COMPANY INFORMATION

The company
A modern production facility based in Mildenhall, Suffolk, UK, exclusively engaged in the design and manufacture of instrumentation for vibration and acoustic measurement, together with a sales office situated in Verdun, France. The company has also a distribution network in several countries.

Product range
Piezo-electric vibration transducers (mono axial and triaxial accelerometers) and dynamic pressure transducers, Analogue signal processing instrumentation.

Engineering capability
All facets of transducer/instrumentation manufacture and test are carried out in house, and encompass fabrication of piezo-ceramic components, hermetic seals and connectors, thick film hybrid electronic products, environmental testing.

Customer support
Accelerometers are application specific. We advise users of the environmental constraints relative to individual transducers, hardware is made available for evaluation. Standard product is stocked in depth for rapid response. We have in house our own calibration facilities.

Quality
Virtual 100% inspection and test, supported by continuous assessment of all facets of manufacture, maintains a high standard of product excellence. Environmental test facilities, simulating actual useage, eliminate uncertainty.

Approvals Our quality management system is BS EN ISO 9001 : 2000 approved

PRODUCT INFORMATION
Piezo-electric accelerometers Piezoelectric accelerometers based on ferro electric ceramics first surfaced in the late 40’s as means of collecting data on the dynamic behaviour of airframes and a variety of military and avionic hardware, supplanting the heavier, less robust velocity transducer.
Early devices comprised a piezo-ceramic disc sandwiched between a reaction mass and a cylindrical base (the means of attachment to the test object), and this manner of construction features in several manufacturers products today. However the art has moved on ; disadvantages inherent in this compression disc design, namely high strain sensitivity and cross axis error, preclude their use for many applications and have directly led to several innovations whereby the acceleration/charge conversion is accomplished by means of a shear couple applied to a piezo-ceramic plate or tube.
Specifically, our KONIC design (UK pat. 1507251), comprising a truncated hollow piezo-ceramic cone, spigot, and concentric reaction mass, provides virtual isolation of the sensing element from mounting induced strain, with the further benefit of minimal cross axis error deriving from its radial symmetry. In addition, the KONIC sensing element is mechanically preloaded, temperature constraint imposed by use of adhesives is eliminated.

KONIC accelerometers are produced in sizes from 0.25gm, weight, 0.5pC/g (A/28/E) sensitivity upwards, maximum 90gm., 300pC/g (A/21, A/21/T). Between these two types we have a large range of accelerometers to accommodate both size/weight or sensitivity requests (A/25/E, A/23/E, A/24/E, A22, A/20, A/29…)
Piezo-ceramic shear plate technology is employed at the periphery of the KONIC range as offering miniaturisation advantages, and sensitivity enhancement by virtue of parallel plate construction. A/600, A/600/T (1.2nC/g, 110gm), A/800, A/800/T, A/800/TC (9nC/g, 400gm).

From 2gm weight all the accelerometers are proposed either with a charge output signal (for instance : A/24/TE, A/20/T, A/20/TC, A/21) and with a voltage output signal, integral electronics accelerometers (corresponding references A/124/TE, A/120/VT, A/120/VTC, A/121/V). Sensitivity in these cases and according to accelerometer type; can be from 6, 10, 31.6, 100, 316mV/g to 1V/g and more.
Some of them can include TEDS facility, internal memory compatible with IEEE P1541.4 (for instance A/120/VM, A/120/VTM, A/120/VTCM).
We propose also some triaxial accelerometers, these tri-axial accelerometers can be also charge output or integral electronics type. They are produced in sizes from 0.9gm (A/38, A/38-1), 7gm (A/32, AT/04 with a single connector), 18gm (A/31, A/34, A/34-2, A/131/V, A/134/V, A/134/V-3) , 38gm (A/30, A/30-1, A/130/V) and a water cooled triaxial accelerometer (A/33, A/33-3, A/33-10).

For long term monitoring of plant and machinery in industrial and under severe operating conditions including high pressure fluid immersion, high temperature we have a special range of accelerometers which can even used hardline cable (A/52/F,A/52/F/HT, A/53/F, A/53/F/HT, A/81/F, A/81/F/HT, A/107/F, A/107/F/HT, A/301/F, A/301/F/HT, A/172/VF).

Piezo-electric microphones
Dynamic pressure transducers based upon piezo-ceramics allow detection of acoustic type phenomena, turbulence, cavitation, associated with fluid flow, and are produced in two basic packages (M/01/F, M/01/T, M/°2/F, M/02/T, M/02/TI-1).
For applications involving significant background vibration, accelerometer compensation may be included (M/01/F1, M/01/TA, M/02/FA, M/02/TA).

The high sensitivity and linearity of these devices allows detection of acoustic levels as low as 70dBA superimposed upon pressure fields up to 500bar.

