1. During parameter measurement, if the displayed value is greatly different from the actual value, check whether the range of the input voltage and current is consistent with the actual value.
2. If the displayed reading is unstable during parameter measurement, check whether there is voltage input. If there is no voltage input, the displayed reading will be unstable during current measurement. If there is voltage input, the unstable reading is the unstable load.
3. When checking the meter, if the error value is large, there are several possible reasons:
A. Wiring error, phase voltage and phase current do not correspond one by one, or a phase power is negative.
B. The photoelectric sampler samples wrongly (i.e. more samples or less samples). At this time, it is necessary to readjust the position or sensitivity of the photoelectric sampler.
C. The current input mode is set incorrectly or the three-phase three wire and three-phase four wire modes are incorrect.
D. The sampling current of clamp type current transformer is too small because the iron core end face is too dirty.
E. The iron core end face of clamp type current transformer is not completely closed.
F. The constant of the meter being calibrated is input incorrectly.
G. The transformation ratio input of the calibrated metering device is incorrect.
H. The field load fluctuates too much, or there is strong electromagnetic interference.