Main features: 1.Accurate active energy measurement for long-term operation without calibration under normal operation condition; 2.Positive and negative active energy measurement (negative energy can be counted into positive energy); 3.Broad dynamic operation range, actual overload capability up to 10times; Excellent error linearity within the range of 1%Ib～Imax; 4.Provided with both photo-electric insulated impulse test output and LED test output for the customers' convenience of choosing; 5.Adopting world famous, long-life and high reliability components ensures it long-life and high reliability; 6.Excellent anti-tamper capability: by adopting anti-magnetism and anti-reverse counter combined with special circuit design.