Isn't capacitance also related to parallel plate area?
Yes it is. In most cases the grounded target area is larger than the Probe's measuring surface, making the probes surface the controlling parameter. The larger probe surface the greater the maximum range. In cases where the target area is smaller than the Probe surface (such as edges or small diameters), extra care must be taken to define the measurement area.
What about target material?
The signal is independent of (ferrous and non-ferrous) material properties that affect other non-contacting systems. Many "semi-conductive" materials can also be measured. To date this has included silicon semi-conductor, carbon and graphite composites, sand, soil, and water surfaces. This property of a capacitive system is extremely useful because it eliminates the need for recalibration when measuring targets of different metals.
Does the target material have to be conductive?
Temperature errors are limited to instrument stability (which is excellent), thermal expansion offsets and the change in the dielectric of air which is generally the dielectric medium. Fortunately, the dielectric constant of air changes only 4% from room temperature to 1400˚F (760˚C). High temperature performance of capacitance probes in air is generally limited by the electrical ionization of air at higher temperatures.
What is the principle of operation?
The Capacitec Amplifier produces an analog output voltage proportional to the distance between the probe face and an electrically conductive surface, connected to the Amplifier signal ground. The principle of this conversion is based on the fact that capacitive reactance (Xc) is proportional to the spacing of a parallel-plate capacitor, which is formed by the Probe's Sensor & Guard and the target surface.
What is a capacitive sensor?
A capacitive sensor detects changes in capacitance between two conductive plates, allowing for precise, non-contact measurement of gaps and distances.
How does a capacitive sensor work?
It measures the change in capacitance caused by the variation in the distance between the sensor and the target surface.
What are the key advantages of capacitive sensors over feeler gauges?
Capacitive sensors provide non-contact measurements, eliminating wear and tear, and offer higher precision and repeatability.
Can capacitive sensors detect small gaps?
Yes, they are capable of measuring very small gaps, offering high resolution and sensitivity.
Are capacitive sensors suitable for high-precision applications?
Yes, they have a thinness of as little as 0.004 “ (0.100mm) with resolutions as fine as 0.0001” (0.003 mm), making them ideal for high-precision measurements.
Can capacitive sensors measure gaps in conductive and non-conductive materials?
Yes, they can detect both conductive and non-conductive targets, including semi-conductive materials like silicon and graphite composites.
What is the typical measurement range of capacitive sensors?
Capacitive sensors can measure distances up to approximately 0.260” (6.60 mm) with high precision.
How fast can capacitive sensors take measurements?
They offer high bandwidth, capable of measuring very quickly, which is beneficial for high-volume applications. Sampling rates of 100Hz to 16Kz are very common.
Do capacitive sensors require direct contact with the target?
No, they are non-contact sensors, which prevent damage to delicate surfaces and eliminates the need for physical calibration.
How does temperature affect capacitive sensor measurements?
Capacitive sensors exhibit low temperature sensitivity, with the dielectric constant of air changing only about 4% from room temperature to 1600°F (800°C).
Are capacitive sensors affected by environmental conditions like humidity?
While they have strong environmental adaptability, extreme humidity levels can influence their performance, necessitating careful design considerations.
Do capacitive sensors require frequent calibration?
No, they generally maintain their calibration over time, reducing the need for frequent adjustments.
Can capacitive sensors be used in harsh environments?
Yes, they are robust and can operate in harsh environments, including exposure to corrosive substances and high-pressure conditions as well as Cryogenic to 1,000°C, Radiation up to 1018 RADS and strong magnetic fields to 10 Tesla.
How do capacitive sensors compare to traditional feeler gauges in terms of speed?
Capacitive sensors provide immediate readings, whereas feeler gauges require manual insertion and measurement, which is time-consuming.
Are capacitive sensors cost-effective?
Yes, ROIs are sometimes calculated in terms of months by increasing accuracy, eliminating waste and rework often due to operator subjectivity.
Can capacitive sensors measure dynamic changes?
Yes, they can measure dynamic changes in position, making them suitable for monitoring moving components.
What is the response time of capacitive sensors?
Capacitive sensors have a fast response time, with some MEMS devices operating in the millisecond range.