Maintenance Of Dry Transformer 3 Phase
Since the coil of the transformer will heat up during operation, it is necessary to take cooling measures. Small-capacity transformers can be dry transformer 3 phase, with natural air cooling or forced air cooling. Large-capacity transformers generally use oil as the cooling medium and must be forced to air-cool.
During the operation of the dry transformer 3 phase, the primary and secondary coils and the magnetic core will generate heat. The transformer oil flows through these parts to take away the heat by heat conduction, and then dissipates the heat into the ambient air through the radiator. In other words, the operation of the transformer is a unity of opposites in terms of heat generation and heat dissipation. Obviously, the amount of heat generated by the transformer is proportional to the size of the load, and the heat dissipation is directly related to the surrounding environment.
Amorphous alloy transformers are both energy-saving and economical. Its notable feature is that the no-load loss is very low, which is only about 20% of the S9 series oil-immersed transformers. The distribution transformer with ideal effect is especially suitable for places with low load rate such as rural power grids.
Notes on maintenance of dry transformer 3 phase in operation:
Overload operation of dry-type distribution transformers
Transformer overload operation means that the load current exceeds the rated current of the transformer. Under normal circumstances, when the transformer is running at a small load, its insulating material cannot fully play its role. During continuous overload operation, the transformer will generate high temperature, which will cause the winding insulation to be hardened and fall off, resulting in inter-turn short circuit; at the same time, the transformer oil produces Sludge accumulates on the tank plate, winding and iron core, resulting in poor heat dissipation of the transformer oil. This vicious circle not only seriously affects the life of the transformer, but also causes accidents such as high-voltage breakdown and transformer burnout. Therefore, the three-phase load current should be observed frequently. The three-phase load current should be consistent, if there is any deviation, it should not exceed 10%.
Unusual sound of distribution transformer
When alternating current passes through the transformer windings, a normal and uniform "humming" sound occurs due to the natural vibration of the iron core. If there is an abnormal sound, you need to find the cause and report it to the relevant department in time. The sound is also different when the transformer is unloaded and loaded. According to the abnormal sound characteristics compared with the past, the cause can be found out before it can be put into operation.
Whether the oil level of the dry transformer 3 phase is normal, and whether there is any leakage, oil leakage or abnormal oil color
There are many reasons for the oil level to drop. Due to poor welding quality and poor sealing, radiating pipes, valves, box edges, etc. are prone to seepage and oil leakage. When the oil level drops below the upper cover of the transformer, the contact surface between the oil and the air increases, and it is easy to oxidize and deteriorate and absorb the moisture in the air, resulting in a decrease in the compressive strength of the oil, thereby destroying the insulation performance of the winding. When the oil shortage is serious, the insulation of the conductive parts of the transformer to the ground and each other is reduced, resulting in the breakdown discharge between phases or to the ground. If you continue to use it at this time, the transformer oil will not be able to circulate and convect normally, which will cause the transformer oil temperature to rise, shorten the life span or even burn out.
Regular cleaning of distribution transformers
Regularly clean the dirt on the distribution transformer, check whether the bushing has flashover discharge, whether the grounding is good, whether there is disconnection, de-soldering, or fracture, and regularly shake the grounding resistance, and its resistance value is not greater than 4Ω (capacity 100 kVA and above) or 10Ω (capacity less than 100 kVA), or take anti-fouling measures and install a casing anti-fouling cap. When connecting and dismantling the lead wires of the distribution transformer, strictly follow the process operation to avoid internal breakage of the lead wires.
Whether there is damage, rupture and discharge traces on the insulating bushing of distribution transformers
If the insulating sleeve is not cleaned for a long time, or there are cracks and discharge traces, in rainy or foggy weather, the leakage current of the insulating sleeve will increase due to the humidity of the air, the insulation will drop, and flashover will occur to the ground. In addition, severe fouling of the insulating sleeve, as well as large fragments and cracks on the insulating sleeve, can also cause flashover or explosion accidents. To solve this phenomenon, in addition to observing the insulating sleeve itself, we should also pay attention to the law of contamination of the sleeve, such as wind direction, surrounding environment, etc., so as to do a good job of cleaning.
