Transformer oil pump parameters?

Transformer oil pump - is a fully sealed structure, built-in submersible three-phase asynchronous motor direct drive a centrifugal or axial-flow vane pump, dedicated to the transmission fluid transformer dielectric fluid medium. Centrifugal transformer oil pump is suitable for transformer strong oil air cooler; axial flow transformer oil pump (low lift, large flow) is suitable for transformer chip radiator.

The transformer oil pump is divided according to the structure of the drive motor: At present, domestic use of a common type of transformer oil pump designed for a traditional three-phase asynchronous motor dedicated submersible; 2 axial air gap (disc type motor) motor-driven disc transformer oil pump. The difference between the two structures is mainly that the drive motor is different, and the use function and installation form are the same. However, due to the special axial magnetic pull force of the disc pump, the worn bearings must be replaced in time to prevent the rotor from falling and causing strong mechanical friction. At present, the transformer oil pump head and flow rate of the common type transformer oil pump specially designed for conventional three-phase asynchronous motors is still widely used abroad, and it is irreplaceable for each specific type of pump because of the characteristics of each type of pump. Only one point on the curve is the most efficient. The point where the pump works is called the rated operating point. When the pump is operating in this area, the pump is not only highly efficient, but also has low noise, reasonable power consumption, stable operation, no harmful eddy current impact and cavitation damage, and can maintain long-term reliable operation.

The selection of the operating point of the oil pump of the transformer oil pump is determined by the resistance characteristics curve of the pipe network system of the main oil cooler circulating oil loop. Different types of coolers and main oil circuit circulation structures have different pipe network characteristics. The intersection point of the resistance characteristic curve of the pipe network system and the operating characteristic curve of the transformer oil pump is the rated working point of the oil pump. Therefore, in terms of transformer oil pump alternatives, arbitrary replacement of different hydraulic parameters or reduced hydraulic parameters is not desirable. He related to the safe operation of the main transformer and the rated heat exchange capacity of the cooler.

Transformer pump oil pump At present, all domestic power grids and bureaus comply with Guodian's requirements: In order to increase the operating life of the transformer oil pump bearing, the original 1450 rpm (4-pole motor) oil pump is changed to 1000 rpm (6-pole motor) Oil pump.

For a 1000 rpm (6 pole motor) transformer oil pump to reach the (4 pole motor) oil pump flow, head, it is necessary to solve the problem by increasing the impeller diameter. An increase in the diameter of the rotating machine results in a decrease in the running stability, and the diameter of the 6-pole drive motor is larger than that of the 4-pole motor. In this way, some older cooler mounting dimensions (eg 4B2 40-16/3V oil pumps fitted) are difficult to achieve during the replacement process. Changchun Northen Motor Co., Ltd. adopts a two-stage pump structure to solve the problem of replacement of such oil pumps, but the manufacturing cost is increased.

In fact, current domestic and foreign pump products for transformer oil pumps are developing toward high speed and high efficiency. A properly high-speed transformer oil pump is not only highly efficient, but also has a small size and good running stability. Of course, low speed can increase the operating life of the bearing. However, with the increase of the diameter of the impeller, the balance problem will become more prominent, especially as the vane pump's consistency in its blade casting and twist angle is inevitably unavoidable in the process. These are the key factors affecting the stability of the operation. Will reduce the bearing's operating life. At present, a large number of domestic units use a large number of disc-type transformer oil pumps driven by axial air-gap (plate motor) motors (this type of oil pump is suitable for low speeds of 1000 rpm or less). Such problems will be more prominent. Because the axial magnetic pull force of the disc motor is very strong, (it is the magnetoelectric coupling by this rotating axial magnetic force to rotate the rotor to complete the electric energy conversion.) Axial magnetic pull force will cause bearing wear The gap is directly converted into a reduction of the air gap between the stator and the rotor until the friction between the stator and rotor iron and iron. (The disc motor is very suitable for braking motor: brake pads are installed between the stator and the rotor, the brake is applied, and the power supply is free to rotate.) Therefore, a common type of transformer oil pump specially designed for conventional three-phase asynchronous motors is widely used abroad. Only we are still widely used as a new product for the disc motor transformer oil pump. If the strict monitoring of bearings is neglected during operation, the probability of accidents will increase with the accumulation of operating time of such structural oil pumps. The description of the disc brake transformer oil pump produced by Japan in this manual provides more space for the maintenance of the bearing, and the formula is as follows:

Lh=(106/60N)(C/Prfw)3a1 a2 a3

Lh: calculated life (hr); N: rotating speed (rot/min); C: rated load (kg); Pr: equivalent bearing load (kg);

Fw: load factor; a1: reliability factor; a2: lubrication coefficient; a3: material coefficient;

The above formula is the recommended value of each parameter. Due to factors such as material selection, environment, and manufacturing process, it is difficult to accurately calculate the operating life of the oil pump. According to the author, the actual responsibility is to give the user.

China's traditional 1450 rpm (4-pole motor) oil pump, and even 2860 rpm (two-pole motor) transformer oil pump performance is very good in some varieties, some products have been running for more than 20 years, is still running well. Therefore, the key is good and professional manufacturing quality and operation and maintenance. It is not because of some quality problems that it is impossible to completely negate it. In fact, the maintenance experience and opinions of some operating units are also worthy of respect.

The 6B4 and 6B5 models of ordinary type transformer oil pumps with a speed of 1000 rpm or less (6-pole motors) have been put into operation. However, due to the late introduction and insufficient publicity, it seems that only 6PB type disc pumps are low-speed pumps. In fact, the hydraulic parameters, installation dimensions, and main performance are completely replaceable between the two.