Omron E3T-ST21 2M Photoelectric Sensor
Omron E3T-ST21 2M is an ultracompact through-beam photoelectric sensor for sensing opaque targets across a distance of up to 300 mm. Its 650 nm red LED establishes the optical path between the emitter and receiver, while the NPN open-collector output transfers the switching state to compatible control equipment. Light-ON operation defines the output behavior, and the sensor responds within 1 ms. It operates from 12 to 24 VDC and includes a 2 m pre-wired cable. Current consumption is 10 mA maximum for the emitter and 20 mA maximum for the receiver. Within the E3T Series, the E3T-ST21 2M provides the Light-ON NPN configuration. Related ultracompact through-beam sensors are available across Omron Sensors.
| Brand | Omron |
| Product | Photoelectric Sensors |
| Model Number | E3T-ST21 2M |
Omron E3T-ST21 2M Photoelectric Sensor – Technical Specifications
| Specification | Value |
|---|---|
| Sensing Method | Through-beam |
| Sensing Distance | 300 mm |
| Standard Sensing Object | Opaque, 2-mm dia. min. |
| Light Source | Red LED (650 nm) |
| Power Supply Voltage | 12 to 24 VDC , ripple (p-p) 10% max. |
| Output Configuration | NPN |
| Connection Method | Pre-wired 2 M cable |
| Current Consumption | 30 mA max. (Emitter 10 mA max., Receiver 20 mA max.) |
| Control Output | Load power supply voltage: 26.4 VDC max. Load current: 50 mA max. (residual voltage: 2 V max. for load current of 10 to 50 mA, 1 V max. for load current of less than 10 mA) Open-collector output |
| Operation Mode | Light-ON |
| Response Time | Operate or reset: 1 ms max. |
| Indicators | Operation indicator (orange), Stability indicator (green) |
| Ambient Illumination | Incandescent lamp: 5,000 lx max., Sunlight: 10,000 lx max. |
| Ambient Temperature Range | Operating: −25 to 55°C Storage: −40 to 70°C (with no icing or condensation) |
| Ambient Humidity Range | Operating: 35% to 85% Storage: 35% to 95% (with no condensation) |
| Insulation Resistance | 20 MΩ min. at 500 VDC |
| Dielectric Strength | AC1,000V, 50/60 Hz for 1 min. |
| Vibration Resistance | 10 to 2,000 Hz, 1.5-mm double amplitude or 300 m/s2 for 0.5 hours each in X, Y, and Z directions |
| Shock Resistance | 1,000 m/s2 3 times each in X, Y, and Z directions |
| Protection Circuits | Power supply and control output reverse polarity protection, Output short-circuit protection |
| Degree Of Protection | IEC 60529 IP67 |
| Material | PBT (polybutylene terephthalate), Denatured polyarylate |
| Weight | Approx. 40 g |
The Omron E3T-ST21 2M Photoelectric Sensor uses through-beam sensing across a maximum distance of 300 mm for opaque targets as small as 2 mm in diameter. A 650 nm red LED establishes the optical path between the emitter and receiver. The NPN open-collector output supports a load supply voltage of up to 26.4 VDC and a load current of up to 50 mA. Light-ON operation defines the switching behavior, while operate or reset time is specified at 1 ms maximum. The sensor operates from 12 to 24 VDC and uses a 2 m pre-wired cable. Total current consumption is 30 mA maximum, consisting of 10 mA maximum at the emitter and 20 mA maximum at the receiver.
For an Omron through-beam sensor requiring NPN output, Light-ON logic, and a 300 mm sensing distance, the relevant model is the E3T-ST21. Ambient-light resistance is specified at 5,000 lx for incandescent light and 10,000 lx for sunlight. Operating temperature extends from -25 to 55°C, while storage is specified from -40 to 70°C without icing or condensation. Power-supply and control-output reverse-polarity protection and output short-circuit protection are provided. PBT and denatured polyarylate are listed as construction materials. The specification also suits searches for an Omron 300 mm through-beam sensor and Omron NPN photoelectric sensor. For the corresponding Dark-ON version with the same sensing distance and NPN output, see the E3T-ST22 2M.
