Miniature DeltaTron Accelerometers Types 4507 and 4508 are specifically designed to withstand the rough environment of the automotive industry. A combination of high sensitivity, low mass and small physical dimensions make them ideal for modal measurements, such as automotive body and power-train measurements, as well as for modal analysis on aircraft, trains and satellites.
The main difference between the two Types is the position of the coaxial connector which is on the top surface perpendicular to the main axis for Type 4508 (top-mounted connector), and on the side surface parallel to the main axis for Type 4507 (side-mounted connector).
Uses
- Modal measurements for automotive body and power-train applications
- Multichannel modal analysis measurements
- Structural analysis measurements
Features
- Robust titanium housing with integrated titanium connector
- Easily fitted to different test objects using a selection of mounting clips
- Low-weight ThetaShear design giving high sensitivity/weight ratio and very low sensitivity to environmental factors
- Triaxial mounting facility
- Connect directly to DeltaTron power supply (ICP® compatible). The DeltaTron principle allows the use of inexpensive cables. Low output impedance so that long cables can be used
- Built-in, low-noise preamplifiers with ASICs give more than 100 dB dynamic range
- Choice of sensitivities from 10 mV/g to 1 V/g
- ID (TEDS) "Smart Transducer Interface" IEEE - P1451.4 (Types 4507 B and 4508 B)
- Sensitivity 5 pC/g
- Operating temperature up to 250°C (482°F)
Miniature DeltaTron® Accelerometers Types 4507 and 4508 consist of a ThetaShear® accelerometer and a DeltaTron preamplifier in a lightweight titanium housing with integrated 10 - 32 UNF connectors. Types 4507-C and 4508-C are similar to the DeltaTron accelerometers but come without the preamplifier.
Design
The 10 - 32 UNF connector is an integrated part of the top piece, which also contains the preamplifier (not 4507 C or 4508 C). The slotted cylindrical stanchion holds a central seismic mass flanked by two piezoelectric plates. This assembly is clamped rigidly by a ring. The parts are firmly held together without the use of any bonding agent other than friction, a principle which has proved extremely reliable in Brüel & Kjær DeltaShear® accelerometers. This assembly is hermetically welded to the titanium housing.
Frequency Response
The following information on frequency response is included on each accelerometer’s accompanying calibration chart. However, certain accelerometers have this information built in electronically (TEDS) as well.
The upper frequency limits given in the specifications are the frequencies where the deviation from the reference sensitivity is less than 10%. It is approximately 30% of the mounted resonance frequency. This assumes that the accelerometer is correctly mounted on the test structure - a poor mounting can have a marked effect on the mounted resonance frequency.
The lower frequency limits and phase response are determined by the built-in preamplifiers. The lower frequency limits are given in the specifications for deviations from reference sensitivity of less than 10%.
Increased measurement accuracy can be achieved by dividing the actual measurement by the individual frequency response.
Frequency response curves generated from the individual TEDS values are given on the calibration chart for the major part of the frequency range. At low frequencies, the curves given are typical.
The calibration chart also includes these individual TEDS values that, together with a general formula, best fit the measured frequency response. The expression can be used for frequency response compensation in the specified frequency range.
Calibration
Each accelerometer is individually calibrated and supplied with a comprehensive calibration chart. Long-term stability and reliability are ensured by artificial ageing during the production process. Field checking and system calibration are straightforward using Brüel & Kjær’s Hand-held Vibration Calibrator Type 4294.
Subsequent Calibration
Brüel & Kjær manufactures a range of equipment for frequency response, sensitivity and system calibrations.
For calibration of Types 4507/4508, Calibration Clip DV 0459 is available. Fig. 12 Calibration Clip DV 0459 Specifications: Material:Base - Stainless steel (hardened)Spring - Stainless steel spring Mounting surface diameter: 21 mm Mounting thread: 10 - 32 UNF Weight: 17 gram.
