Eaton PKE12 Series Manual

Also see for PKE12 Series: Instruction leaflet Manual Manual Instruction leaflet Instruction leaflet

4710/15 MN03402004Z-DE/EN6 EngineeringOverload monitoringof Ex e motorsThe Ex e protection of motors is achieved by means ofspecial design measures. The motors are assigned to temper-ature classes on the basis of the highest permissible surfacetemperatures. In addition, temperature rise time tE and theratio of the starting current to the rated operational currentIA/IN are also determined and specified on the motor.The temperature rise time tE is the time in which the temper-ature of a winding rises from the final temperature in normaloperation to the limit temperature when a starting current ispresent IA.However, e motors are not safe on their own. Explosionsafety can only be achieved by taking additional measuresduring installation and by selecting appropriate operatingconditions (PTB testing regulations), e.g. by adding acorrectly rated and set overload protection to the circuit.Setting of the overcurrentprotection devicej Danger!The current-dependent protective device must be selectedso that not only the motor current is monitored but alsothe blocked motor is switched off within the temperaturerise time tE. This means that the protective device must berated in such a way as to ensure that tripping time tA forthe explosion-proof electric motor‘s ratio IA/IN is notlonger than the motor‘s temperature rise time tE accordingto the motor's characteristic curve. This is to ensure thatthe motor will be reliably switched off within the temper-ature rise time.The tolerance of the overcurrent release of g20 % is to beobserved (a following example).