Detailed Product Description DD28 single phase watt-hour meter is an induction meter which is applicable to measure the rated frequency of 50Hz. Meter has the features of small volume, tightly structure design, low power loss etc. Meter technical conformed to National Standard GB/T 15283-94 idt International Standard IEC 521. The watthour meter is consisted by glass cover, big terminal cover, the current rate is 10(30)A, 10(40)A.