Eddy current sensor

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Eddy current sensor


MJ-VR9810 Vibration Transmitter

YD9810 Vibration Transmitter


Centrifugal pumps

Turbo compressors

Steam turbines

Fans and blowers


Electric motors

Gear boxes

Journal bearing machines

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Brief Introduction

 ● With the popularity of the DCS system, the traditional secondary instrument functions can be achieved basically by DCS system. We have successfully developed MJ-VR9810 vibration transmitter based on the eddy current displacement sensor.MJ-VR9810 vibration transmitter normalized and linearized the peak-peak vibration displacement sampled by the transmitter, directly output 4-20mA signal. MJ-VR9810 vibration transmitter connected with eddy current sensor probe and cancel the transmitter or instruments (like monitors).Reducing wiring link, installation link and the failure rate. It will lead the traditional proximitor and instrumentation section filtering, signal normalization processing, modularized signal output function, enhanced system integration, small size and improved reliability.

●  MJ-VR9810 vibration transmitter directly connect with DCS, PLC interface provides a simple, low-cost way to monitor rotating machinery rotor vibration and transmitter vibration. It can really play the right equipment protection through real-time monitoring the vibration of host and auxiliary equipment such as turbines, compressors, fans and pumps group .It measures accurate, stable and reliable with high anti-jamming performance.


Probe Installation 

1 Ensure that the test surface is made of 40CrMo or it’s vortex effect is close to 40CrMo. Most of the turbine shaft, blowers and other equipment was made of 40CrMo material or similar material such as 45 steel. Therefore, unless customer specified in the order, or we will usually uses 40CrMo material for specimen calibration. 

2 The MJ-VR9810 vibration transmitter effect is mainly concentrated in the surface to be measured .Since the effect of residual magnetism in the formation process, and non-uniform quenching, uneven hardness, the crystal structure will affect the unevenness sensor characteristics. API670 standard test surface residual magnetism is not recommended more than 0.5 micro tesla .The actual measured body should be calibrated if the application requires a higher measurement accuracy.

3, When you measure the MJ-VR9810 vibration transmitter , each measuring point should install two sensor probes .Two probes are mounted spaced 90 ° (± 5 °) on the same plane on both sides of the bearing.Since the bearing cap is generally horizontally split, so the two probes are usually mounted on each side of the vertical centerline 45 °, the probe is defined as X (horizontal) and Y probe (vertical direction). Usually see from motor end,Y probe should be on the left side to the right of the vertical center line and X probe should be on the right side to the right of the vertical center line.

4 Installation position of the probe should be close to the bearing, otherwise due to the deflection of the shaft, the measured values obtained will contain additional error. The maximum distance of probe position and the bearing are in the table below .

Notice :API 670 standard, the radial vibration probe position and the bearing should within 76mm.

5 Center line axis of the probe should be orthogonal. Monitoring the probe surface (surface facing the entire circumference of the sides of the center line of the probe is 1.5 times the width of the probe shaft diameter should be no scribe marks or any other non-continuous surface (such as a hole or groove, etc.) and within this range have no sputtering or plating metals , the surface roughness should be between 0.4μm ~ 0.8μm.

 6 Unless otherwise noted, the radial vibration probe is usually mounted on the midpoint of the linear range of the sensor. The output voltage of the transmitter corresponding to the midpoint voltage (the midpoint of the linear range of the midpoint of the gap value and the voltage value from the calibration data sheets or calibration curve found), usually it is 6V.Especially for large bearing machines, if the maximum bearing clearance is close to sensor linear operating range (suggest to use of a wider range of linear sensors). But for large horizontal machine, when the machine is started, the shaft will raise about 0.25mm, so when the probe is installed vertically down, you should install clearance (cold gap) adjustment to the midpoint of the linear range of the sensor 0.25mm larger .Corresponding transmitter output voltage can be found from the calibration data sheets or calibration curve.

7 The MJ-VR9810 vibration transmitter should be installed to ensure that no less than a certain distance between the probe head and the mounting surface. The probe head body should be fully exposed to mounting surface. Otherwise, the mounting surface should be processed into a flat-bottomed hole or chamfer.

