Dry running valve for pumping station. Connection of dry running relay and pressure switch. How to connect a dry running sensor - the correct procedure

18.10.2019

The water supply system of a private house is impossible without a pump. But it must somehow be turned on and off, to ensure that it does not work in the absence of water. The water pressure switch is responsible for turning the pump on and off, and protection against dry running of the pump should monitor the presence of water. How to implement this protection in different situations and consider further.

What is a dry running pump

Wherever the pump pumps water, at times a situation is created that the water is over - with a small flow rate of a well or well, you can simply pump out all the water. If water is pumped from a centralized water supply, its supply can simply be stopped. The operation of the pump in the absence of water is called dry running. Sometimes the term "idling" is used, although this is not entirely correct.

In order for the water supply at home to work normally, you need not only a pump, but also a dry water protection system, automatic on-off

What's wrong with dry running, besides wasting electricity? If the pump runs without water, it will overheat and burn out - the pumped water is used to cool it. No water - no cooling. The engine will overheat and burn out. Therefore, protection against dry running of the pump is one of the components of automation, which will have to be bought in addition. There are, however, models with built-in protection, but they are expensive. Cheaper to buy automation.

How can the pump be protected from running dry?

There are several different devices that will turn off the pump in the absence of water:

dry run protection relay;
water flow control devices;
water level sensors (float switch and level control relay).

All these devices are designed for one thing - turn off the pump in the absence of water. They just work differently and have different applications. Next, we will understand the features of their work and when they are most effective.

Dry run protection relay

A simple electromechanical device controls the presence of pressure in the system. As soon as the pressure drops below the threshold, the power circuit breaks, the pump stops working.

The relay consists of a membrane that reacts to pressure and a contact group that is normally open. When the pressure drops, the membrane presses on the contacts, they close, turning off the power.

This is what dry running protection looks like.

The pressure to which the device responds is from 0.1 atm to 0.6 atm (depending on factory settings). This situation is possible when there is little or no water at all, the filter is clogged, the self-priming part is too high. In any case, this is a dry running condition and the pump must be turned off, which is what happens.

An idle protection relay is installed on the surface, although there are models in a sealed housing. It works normally in an irrigation scheme or any system without a hydraulic accumulator. Works more efficiently with surface pumps when check valve installed after the pump.

The electrical circuit for switching on the pump protection relay against dry running

You can put it in a system with GA, but you will not get 100% protection against dry running of the pump. It's all about the features of the structure and operation of such a system. They put a protective relay in front of the water pressure switch and the accumulator. In this case, there is usually a check valve between the pump and the protection, that is, the membrane is under pressure created by the accumulator. This is a common scheme, but with this method of switching on, a situation is possible when a running pump, in the absence of water, does not turn off and burns out.

For example, a dry run situation has been created: the pump has turned on, there is no water in the well / well / tank, there is some water in the accumulator. Since the lower pressure threshold is usually set on the order of 1.4-1.6 atm, the protective relay membrane will not work - there is pressure in the system. In this position, the membrane is pressed out, the pump will run dry. It will stop either when it burns out or when most of the water supply is used up from the accumulator. Only then will the pressure drop to critical and the relay will be able to work. If such a situation arose during the active use of water, nothing terrible will happen in principle - a few tens of liters will run out quickly and everything will be fine. But if it happened at night, they let the water out of the tank, washed their hands and went to bed. The pump has turned on, there is no signal to turn off. By the morning, when the analysis of water begins, it will be inoperative. That is why in systems with hydraulic accumulators or pumping stations it is better to use other devices to protect against the dry running of the water pump.

In any situation that causes the pump to run dry, there is insufficient or no water flow. There are devices that monitor this situation - relays and water flow controllers. Relays or flow sensors are electromechanical devices, controllers are electronic.

Relay (sensors) of the flow

The flow switch is of two types - petal and turbine. Flap has a flexible plate that is in the pipeline. In the absence of water flow, the plate deviates from the normal state, contacts are activated that turn off the power to the pump.

