A multi-product electrical calibrator is designed to calibrate multifunction products like handheld digital multimeters, clamp meters, thermocouples and RTDs, and more. They may also offer options to calibrate additional workload items like oscilloscopes or power quality analyzers. Some can be automated with software to increase throughput and reduce errors.
To ensure that digital multimeters and other products continue to test and measure properly and within specification, regular calibration is a must.
So how do you choose a multi-product calibrator? They are not all the same. Here are seven essential points to consider:
1. Workload should drive your purchase requirements.
Check the manuals for your workload items to see what type of calibration capabilities they recommend. Depending on your workload, you may only need basic capabilities like ac/dc current, voltage and resistance. Or you may need additional capabilities to cover other workload items.
2. Don't let ambitious banner specifications mislead you -- and don't ignore floor specifications.
Banner specs advertise a product's best capabilities, but they can be misleading, and they are almost always associated with a floor specification. Check the specifications and be sure to read the footnotes carefully.
3. As calibrator accuracy increases, so does the price.
Most labs prefer a 4:1 test uncertainty ratio. Buy the calibrator that gives you the best return on your investment for the accuracy that you require.
4. Pay close attention to the calibrator's ac/dc current output.
Consider whether it has enough accuracy, and enough compliance voltage to drive a current coil or the workload you need to calibrate. At higher currents, many calibrators limit how long you can continuously output high current. Typically, a multifunction calibrator works for the common workload up to 1,000 amps. For higher currents, you can use an amplifier like the 52120A Transconductance Amplifier.
5. Temperature is a common need, but it can be confusing.
Many DMMs have a thermocouple input that allows them to measure temperature; others have RTD measurement capability. If your calibrator can simulate an RTD and measure and simulate a thermocouple, you should have sufficient capability for measuring temperature.
6. Don't overlook portability, robustness, and environmental specifications.
If you calibrate on-site the instrument must be transportable to the field. It also needs to be robust enough to handle routine shipments for annual calibrations. Consider also the possibility of accidental misuse -- what safety provisions are in place?
7. Software and remote communication are very important.
Make sure the calibrator can communicate over common interfaces like RS-232, GPIB, or USB. And consider that automating calibration via software can save hundreds of man-hours per month in calibration time plus help you avoid manual calibrator errors. Ideally you’ll want a calibrator that can be automated by software that is comprehensive and calibrates a wide variety of workload.