Start-up device for pumps. Soft start of the pump motor or how to solve the problem with high starting currents. Installation of automation for a borehole pump
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There are many reasons to turn on domestic pumps through a soft starter.
Usually, a submersible or surface pump is connected through an electromechanical or electronic relay, an automation unit or a magnetic starter. In all of the above cases mains voltage is supplied to the pump by closing the contacts, that is, through a direct connection. This means that we apply full mains voltage to the stator windings of the electric motor, and the rotor does not yet rotate at this time. This results in an instant powerful torque on the rotor of the pump motor.
This connection scheme is characterized by the following phenomena when starting the pump:
Current surges through the stator (respectively, through the supply wires), since the rotor is short-circuited.
In a simplified sense, we have short circuit on the secondary winding of the transformer. According to our experience, depending on the pump, the manufacturer and the load on the shaft, the pulsed starting current can exceed the operating current from 4 to 8, and in some instances up to 12 times.
The sudden appearance of torque on the shaft.
It renders negative impact on the starting and working windings of the stator, bearings, ceramic and rubber seals, significantly increasing their wear and reducing the service life.
The appearance of a sharp torque on the shaft leads to a sharp rotation of the housing well pump relatively pipeline system.
We have repeatedly witnessed how, because of this, the well pump was disconnected from the pipelines and fell into the well. When pumping station on the base surface pump installed on the accumulator platform, this leads to loosening of the fixing nuts and destruction of the weld points and seams of the accumulator. Also, when the pump is turned on directly, the service life of the plumbing and stop valves especially at their junctions.
It is generally accepted that the accumulator removes water hammer in the water supply system.
This is true, but water hammers disappear in pipelines only starting from the place where the accumulator is connected. In the gap between the pump and the accumulator, when the pump is connected directly, the water hammer remains. As a result, in the interval from the pump to the accumulator, we have all the consequences of a water hammer on all parts of the pump and on the pipeline system.
In water filtration systems, water hammer, which occurs when the pump is directly connected, significantly reduces the life of the filter elements.
If the local power grid weak, then your neighbors will also know about the start of a pump with a power of more than 1 kW with a direct connection by a sharp drop in the voltage in the network at the moment the pump is turned on.
If a the local network EXTREMELY WEAK, and your neighbor also enjoys life by connecting to the network all available electrical devices, then a well pump submerged to a great depth may not start. Such a power surge can damage electronic devices connected to the network. There are cases when, when starting the pump, an expensive refrigerator stuffed with electronics failed.
The more often the pump is turned on, the less its service life.
Frequent starts through a direct connection lead to failure of the plastic couplings of the borehole pumps connecting the electric motor to the pump part.
You and I went through the problems that arise when starting the pump without soft starters (UPP) .
It should be noted that even when the pump is turned off without SCP with a direct connection scheme, there are negative points:
When the pump is turned off, a water hammer also occurs in the system, but now due to a sharp decrease in the torque on the pump shaft, which is tantamount to creating an instantaneous vacuum.
A sharp decrease in the torque on the pump shaft also leads to the rotation of the pump housing, but in the opposite direction.
Think about pipelines and threaded connections pump.
In ordinary household pumps electric motors are asynchronous and have a pronounced inductive character.
If we abruptly interrupt the supply of current through an inductive load, then there is a sharp voltage jump on this load due to the continuity of the current. Yes, we open the contact, and all the high voltage should remain on the pump side. But with any mechanical opening of the contact, the so-called "contact bounce" is present, and the impulses high voltage get into the network, and therefore get into the devices connected at that time to the network.
Thus, when the pump is connected directly, increased wear of the mechanical and electrical parts pump (both at start-up and at shutdown). Devices connected to the same network also suffer, and the service life of filtration systems and plumbing fittings is reduced.
Usage soft starters ("Aquacontrol UPP-2.2S") allows you to smooth out most of the shortcomings described above. In device UPP-2,2S a specially calculated voltage rise curve on the pump has been implemented, which allows, on the one hand, to start the pump in the most unfavorable operating conditions, and on the other hand, to smoothly increase the shaft speed. Also, protection against low and high voltage of the mains is built into this device to protect the pump from extreme operating modes and switching on.
AT UPP-2,2S phase triac control is used. At the moment of start-up, a part of the mains voltage is supplied to the pump, which creates a torque sufficient to guarantee the start of the pump. As the rotor spins up, the voltage on the pump gradually increases until the voltage is fully applied. After that, the relay turns on and the triac turns off. As a result, when using UPP-2,2S the pump is connected to the network through the relay contacts, that is, in the same way as with a direct connection. But for 3.2 seconds (this is the soft start time), the pump is energized through the triac, which provides a “soft start”, without sparks on the relay contacts.
With such a start, the maximum starting current exceeds the operating current by no more than 2.0-2.5 times instead of 5-8 times. Using UPP-2,2S, we reduce the starting loads on the pump by 2.5-3 times and prolong the life of the pump by the same amount, provide more comfortable operation of devices connected to the electrical network. UPP-2,2S can be called a device with resource-saving technology.
