This Appleton AMP EXPLOSION PROOF SNAP SWITCH 120/277 VAC EDSF21AQ EDSC372SA is a sensor/switch manufactured by Appleton. It detects a change in state, position, or presence and relays that information to a controller or operator interface. Key specifications noted on this listing include 277 VAC, 20 AMP. It is commonly in packaging machinery, material handling, and automated inspection systems.
