Shaft vibration transmitter

Shaft vibration transmitterInstruction Manual

1、 Introduction

withDCSWith the popularization of the system, the functions of traditional secondary instruments can basically be achieved byDCSSystem implementation. Our company has successfully developed and researched based on eddy current displacement sensorsShaft vibration transmitter.Shaft vibration transmitterAfter linearizing and normalizing the vibration displacement peak to peak signal sampled by the sensor, it is directly output4-20mASignal.Shaft vibration transmitterPaired with the eddy current sensor probe, the transmitter or instrument is eliminated, the wiring and installation steps are reduced, and the failure rate is reduced. It modularizes the traditional external preamplifier and instrument functions such as filtering, signal normalization processing, and signal output, enhancing the system's integration, small size, and improving reliability.

Shaft vibration transmitterTo directly communicate withDCSThePLCThe interface provides a simple and low-cost way to monitor the shaft vibration of rotating machinery rotors. Real time monitoring of shaft vibration for main and auxiliary equipment such as steam turbines, compressors, fans, and pump groups can truly protect such equipment. It measures accurately, stably and reliably, and has strong anti-interference performance.

2、 Technical indicators

1Power supply:+24VdcThe maximum working current is less than35mA.

2, lose Enter: Eddy current sensor probe.

3Buffer output:1～3VMaximum transmission distance300Rice.

4Installation voltage: Buffer output10±1V

5, Precision Degree: ＜ ±2%.

6, lose Out:4～20mA, maximum load resistance500Oh.

7Output ripple: ≤20mV.

8, frequency Sound:10～1kHz(-3dB).

9Temperature Float: ≤0.1%℃。

10External dimensions:90mm(W)×35mm(L)×70mm(H).

11Installation dimensions:Bottom plate installation,51mm×51mmUsing fourM4×12 GB29-76Bolt installation;

Rail installation, can be easily installed on standard35mmOn the guide rail.

12Wiring method: AdoptingSpringLocThe terminal has an automatic fastening function and can be wired without the need for installation tools. As it does not require bolt fixation, it will not loosen.

13Working temperature: -30℃～80℃。

3、 Installation and use

Installation of probe

1Ensure that the material of the tested surface is45#, or its eddy current effect and45#Approaching each other. The shafts of most steam turbines, blowers, and other equipment are used45#Materials or similar materials, such as45Steel manufacturing. Therefore, unless otherwise specified at the time of ordering, the sensor system is usually used before leaving the factory45#Calibration of material specimens.

2The eddy current effect is mainly concentrated on the measured surface. Due to the residual magnetic effect formed during the machining process, as well as uneven quenching, uneven hardness, and uneven crystal structure, the sensor characteristics can be affected,API670The standard recommends that the residual magnetic field of the tested surface should not exceed0.5Micro Tesla. When higher measurement accuracy is required, actual object calibration should be applied.

3When measuring the radial vibration of the shaft, two sensor probes should be installed at each measuring point, and the two probes should be installed on the same plane on both sides of the bearing, separated by a distance90°(±5°)Due to the fact that the bearing cover is generally horizontally divided, two probes are usually installed on each side of the vertical centerline separately45°, defined asXprobe(horizontal direction)andYprobe(vertical direction)Usually, from the perspective of the prime mover,XThe probe should be on the right side of the vertical centerline,YThe probe should be on the left side of the vertical centerline.

4The installation position of the probe should be as close as possible to the bearing, otherwise the measured value will contain additional errors due to the deflection of the shaft. The maximum distance between the installation position of the probe and the bearing is shown in the table below.

※API 670According to the standard, the installation position of the radial vibration probe of the shaft should be at a distance from the bearing76mmInside.

5The centerline of the probe should be orthogonal to the axis, and the surface monitored by the probe should be(Facing the centerline of the probe on both sides1.5The entire circumferential surface of the axis, which is twice the diameter width of the probe, should be free of scratches or any other discontinuous surfaces(Like oil holes or keyways, etc)Within this range, there should be no metal spraying or electroplating, and the surface roughness should be within0.4Mm～0.8Mmbetween.

