What is Shunt Calibration?

The Epsilon Shunt Calibration System makes it easy to transfer Epsilon’s extensometer calibration to a customer’s electronics and is available for any strain-gaged extensometer.

Image Credit: Epsilon Tech

What is Shunt Calibration?

The Epsilon Shunt Calibration System offers an easy method to calibrate an extensometer as well as signal conditioning electronics, without using a mechanical calibrator. With shunt calibration, on-site electrical calibration can be performed with almost all types of electronics and controllers. Shunt calibration also makes it easy to “spot check” the calibration of the electronics on a periodical basis. This will help to make sure that the electronics and extensometer are properly calibrated.

It must be noted that the Epsilon Shunt Calibration System does not substitute the requirement for on-site verification using a mechanical extensometer calibrator. Many laboratories and testing standards require on-site verification.

Which Extensometers Include the Epsilon Shunt Calibration System?

Every new Epsilon strain-gaged extensometer includes the Epsilon Shunt Calibration System. Customers who wish to include the Epsilon Shunt Calibration System to an existing extensometer that does not have it can send their extensometers to Epsilon for re-calibration service. Epsilon will not only install the Epsilon Shunt Calibration System, but will also perform a calibration and return the retrofitted extensometer to the customers with a new Epsilon Test Certificate.

How Does Shunt Calibration Work?

The Epsilon Shunt Calibration System is employed for two-point calibrations. The first point is the gauge length of the extensometer, while the second point is the shunt calibration point. Upon plugging the Epsilon Shunt into the Shunt Connector, the shunt resistor, which is placed in the Shunt Connector, is electrically connected across one arm of the Wheatstone bridge in the extensometer. The result is that the output of the extensometer is electrically set to a known calibration point without any need to mechanically displace the arms of the extensometer. The known calibration point is displayed as Shunted Reading on the extensometer’s Test Certificate. The Shunted Reading was set at Epsilon using an accredited ISO 17025 calibration process and traceable mechanical calibrators.

In order to complete the shunt calibration, adjustments are made to the signal conditioning electronics or software so that the readout of the extensometer corresponds with the Shunted Reading displayed on the extensometer’s Test Certificate.

Using the Epsilon Shunt Calibration System is a Simple Two-Step Process

1. First, set the extensometer to its gauge length and then zero its output. This sets point 1 in the example graph.
2. Plug the Epsilon Shunt into the Shunt Connector and alter the signal conditioning electronics or software so that the readout of the extensometer corresponds with the Shunted Reading on the extensometer’s Test Certificate. This sets point 2 in the example graph.

Image Credit: Epsilon Tech

That’s All It Takes

This process can be applied to nearly any combination of strain-gaged extensometer and signal conditioning electronics or software. The process works even if the test controls have their own internal shunt calibration capability. In addition, it is useful for analog controllers, digital test machine controllers, stand-alone extensometer signal conditioning electronics, and data acquisition systems. For periodic recalibration, the extensometer can also be sent to Epsilon for recalibration service.

For more information, customers can contact Epsilon regarding Epsilon Shunt Calibration System retrofits and recalibration.

This information has been sourced, reviewed and adapted from materials provided by Epsilon Tech Corp.

For more information on this source, please visit Epsilon Tech Corp.