Non-contact vibration eddy current sensors

Non-contact vibration eddy current sensors

CWY-DO series eddy current sensor introduction

The eddy current sensor is a non-contact measurement sensor that accurately measures the relative position of the measured body (which must be a metal conductor) to the end face of the probe, with the voltage signal output by the sensor being proportional to the distance between the end of the probe and the measured conductor. It is capable of both static (displacement) and dynamic (vibration) measurements. It is mainly used for the measurement of shaft displacement, shaft vibration, shaft speed and other parameters of rotating machinery, which can effectively monitor and protect the equipment.

Product characteristics

Good interchangeability

interchangeable probes of the same type

interchangeable extension cables of the same type

interchangeable preamps of the same type

(identical performance after interchange)

High reliability

probes are resistant to high temperatures and oil and corrosion

Special probe encapsulation technology

advanced production process

stringent factory inspection standards

Standards

conforms to EMC EN61000-6-2, EN61000-6-4

in accordance with API670

Customizable

Probe sizes are customizable

range support customization

Application Live View

Principle of sensor operation

The high frequency oscillation circuit in the preamplifier generates a high frequency signal which is sent through the cable to the coil at the end of the probe, generating an alternating magnetic field at the end of the probe, which generates an induced current (eddy current) on the metal surface when the measured metal body is close to this field. The amplitude and phase of the high-frequency current in the head coil is changed (the effective impedance Z of the coil is changed) due to its counteraction. The change in the coil impedance Z, i.e. the change in the distance D between the head coil and the metal conductor, is then transformed into a voltage or current output signal through the processing of the preamplifier's electrical conditioning circuit, thus enabling the measurement of displacement, vibration and other parameters.

Components of the sensor

Eddy current sensor consists of three parts: probe, extension cable and preamplifier.

Probe
The probe consists of a coil, protective cover, stainless steel housing, coaxial cable,high frequency connector, etc. Depending on the measuring range,different diameters of the probe can be selected, e.g. Φ5mm, Φ8mm, Φ11mm,Φ18mm, Φ25mm, and depending on the installation requirements,different mounting methods can be selected, e.g. front-mounted, reverse-mounted,non-threaded, and depending on the installation conditions, the length of the probe cable can be selected, e.g. 1m or 0.5m. Depending on the installation conditions, the cable length can be selected, e.g. 1m or 0.5m.
Preamplifier
The preamplifier is the core part of the system, which includes the oscillation,linearity detection, filtering, linearity compensation and amplification circuits of the entire sensor system. The VB-Z98 preamplifier is divided into Φ5mm, Φ8mm, Φ11mm, Φ18mm and Φ25mm according to the diameter of the probe to be used.
Extension Cable
Both ends of the extension cable are equipped with SMA self-locking connectors with oil-proof heat-shrinkable sleeves to protect the connection between the self-locking plug and the cable from contamination by oily media and to increase system reliability. Extension cable lengths are available in 4m, 4.5m, 8m and 8.5m. Note: Requires probe cable length + extension cable length = 5m or 9m.

