The CWCS10 Series Capacitance Sensor is a non-contact position measuring system based on the principle of capacitance micrometry.
The CWCS10 Series is suitable for vacuum,high temperature and lowest temperature. And we are able to customize the sensor to a wide range oftechnical specifications.
Measurement ranges 50 µm up to 10 mm
extremely high resolution (Nanometer)
High class electronics, one or multi-channel
Accuracy is independent of temperature
MAIN FEATURES
Measurement ranges 50 µm up to 10 mm High class electronics, one or multi-channel,Cost efective electronics CL extremely high resolution (Nanometer) Accuracy is independent of temperature Temperature range -50 to +200 °C,custom probes up to +450 °C Analog output 0...10 V Protection class sensors up to IP68 Reliable measurements even in extreme environments,like nuclear radiation, high vacuum or near 0 K Customized probes feasible | |
Influence of temperature
The main temperature influence is the longitudinal elongation of the sensor material. Customised versions made of INVAR are available on request. The maximum operating temperature is limited by the melting temperature of the soldering material inside the connector. Measurements at extremely low temperatures, close to the absolute zero, were successfully conducted with our standard probes (Fa. Dornier, FZ Karlsruhe, ETH Zürich).
Measurements in liquids
When carrying out measurements in liquids, which should only be done in special cases, one should consider that the measurements are not only affected by impurities but also by gas bubbles. The real distance is found by multiplying the distance (provided by the meter) with the dielectric constant (epsilon) of the fluid. Please also consider that generally the dielectric constants of liquids are temperature dependent and that the dielectric losses of the liquids used must be negligible, i.e. the liquids must be insulating.
Magnetic fields
Magnetic fields can be neglected, as long as there is no exertion of force to the measurement system. On request the sensor heads can be made of non-magnetic material, like Titanium.
Radioactive radiation
Radioactive radiation has no influence on measurements performed by capacitive sensors. Appropriate insulation materials guarantee long term operation, without failure.
Specific resistance
The relatively low carrier frequency of the system allows measurement at materials in the micro ohm to kilo ohm range (μΩ cm up to > 1000 Ω cm) without special recalibration. This also covers the entire range of the semiconductor silicon. This fact is of great importance when measuring on case-hardened shafts in the mechanical engineering sector. This is because an inhomogeneous micro-structure has no influence on the measurement results. There is almost no other method to control the displacement of a shaft running in oil in a sliding bearing than by a capacitive sensor.
Measurements on insulation material
The capacitive sensors can also be used to measure the thickness of non-conductive materials such as plastics, foils, quartz, glass, ceramics, etc.
Averaging
The sensors active area measures the average distance to the object. The roughness of an objects surface is automatically averaged by the system. This feature is of advantage when small irregularities should not be observed. The average distance is also measured in cases where the target has a curved surface.
Customised probes (sensor heads)
No other measurement principle allows for such cheap and simple adaptations of the probe housing or the active area according to the customer needs. The reason for this is the pure mechanical construction consisting of conducting electrodes and insulating barrier sheets (plastics, ceramics, glass).
Features
The device measures, without contact, the distance between the front side of the sensor and the conductive surface of the target. Sensor and target form an electrical capacitor. The device is calibrated in length units. It includes a display and a compensator with digits. Therefore, static measurements with the compensation method as well as the deflection method are possible. An outlet provides a voltage value proportional to the distance for static and dynamic measurements. The zero point of the output voltage may be accurately shifted by means of the compensator.
Typical applications
The CS system can be used to measure shaft movements in bearings, rotor vibrations, the smoothness of running of machine tools, static and dynamic deformations, vibrations in a plane, module of elasticity, coefficient of thermal expansion, circularity of shafts and bore holes and so on.
Changing the sensor head
Due to the small sensitivity tolerances of the sensors it is possible to exchange sensors without recalibrating the CS electronics. A total accuracy of ±0.5% is still guaranteed.
Additional output
For special applications the sensitivity of the output voltage may be adjusted by a factor 0 to 10 (Socket “VARI.” and adjustment by “FACTOR”).
CWCS10 Series Sensors has been widely used for vibration control or measurement and for position drift measurement.
