Solar well pumps usage is the most frequently method of reducing the starting current. During the start-up solar well pump included in the “star”, and after the start switch to the “triangle”. This switching is done automatically after a preset time interval.
When starting in the “star” in the current one-third lower than at start-up through direct inclusion and lies within 1.8-2.5 of the nominal. The method is relatively inexpensive, simple and reliable.
For pumps with a small moment of inertia, such as immersion, start-up by the method of “star-triangle” is not very effective or even uneconomical. The fact that the diameter of submersible well pumps and drive pumps is small. Therefore, the mass of the impeller is small, so that small moment of inertia. As a result of a submersible pump to accelerate from 0 to 2900 min-1 requires only 0.1 s. It also means that the pump when switching current stops immediately.
A comparison of starting currents arising from the inclusion of direct and when you turn on the method of “star-triangle” in the first phase shows a marked decrease in the current. When switching from the “stars” in the “triangle” to quickly stop the pump and the second time should be run directly. The diagram shows that the second phase of a significant reduction in starting current does not occur.
Somewhat different from a situation of centrifugal pumps having a larger diameter and greater weight and have a longer moment of inertia. In pumps of more than 45 kW can usually achieve a significant reduction of the second peak current.
It should be noted that the operation of the pump is too long in the “star” leads to overheating and, hence, reduces the life span.
Plants containing submersible well pumps with electric pumps included in this method are often more expensive than analogs, because the pump requires two connecting cables (instead of the normally required one).