Datasheet

Instrument Selection
Vishay Micro-Measurements
www.vishaymg.com [e-mail] Document Number: 11048
2 Revision: 12-Oct-06
Considerations for Instrument Selection
STRAIN INDICATORS
Basic instrumentation requirements call for stability, accuracy and high resolution when
making measurements under static loading conditions, and particularly where
measurements are to be taken over long periods of time. Vishay Micro-Measurements offers
two strain indicator models meeting these demanding criteria.
The Model P3 Strain Indicator and Recorder is a portable, battery-operated instrument
capable of simultaneously accepting four inputs from quarter-, half-, and full-bridge
strain-gage circuits, including strain-gage-based transducers. A highly stable measurement
circuit, regulated bridge excitation supply, and precisely settable gage factor enable
measurements of ±0.1% accuracy and 1 microstrain resolution. Data, recorded at a
user-selectable rate of up to 1 reading per channel per second, is stored on a removable
multimedia card and is transferred by USB to a host computer for subsequent storage,
reduction and presentation with third-party software. The P3 can also be configured and
operated directly from your PC with a separate software application included with each
instrument.
The Model 3800 Wide Range Strain Indicator is a versatile, high-precision laboratory-type
instrument designed for use with strain gages and strain gage based transducers. Principal
features of the Model 3800 are wide-range control of gage factor; excitation precisely
settable over 1 – 15 volt range; and wide balance range with no bridge loading effect. With
these extended operating capabilities, the Model 3800 can be used for the most demanding
measurement tasks which are not possible with conventional strain measuring instruments
and general-purpose transducer indicators. Resolutions achievable with the Model 3800 are
0.10 microstrain when used as a strain indicator, and 0.10μV/V when used as a transducer
indicator (0.025μV/V with suppressed zero).
SIGNAL CONDITIONING AMPLIFIERS
When signals are produced by dynamically applied loads at frequencies above 0.1Hz, or are
transients, measuring instrumentation requires adequate frequency response, and a wide
amplifier gain range for output to the appropriate recording or display device. Such an
instrument consists of an amplifier and signal conditioner with a built-in or shared power
supply. Individual units are normally required for each channel when simultaneous recording
or multiple channels are needed. With the output sent to a suitable display device, signal
conditioning amplifiers can be used for making long-term measurements under static loading
conditions, when maximum stability and accuracy are not primary considerations.
The A2, 2200, and 2300 Systems accept low-level signals, and condition and amplify them
into high-level outputs suitable for multiple channel, simultaneous, dynamic recording. All of
these systems can be used in conjunction with a variety of recording devices.
DIGITAL DATA SYSTEMS
Depending on their design, digital data systems can be used for measurement of static,
dynamic, or both kinds of signals. Vishay Micro-Measurements offers three digital data
systems, each controlled with StrainSmart
®
software.
System 5000 is used for static signals with a scanning rate of 1ms per scan for up to 1200
channels. Typical usage is fifty complete scans per second. Input channels in each single
scanner are scanned sequentially at 0.04-ms intervals and stored in random access memory
within a 1-ms window. Multiple scanners acquire data concurrently.
System 6000 is used for dynamic signals with scanning rates up to 10,000 samples per
second per channel and up to 1200 channels. System 6000 provides individual
analog-to-digital conversion on each channel and simultaneous sampling data acquisition
for all channels. Selectable, digital Finite Impulse Response (FIR) low-pass filtering is
incorporated into each instrumentation channel to meet a variety of testing requirements.
Custom filters are also available.
System 7000 is a high performance dynamic data acquisition instrument with measurement
accuracy of ±0.05% of full scale. Each sensor card employs a 24-bit analog to digital
converter enabling 0.5 microstrain resolution. Scan rates up to 2048 samples per second are
available for simultaneous reading of all sensor inputs. A combination of analog and flexible
Finite Impulse Response (FIR) filters are available to provide adequate anti-alias filtering at
all scanning rates. Electronically selectable bridge completion resistors allow the user to
choose between 120-, 350-, and 1000-ohm strain gages through software selection. System
7000 is capable of self-calibration with a removable calibration reference.