6Unless otherwise specified, the radial vibration measurement probe of the shaft is usually installed at the midpoint of the linear range of the sensor, and the corresponding transmitter output voltage is the midpoint voltage(The midpoint gap value and midpoint voltage value in the linear range can be found from the calibration data sheet or calibration curve)Usually, it is6VEspecially for large bearing machines, when the maximum bearing clearance approaches the linear working range of the sensor(Suggest using sensors with a wider linear operating range)However, for large horizontal machines, the shaft will be raised when the machine is started0.25mmLeft and right, therefore, when installing a vertical probe during shutdown, the installation gap should be adjusted(Cold state gap)Adjust to the linear range of the sensor, where the midpoint is too large0.25mmThe corresponding transmitter output voltage can be found from the calibration data sheet or calibration curve.

7The installation of sensors should ensure that the distance between the probe head and the installation surface is not less than a certain distance. The engineering plastic head body should be exposed from the installation surface, otherwise the installation surface should be machined into a flat bottom hole or chamfered.

8The installation distance between the heads of each probe should not be less than the minimum installation distance. To prevent adjacent interference between two probes, different specifications of probes and installation methods require different spacing.

When measuring the radial vibration of the shaft, the diameter of the shaft is greater than40mm.

9The strength of the probe installation bracket should be as high as possible, and the resonant frequency of the bracket is generally required to be at least ten times the machine speed to ensure measurement accuracy.

10Using the output of the measuring sensor to adjust the installation gap of the sensor, when the probe head has not yet exposed the installation hole, due to the influence of metal around the installation hole, the sensor output may be equal to the voltage or current value corresponding to the installation gap, but at this time, the probe is not measuring the object to be measured. Adjust the probe to the correct installation position, and the sensor output should be: first, a large saturation output(At this point, the probe has not yet been inserted into the installation hole)Next is the smaller output(At this point, place the probe into the installation hole)Continue to screw the probe into the installation hole, and the sensor output will become larger(At this point, the probe head is exposed through the installation hole, but there is a large gap between it and the measured surface)Twist in the probe again, and the sensor output is equal to the value corresponding to the installation gap. At this point, the probe is the correct installation gap.

11When screwing the probe into the threaded installation hole, do not apply too much force, otherwise it may crush the probe and the measured object.

When screwing the probe into the threaded installation hole, the cable carried by the probe must be rotated at the same time, otherwise the cable may be twisted and broken. If there is an extension cable, it should be removed.

12The cable connector of the probe is connected to the internal circuit and does not have sealing properties. To avoid contact between the joint and the casing and enhance sealing, heat shrink tubing should be used to heat shrink wrap. This can also prevent the joint from loosening. Do not use sticky electrical tape to insulate joints, as oil mist can dissolve the adhesive on the tape and contaminate the joints.

13The material of the probe head isPPSEngineering plastic, shell material is1Cr18Ni9TiAcid and alkali resistant stainless steel. During installation, attention should be paid to whether there are chemical substances in the environment of the tested object that may damage the probe.

The probe material and performance will not be affected by long-term exposure to the following substances:

Air, water, lubricating oil, ammonia hydroxide, alcohol, gasoline, dilute sulfuric acid, sodium hydroxide.

The probe should not come into long-term contact with the following substances:

Anhydrous ammonia, benzaldehyde, nitric acid98%Sulfuric acid.

14、Once the length of the probe cable and extension cable is selected, they cannot be arbitrarily shortened or lengthened during use, otherwise it will cause changes in the sensor system.

Installation of transmitter

transmitterThe requirements for the working environment are much stricter than those for probes. It is usually installed far away from hazardous areas, and the surrounding environment should be free of corrosive gases, dry, with minimal vibration, and the ambient temperature should not differ much from room temperature. Installed next to the machine to ensuretransmitterIt is necessary to use a dedicated installation box for safe and reliable work.

