Grounding transformer core location to find 4 methods

Grounding transformer core location for 2019-4 methods 03 - 30 15:05:32 grounding transformer core is more a fault in the transformer, sure there transformer core multipoint earthing faults, can further to find the location of the point of failure. After hanging hood, for sundry caused by grounding, more intuitive, and easy to handle. But there are some cases, after the outage hoisting cover can't find the point of failure, in order to exactly find the location, the scene can adopt the following methods: 1, the dc method. Open the iron core with clamp connection piece, the iron yoke on either side of the silicon steel sheet on 6 v dc, and then use dc voltmeter measurement voltage between silicon steel sheet at all levels, in turn, as shown in figure 1 30, whose hands instructions is reversed when the voltage is equal to zero or may think there is a fault location. 2, communication method. The transformer low voltage winding is connected to the 220 ~ 380 v ac voltage, there are magnetic flux in core at this time. If there is a multipoint earthing faults, there will be a current is measured with a milliammeter ( Iron core and a connection piece should be open) 。 With milliammeter along the iron yoke point measurement, at all levels in the table when ma current is zero, is the place for the point of failure. The current measurement method than voltage measurement method are accurate and intuitive. If use the above two methods, still did not find the fault point, can be identified as core under a wooden block with iron yoke ladder be affected with damp be affected with damp or surface of sludge. Will take place after the sludge is clean, dry processing, the fault can be ruled out. General micro water analysis of transformer oil can be found that whether be affected with damp be affected with damp. 3, core pressure method. Is the core of the normal ground disconnect, voltage with ac testing device for core, if the fault point contact is not strong, in the process of booster will hear discharge, according to the spark discharge can be observed point of failure. When the test unit current increases, the voltage rise not to go up, no discharge, showed that the ground fault point were stable, can use the following current method at this time. 4, core increases current method. Also is the core of the normal ground broken, with welding device to the core current. When the current gradually increases, and the iron core fault transfer place resistance is big, the fault point temperature quickly, transformer oil will break down and smoke, and a point of failure parts can be observed. Whether the point of failure to eliminate available core pressure method validation.