Sensor Composition Diagram

Application Schematic

Typical configuration for turbine monitoring

CWY-DO series eddy current sensor technical indicators

System Abbreviation	φ5 system or 5mm system	φ8 system or 8mm system	φ11 system or 11mm system	φ18 system or 18mm system	φ25 system or 25mm system
Model	CWY-DO-401	CWY-D0-402	CWY-D0-404	CWY-D0-410-18	CWY-D0-410-25
Measuring and Electrical Properties
Measurement Principle	Measurement Principle
Calibrating Target Disc Materials	45# Steel
Standard Range	1.5mm	2mm	4mm	10mm	10mm
Standard Measuring Range	0.25-1.75mm	0.5-2.5mm	1-5mm	0.5-10.5mm	1 -11 mm
Customisable Maximum Range	2mm	3mm	6mm	10mm	16mm
Standard Sensitivity	8mV/um	8mV/um	4mV/um	0.8mV/um	0.8mV/um
Sensitivity Error	≤±2%	≤±3%		≤±1%
Sensitivity interchangeability error	≤±5%			≤±3%
Non-linearity	<1%			<1.5%
Resolution	±1um	±1um	±2um	±10um	±10um
Frequency Response	DC to 10kHz (-3dB)			DC to 3kHz(-3dB)	DC to 1kHz(-3dB)
Output Signal Range Corresponding to Range	-2 to -14V	-2 to -18V	-2 to -18V	-2 to -10V	-2 to -10V
Max. Output Voltage	-23 V
Output Resistance	100Ω
System Temperature Drift	±3% F. S. (-20°C to +80°C)
Recommended Installation Voltage	-10V			-6V
Front-end Power Supply	-24VDC±10%
Maximum Current Consumption	≤ -20mA
Probe Resistance	8.2±0.3Ω	4.9±0. 3Ω	6.5±0.3Ω	4.2±0. 2Ω	0. 9±0.3Ω
Protection Classes
Probe and Extension Cable Operating Temp.	-40°C to +170°C
Front-loader Operating Temp.	-40°C to +80°C
Probe Protection Classes	IP68
Front-loader Protection Classes	IP40
Electromagnetic Compatibility Specification	EN61000-6-2, EN61000-6-4
Physical Properties
Probe Protection Cover Material	PPS			PEEK
Probe Protection Cover Diameter	5.5mm	8.4mm	11.2mm	16.7mm	27.0mm
Probe Screw Material	Stainless steel
Probe Screw Thread Specification/Customizable	M8 or M10	M10	M14	M18	M30
Probe Cables and Extension Cables	Three-core coaxial cable
Cable Length	Probe cable + extension cable = 5m or 9m (Customisable )
Cable Sheathing Materials	FEP
Min. Turning Radius of Cable	30mm
Front-loader Material	ADC12(Die-cast aluminium alloy)
Total System Weight	500g±3%			700g±3%
Remarks	1) Sensitivity interchangeability error refers to the interchangeability of any component for comparison with the standard sensitivity.

Preamplifier Selection and Size

Preamplifier Selection

Dimensions of the preamplifier housing and mounting tabs

Extension cable size and selection

Extension cable armouring

Normal Extension cable

Extension cable selection

5mm（Φ5）Probe diagram and selection

5mm（Φ5）Probe diagram

5mm（Φ5）Probe Selection

8mm（Φ8）Probe diagram and selection

8mm（Φ8）Probe diagram

8mm Reverse Probe diagram

8mm（Φ8）Probe Selection

11mm（Φ11）Probe diagram and selection

11mm（Φ11）Probe diagram

11mm（Φ11）Probe Selection

18mm（Φ18）Probe diagram and selection

18mm（Φ18）Probe diagram

18mm（Φ18）Probe Selection

25mm（Φ25）Probe diagram and selection

25mm（Φ25）Probe diagram

25mm（Φ25）Probe Selection

Mounting precautions for the subject and probe

P 1  d ：When the measuring body is a disc, it does not affect the minimum target surface diameter to be measured.

P 2  A ：Minimum distance of the mounting surface of the bracket from the end of the probe without affecting the measurement.

       B ：Minimum spacing for slotting of brackets without affecting measurements.

P 3  C ：The minimum distance between the probe and the side masking surface or from the edge does not affect the measurement when there is masking metal on the side of the body being measured or when there is an edge.

P 4  E ：Double probes mounted parallel to each other with minimum spacing that does not affect the measurement.

P 5  F ：Double probes are mounted vertically to measure the shaft body without affecting each other's minimum diameter.

P 6  G ：Minimum distance between probes that do not interfere with each other's measurements when dual probes are mounted vertically to measure a block.

                                                                                                                                                                                           unit:mm

	d	A	B	C	E	F	G
5mm probe（Φ5）	15.2	6	18	8	40.6	50	23
8mm probe（Φ8）	22	8	22	10	50	60	26
11mm probe（Φ11）	30	12	32	15	60	75	36
18mm probe（Φ18）	50	18	60	28	90	-	-
25mm probe（Φ25）	75	31	92	40	152	-	-

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