GB2464666A - Detecting the direction and motion of a source of vibration - Google Patents
Detecting the direction and motion of a source of vibration Download PDFInfo
- Publication number
- GB2464666A GB2464666A GB0819140A GB0819140A GB2464666A GB 2464666 A GB2464666 A GB 2464666A GB 0819140 A GB0819140 A GB 0819140A GB 0819140 A GB0819140 A GB 0819140A GB 2464666 A GB2464666 A GB 2464666A
- Authority
- GB
- United Kingdom
- Prior art keywords
- machine
- motion
- magnetic field
- vibration
- motor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000001514 detection method Methods 0.000 abstract description 3
- 239000007788 liquid Substances 0.000 description 4
- 230000001364 causal effect Effects 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/80—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using ultrasonic, sonic or infrasonic waves
- G01S3/802—Systems for determining direction or deviation from predetermined direction
- G01S3/808—Systems for determining direction or deviation from predetermined direction using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
- G01S3/8083—Systems for determining direction or deviation from predetermined direction using transducers spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems determining direction of source
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
A detector for the direction of motion of the magnetic field within an electrical machine where direct detection of that field is not practicable comprises two vibration transducers, and a phase comparator. Amplifiers and/or filters may be incorporated to enhance signal quality. Means may be incorporated to convert the output signal into the required format. The invention may be used to detect the direction of motion of the magnetic field within shielded electrical machines such as a power station boiler circulation pump motor, and from this can be inferred whether the machine is operating in the correct direction for its efficient operation.
Description
I
DirectiOflOf-OPeFat10fl detector for shielded electrical machines This invention relates to the detection of the direction of operation of electrical machines, in those cases where the moving parts of the machine cannot be seen and where shielding prevents monitoring of the magnetic field which radiates from the machine.
Machines includes motors and generators and motorgefleratO1S.
Direction-of-OPeration in the case of a rotating machine, refers to direction of rotation, i.e. whether the machine is operating in a clockwise or a counter-clockwise direction as seen from a particular end. In the case of a linear machine, this refers to the machine's direction of linear motion, i.e. whether the machine is operating in direction A to B along the machine's axis, or B to A. It is of economic importance that equipment is operated in the correct direction for its efficient operation. For example, a pump may operate efficiently when operated in one direction, but not when operated in the opposite direction.
Operations performed on equipment during its construction or installation or repair or maintenance may determine its direction of operation, therefore, following such operations confirmation may be required that the direction of operation is correct.
In some cases the information may be difficult to obtain, for example a pump and its driving motor may be enclosed within a thick casing which is necessary for the function of the equipment but which is an obstacle to the detection of the direction of operation of the machine.
To overcome this, the present invention proposes two vibration transducers and a phase comparator.
The transducers are located near to or in contact with the outside of the machine so as to pick up vibration which is produced by the machine's alternating magnetic field acting on materials within the machine, by the process known as magtnetostriCtiOfl.
Each transducer is located andlor oriented differently from the other so that their signals differ in phase.
The signals from the transducers are received by the phase comparator, which outputs a signal corresponding with the phase difference between the vibration transducers' signals.
This phase-difference signal corresponds with the direction of motion of the field of stress and strain within the machine which is caused by magtnetostriCtiofl. This field moves in the same direction as the causal magnetic field.
From this can be inferred the direction of operation of the machine.
For example, a cage induction motor of the rotary type will drive a passive load in the same direction of rotation as its internal magnetic field. If the motor viewed from a particular end has a clockwise rotating magnetic field, then the motor will try to drive its load in the clockwise direction.
A liquid filling within a machine provides a medium which more efficiently than air transmits magtnetostriction-generated vibration from the magnetic core of the machine, outward to the machine's outer casing.
This detector is especially suitable for use on liquid-filled machines, including a machine which is enclosed within a thick-walled vessel, the whole being liquid-filled.
Preferably, means of amplification should be provided to ensure adequate signal levels.
Preferably, means of filtering should be provided to reduce interference from frequencies outside the operating range.
If required an output device may be incorporated to make the signal visible, and this may be calibrated in terms of direction of operation.
The detector will indicate the direction of operation of the equipment, enabling corrective action to be taken if required, to ensure that the equipment operates in the correct direction for its efficient operation.
An example of the invention will now be described by referring to the accompanying drawing: -figure 1 shows a detector designed to detect the direction of rotation of the magnetic field within a power station boiler circulation pump motor.
The motor is enclosed with a pump, within a thick-walled pressure vessel 1 which is water-filled.
The motor is a cage induction motor of the rotary type.
The motor's magnetic field cannot be reliably detected from outside the pressure vessel.
However, the motor's rotating magnetic field acts on materials within the motor by the process known as magtnetostriction, to produce a field of stress and strain which rotates in the same direction as the causal magnetic field and which appears to a stationary observer as vibration. The frequency of this vibration is equal to twice the frequency of the power supply to the motor.
As the motor is normally energised, and as both the motor and its containing vessel are liquid-filled, this vibration is clearly detectable on the outside of the containing vessel.
Transducers sensitive to vibration are used.
The two transducers 3 and 4 are oriented at 90 degrees relative to one another so that a usable phase difference will be obtained with the transducers located within the same small housing 2.
The housing 2 is held in contact with the outside of the water-filled casing containing the motor, near to the magnetic core of the motor.
The housing may be held in position by a person or by a structure or by both.
Cables 5 and 6 each carry the output signal from one transducer within a screen to enclosure 7 which is also screened. 5 and 6 may alternatively each be comprised of separate cores within one multicore cable.
Amplifier-filter unit 8 and amplifier-filter unit 9 each amplify and filter the signal from one transducer.
The filters are selective in favour of a frequency equal to twice the frequency of the power supply to the motor.
Phase comparator 10 outputs a signal which represents the phase difference between the signals output from the two transducers.
Indicator 11 makes the phase-difference signal visible to the person operating the equipment. This indicator is calibrated in terms of direction of rotation.
The detector can be constructed as a battery-powered, portable hand-held unit.
When required, this can then be applied to the outside casing of a machine which is running and the machine's direction of operation read in a few seconds.
The detector may be calibrated by reference to a machine which operates in a known direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0819140A GB2464666A (en) | 2008-10-20 | 2008-10-20 | Detecting the direction and motion of a source of vibration |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0819140A GB2464666A (en) | 2008-10-20 | 2008-10-20 | Detecting the direction and motion of a source of vibration |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0819140D0 GB0819140D0 (en) | 2008-11-26 |
| GB2464666A true GB2464666A (en) | 2010-04-28 |
Family
ID=40097652
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0819140A Withdrawn GB2464666A (en) | 2008-10-20 | 2008-10-20 | Detecting the direction and motion of a source of vibration |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2464666A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2440995A (en) * | 2006-03-28 | 2008-02-20 | Michael David Brown | Detecting the direction and motion of a source of radiation |
-
2008
- 2008-10-20 GB GB0819140A patent/GB2464666A/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2440995A (en) * | 2006-03-28 | 2008-02-20 | Michael David Brown | Detecting the direction and motion of a source of radiation |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0819140D0 (en) | 2008-11-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |