The SICK WT34-R220 is a diffuse reflection photoelectric proximity sensor with background suppression from the W34 series. It detects objects up to 2.5 m with a minimum sensing distance of 100 mm, using an LED infrared light source. The relay changeover contact output handles up to 4 A at 250 V, switching light-ON or dark-ON. Response time is 10 ms.
The 2.5 m sensing range with background suppression means the sensor ignores reflective backgrounds beyond the set point — useful on conveyors where the belt or a far wall could cause false triggers. The 100 mm minimum sensing distance sets the close-in blind zone; objects nearer than that won't be reliably detected. The relay output (1 changeover contact) rated at 4 A / 250 V can switch a small contactor or PLC input directly, but watch the inrush if driving a DC load — the relay's mechanical life is the limiting factor, not the 4 A continuous. The 10 ms response time is typical for a relay-output photoelectric; fine for box detection on a slow line, too slow for high-speed counting. IP67 means the housing is dust-tight and protected against temporary immersion — good for washdown areas but not continuous submersion. The M16 terminal connection allows field wiring without a separate connector, though you'll need to gland the cable properly to maintain the seal.
This class of background-suppression photoelectric sensor is common on packaging lines, material handling conveyors, and automated assembly stations — anywhere you need to detect an object's presence against a variable or reflective background. The 2.5 m range covers most short-to-medium distance detection zones inside a machine guard.