Iron chip grounding is a common type of fault in transformers. Once multiple grounding points are identified in the iron chip of a transformer, the specific location of the fault can be further investigated. After hanging the cover, grounding caused by debris is more intuitive and easier to handle.

But there are also certain situations where the problem cannot be found after a power outage, and in order to accurately locate the grounding address, the DC method can be used. Open the connection piece between the iron chip and the clamp, apply 6V DC to the silicon steel sheets on both sides of the iron yoke, and then use a DC voltmeter to measure the voltage between each level of silicon steel sheets in sequence. When the voltage is zero or the pointer indicates the opposite direction, it can be considered as the faulty grounding address.

Alternatively, using the communication method, connect the low-voltage winding of the transformer to a communication voltage of 220-380V, where there is magnetic flux present in the iron chip. If there are multiple grounding faults, measuring with a milliampere meter will display the current. Measure point by point along the iron yoke with a milliampere meter. When the current in the milliampere meter is zero, it is the fault point. This current measurement method is more accurate and intuitive than the voltage measurement method.

If the above two methods still cannot identify the problem, the iron chip pressurization method can also be used. Disconnect the normal grounding point of the iron core and apply voltage to the iron chip using a communication test device. If the faulty point is not firmly connected, discharge sound will be heard during the boosting process, and the faulty point can be observed based on the discharge spark.

When the current of the experimental device increases, the voltage cannot rise and there is no discharge phenomenon, indicating that the grounding fault point is stable. At this moment, the current method can be used. Disconnect the normal grounding address of the iron chip and apply current to the iron core using a welding machine device. When the current gradually increases and the resistance of the faulty iron core is high, the temperature of the faulty point rises quickly, and the transformer oil will decompose and smoke, and then the location of the faulty point can be observed. Whether the problem can be eliminated can be verified by using the iron core pressurization method.

Article source: Silicon steel sheet manufacturerhttp://www.cheungshun.com