The invention relates to the technical field of
electric energy meter data testing, in particular to a zero line breakage detection circuit and detection method for an acquisition terminal. The detection circuit comprises an AC sampling module MK1,
four current transformers CT1-CT4, a
relay K1, resistors R1-R4, a
diode D1, an NPN
triode Q1 and a processor N1. The circuit collects three-phase
voltage and zero line
voltage and current through the MK1, preliminarily judges whether the zero
line current is larger than a preset threshold value I0 or not, further calculates the absolute value of the three-phase
voltage vector sum, compares the absolute value with a threshold value U0, changes the load state of the circuit through the
relay K1, and then performs re-judgment so as to accurately judge whether the zero line is broken or not. The method comprises the steps of initial sampling, current preliminary judgment,
voltage vector sum preliminary judgment,
relay action and re-judgment preparation,
voltage vector sum re-judgment and detection ending and responding. The zero line breaking fault can be accurately detected, misjudgment is avoided, and the detection accuracy and reliability are improved.