Chauvin Arnoux DTR 8510 [P01157702] Digital Transformer Ratiometer. The Chauvin Arnoux DTR 8510 Ratiometer digital Cat III 300V c/w Leads & Carry Case is capable of calculating ratios that meet IEEE C57 standards. The digital ratiometer can ensure great levels of safety, too, by performing all tests by excitation of the primary, and measurement on the secondary. The Chauvin Arnoux digital ratiometer has a lid and handle to keep the controls and screen safe, and to make it easier to carry. It comes with all the leads required, too, to connect with the equipment you need to test. Furthermore, the Chauvin Arnoux device features battery life of up to 10 hours, with an NiMH battery. It has automatic calibration and balancing, which saves plenty of time, due to not requiring adjustments. It can also perform low voltage tests, preventing errors due to saturation of CT when testing at a high voltage. Furthermore, the digital display shows you rations, winding direction, excitation current and much more. There is also a bar graph that indicates the progression to auto-calibration and measurement. Finally, the degauss function helps eliminate magnetic effects and improve accuracy.