8 Installation distance between each probe head should not be less than the minimum installation distance. To prevent adjacent-channel interference between the two probes, probe and different specifications for different installation methods require the spacing is different. Diameter of the probe should larger than 40mm when you measure the radial vibration transmitter vibration .

9 Probe mounting bracket to the intensity as high as possible. General requirements bracket resonant frequency is at least ten times the speed of the machine, so as to ensure the accuracy of the measurement.

10 By measuring the sensor output to adjust the gap sensor is installed. When the probe head has not been exposed to the mounting hole, since the installation of metal influence around the hole, you may install the sensor output gap is equal to the corresponding voltage or current value. However, the examinee is not right. If the probe is adjusted to the proper installation location, sensor output should be: first the larger saturation output (in this case the probe has not been put into the mounting hole), and then outputs the smaller (in this case the probe have been put into the mounting hole), to continue the probe is screwed into the mounting hole, sensor output becomes larger output (in this case the probe head is exposed to the mounting holes, but a large gap with the measured surface).Then screwed into the probe, the value of the output gap is equal to the corresponding sensor is installed, then the installation of the probe is the correct gap.

11 When the probe is screwed into the threaded mounting holes, not excessive force, otherwise it may crush the probe and the measured body. When the probe is screwed into the threaded mounting holes must be carried by the cable while rotating the probe, or the cable maybe broken. If have extension cables, extension cables should be removed.

12 The cable connector and the probe is in contact with the internal circuit, but do not have the sealing property. In order to avoid contact with the chassis and the strengthening of joints and sealing.Should use heat shrink tubing heat shrink wrap. This can also play a role in preventing joint loosening. Do not use sticky tape to insulated electrical connectors, as oil mist will dissolve sticky substance on the tape and pollution joints.

13 The probe head material is PPS plastic, casing material is 1Cr18Ni9Ti acid stainless steel. Installation should pay attention to the existence of the examinee environmental chemicals that damage the probe. Long-term exposure following substances probe, the probe material and performance will not be affected: air, water, oil, ammonia hydroxide, alcohol, gasoline, ether, sulfuric acid, sodium hydroxide. Probe can’t contact with the following substances for long-term: anhydrous ammonia, benzene, formaldehyde, nitric acid, chloroform, potassium permanganate, 98% sulfuric acid.

14 If probe cable and extension cable length is chosen, you can’t be arbitrarily shortened or lengthened, otherwise it will cause changes in the sensor system.

Extension Cable Installation 

Extension cable is connected to the middle part of the probe and the proximitor is also one of the main portion of the sensor performance. Installing the extension cable should ensure that the course is not easy to be damaged. Under normal circumstances suggested pipe laying, or use an extension cable with armored. Excess cable can’t be arbitrarily cut off, or it may cause serious tolerance or sensor does not work! 

① extension cable put in the disk, because of the material should be avoided due to the disk radius is too small to put leaving the cable break. 

② in the selection, should ensure that the length of the extension cable plus probe cable length is larger than the distance between the probe and the proximitors, and usually the proximitor devices are focused on the same side of the machine. 

● Sealed and insulated extension cable adapter's 

Extension cable and probe cable connector with signal "ground" connected, but does not have a seal. Connection with the case in order to avoid contact, strengthening sealing joints should be insulated to join at protection.Usually heat shrink tubing shrink wrap. 

※ Do not use sticky tape to insulated electrical probe connector, because the oil will dissolve the sticky substance on the tape and pollution probe.

Transmitter Installation 

Transmitters of the work environment is much more demanding than the probe. Usually it is installed away from the danger zone, and its surroundings should be non-corrosive gases, dry, vibration, ambient temperature and room temperature or less. Next to the machine installation, in order to ensure safe and reliable transmitter, it is necessary to use a dedicated mounting box. In order to prevent interference caused by different ground potentials must be single-point ground. 