It looks like petal flow sensors The device of the petal sensor The device of the turbine water flow sensor Water flow sensor for water supply Types and parameters of water flow sensors for the pump

Turbine flow sensors are somewhat more complicated. The basis of the device is a small turbine with an electromagnet in the rotor. In the presence of a flow of water or gas, the turbine rotates, an electromagnetic field is created, which is converted into electromagnetic pulses read by the sensor. This sensor, depending on the number of pulses, turns on / off the power to the pump.

flow controllers

Basically, these are devices that combine two functions: protection against dry running and a water pressure switch. Some models, in addition to these features, may have a built-in pressure gauge and check valve. These devices are also called electronic pressure switches. These devices cannot be called cheap, but they provide high-quality protection, serving several parameters at once, providing the pressure required in the system, turning off the equipment when there is insufficient water flow.

NameFunctionsSettings for dry-running protectionConnecting dimensionsCountry/manufacturerPrice

BRIO 2000M Italtecnica	Pressure switch + flow sensor	7-15 sec	1" (25mm)	Italy	45$
AQUAROBOT TURBIPRESS	Pressure switch + flow switch	0.5 l/min	1" (25mm)		75$
AL-KO	Pressure switch + check valve + dry running protection	45 sec	1" (25mm)	Germany	68$
Dzhileks automation unit	Pressure switch + idle protection + pressure gauge		1" (25mm)	Russia	38$
Aquario automation unit	Pressure switch + idle protection + pressure gauge + check valve		1" (25mm)	Italy	50$

In the case of using an automation unit, a hydraulic accumulator is an extra device. The system works perfectly on the appearance of a flow - opening a tap, triggering household appliances etc. But this is if the headroom is small. If the gap is large, both a GA and a pressure switch are needed. The fact is that the pump shutdown limit in the automation unit is not adjustable. The pump will only turn off when it reaches maximum pressure. If it is taken with a large margin of pressure, it can create excess pressure (optimal - no more than 3-4 atm, anything higher leads to premature wear of the system). Therefore, after the automation unit, they put a pressure switch and a hydraulic accumulator. This scheme makes it possible to regulate the pressure at which the pump is turned off.

Water level sensors

These sensors are installed in a well, borehole, tank. It is advisable to use them with submersible pumps, although they are compatible with surface pumps. There are two types of sensors - float and electronic.

float

There are two types of water level sensors - for filling the tank (protection against overflows) and for emptying - just protection against dry running. The second option is ours, the first one is needed when filling the pool. There are also models that can work this way and that, and the principle of operation depends on the connection scheme (included in the instructions).

The principle of operation of the float switch

The principle of operation when used to protect against dry running is simple: as long as there is water, the float sensor is pulled up, the pump can work as soon as the water level has dropped so much that the sensor has dropped, the contactor opens the pump power circuit, it cannot turn on until until the water level rises. To protect the pump from idling, the float cable is connected to a break in the phase wire.

Level control relay

These devices can be used not only to control the minimum water level and dry running in a well, well or storage tank. They can also control overflow (overflow), which is often necessary when there is a storage tank in the system, from which water is then pumped into the house or when organizing pool water supply.

Electrodes are lowered into the water. Their number depends on the parameters they track. If you only need to monitor the presence of a sufficient amount of water, two sensors are enough. One - falls to the level of the minimum possible level, the second - the base - is located a little lower. The work uses the electrical conductivity of water: while both sensors are immersed in water, small currents flow between them. This means that there is enough water in the well / well / tank. If there is no current, it means that the water has dropped below the minimum level sensor. This command opens the power supply circuit of the pump and it stops working.

The same device can control different levels, including the minimum

These are the main ways in which protection against dry running of the pump is organized in the water supply systems of a private house. There are also frequency converters, but they are expensive, so it is advisable to use them in large systems with powerful pumps. There they quickly pay off due to energy savings.

