shell 11 in particular the cover 24 is substantially monolithic with the shell 11 to which it is pivoted with a side hinged movement by way of a longitudinal flexible articulation portion 25 the cover 24 also has a coupling 26 for reversible engagement with a locking tooth 27 in particular the described embodiment is particularly useful for motors intended for example for vacuum cleaners in motors intended for example for application in pumps it is instead better to provide the solution without a cover with particular reference to fig4 and 5 the device 10 is applied to an electric motor 15 which is provided with a particular connector 29 in a plastic cover 33 which accommodates electrical terminals 30 for connection to the windings 14 in particular the figures show the position of the protector 12 which is substantially perpendicular to the electrical terminals 30 to which it is connected by means of the laminas 17 in this case the cover 33 of the motor 15 has feet 34 which keep the thermal protector 12 pressed against the bottom of the shell 11 the application of a device 10 in a motor generally designated by the reference numeral 115 is described with particular reference to fig6 and 7 here too attention is called to the particular configuration of the connection between the protector 12 and inside a connector 131 of the cover 133 electrical terminals 132 for connection to the windings 114 in this case the cover 133 of the.