In order to prevent interference caused by different ground potentials, a single point grounding must be used.The housing of the preamplifier is made of aluminum casting. In order to shield external interference, the housing has been connected to the signal terminal inside the transmitter; The installation base plate and guide rail socket are both made of engineering insulating plastic, which ensures that the transmitter housing is isolated from the ground when installing the transmitter(That is, 'floating ground').

The connection diagram is as follows

4、 Calibration and Maintenance

1Calibration

Under what circumstances should the transmitter be recalibrated?

Ø The transmitter has not been used for more than one year;

Ø The transmitter has been used continuously for two years;

Ø The tested material does not match the factory calibration material;

Ø After troubleshooting.

Calibration devices and equipment

Ø Displacement calibrator

Ø micrometer

Ø Digital Multimeter

Ø +24VDC power supply

Ø Sine wave signal generator

Calibration of displacement characteristic curve

Select a specimen with the same material as the tested object.

Install the probe and micrometer (the range should be greater than the sensor range)20%）.

Connect the power supply, digital multimeter, and probe to the transmitter separately.

Rotate the displacement calibrator adjustment knob to make the probe closely adhere to the plane of the specimen, and then adjust the distance between the probe head and the specimen to the linear starting distance of the sensor.

Verification of transmission output

Turn on the power,Rotate the displacement calibrator adjustment knob,Adjust the probe to the linear midpoint and observeOUTIs the output4.00mA±1%Fix the sensor on the vibration table, select the appropriate vibration frequency and midpoint vibration amplitude, and checkOUTIs the output12mA±1%Select the appropriate vibration frequency and endpoint vibration amplitude, and viewOUTIs the output20mA±1%If the above conditions are not met, it needs to be sent to the manufacturer for calibration;

2Fault repair

When abnormal phenomena occur during calibration or operation of the sensor system, first conduct a preliminary inspection by yourself. If the problem is serious, please contact our company or our sales and service agents in various regions.

● System check

1) Is the wiring terminal connected incorrectly;

2) Whether the wiring is short circuited or open circuited;

3) Is the power supply voltage correct;

4) Check if the measuring instrument is short circuited or open circuited.

● Probe inspection

1) Check if the high-frequency plug and probe head of the probe are clean. If there is any dirt, please wipe them with cleaning agent.

2) extension cable(If there is an extension cable)Is there a short circuit or open circuit? If there is a fault, the extension cable should be replaced.

3) Check if the probe is short circuited or open circuited: first disconnect the extension cable(if any)Then use a digital multimeter to measure the resistance value between the high-frequency plug pin of the probe and the plug housing. The normal value should be within2.0～10.0Between Ω, if the resistance value is very small(less than1.0Ω)This indicates that the probe has a short circuit; If the measured resistance value is very large(greater than10Ω)This indicates that the probe has an open circuit or poor contact. When the above two situations are found, the probe needs to be replaced.

● Inspection of transmitter

1) First, check if the probe and extension cable are compatible with the transmitter. If there is an extension cable, it must be connected.

2) Connect the probe that has been determined to be intact to the transmitter. When the probe head is close to the metal conductor, the original signal output of the transmitter should be minimized; When the probe head is far away from the metal conductor, the original signal output of the transmitter should be at its maximum. Otherwise, it can be determined that the transmitter is damaged or the sensor system has poor contact. In this case, the system should be repaired or the transmitter should be replaced.

4、 Probe installation requirements

The range to be measured refers to the linear range of the sensor, and the probe specification (Φ) is selected5ｍｍ、Φ8ｍｍ、）,Determine the probe type based on the space and structure of the on-site mechanical installation（For example: formal, reverse, non threaded）Select the probe cable length based on the size（1mThe0.5m）.

2.Determine the total length of the system cable by measuring the distance from the on-site measurement point to the installation point of the preamplifier(5mThe9m)Choose the length of the probe cable again（1mThe0.5m）Length of supporting extension cable（4ｍ、4.5ｍ、8ｍ、8.5ｍ）。

3.Total length of system cables（5ｍ、9m) And probe specifications (Φ)5ｍｍ、Φ8Mm) Determine the type of preamplifier.