Alexei 28.01.2015 Pumping stations
Happy owners country houses and dachas very often face the problem of water supply to their homes.
Bring and store water large containers is possible only at the construction stage, and subsequently the problem of water supply is solved in other ways. One of them is the arrangement of a separate well at the site.
A special device is installed in it for uninterrupted water supply. This unit can supply water not only to the house, but also to the garden. Connecting and installing a submersible pump is not at all complicated and can be done independently. Let's try to figure out how it's done.
Types of equipment for the water supply system
This type of device differs from others in that it works on pressure, it pushes the liquid to the surface. In this regard, they are subjected to significantly less stress and, as a result, consume much less electricity. And this is an essential factor for any economy today.
The pump, unlike a conventional stationary station, makes much less noise and does not lead to vibration on the surface and in the house. Another advantage should be considered that it is made of parts that are not susceptible to rust and cannot fail under the influence of water. After opening the tap in the house, you will hear only a small click, indicating that the pump installed in the well has been connected.
Watch the video, a little about the types of pumps:
Currently released different types equipment. They are subdivided according to various characteristics, including the principle of action on:
- dynamic;
- Volumetric.
Depending on which method of filing is used, they are divided into:
- Submersible;
- Surface.
The most popular among owners of suburban housing are submersible pump models, which in turn can be divided into several categories: fountain, circulation and drainage.
The main part of the devices belongs to the dynamic ones. In this equipment, the pumping of liquid occurs as a result of exposure to some of its components. Among them are the following models:
- Bladed;
- Inkjet;
- Air.
The first type of devices is divided into several more groups: axial, diagonal and centrifugal.
Varieties of centrifugal units
This category of devices is most widely used in private homes. They have sufficient power for this, and their operation is quite easy. The connection diagram for such a pump is available to everyone and is not particularly difficult.
The use of devices is quite wide. In addition to supplying water, they are designed to remove sewage or other liquids. In private courtyards, they equip the sewerage system with their help.
Pump device
Device centrifugal pump submersible type may be different. Two types are used:
- Rod;
- Rodless.
In the first case, the device is equipped with a drive, which is located above the water. This model can be used in wells with shallow depths.
The second option is made as a complete device. Power is supplied by using an electrical cable in reliable insulation, immersed in water along with the unit.
Currently, you can choose any device for a water submersible centrifugal pump that is suitable for certain operating conditions. Manufacturers produce various models, differing from each other both in size and in working volume. This makes it possible to purchase the necessary device without spending extra money for, for example, a very powerful one, but not quite suitable for certain conditions.
Connecting equipment
In order to do this correctly, you must strictly follow some rules and follow these recommendations. Here is how, for example, you need to connect pressure tank that will be powered by the machine. To perform such an automation connection to any submersible pump, the following devices will be required:
The scheme of the submersible pump is carried out in this way: first of all, we connect a pre-prepared valve and nipple to the device. This is done with a hose, which is usually included in the kit. Next, a thorough sealing of all joints should be carried out. This can be done using a special adhesive tape used in construction. After that, it is necessary to connect the nipple to the check valve.
We watch the video, the stages of installing the pumping group:
The next step is to connect the water supply hose of the pump. The tip of the pipe is fixed with a nipple.
Then, in the overlap of the well, it is necessary to install a hose going to membrane tank installed in the house. Again, all joints must be carefully sealed. This will protect the system being arranged not only from minor leaks, but also from possible serious breakdowns associated with this.
The pump cable is pulled through a special hole in the tip and after that the connection itself is made. The next step is to close the well, which does not allow debris to enter it.
Starting protection device (PZU) for submersible pumps
Automation connection diagram
This element is used during the initial start-up of the device and for the subsequent acceleration of its engine. This moment is the most unfavorable mode for electric motors, the water-taking part of the well and pipes through which water rises.
In order to prevent the negative consequences that occur during the start-up of pumps, this equipment is used. The ROM serves as a current protection for the electric motor, automatically turning it off when an overload occurs. This is done using a thermal relay located in the housing.
In addition to the relay, the device includes:
- Capacitor block;
- Klemnik.
All elements are combined into one electrical circuit.
Hydraulic accumulators and features of their connection
Being one of the important components in the water supply of a private house, they are used to accumulate water under pressure and, if necessary, entering the system. They are made in the form of a metal container, inside it there is a rubber pear, which plays the role of a membrane.
Watch the video, completing the work and the first launch:
Before connecting a water submersible pump to a hydraulic accumulator, it is imperative to check the presence of pressure in the tank. It should be 0.2-1 bar less than the value set on the relay.
In some cases, it is preferable to install the accumulator at the highest possible height, for example, in the attic or on the second floor of a building.
conclusions
To ensure proper water supply country house with absence central water supply most often used submersible pumps that are able to function in wells. They are reliable and easy to operate, and their installation scheme is quite simple. Installation is carried out using the most conventional materials and for every homeowner.