• Dynamic measurement on turbines and motors
• Offset and wear measurement on bearings
• Concentricity measurement on axes, shafts and bores
• Measurement of modulus of elasticity and thermal expansion
• Distance measurement in the low temperature range and high temperature range up to 450 °C
• Reference system for other distance sensors
• Tolerance verification in mass production
• Vibration measurements
• Elongation measurements
• Thickness measurement and control of thin metal foils and plastic foils, also during production
• Measurement of thickness, bevel and deflection of wafers in semiconductor production
| C0005 | C0020 | C0050 | C0100 | C0200 | C0300 | C0500 | C1000 | ||
| Measurement range | [mm] | 0.05 | 0.2 | 0.5 | 1 | 2 | 3 | 5 | 10 |
| Linearity 1) | [%] | ±0.2 | |||||||
| Resolution dynamic 1) | [%] | 0.01 | |||||||
| Sensitivity | [μm/V] | 5 ±0.2% | 20 ±0.2% | 50 ±0.2% | 100 ±0.2% | 200 ±0.2% | 300 ±0.2% | 500 ±0.2% | 1000 ±0.2% |
| Tolerance of sensitivity 2) | [%] | ±2 | ±1 | ±0.5 | |||||
| Temperature error sensitivity | [x10-6/K] | -3 | -0.3 | -11 | -1.1 | -3 | |||
| Coefficient of thermal expansion | [μm/K] | 0.03 | 0.06 | 0.17 | |||||
| Operating temperature | [°C] | -50...+200 | |||||||
| Diameter active area | [mm] | 1.1 | 2.3 | 3.8 | 5.5 | 7.9 | 9.8 | 12.6 | 17.7 |
| Minimum target diameter | [mm] | 3 | 6 | 7 | 9 | 17 | 27 | 37 | 57 |
| Connection cable 3) | L13-12, L13-14, L33-12, L33-14 | L13-11, L13-13, L33-11, L33-13 | |||||||
| Weight | [g] | 1.7 | 2.5 | 5.7 | 7.1 | 61 | 95 | 120 | 230 |
| Housing material (DIN EN 10027-2) | 1.3912 | 1.4104 | 1.4305 | ||||||
| 1) depending on the connected electronics 2) manufacturing tolerance 3) only use listed cables. For more information see section „Cables“. | |||||||||
| CL | CL3M | C1 | CS1 | ||
| Number of channels | 1 | ||||
| Linearity 1) (at 0...40 °C, dielectric: air) | [%] | <±0.4< td=""> | ±0.2 | ±0.1 | ±0.2 |
| Repeatability | [%] | 0.02 2) | ±0.05 1) | ||
| Sampling rate | [kHz] | 0.5 | 4.5 | ||
| Display | - | 4.5 digits | |||
| Power supply | 100...240 V, 50 Hz / 60 Hz | 115 V, 60 Hz / 230 V, 50 Hz | |||
| Power consumption | [VA] | 5 | 9 | 18 | |
| Operating temperature | [°C] | 0...+70 | 0...+85 | 0...+50 | |
| Storage temperature | [°C] | -20...+80 | -20...+90 | -20...+70 | |
| Warm up time | [min] | 3 | 30 | ||
| Weight | [kg] | 0.35 | 0.7 | 3.7 | 4 |
| Dimensions (W x H x D) | [mm] | 64 x 35 x 115 | 80 x 60 x 170 | 180 x 150 x 265 | 260 x 150 x 265 |
| Housing construction | aluminium die-cast | 19“ system, 3 HE | |||
| Amplifier with trimming potentiometer | no | yes | no | ||
| Voltage output | „OUT“ | „NORM“ | „OUT“ | ||
| Sensitivity 3) | 10 V/mm ±0.2% | ||||
| Linearity | [%] | <±0.4< td=""> | ±0.2 | ||
| Temperature error sensitivity | [%/°C] | <0.02< td=""> | <0.01< td=""> | ||
| Temperature drift offset (Ua = 0 V) | [mV/°C] | - | <±0.3< td=""> | ||
| Long term drift offset (Ua = 0 V) | - | <±1 mV/week, <±10 mV/year | |||
| Output voltage max. | ±10 V | ||||
| Output current max. | ±5 mA | ||||
| Frequency dependency | 0...500 Hz (-3 dB) | 0...4 kHz: ±1 % / 0...6 kHz: -3 dB | |||
| Noise | <10 mVPP | Ua = 0 V:<5 mVPP, typ. 2 mVPP / Ua = 10 V:<10 mVPP | |||
| Connector | LEMO | BNC | |||
| Additional output 4) | - | „VARI“ | - | ||
| Sensitivity factor | - | 0...10 | - | ||
| 1) based on the measurement range 2) based on the resolution 3) These specifcations are valid for the use of the probe C0100 (measurement range 0...1000 μm). The display and its labelling are designed for 0...1000 μm. All other probes may also be used with the electronics. The reading has to be converted with an integer factor according to the used probe. 4) Ua = 0 V: The output voltage can be adjusted to zero over the full scale by using the potentiometer. By doing this the influence of drift, temperature and noise are the smallest (= compensation method). Especially during long-term measurement with small value changes this method is recommended. | |||||
| CS2 | CS3 | CS4 | CS5 | CS6 | CS7 | CS8 | ||
| Number of channels | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |
| Linearity 1) (at 0...40 °C, dielectric: air) | [%] | ±0.2 | ||||||
| Repeatability 1) | [%] | ±0.05 | ||||||
| Sampling rate | [kHz] | 4.5 | ||||||
| Display | 4.5 digits | |||||||
| Power supply | 115 V, 60 Hz / 230 V, 50 Hz | |||||||
| Power consumption | [VA] | 18 | 22.7 | 27.3 | 32 | 36.7 | 41.3 | 46 |
| Operating temperature | [°C] | 0...+50 | ||||||
