Explosion-proof transformerWhat inspections are needed before use
Explosion-proof transformer The following work needs to be done before commissioning:
a. Check whether the oil level gauge on the oil conservator is intact, whether the oil level is clear and on the oil baseline consistent with the natural environment. If too high, after the transformer is put into operation with load, the oil temperature rises, and the oil may overflow from the connection pipe of the breather at the top of the conservator; if too low, during light load in winter or short-term shutdown, the oil level may drop to a point invisible on the oil level gauge.
b. Check whether the sealing of the rear cover, bushings, oil level gauge, oil drain valve, etc. is good, and whether there is any oil leakage. Otherwise, when the transformer is under load, under thermal conditions, more serious oil leakage will occur.
c. Check whether the explosion-proof membrane of the explosion-proof pipe is intact.
d. Check whether the desiccant in the breather is ineffective.
e. Check whether the grounding device of the transformer casing is firm and reliable, because it plays a direct protective role for the transformer.
f. Check whether the primary/secondary outgoing bushings of the transformer and their connections with the transmission lines are good, and whether the phase colors are appropriate.
g. Check whether the nameplate on the transformer matches the specified transformer model and specification. For example, the rated voltage on each side, the wiring level of the transformer, the capacity of the transformer, and the position of the tap changer, etc.
h. Measure the insulation of the transformer. Use a 10500~2600MΩ meter to measure the ground resistance of the primary/secondary windings of the transformer, and the resistance between the primary and secondary windings, and record the ambient temperature during measurement. There is no clear regulation on the control value of the ground resistance, but it should be compared with historical data or original records, and should not be lower than 75% of the factory value (when the temperature of the tested transformer is not directly the same as that during the factory test, it should be calculated to the same temperature for comparison).
i. Measure the DC resistance of the transformer windings connected to the bushings. According to Article 6.0.2 of GB50150-1991 "Standard for Handover Test of Electrical Equipment in Household Electrical Equipment Installation Engineering", the mutual error of the DC resistance of each phase of the explosion-proof transformer should be less than 4% of the average value, and the mutual error of the DC resistance between lines should be less than 2% of the average value.
If all the above inspections pass, first energize the transformer without load. Check whether the electromagnetic sound is abnormal, and measure whether the secondary side voltage is balanced. If balanced, it indicates that the transformer ratio is normal and there is no inter-turn short circuit, and the transformer can operate normally with load.
