335, Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 59+ for electromagnetic switches with time delay means.
(Electricity: Magnetically Operated Switches, Magnets, and Electromagnets; subclasses; 59+ for electromagnetic switches with time delay means)
Electricity: Magnetically Operated Switches, Magnets, and Electromagnets
subclasses
59+ for electromagnetic switches with time delay means