Eddy current measurement is a non-contact technique that allows for precise displacement detection without physical contact with the object being measured. This makes it ideal for applications where mechanical contact could damage the surface or interfere with the measurement process. Non-contact sensors are especially useful in environments where the surface must remain untouched, or when long-term reliability and sensor life are critical.
In technical terms, eddy current measurement falls under the category of inductive sensing. The principle relies on an oscillating circuit that generates a magnetic field around a coil within the sensor probe. When a conductive material is placed near this field, eddy currents are induced in the material due to Faraday’s law of electromagnetic induction. These currents create their own opposing magnetic field, which alters the impedance of the coil. This change in impedance is directly proportional to the distance between the sensor and the object, allowing the system to calculate the position accurately.
The eddy current method can be used on all electrically conductive materials. Even if the surface is covered by an insulating layer, as long as there is a conductive material beneath, the sensor can still function effectively. The design of the coil allows for compact sensors that can operate reliably in high-temperature environments, making them suitable for industrial and demanding applications.
German eddy current sensors are known for their robustness and ability to perform in harsh conditions such as dust, moisture, oil, and pressure. However, they do have certain limitations. For instance, each application typically requires specific linearity calibration, and the output signal can be influenced by the material properties of the object being measured. Despite these challenges, these sensors are capable of achieving nano-scale resolution, making them highly accurate.
Currently, German eddy current sensors can measure ranges from 100 micrometers to 100 millimeters, with installation spaces varying from 2 mm to 140 mm depending on the range. In mechanical engineering, displacement sensors are essential for controlling motion, monitoring fluid levels, and ensuring product quality. They are often used in extreme environments, including exposure to oil, steam, temperature fluctuations, vibration, and strong electromagnetic fields.
Some applications require high accuracy, temperature stability, fine resolution, and fast response times. Different measurement techniques have their own advantages and disadvantages, so there's no one-size-fits-all solution. Eddy current sensors can be either shielded or unshielded. Shielded sensors produce a more focused electromagnetic field and are less affected by nearby metallic objects, while unshielded sensors have a broader range but may be more sensitive to external interference.
With over 40 years of experience, German manufacturers continue to innovate and improve displacement sensor technology. Their advancements have been crucial in research, testing, quality control, and equipment monitoring. The eddyNCDT product family, for example, offers a maximum cut-off frequency of 25 kHz while maintaining nanometer-level precision.
A common application of eddy current sensors is in fully automatic welding testers, which are used for weld quality control. These sensors are preferred in such settings because they can withstand the strong electromagnetic fields generated by welding robots. They also provide micron-level accuracy over a 4 mm measurement range, making them ideal for precise and reliable monitoring in industrial environments.
APM DC source system is programmable DC Power Supply which can output high power. Users can set the output voltage,current arbitrarily .Measure all kinds of features and display on VFD. As for this DC source system,output voltage is up to 1200VDC max (recommend not to exceed 800V) by connecting the internal single unit in series.
High voltage dc power supply output current is up to 2000A max by connecting the internal single unit in parallel. Maximum power and height of the adjustable power supply is in 10.8kW, 21.6kW, 36kW and 6U, 12U ,20U high respectively.
Some features as below:
- With accurate voltage and current measurement capability.
- Coded Knob, multifunctional keyboard.
- Standard RS232/RS485/USB/LAN communication interfaces, GPIB is optional.
- Remote sensing line voltage drop compensation.
- Equips with LIST waveform editing function.
- Use the Standard Commands for Programmable Instrumentation(SCPI) communication protocol.
- Have obtained CE certification.
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APM Technologies Ltd , https://www.apmpowersupply.com