According to the operating experience, there are many reasons for abnormal sounds, and the parts that occur are different. Only by accumulating experience, can we make realistic judgments. Here are a few common examples.
(1) Overvoltage (such as neutral phase ungrounded system single-phase grounding, ferromagnetic resonance, etc.).
(2) Overcurrent (such as overload, large power load start, through short circuit, etc.). The sound caused by this reason is the same as the previous one, and the sound is larger than the original, and it is a "beep" sound, no noise. However, sometimes it may be accompanied by a drastic change in the load, and the intermittent sound of "cutting, cutting, cutting" assaults is presented. When this sound occurs, the pointer of the transformer's indicating instrument (current meter, voltmeter) operates at the same time, which is easy to discriminate.
(3) Loose screws that clamp the iron core. This kind of reason can cause very amazing hammering and windy sounds, such as "clam dangling" and "calling...calling...", but the indicator is normal at this time, oil color, oil level, oil temperature Also normal.
(4) The transformer casing is caused by collision with other objects. This is because the vibration of the inner core of the transformer causes vibration of other components, causing the contacts to collide with each other. For example, when the hose of the control line of the transformer collides with the outer casing or the radiator, the sound of “sand sand†will appear, which has the characteristics of continuous long and intermittent, and the transformer parts will not exhibit an abnormal phenomenon. At this time, you can find the sound source, hold it down with the hand or the stick on the loudest side, and then listen to the sound to change it.
(5) The sound of discharge caused by the influence of external weather. Such as foggy days and snowy days, causing corona discharge or glow discharge at the casing, showing a "beep" or "beep" sound, and a small blue spark at night.
(6) The core failure is caused. If the iron core ground wire is disconnected, it will produce a crack like a discharge, and the iron core will cause an abnormal sound.
(7) Caused by a short circuit between turns. Due to the local severe heat in the short circuit, the oil is partially boiled, and the sound like "squeaking, smashing" is like a water. This kind of sound is especially important.
(8) The tap changer is faulty. Poor contact of the tap-changer, localized heating can also cause the kind of sound that occurs when the winding turns short between turns.
The reasons for the abnormal sound of the transformer are numerous and complicated, just to name a few. In order to detect faults in time, the inspection of the transformer should be strengthened.
The normal inspection inspection items of the transformer are:
(1) Whether the sound, oil level and temperature are normal;
(2) Whether the gas relay is full of oil, whether the transformer casing is clean, whether there is leakage, and whether the explosion-proof pipe is intact without cracks;
(3) Whether the insulating sleeve is clean, cracked, fired or not, whether the lead joint is good, and whether there is overheating;
(4) Whether the cooling system is normal, whether the respirator is unblocked, and whether the moisture absorption agent has deliquescent;
(5) Whether the operation of the load and the on-load voltage regulator is normal, and whether the position of the tap changer meets the voltage requirements.
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