GDDO-20C AC/DC Electric Meter Calibration Device digunakake kanggo ndeteksi kesalahan dhasar saka macem-macem instrumen listrik frekuensi daya ing sistem daya, kalebu voltmeter, ammeter, wattmeter, ohmmeter, siji phase & telung phase AC meter energi (opsional) lan kesalahan dhasar saka DC volt-meter lan ammeter.