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Dry running relay for the pump: wiring diagram, principle of operation, adjustment

If the pressure in the pump drops, the device needs protection. For this purpose, special relays are used. The standard model consists of a pin, a set of contacts and a special cable for closing. There is an adjustment screw on the top of the device. There is a small spring on the pin. The contactor in the device is installed with a trigger mechanism. Cases are most often made of aluminum alloy. In the lower part of the modifications, branch pipes of different diameters are installed.

The principle of operation of the modification

How does a dry running relay for a pump work? When the pressure inside the system decreases, the contactor is activated. Voltage passes through the contacts, which is applied to the winding. The screw acts as a retainer. The spring is compressed by a pin. When the pressure drops, the contacts open. A contactor is used to turn off the voltage.

Dry running relay for pump: wiring diagram

The device must be connected via an adapter. In this case, the outlet pipe is connected to the tube. The cable is terminated at the terminal. The cover is directly fixed on the pump housing. To tighten the outlet, you need a nut. The nozzle is often fixed with a clamp. Some types of relays are connected through a pass-through adapter to two outputs. If we consider a circuit with several pumps, then a contactor expander is used.

Relay adjustment

In order to adjust the device, a screw is used, which is located in the upper part of the case. To set up the model, readings are taken from the sensor. To raise the level of allowable pressure, the screw is turned clockwise. With reduced voltage, the speed of contact closure slows down. Also, the problem may lie in the contactor with the starting system. To lower the pressure level, the screw is turned counterclockwise. Much in this case depends on the parameters of the relay and the maximum power of the pumps.

Device types

There are flow and float devices. Models can be made with one or more cameras. Low pressure versions suitable for pumps low power. Streaming devices come in a variety of sizes. For powerful pumps there is a relay high pressure.

Streaming Devices

In hydropower plants, dry-running flow relays for the pump are often found. The principle of operation of the modifications is based on changing the limiting pressure. going on this process by changing the position of the plate. It is located at the bottom of the case. It should also be noted that the relays of this type are equipped with wired contactors. There is only one start button. Many models use power contacts. The circuit is closed by pressing the plates. The dry running relay for the pump is connected through an adapter.

float models

The most dimensional is considered to be dry-running float switches for the pump. The device is adjusted by tightening the screw. The principle of operation of modifications is based on a change in pressure. All models have one pin in the body. In this case, the branch pipe is located with a ring in the lower part of the structure. Most relays use a manual setting system. Devices of this type operate from a 220 V network. The frame, as a rule, is made of plastic. The contact plates can be in a vertical position. Most relays operate at low frequency. Models are suitable for pumps from 4 kW. The operating frequency averages 55 Hz. At the top of the modification is a nut. In this case, the clamping screw is located on the pin.

Devices with level sensor

A dry-running relay for a pump with a level sensor is considered quite common. However, it is important to note that the models have a number of disadvantages. First of all, experts say that the models are difficult to configure. If he talks about relays on contactors, then they use one input. Thus, failures often occur. It is also important to note that the models are not capable of working with submersible pumps. Devices are connected via cable. The camera at the relay is made with a solid base.

Low pressure models

Dry running relays for low pressure pumps are produced with only one chamber. Contactors for modifications may differ in design. Most devices operate on a 220 V network. At the same time, their operating frequency is at least 45 Hz. It should be noted right away that the models are suitable for pumps with a power of not more than 3 kW. The contacts on the plate are in a horizontal position. The pins are installed next to the plate. In total, modifications have two nuts. A clamping screw is used to adjust the pressure. Pins are quite often used with small diameters. Models of this type are well suited to work with submersible pumps. Frames in devices are used with varying degrees of security, and in this case, much depends on the manufacturer.

