This Siemens 52NL37 preprinted legend plate is 1-7/16" height and 2" width, has black letters on a silver background, and reads "HAND-OFF-AUTO." for identifying Siemens selector switch units. The legend plate is used with 3/4" National Pipe Straight Mechanical (NPSM) and 30 mm threaded mounting shafts (not included) that are located on a minimum of 2-1/2" centers. This legend plate is made of brushed aluminum for resistance to corrosion and weather and is suitable for use in an explosively hazardous or wet and oily location in a manufacturing process control system.
Pushbutton switches make or break electrical connections as part of a system that controls a process, such as a manufacturing line. Indicator lights with labels or color-coded caps are used to display the current state of a process, such as "completed." The pushbutton unit is composed of a pushbutton actuator for making or breaking electrical connections, a holder for securing the actuator to a control panel and for housing a light, and one or more contact blocks for connection to electrical wiring. Contacts within a contact block can be normally open (NO) or normally closed (NC), so that pressing the button starts or stops a process. Holders accommodate a range of control panel thicknesses and may include lamps to illuminate the button. Pushbutton actuator head types include mushroom, flat-surface, raised-surface, and key-operated, and may be illuminated, color-coded, and labeled. According to the requirements of an application, actuators may operate only as long as the button is held or they may lock into position when pushed and unlock when pulled or twisted. Pushbuttons and indicator lights are used in applications such as manufacturing process controls and as emergency shutoffs in industrial workplaces.
Siemens manufactures electronic products for building automation, industrial drives, lighting, energy generation, medical equipment, and rail transportation. The company, founded in 1847 and headquartered in Munich, Germany, meets International Standards Organization (ISO) standards 14001, 9001 and TS 16949.