| Storage temperature | [°C] | -20...+70 | ||||||
| Warm up time | [min] | 30 | ||||||
| Weight | [kg] | 4 | 4.7 | 5.3 | 6 | 6.7 | 7.3 | 8 |
| Dimensions (W x H x D) | [mm] | 260 x 150 x 265 | 295 x 150 x 265 | 330 x 150 x 265 | 365 x 150 x 265 | 400 x 150 x 265 | 435 x 150 x 265 | 470 x 150 x 265 |
| Housing construction | 19“ System, 3 HE | |||||||
| Voltage output | „OUT“ | |||||||
| Sensitivity 2) | 10 V/mm ±0.2% | |||||||
| Linearity | [%] | ±0.2 | ||||||
| Temperature error sensitivity | [%/°C] | <0.01< td=""> | ||||||
| Temperature drift offset (Ua = 0 V) | [mV/°C] | <±0.3< td=""> | ||||||
| Long term drift offset (Ua = 0 V) | <±2 mV/week, <±20 mV/year | |||||||
| Output voltage max. | ±10 V | |||||||
| Output current max. | ±5 mA | |||||||
| Frequency dependency | 0...4 kHz: ±1 % / 0...6 kHz: -3 dB | |||||||
| Noise | Ua = 0 V:<5 mVPP, typ. 2 mVPP / Ua = 10 V:<10 mVPP | |||||||
| 1) based on the measurement range 2) These specifcations are valid for the use of the probe C0100 (measurement range 0...1000 μm). The display and its labelling are designed for 0...1000 μm. All other probes may also be used with the electronics. The reading has to be converted with an integer factor according to the used probe. | ||||||||
The design of the CS electronics is based on the fact that the reactance of an ideal plate capacitor is proportional to the distance between the plates. The measurement sensor is a guard ring capacitor, whose guard ring is connected to the inner shield of the double shielded measuring cable. A negative feedback amplifier keeps this protective shield tuned exactly to the potential of the sensor’s centre electrode. This ensures an almost homogeneous field between the capacitor plates along the entire measuring range and nearly complete independence of changes in cable capacity. If an alternating current of constant amplitude and frequency passes through the sensor capacitor, the amplitude of the alternating voltage between the capacitor plates (electrode of sensor and object to be measured) is proportional to the distance between the two. The sensor’s power supply as well as a compensating voltage which can be selected by means of a precision potentiometer is provided by a 20-kHz-oscillator of highly constant amplitude and frequency. The sensor voltage and the compensating voltage are rectified by means of a rectifier with high linearity and zero stability. Through a low-pass filter and an amplifier the voltage difference is conducted towards the output terminal. The display shows the distance between the object to be measured and the front side of the sensor.
As described in the above section the measurement of the distance meter is affected by the properties of the dielectric. Generally, the sensor will be used for measurements in air. The area between the sensor and the target should be completely free of dust, oil or water. If necessary, this can be achieved by blowing air through the gap between sensor and target.
CWCS10 Series Sensors has been widely used for vibration control or measurement and for position drift measurement.
• Dynamic measurement on turbines and motors
• Offset and wear measurement on bearings
• Concentricity measurement on axes, shafts and bores
• Measurement of modulus of elasticity and thermal expansion
• Distance measurement in the low temperature range and high temperature range up to 450 °C
• Reference system for other distance sensors
• Tolerance verification in mass production
• Vibration measurements
• Elongation measurements
• Thickness measurement and control of thin metal foils and plastic foils, also during production
• Measurement of thickness, bevel and deflection of wafers in semiconductor production
CWCS10 Series Sensors has been widely used for vibration control or measurement and for position drift measurement.
• Dynamic measurement on turbines and motors
• Offset and wear measurement on bearings
• Concentricity measurement on axes, shafts and bores
• Measurement of modulus of elasticity and thermal expansion
• Distance measurement in the low temperature range and high temperature range up to 450 °C
• Reference system for other distance sensors
• Tolerance verification in mass production
• Vibration measurements
• Elongation measurements
• Thickness measurement and control of thin metal foils and plastic foils, also during production
• Measurement of thickness, bevel and deflection of wafers in semiconductor production
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