Transformer oil pump - is a fully enclosed structure, built-in submersible three-phase asynchronous motor direct drive shaft drive a centrifugal or axial vane pump, dedicated to the transmission of oil insulating fluid medium fluid machinery. Centrifugal transformer oil pump for transformer strong oil air cooler; axial transformer oil pump (low head, large flow) for transformers radiator.
According to the structure of the drive motor: Currently supporting the use of traditional three-phase asynchronous motor designed for ordinary oil-immersed transformer oil pump; â‘¡ axial gap (disc motor) motor-driven disc transformer pump. The difference between the two structures is mainly driven motor different, use the function, the installation form is exactly the same. However, due to its unique axial magnetic disc pulling force, the operation must be promptly replaced with worn bearings to prevent the rotor fall caused by strong mechanical friction. Currently still widely used abroad is still a traditional three-phase asynchronous motor designed for general-purpose transformer pump head, the flow for each specific type of pump is irreplaceable, because each model pump curve is only one thing Most efficient. This point of the pump work is called the rated operating point, pump work in this area, not only high efficiency, low noise, reasonable power consumption, stable operation, no harmful eddy current impact and cavitation damage, to maintain long-term reliable operation.
The above conditions point of choice: the main transformer oil circulating oil loop piping system resistance characteristics of the decision. Different types of coolers and main circuit oil circulation structure, the pipe network characteristics of different curves. Pipe network system resistance curve and the intersection of transformer and pump characteristic curve intersection point is the rated operating point of the oil pump. Therefore, in the alternative of transformer oil pump, different hydraulic parameters or reduce the arbitrary replacement of hydraulic parameters is not desirable. He is concerned with the safe operation of the main transformer and the rated heat transfer capacity of the cooler.
At present, according to the requirements of Guodian: In order to improve the running life of the transformer oil pump bearings, the original 1450 rev / min (4-pole motor) pump is replaced with an oil pump of 1000 rev / min (6 pole motor)
Transformer oil pump of 1000 rev / min (6-pole motor) To reach the flow of the oil pump (4-pole motor) and lift, the impeller must be solved by increasing the impeller diameter. As the diameter of the rotating machine increases, operational stability decreases, and the 6-pole drive motor has a larger diameter than the 4-pole motor. As a result, some older cooler mounting dimensions (such as with a 4B2 40-16 / 3V oil pump) are difficult to achieve during the replacement process. Changchun Northrend Motor Co., Ltd. uses a two-stage pump structure to solve such alternative problems of oil pumps, but the manufacturing costs increase.
In fact, at home and abroad pump products to high-speed, high efficiency direction. Appropriate high-speed transformer oil pump not only high efficiency and small size, good running stability. Of course, low speed can improve bearing operating life. However, with the increase of impeller diameter, the balance problem will be more prominent, especially as the vane pump blade mold, the consistency of the twist angle in the process of error is inevitable, these are the key factors that affect the stability of the operation, it is not good Will reduce the operating life of bearings. At present, a large number of domestic units use a large number of axial air gap (disk motor) motor driven disk transformer pump (this pump is suitable for low-speed 1000 rev / min), such issues will be more prominent. Because of the axial magnetic pull of the disc motor is strong, (it is by this rotating axial magnetic pull magnetic coupling to make the rotor rotate to complete the electric energy conversion.) Axial magnetic pull will make the bearing wear The amount of gap directly into fixed, reduce the gap between the rotor, until the set, the rotor iron and iron strong friction. (Disc motor is very suitable for brake motor: stator and rotor brake pads installed, power brake, power loss free rotation.) Therefore, the widespread use of foreign or traditional three-phase asynchronous motor designed for ordinary transformer pump. Only we are still using the disc motor transformer pump as a new product. Ignoring the tight monitoring of the bearings during operation, the probability of an accident increases with the cumulative operating hours of the pump. Japan's production of this disc-type transformer pump manual instructions on bearing maintenance carried out more space, and the introduction of the formula is as follows:
Lh = (106 / 60N) (C / Prfw) 3a1 a2 a3
Lh: Calculated lifetime (hr); N: Rotational speed (rot / min); C: Rated load in kg; Pr: Equivalent bearing load in kg;
fw: load factor; a1: reliability coefficient; a2: lubrication coefficient; a3: material factor;
The above formula is given the recommended value of each parameter, due to its selection of materials, environmental, manufacturing processes and so on, it is difficult to accurately calculate the operational life of the pump. In my opinion, the actual is the responsibility to the user.
Our traditional 1450 rev / min (4 pole motor) pumps, and even 2860 rev / min (2 pole motor) transformer pump some varieties run very well, and some products have been running for 20 years and is still running well. Therefore, the key is good, professional manufacturing quality and operation and maintenance. In the meantime, we can not totally negate the quality problems because of some quality problems. In fact, some operating units maintain their experience and opinions quite respectfully.
Ordinary Transformer Oil Pumps Model 6B4,6B5 with low speed of 1000 rpm or less (6-pole motor) have been put into operation in large quantities. However, due to lack of time and poor publicity, it seems that only a 6PB type disc pump is a low-speed pump. In fact, between the two in the hydraulic parameters, installation dimensions, the main performance can be completely replaced.