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Proving units are portable, lightweight calibration tools that are designed for use with two-pole voltage testers. The function of a proving unit is to evaluate that the internal components of the voltage tester are working correctly and that measurement accuracy is maintained.
Although regular, formal calibration is still a priority, using a proving unit in combination with a two-pole voltage tester is an ideal way to ensure measurement accuracy is maintained in the time period between official calibration procedures. Most manufacturers recommend that a proving unit is used both before and after testing using a voltage tester; this way, damage to the machine during transportation can be detected before testing or damage to the machine during the actual testing procedure can be detected afterwards.
Proving units come in many different forms in order to accommodate for the vast voltage range spectrum that can be applied to two-pole testers. Some proving units might be designed for measuring low voltage testers, while others may be designed for higher voltage. Some may also be suitable for both low and high voltage testers, measuring across the entire spectrum. A common function found on these units is ramp voltage. The proving unit applies several different voltages to the two-pole voltage tester that is inserted into ports on the proving unit and the device measures whether everything is working correctly with the applied voltage. The indicators are usually expressed via the use of LED lights and if everything is correct the LED light indicators should tell you that this is case.
Stepped voltages again vary depending on the proving unit being used.
Using a proving unit to maintain accuracy is particularly important as frequent usage of a tester can result in the compromisation of measurement accuracy. Other factors such as knocks and bumps, dust, water and other forms of natural contaminants can also effect the accuracy of a tester over a time period and if these inaccuracies go unnoticed it can make the tester unsafe and also produce incorrect readings when used on a system.
Our range of proving units come from many different manufacturers, including Kewtech, Martindale, Megger, Seaward and Socket and See. As mentioned earlier their capabilities vary from tester to tester, so knowing which unit you need before making a purchase is highly recommended. If you're confused about which unit you need we're more than happy to help you make a decision - simply give us a call on the numbers at the top of this page and we'll help you out choosing the right proving unit for use with your voltage tester.