GB2440995A

GB2440995A - Detecting the direction and motion of a source of radiation

Info

Publication number: GB2440995A
Application number: GB0606173A
Authority: GB
Inventors: Michael David Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-28
Filing date: 2006-03-28
Publication date: 2008-02-20
Also published as: GB0606173D0

Abstract

A detector for the direction of motion of electromagnetic, mechanical, seismic, vibrational or acoustic fields, contains two antennae or tranducers which are sensitive to the type of field to be tested, and a phase comparator which receives the signals from the antennae or transducers. The resulting phase difference signal corresponds with the direction of motion of the field, and also with the direction of operation of the equipment from which the field emanates. 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 and operation of shielded electrical machines such as a boiler circulation pump.

Description

I

Direction detector for energy fields and associated equipment This invention relates to the detection of the direction of motion of electromagnetic or mechanical or seismic or vibrational or acoustic fields and to the direction of

motion of equipment associated with these fields.

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 this 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 motion of the machine.

To overcome this, the present invention proposes two field-sensitive devices and a phase comparator.

The field-sensitive devices respond to the type of field to be tested, and they are located and/or orientated so that their inputs differ in phase.

The signals output from the field-sensitive devices are received by the phase comparator, which outputs a signal corresponding with the phase difference

between the field-sensitive devices' signals.

This signal also corresponds with the direction of motion of the field under test.

If required an output device may be incorporated to make the signal visible, and this may be calibrated in terms of direction of motion.

The detector will indicate the direction of motion of the field and 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.

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.

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 a power station boiler circulation pumpset.

The pumpset comprises an electric cage induction motor driving a boiler circulation pump. The pumpset is enclosed within a thick-walled pressure vessel I which is water-filled.

The motor's electromagnetic field cannot be reliably detected from outside the pressure vessel.

Transducers sensitive to mechanical or seismic or vibrational or acoustic input 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 single 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 both.

Cable 5 carries the transducers' output signals each within an individual screen to enclosure 6 which is also screened.

Amplifier-filter unit 7 and amplifier-filter unit 8 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.

This is the frequency of the mechanical or seismic or vibrational or acoustic field produced by the action of the electromagnetic field on substances, by the process known as magtnetostriction.

MagtnetostrictiOn produces a field which has the same direction of motion as the

causal electromagnetic field.

Phase comparator 9 outputs a signal which represents the phase difference between the signals output from the two transducers.

Indicator 10 makes the phase-difference signal visible to the person operating the equipment. This indicator is calibrated in terms of direction of rotation.

Claims

Claims 1. A direction detector containing two field-sensitive devices

which each converts the value of the field detected by it into a representative signal, and a phase-sensitive means whereby the phase difference between the signals output by the field-sensitive devices may be converted into a signal which represents phase difference, and which also corresponds with the direction of motion of the field under detection.

2. A direction detector according to any of the other claims, in which means of amplification is provided to ensure adequate signal levels.

3. A direction detector according to any of the other claims, in which means of filtering is provided, to attenuate the levels of unwanted frequencies.

4. A direction detector according to any of the claims from I to 3, in which the field-sensitive devices are sensitive to electromagnetic fields.

5. A direction detector according to any of the claims from I to 3, in which the field-sensitive devices are sensitive to mechanical or seismic or vibrational or

acoustic fields.

Amendments to the cLaims have been fiLed as follows 1. A direction-of-operation detector which by reference to that component of the vibration which originates within an electromagnetic machine and which component has a frequency equal to twice the frequency of the electrical energisation of the stator winding of that machine, and by the use of two vibration transducers which are located outside that machine and which transducers are each located differently from the other transducer so that each transducer will pick up a differently phased part of that vibration, and by the use of two means of signal conditioning, whereby the output from each vibration transducer is processed so that the component of that transducer's output signal which has a frequency equal to twice the frequency of the electrical energisation of the stator winding of the machine, is adjusted to facilitate further processing, while other components of that transducer's output signal are attenuated to prevent interference, and by the use of a means of phase comparison, whereby the signals output from the two means of signal conditioning are compared in phase, the means of phase comparison therefore outputting a signal which represents the phase difference between its two inputs, and that output phase difference signal corresponds with the direction of operation *:*::* of the machine.