalling protection for PHT motor?
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1 Answer

Answer :

Because locked rotors withstand time of motor is less than starting time of motor under reduced voltage conditions.

Stage 1 = 350% 6 sec for starting at rated voltage

(Because starting time = 6 sec + hot stall time = 7 sec)

Stage 2 = 175% 15 sec to permit 14 seconds starting time under reduced voltage condition

(Since starting current is less, stage 1 will not operate) 
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