High pressure devices

Dry running relays for high pressure pumps are very popular. First of all, the models are used in hydroelectric power stations. They are well suited for pumps that are used in the plumbing system. Their contactors are used for two outputs. The working nuts are located in the upper part of the housing. It should also be noted that there are modifications for two cameras. Their outlet is located in the center of the base. Most models are formed on the basis of a dipole contactor. Modifications use several pins. The devices are well suited for submersible pumps. Branch pipes are available with a diameter of 2.3 cm. Relays operate at least at a frequency of 40 Hz. The output cable must be connected to the terminal box. There is a clamping screw for adjusting the plate. To equalize the pressure inside the system, the nut is turned clockwise. Sensors are very rare in modifications of this type. The start buttons are located directly on the contactors. The models are very easy to maintain.

Single chamber models

Single chamber dry running relays for pumps are available with one or more pins. Most modifications work at low pressure. If we consider a simple relay, then it uses a wired contactor from a 220 V network. The minimum operating frequency is at 45 Hz. The first nut is located on the pin. To increase the pressure in the system, the screw is turned clockwise. If we consider a dry-running relay for the Grundfos pump (with a double contactor), then it uses two cable outlets. The minimum frequency for a modification of this type is 55 Hz.

Dual chamber devices

Two-chamber devices are manufactured with low conductivity contactors. Most models are equipped with multiple pins. The nuts are usually located at the top of the housing. The outlet pipe is used with a diameter of 4.4 cm or more. The devices are suitable for high power pumps. Modifications work from a 220 V network. If we consider models with drive contacts, then they use a start-up mechanism from the module. The minimum operating frequency is 30 Hz. The frame is often made of steel. The increase in pressure is due to the adjustment of the screw. The clamping plate in the devices is located under the contactor. The base of the relay has a seal. Most devices are equipped with a cap for lubricating the pin.

Models for three cameras

Devices for three chambers allow you to very accurately regulate the pressure inside the system. Most modifications are launched from the module. To connect the device, adapters with a ring are used. Models are suitable for pumps from 4 kW. Their operating frequency is at least 4 Hz. Some relays are made on drives. Covers are usually installed over the pin. Some devices are manufactured with two clamping plates. The output cable comes off the contactor. This type of relay operates as standard from a 220 V network.

Devices for 2 kW pumps

Relays for pumps are usually made with one pin. Most modifications are equipped with overlays. If we consider devices with wired contactors, then they have two outputs. It is also worth noting that there are models with support racks. Cases are most often made of stainless steel. The cable at the relay departs from the contactor. The devices operate from a 220 V network. Connection to the pumps occurs through a branch pipe.

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Pumping equipment works correctly only when fluid flows through it constantly. If the fluid supply stops, a dry run occurs, and, as a result, the pump breaks down.

To prevent the pump from running in dry running mode, install on the water supply special devices.

Relay "dry running": about the purpose and device

There are several types of devices that will turn off equipment without water supply:

dry running relay for the pump;
liquid flow control sensor;
water level sensor.

Each of these devices has a different scope and principle of operation.

The dry-running protection relay is a simple electromechanical device that monitors the presence of pressure in the water supply: as soon as the pressure drops below acceptable level, the electrical circuit will open and the pump will turn off.

The relay device has a sensitive membrane that reacts to pressure and a contact group that is open in the normal state. As soon as the pressure drops, the membrane presses on the contacts, they close, and the power supply is turned off.

A drop in pressure is possible when the water supply in the pipeline stops, the filter is clogged with debris, or the suction pipe is above the liquid level. In each of these cases, a "dry run" of the pump occurs, which must be stopped, which is what the protective element does.

The operating pressure of the medium, to which the dry-running relay reacts, is set by the manufacturer, and is in the range from 0.1 atmospheres to 0.6 atmospheres. The idle relay is mounted on the surface, but there are also models for internal placement in a sealed enclosure. to the menu

Installation

The device works normally in any pipeline design that does not provide for the presence of a hydraulic accumulator. It can also be installed in combination with a hydraulic accumulator, but such a scheme will not be a complete protection against the dry running of the pump.

The reason is in the peculiarities of the structure and principle of operation: the protective element is installed in front of the fluid pressure switch and the hydraulic accumulator, and a check valve is mounted between the pumping unit and the protective device.

