铁芯加压法。将铁芯的正常接地点断开，用交流试验装置给铁芯加电压，若故障点接触不牢固，在升压过程中会听到放电声，根据放电火花可观察到故障点。当试验装置电流增大时，电压升不上去，没有放电现象，说明接地故障点很稳固，此时可采用下述的电流法。
Core pressure method. The normal grounding point of iron core is disconnected and voltage is applied to iron core with AC test device. If the contact of fault point is not firm, the discharging sound will be heard during the boosting process. According to the discharging spark, the fault point can be observed. When the current of the test device increases, the voltage does not rise up and there is no discharge phenomenon, which indicates that the grounding fault point is very stable. At this time, the following current method can be used.
铁芯加大电流法。将铁芯的正常接地点断开，用电焊机给铁芯加电流，。当电流逐渐增大，且铁芯故障接地点的电阻大时，故障点温度升高很快，变压粉由将分解而冒烟，从而可以观察到故障点部位。故障点是否消除可用铁芯加压法验证。
Increased current method with iron core. The normal grounding point of the iron core is disconnected and the current is added to the iron core by the welding machine. When the current increases gradually and the resistance of the core fault grounding point is large, the temperature of the fault point rises rapidly, and the transformer powder will decompose and smoke, so that the fault point can be observed. Whether the fault point can be eliminated or not can be verified by the core pressurization method.