Piezo-electric sensor signals need be further processed, primarily because signal levels are inadquate for monitoring and control purposes without amplification, and will most probably contain additional data and noise from which the measurement of interest must be recovered.

One problem that was early addressed resulted in the introduction of the charge amplifier in 1957*. This breakthrough substituted an operational amplifier summing junction interface for the voltage follower hitherto used, thus eliminating the signal attenuating effect of the sensor connecting lead which forms a voltage divider in conjunction with the source capacitance of the sensor.

Noise
Both piezo-electric accelerometers and pressure transducers provide real time, wideband, dynamic data plus additional, perhaps significant noise. In addition, noise is a side effect of amplifying systems and is generated by flexure of sensor cables. Sensors should respond solely to a specific stimulus, however piezo-ceramics are essentially converters/translators of dynamic mechanical strain and thermal inputs, therefore these physical sources, if manifest, will contribute spurious additional signal.

Instrumentations
The instrumentation function comprises charge amplification, spectral processing, display/analysis/control. Real time, continuous data may of course be subject to analogue or digital processing, the latter requiring additional digitising hardware complexity and some software overhead. Digital methodology may be applied to the control of test/measurement programmes and to the analysis and presentation of data, and enhances efficiency at the expense of initial overhead and flexibility.
Specialist areas include the parameterisation of bussable (RS232, IEEE-488) instrumentation and the spectral and statistical analysis of real time signals.

Instrumentation selection is a judgemental area involving considerations of the operating environment(s), the desired information format, vendor assessment in terms of capital cost, support, reliability, multi vendor product compatibility.
We produce modular sensor interface (QV/01, QV/02 miniature charge to voltage converter), analogue signal processing level display and alarm annunciator instrumentation, together with thick film hybrid circuit based products and hand held vibration meters. Modular instrumentation minimises redundancy in meeting specific output formats, and is sufficiently robust for general trials use in aircraft and vehicles as well as for laboratory and industrial applications.
Thick film based products are produced for inclusion as interface amplifiers within transducers, and as stand alone interface/signal processing products packaged to conform to Vibration severity test level 2 for tracked vehicles (DEF STAN 07-55Pt.2). Thick film technology offers miniaturisation and reliability advantages for trials type applications.

A plethora of applications has evolved for vibration measurement and control. These include analysis and verification of the dynamic behaviour of structures and machines, predictive maintenance and fault diagnosis. Our early involvement as innovators in piezo-electric sensor and instrumentation technology, coupled with a continuous updating of products and manufacturing facilities, is reflected in the breadth of range of sensors and instrumentation described in this catalogue. *Paper published Electronic Engineering April’60.

Modular instrumentation overview Series 04
Data derived from piezo-electric transducers is in the form of an electric charge analogous to some dynamic physical parameter, and must be further processed in order to extract specific information.

The initial task comprises charge to voltage conversion, thus presenting the source signal in amplified, low impedance format. This process may be further partitioned into charge to current and thence current to voltage conversion for enhanced long distance signal transmission.

The broad band data contained in these signals relates to the dynamic behaviour of machinery and structures, fluid flow, turbulence, together with spurious information relating to additional environmentally induced effects and noise.

Further frequency selective processing may therefore be needed to extract specific information for display and control. By way of illustration, vibration data derived from a rotating machine will contain information correlating to bearing condition. This may be extracted from a wideband signal by bandpass filtering and used as a basis for wear diagnosis.

The vast range of applications for analysis, display and control of piezo-electric transducer derived dynamic information gives rise in turn to a multiplicity of analogue and mixed format (analogue/digital) instrumentation options. A specific choice may be somewhat subjective, involving judgements in such areas as vendor support, but cost/benefit criteria are likely to predominate.

The modular instrumentation is, in essence, a partitioning of the hardware means of extracting realtime information relating to vibration and related physical phenomena.

Partition bands comprise transducer interface, wave filtering including integration, display and control. Within each band individual modules offer an additional high degree of flexibility, thus overall is the capability of meeting a wide diversity of vibration measurement/control requirements with minimal hardware redundancy and customisation.

We can also propose hand held vibration meters, pocket size which read acceleration, velocity, displacement, autoranging digital readout (VT1, VT2).
We have also CA/100, CA/100/F hybrid charge amplifier which are thick film hybrid microcircuit housed in a 24 pin hermetic dip and packaged together with gain controls and connectors, the whole constituting an extremely robust product capable of sustained operation under conditions of high vibration (severity test level 2 for tracked vehicles DEFSTAN 0755pt.2), mechanical shock and temperature extremes (-50°C / +125°C).

04 SERIES INSTRUMENTATION
comprises a comprehensive familiy of analogue piezo-electric signal conditioning modules based upon a 2U (3 1/2“) height front panel. Module panel width is dictated by the requirements of front panel controls and is an integer multiple of the standard single width (1.4“). The 04 series comprises transducer interface, wave filtering, level display and comparator modules, together with housings for up to twelve single width panels.

