Description
Probe tube and silo wall are the two electrodes of a capacitor. With air between them the capacitance has a given value; when bulk material with a higher dielectric constant replaces the air, the capacitance rises and the charging time with it. The electronics evaluate that change and switch the relay contact when the adjusted limit is reached. The probe is a zinc-plated steel tube of 1 inch and 1000 mm carried by a Pythagoras ceramic; the angle between probe and body is adjustable between 90 and 180 degrees. The device is flanged to the silo with DN100 and a mating flange welded to the wall, which makes it suitable for steel silos and steel hoppers; with a modified mounting — a counter electrode of grating — concrete silos are possible too. Inside the silo it works up to +400 °C. The output is one potential-free change-over contact; a red LED shows the switching state.
Measurement and output
- Capacitive against the silo wall
- Bulk goods with dielectric constant > 2.5
- Initial capacitance adjustable to approx. 400 pF
- Switching range 0 … 0.5 m
- Output 1 potential-free change-over contact
- 250 V AC / 4 A, 100 V DC / 4 A
- Switching delay approx. 0.5 s plus 1.5 s
- Red LED shows the switching state
Device and mounting
- Process connection flange DN100/114
- Mating flange DN100 to weld onto the silo
- Probe steel tube 1", zinc plated, 1000 mm
- Carrier Pythagoras ceramic Ø 65 × 283 mm
- Probe angle 90 … 180°, adjustable
- Enclosure diecast aluminium, IP 65
- Cable entry 1 × M 20 × 1.5, up to 2.5 mm²
- In the silo 0 … +400 °C, weight approx. 20 kg
All technical data, dimensions and available versions are listed in the datasheet for download.