How to connect a pump

Cottage, cottage, just some country house or private estate - all this has one thing in common. All these "residences" usually need an autonomous water supply, their own sewage system, and sometimes a system that ensures the pumping out of melt and emergency polluted water from the basement. The implementation of such systems is carried out using pumps and pumping stations.

A pump is considered to be a mechanism designed to pump pressure in a liquid medium, and a pump station is a device that includes, in addition to the pump, the necessary drive (most often an electric one), a storage tank, and elements of an automation system. In order to understand how to connect a household pump, you need to get acquainted with the classification of pumps and their applications.

According to the type of pumped liquid, household pumps are conditionally divided into water, drainage and fecal. In this case, fecal pumps designed for pumping sewage can pump almost any liquid, even mixed with sand and mud. Drainage pumps are designed for pumping water contaminated with sand or silt; they are ideal, for example, for watering garden plants with water from a nearby pond. A water pump can pump only clean water for drinking and domestic needs.

To pump water from a shallow depth of not more than eight meters, you can use a pump located on the surface, in other words, a “surface” pump. These same pumps are often called self-priming, as they create pressure, being much higher than the liquid level. And to raise water from a deep well or well, the depth of which is tens of meters, you will need a submersible borehole or well pump.

How to connect a surface or self-priming pump

Automation of self-priming pumps is reduced to the installation of minimum and maximum level sensors in the storage tank. Typically, float-type sensors are used, the contacts of which are located in the coil circuit of a separate starter that controls the inclusion of the pump. The current rating of the contacts of this starter, as well as the rating of the pump circuit breaker, should be selected based on the power of the unit and its phase.

Most household surface pumps are single-phase, and their power varies from 0.3 to 2 kW, so a second magnitude starter is usually enough. The pump motor will be useful to protect against overload with a thermal relay. The pump housing must be connected to the PE bus and turned on potential equalization system. The pump power circuit must have differential protection in the form of RCD or differential. automaton 30 milliamps or less.

The algorithm of the self-priming pump is as follows: when the water level in the tank reaches the minimum level, the starter turns on the pump. Upon reaching the maximum level, the contacts of the second sensor open, and the pump shuts down. Water flows by gravity from the storage tank, so you can not expect high pressure and high performance from such a water supply system.

In case of failure of any of the level sensors in such a system, there is a risk of overflow of water and flooding of the room in which the pump is located. To avoid this situation, the storage tank must be equipped with overflow protection in the form of a pipe, the input of which is placed above the maximum level. In addition, level sensors do not provide the pump with protection against dry running, that is, switching on when there is no water at the pump inlet.Dry running is dangerous for the drive motor and pump mechanism with additional overloads.

Because of these shortcomings, instead of a circuit with level sensors and a starter, pumping stations with self-priming pumps and hydraulic accumulators are often used. At the same time, it is not the water level in the tank that is controlled, but the pressure in the accumulator. Here, some analogy with the on-board network of the car is obvious.

When using such a circuit, a special electronic unit containing microcontroller. The microcontroller analyzes data with pressure sensor in the accumulator, and also monitors the status of the water level sensors at the inlet of the pumping station. The latter is necessary specifically for protection against dry running.

Using a microcontroller to control a self-priming pump allows you to constantly maintain the necessary pressure in the pipeline and operate the electrical equipment of the pumping station in the most efficient mode.

How to connect a submersible pump

Submersible pumps are more sophisticated and demanding equipment, operating in difficult conditions when immersed up to 150 meters below the surface of the water. Therefore, the capacity of submersible pumps is usually greater - up to several kilowatts.

When purchasing a submersible pump, it is necessary to accurately determine the following initial data: the depth of the well or well, the required pump capacity in cubic meters per hour, and the static and dynamic water level in the well. Only with all these numbers you can accurately determine the required electrical power of your submersible pump.

The submersible pump must be constantly located under the surface of the water at a distance of at least 30 centimeters from it. On the other hand, it should not be submerged too deep - a distance of at least one meter should remain to the bottom or cork of the well or well. This requirement is due to the fact that in any case sand and sludge accumulate at the bottom, which can interfere with the normal operation of the pump.

The motor of the submersible pump is mounted to it by a flange and is usually controlled by an electronic unit mounted on a surface in an area accessible for maintenance. The cable for powering the motor has a special design, is mounted in a waterproof sheath and comes complete with a pump. The cable is connected to the pump with a special sealed plug with a grounding electrode.

When installing a submersible pump, one should not forget about the non-return valve in the pump nozzle, which is necessary in order to prevent the return of water to the well. The position of the pump in the well is insured with a steel cable, with which, if necessary, the pump is removed from the well. Pulling the pump by the power cable is strongly discouraged.

The submersible pump controller always provides protection against dry running. In his work, he focuses on water level sensors and a pressure sensor in the pipeline.

To supply a submersible pump, as well as a surface one, it is necessary to provide in the shield a separate three-pole circuit breaker of the corresponding current rating and a differential protection device for 30 or less milliamps.

Alexander Molokov

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