Adjustable speed drive systems shall be protected against motor overtemperature conditions by all but which of the following choices? Note that the overtemperature protection is in addition to the conductor protection required in 430.32.
A) A thermal sensor embedded in the motor that’s received and acted upon by an adjustable speed drive
B) An overtemperature protection relay that uses thermal sensors embedded in the motor and meeting the requirements of 430.32(A)(2) or (B)(2)
C) An adjustable speed drive controller with load and speed-sensitive overload protection and thermal memory retention upon shutdown or power loss
D) Motor thermal protector in accordance with 430.32
E) All of the above
Explanation: Per a 2005 change, 430.126 was added to take into account overtemperature of adjustable speed drive systems. The four items listed are all permitted to be used.
Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at [email protected].