According to EN 60079-7 the temperature rise for machines with cage rotors shall be limited. This can be done by using a current-dependent safety device.
In this case the fault tolerance according to the temperature rise of the motor is 0. A safety device with SIL 1 and a hardware fault tolerance of 0 is necessary to fulfil the requirements of Category 2 equipment. This has additionally to be considered, when designing a complex overload protective device for an Ex e motor according to EN 60079-7.
NOTE The general requirements for Ex e overload protection devices are given in EN 60079-7 and EN 60079-14
Keep up good work!
Arpad
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