Control system for a pump

Abstract

The present invention relates to pumps comprising variable frequency drive means and methods for operating such pumps. The inventive method for operating a pump (1) comprises the steps of obtaining values of operating parameters of the pump (1) indicating pump conditions, communicating said values of operating parameters from variable frequency drive means (2) to a control device (11), determining if a predetermined condition is fulfilled, communicating instructions from the control device (11) to the variable frequency drive means (2), based on the fulfillment of said predetermined condition. Furthermore, a computer program product loadable into a memory of a digital computer device, including software code portions for performing the inventive method, a pump (1), a pump system and a control device (11) for a pump are described.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates generally to the field of pumps, and more specifically the present invention relates to pumps comprising variable frequency drive means. Furthermore, the present invention also relates to a method for operating such pumps.BACKGROUND OF THE INVENTION AND PRIOR ART[0002]Pumps comprising variable frequency drive means, such as sewage pumps, drainage pumps and de-watering pumps as well as submersible pumps, for example, are commonly used for pumping fluids in mining applications such as in mining shafts, wells, at construction sites, or at other applications. Normally, submersible pumps are submersed, wholly or partly, during long periods of time both when they are in operation and when in an off-state.[0003]A problem often encountered with pumps in general and with submersible pumps in particular, is so called snoring operation, which means that the pumps sucks partly liquid and partly air. This is due to the fact that...

AI Technical Summary

Benefits of technology

[0031]According to an another embodiment of the present invention, a detection whether the pump is clogged is performed; and if it is detected that the pump is clogged, the pump is ran reversely at a predetermined speed during a period of time having a predetermined length. Thereafter the pump is stopped and started in the normal direction. Moreover, the step of running the pump impeller reversely, stopping it and change the operating direction is repeated until it is detected that the clogging condition has ceased. Thus, the problem of clogging or jam of the intake and/or pumping house, which may be caused by particles in the fluid that sediment

Problems solved by technology

A problem often encountered with pumps in general and with submersible pumps in particular, is so called snoring operation, which means that the pumps sucks partly liquid and partly air.

This is due to the fact that the liquid level has fallen below the required level of the pump causing the pump to start sucking partly air.

From this moment the pump is no longer productive and uses energy unnecessarily.

As long as the pump is in this snoring state, those particles remain at the hydraulics and cause extra wear on the impeller, the suction cover, the seals, etc.

This ineffective pumping contributes in a significant way to the increase of the overall operating costs of the pump.

In addition, this snoring operation may damage the pump motor due to overheating.

However, these level sensors may, for example, be blocked or be subjected to a level shift due to a collision with subjects in the fluid such as a tree branch, and will thus in such a case deliver an erroneous signal.

However, this pump system embraces great disadvantages.

In another case, the pump system is not able to detect if the water level is high enough for pump operation upon start of the pump, since in this state there cannot be a sudden increase of the speed of the motor or a sudden drop of the motor torque.

Thereby, the pump will run for a considerable time until it is switched off due to overheating, and the pump runs the risk of getting seriously damaged.

Another problem of frequent occurrence, especially when the pump has been in an off-state for quite a long period of time, is clogging of the inta

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