It is a desirable form of overload protection, particularly if the protected motor is exposed to above-normal ambient temperature. Winding insulation heated by routine operation AND high ambients should properly use some means of stator-temperature sensing, and that is not possible with a starter-mounted overload block, and is especially useless if the starter-mounted overload relay is "ambient compensated."
Be careful if "2-wire" control is used—there is a potential violation at 430-43. Automatic Restarting.
Motor replacement in a hazardous location is usually more expensive than for open-drip or TEFC motors, from a process-interruption standpoint.
[This message has been edited by Bjarney (edited 04-10-2003).]