The process of module specification is simply that of partitioning the measurement task in terms of a string of module functions. At its most trivial this would comprise just one module. Attention should be given to environmental factors that affect choice of transducer and interface amplifier.

Transducer interface amplifiers
Charge amplifiers convert piezo-electric charge to low impedance voltage; conversion gain is unaffected by transducer connecting lead capacitance ; transducer charge sensitivity entered as gain control parameter calibrates normalises) output ; additional range amplifier increases controllable dynamic range to 90dB (1V/pC max.); range comprises low noise, extended low frequency variant CA/04/N, CA/04/NL, CA/04/NH, CA/04/EH, (0.1Hz min), CA/04/D, CA/04/DH, (differential input), and CA/04/V which includes an integrator for conversion of periodic acceleration to velocity.

Long distance transmission of piezoelectric signals is subject to noise degradation that may be sufficient to seriously impair data integrity, amplification local to the transducer mitigates the problem.

VV/04 interface two wire charge/voltage (QVC) transducer signal boosters respectively, combining co-incident booster power source and signal extraction, together with normalising, ranging and fault diagnosis.

Wave filters, integrators
All filters have unity passband gain, integrators include a high pass noise limiting filter. Resultant integrator output (velocity, displacement) is valid for steady and quasi steady state periodic signal inputs only, fundamental frequency > filter corner frequency.
Single integrator VM/04 and double integrator DM/04 convert periodic acceleration to velocity, displacement format respectively, have 50dB switched gain variation, and are available in a wide range of scaling options. Filters include HP/04 highpass, LP/04 lowpass, BP/04 fixed frequency bandpass, and TF/04 manually tuneable bandpass. Both HP/04 and LP/04 are switch tuneable over a 50 : 1 frequency range ; BP/04 is intended as an application specific noise reduction filter ; TF/04 allows manual spectral analysis.

Display/control
Analogue/digital meters for signal levels display, level comparator for vibration severity detection/control. Analogue meters MU/04, MU/04/E and MU/04/L display true rms level.
MU/04/L also includes logarithmic compressor giving optional 60dB dynamic range readout.
DD/04 and variants are autoranging 31/2 digit true rms LCD displays with extended low frequency response, PM/04 is a peak hold meter with digital readout.
LA/04 level comparator switches state when vibration severity exceeds setpoint for a specific time interval. Timeout constraint prevents spurious activation.

Input and inter module switching
Input and inter module switching is catered for by the IS/04 and OS/04 range of switch modules.

Module housings
These contain module backplane, rear panel mounted input/output signal connectors, power supply.
Modules may have intermediate outputs, may be cascaded. All outputs, not only final output(s), are, subject to availability of space, observable.
Power supply options include 230/110V. 50/60Hz mains (/PS), combined mains/internal rechargeable battery (/B) . External battery DC supplies 12/15V @ 24/28V via DC/DC converters (/XB).
Housings accomodate from 2 to 12 single width modules.
These can be portable cases (PC/04/n*/PS, PC/04/n*/PS/B, PC/04/n*/PS/XB, *= number of modules, n= 2,4, 6, 8 or 10), or 19” rack mounted housings for up to 12 single width modules (SR/04/11/PS, SR/04/12/PS, SR/04/11/PS/XB, SR/04/12/PS/XB).

Cables, connectors and accessories
We can look at nay special cables requests (connectors, marking, labels, armours…) and also repairs of cables.
About cable, we can propose a large range of low noise cables from 0.8mm up to 3mm diameter cables with different temperature ranges (T08, T10, T18, P20, P30, P31, P39, P45, T23…) and we have also other coaxial cable (S18, S28…).
We can also make hard line cable assemblies (HL15, HL25, HL30) suitable for long term monitoring of plant and machinery in environments likely to be deleterious to less robust products, very high temperature, high pressure immersion.
About connectors, we are manufacturing our own 10-32 UNF Microdot plugs (straight M1, M8, MP, right angle MR, sealed flanged SS), socket (MS), high temperature Microdot (M2). But we also offer BNC, TNC, Lemo, 2 pole 7/16” UNS socket (7S), plug (7P).

We have also a large range of bulkhead sockets and inline joiners: for instance MB, MJ, BJ, BB, TJ Microdot to Microdot or Microdot to BNC, TNC…

About mounting studs, we have non-insulated and insulated adapters for adhesive mounting (SF/01, SF/02, SF/02/A, SF/03) and we can make some special ones according to customers request. We can also propose case insulated studs (SI01, SI/02, SI/03…SI/10).

The case isolated studs isolate the accelerometer from the mounting surface, thus eliminating earth loop problems.
Finally we have also case isolated mounting magnet (IM01).