Schneider Electric Harmony XB4 Series, Key Release, Emergency Stop Push Button Head

The Harmony XB4 metal range of modular control and signalling units combines simplicity of installation, flexibility, and robustness. This range meets the requirements of the majority of industrial applications.
These units are either complete products or separate components for customer assembly.
This range of XB4 includes:
•Pushbuttons, selectors/key switches, emergency stop functions or multiple-headed pushbuttons designed for parameter settings, adjustments, and start/stop control of machines and installations
•Pilot lights, illuminated pushbuttons, illuminated selector switches, and
•illuminated Emergency stop functions designed for visual signalling
The installation process is both simple and quick:
•Mounting by single installer (self-maintaining of the head in its cut-out)
•Clip-together component system (head, body, contact blocks, and LED)
•Attached using a single locking screw
•Anti-loosening system for screw clamp terminals on contact blocks

The performance of the Harmony XB4 range meets the most demanding international standards and approval, such as:
•EN/IEC, CE marking, UL, CSA, CCC, EAC, JIS, NEMA, and marine approvals
•Protection against ingress of solid objects, dust, and water: IP 66, 67, 69,69K and type 4X
•Shock protection level up to IK06
•High vibration resistance with shake proof connection screws (periodic retightening unnecessary)
For outdoor applications the operating temperature oscillate from -40 °C to +70 °C/-40 °F to +158 °F.

The range of XB4 can be used in the following applications:
•Industry (machine and control panels in packaging, material handling, material working, and pumping)
•Building and infrastructure (energy distribution panels, public works, restaurants, commercial buildings and airports)

This ZB4BS934 is a chromium plated unit (bezel material), which has mechanical durability up to 300000 cycles.
The resistance to high pressure washer is 7000000 Pa at 55 °C, distance: 0.1 m.
This item is classified as ’’ Green Premium Product ’’, which provides the following:
•Environmental information about the unit
•Minimal use of hazardous substances in, and beyond, compliance with regulations (RoHS, REACh)
•A promise of sustainable and environmentally friendly performance
•Product Environmental Profiles (PEPs) for easy carbon footprint calculation
•End-of-life instructions for reduced cost and optimised recycling

What is the different between a push button switch for an emergency stop and a general-purpose push button switch?