....Interfacing Extensometers to
    Test Equipment ....

All strain gauged transducers (load cells, extensometers, etc.) are normally a full wheatstone bridge design. They are excited or powered by a voltage, typically 5 or 10 VDC. The output is proportional to the excitation. For this reason the calibrated output is often expressed as 2.345 mV/V, for example. This means the output at full scale will be 23.450 millivolts if the excitation is exactly 10 volts. This data is provided by Epsilon on the calibration certificate.

All strain gauged sensors must be connected to some external electronics to provide readings. This electronics provides the excitation and normally amplifies the output to a high level DC voltage. This resultant voltage is used for readout or control of the test machine. In newer digital systems the voltage output is converted via data acquisition hardware into engineering units of strain. In instances where a chart recorder or X-Y recorder is used, the output is set to easily yield a specified strain/cm on the graph.

When any new device like an extensometer is first used, the electronics must be set up with the unit to read correctly. There are several ways to accomplish this. Generally the process is very straightforward. If your extensometer will be connected to an available channel for an extensometer in your test controller, we normally supply the unit with the correct connector to plug right in. For data acquisition systems, the required strain gauged signal conditioning is required. Often this is part of the system. For boards that require high level inputs or for use with recorders, Epsilon offers the electronics you need.

Detailed calibration procedures are provided by Epsilon to cover virtually all approaches to calibration.

Calibrating Extensometers with Electronics
Required for any extensometer you buy, this step can be done many ways, most of which are quite simple. The most common options are:

Using Epsilonís Shunt Calibration Module
As detailed in shunt calibration section, this is a very quick and easy way to set your electronics, regardless of brand. The two points needed for the calibration are provided.

With Electronics from Epsilon

All extensometers purchased with electronics from Epsilon are shipped as fully calibrated systems. The output and/or display are factory set to exact values. No further calibration is required. Periodic re-calibration can be done by Epsilon.

With an extensometer calibrator from Epsilon
Epsilonís model 3590 Digital Electronic Calibrator is the easiest to use unit available. This is an ideal way to perform calibrations if you have many extensometers and wish to calibrate your own. They allow you to check many data points along the curve, for the highest accuracy.

By calibration services such
as the equipment manufacturer.
Epsilonís extensometers can be calibrated with test controls by any calibration service with the capability of calibrating extensometers. Many customers have their entire test machine re-calibrated annually by the service department of the manufacturer. This includes the load cell, extensometers and any other sensors. Any competent service will have no difficulty with Epsilonís extensometers.



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