
Source: Siemens 2023 | Author: Daniel Henningsen
Siemens offers a comprehensive portfolio for level measurement. This is divided into four different measurement principles:
- Rotation
- Vibration
- Capacitive
- Ultrasonic
This document aims to provide an overview of the individual measurement principles, understand the differences, and learn about their respective applications.
Technical Differences and Applications

Rotation - Rotary Paddle Detector
- A bearing-mounted paddle is driven by a synchronous motor.
- The product stops the rotation.
- Signal output indicates obstruction of the rotation.
- Once the paddle is free from the product, it resumes rotation, and the signal output (relay) indicates "probe free".
- Sensitivity is adjustable through the geometry of the paddle and the spring's return force.
Applications:
- Bulk materials (grain, feedstuffs, cement, plastic granules, wood chips)
- Food, stone/earth industry, glass, metallurgy, energy production, etc.
- with a bulk density of at least 15 g/l
- up to 10 m cable extension possible

Vibration - Tuning Fork and Rod
- The product covers the probe and dampens the vibration
- Signal output (relay or transistor) indicates probe covered
- When the probe is free from material pressure, it resumes vibration, and the signal output indicates "probe free"
- Various designs for liquids and bulk solids
- Depending on the model, extensions up to 4000 mm possible
Application Areas:
- Food, stone/earth industry, glass, metallurgy, energy generation, etc.
- LVS100: from 30 g/l → for free-flowing bulk solids
- LVS200: various designs
- Standard bulk solid (20 g/l)
- Interface measurement (50 g/l)
- Low bulk density (5 g/l)
- Monitoring of material buildup through optional 4-20 mA output possible - LVL100: Measurements under challenging conditions (air bubbles, foam, etc.)
- Sludges and liquids in confined installations and small pipes
- LVL200: Full, demand, and empty signaling for bulk solids with a minimum density
> 0.5 g/cm3

Capacitive RF Switches
- The probe serves as the measuring electrode of an electrical capacitor
- When the product reaches the probe, the capacitance increases, or the frequency decreases
- Signal output (relay or transistor) indicates probe covered
- When the probe is free again, the capacitance decreases (frequency increases) and the signal output indicates “probe free”
- Material build-up does not affect performance due to Active Shield Technology2
- CLS200 / CLS300 available in standard and digital versions (PROFIBUS PA)
Applications:
- Liquids, slurries, granulates
- Food, pharmaceutical, chemical industries, etc.
- CLS100/CLS200: capacitive switch with short installation length and cable extension
- CLS300: for extreme conditions, high temperatures, and pressures

Ultrasonic Level Switch
- Sending and receiving an ultrasonic wave
- The distance to the product is continuously measured
- When a predefined product distance is reached, the signal output switches
- If the distance increases, the signal output (relay or transistor) switches again
Applications:
- Bulk goods, sludges, and liquids
- Stone/earth industry, water/wastewater, etc.
- Max 3 m for bulk goods and 5 m for liquids
- Two switching contacts, pump control possible
Summary

1 Separation layer: In a separation layer, there are two media with different densities in a container, for example, water and oil.
2 Active Shield Technology: Measurement is unaffected by material deposits on the shielded part of the probe.