Proximitor is made of aluminum casting. In order to shield the outside interference in the internal transmitter signal has been housing and end connection; mounting plate and deck rails are engineering insulating plastic, so you can ensure that when you install the transmitter, so that the transmitter housing and the earth isolation (ie "floating"). The system includes a connection system connected to the sensor probe, extension cable (if any) the electrical connection between the transmitter and the DCS system, in order to be able to work the composition measurement system. With heat shrink tubing heat shrink wrap, to prevent loosening and connectors for shorted to ground. The output of the transmitter should be net shielded cables. Shielded cable shield should be connected to the DCS system at one end of a single point of access signal ground, that the shield is not connected to the proximitor, DCS system connect ground. Original signal transmitter output cable length should not more than 300 meters, otherwise the signal attenuation will be too large. 

Connection diagram is as follows:

Calibration and Maintenance 

1 Calibration 

Under what circumstances should recalibrate the transmitter? 

ØTransmitter will not be used for more than one year;

ØTransmitter used continuously for two years;

ØTested material and factory calibration material discrepancies;

ØAfter troubleshooting. 

Calibration devices and equipment 

ØDisplacement calibrator 


Ø Digital Multimeter 

Ø+24V DC power supply 

ØSine wave signal generator 


Displacement characteristic curve calibration 

Select the same material tested specimens.

Installed probe micrometer (range should be larger than the sensor range 20%). 

Respectively, power, digital multimeter probe to the transmitter. 

Rotary displacement calibrator knob so that the specimen plane close to the probe, the probe head and then transferred to the sensor and sample spacing linear starting distance. 


Check transmitter output 

Turn on the power, rotational displacement calibrator knob, adjust the probe is linear midpoint, see OUT output whether 4.00mA ± 1%; sensor fixed on the vibration table, select the appropriate midpoint of the vibration frequency and vibration amplitude, view the output OUT whether 12mA ± 1%; selecting the appropriate end of the vibration amplitude and the vibration frequency, to see if the output OUT is 20mA ± 1%; does not meet the above needs to be sent if the factory calibration; 


2 Fault repair 

Sensor system anomalies appear in the calibration or work, first on their own preliminary examination, the problem is serious, please contact the Company or the Company throughout the sales and service agents. 

● System Check 

1) Terminals wiring is wrong; 

2) Wiring short or open; 

3) Power supply voltage is correct; 

4) Measuring instruments are shorted or open. 


●Probe Check 

1)High frequency probe and probe head plugs are clean, if dirty, please use ethanol scrub. 

2)Extension cable (extension cable if there is any) whether short or open circuit, if the fault, replace the extension cable. 

3)Check whether the probe shorted or open: first extension cable disconnected (if any), and then a multimeter to measure the resistance of high frequency probe pin plug and the plug housing between digital, its normal value should be in the 2.0 to 10.0 between Ω, if the resistance value is very small (less than 1.0Ω), the description of this probe short-circuit; If the measured resistance value is very large (greater than 10Ω), a description of this probe is open or poor contact. When found in both cases, you have to replace the probe. 

● Check the transmitter 

1) To check whether the probe and extension cable supporting the transmitter. If there is an extension cable, be sure to connect the extension cable. 

2) The determination of the intact probe, connected to the transmitter. When the probe head against the metal conductor, the original signal output of the transmitter should be minimized; When the probe head away from metal conductors, the original signal output of the transmitter should be maximized. Otherwise it can be determined that this transmitter has been damaged, or the sensor system is bad, then the system should be repaired or replaced transmitter.

1 Power supply: +24VDC

  Maximum operating current: 50mA

2 Input : Proximity Probe

3 Original signal buffered output: + 2V ~ + 10V, 

  Maximum transmission distance: 300 meters. 

4 Transmitter sensitivity:8V/mm. 

5 Vibration transmitter peak-peak output: 4 ~ 20mA

  Maximum load resistance: 500Ω. 

6 Output ripple: ≤20mV. 

7 Frequency response: 10 ~ 1kHz (-3dB). 

8 Temperature drift: ≤0.1% ℃. 

9 Dimensions: 90mm (W) × 35mm (L) × 70mm (H). 

10 Mounting dimensions: (1) Floor installation, 51mm × 51mm, using four M4 × 12                           GB29-76 bolt installation;  (2) Rail mounting, can be easily mounted on standard 35mm rail. 

11 Connection method: SpringLoc terminals, automatic fastening function, no need installation tools. No loosening because of no bolts.

12 Operating temperature: -30 ℃ ~ 80 ℃.

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