The spatial electromagnetic field and transient ground potential rise level of the secondary equipment are measured. The AD7656, AD7606 and AD92883 analog-to-digital (A/D) converter chips commonly used in the electronic transformer acquisition unit boards are selected as the objects to study, and the analog boards for immunity test of these chips are developed. The electrostatic discharge and surge immunity tests are carried out, the severity degree of device damage is judged, and the failure characteristics of different chips are summarized. Electromagnetic compatibility (EMC) protection measures are added layer by layer on the circuit board, and the inhibition effect of different protection levels on various types of interference is obtained.