In this case, the membrane of the device is constantly under pressure, which creates a hydraulic accumulator. This is standard scheme, but sometimes situations arise when a running pump does not turn off when the water flow stops and fails.

For example, a dry running situation arose: the pump is on, the tank or well is almost empty, but there is a small amount of liquid in the battery. Since the lower pressure threshold is set to work at 1.4-1.6 atmospheres, it is there, but the membrane will be pressed out, and the pump will continue to idle.

It will stop its work when most of the water from the accumulator is pumped out or when its engine burns out. This means that the pressure in the pipeline has dropped to a critically low level and the protective relay has tripped. Based on this, in systems with hydraulic accumulators, it is advisable to install other devices to protect against dry running of the pump.

The most effective connection of a dry-running relay is paired with a surface pumping unit when a check valve is installed after the pumping equipment. to the menu

float switch

A float switch is the simplest and cheapest way to protect circulation pump from overheating and breakage when running dry. The advantage of the device is that it can be used as a working medium level sensor and as an actuating element.

They install switches in tanks, wells, reservoirs and use them in the management of household and industrial pumps in water supply and sewer mains. The desired level of operation of the switch is set by the length of the cable.

Several float switches can be placed in one container, each of which will perform a separate function for controlling the main or backup pump equipment.

Dry running float switches are available in light and heavy types. The former are used for supply and drainage of water, the latter - in sewers and drainage pipelines.

Float switch MS-1

For the correct operation of the device, a minimum well diameter of 40 cm is required. This feature does not allow float switches to be considered a universal means of protecting the pump from running dry. to the menu

Safety pressure switch

The device is a conventional pressure switch, equipped with additional protection against idling when the pressure drops below the factory settings.

This pressure switch controls the on and off of a surface or borehole pump if the piping scheme includes a hydraulic accumulator or is intended to be connected to pumping station automatic. The relay operates at 0.4-0.6 atmospheres. This parameter is set at the factory and cannot be changed.

If the pressure fluctuations inside the pipeline are within the specified limits, then the pressure switch does not work and the pump operates normally. When the pressure drops to the set values, which happens in the absence of water, the dry-running sensor is triggered, the contacts that feed the circuit open, and the device for the pressure movement of the liquid turns off.

Scheme of connection to the deep pump water pressure switch

The process of starting the pump is carried out only manually by pressing the lever. Before that, the cause of the engine stop is determined and eliminated. A prerequisite during start-up is filling the pump with water. to the menu

Which protective device to choose?

The choice of a device to protect the pump from dry running is determined by the model of the pump itself and the tasks that it needs to cope with. The best option is when a dry running sensor is used for a pump in the form of a float and a pressure switch. Connecting these devices to the pipeline will fully reduce the risks of breakdown of pumping equipment.

The use of protective elements is optional if:

the depth of the well or tank is large enough;
maintenance of the pumping unit is carried out by an experienced master;
the water level in the system does not change - it makes no sense to connect with protection devices.

The operation of the pump requires increased attention: as soon as the water disappears or the heat relay is activated and the engine turns off, you should immediately find out the cause and eliminate it, and only then resume the operation of the pump unit. to the menu

Description of the connection of the pumping station (video)

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Dry running relay (sensor) for the pump: principle of operation

For long and trouble-free operation of the pump (pumping station), a prerequisite for operation is the presence of a sufficient amount of water. Regardless of where the fence comes from (well, well, open water, centralized or drainage systems), pumping equipment must be equipped with protection against idling. This is due to the fact that water, when passing through the pump, provides its lubrication and cooling. In the absence of water or its insufficient quantity, the operating pump overheats and fails.

In order to exclude damage that is not covered by the manufacturer's warranty obligations, a pump dry-running protection relay should be installed.

Causes of dry running

It is necessary to connect a dry-running relay to protect pumping equipment in the following cases:

when the performance (power) of the borehole pump significantly exceeds the resource capabilities of self-recovery of a sufficient volume of water in the well;
the natural water level in the source is significantly lower than the installation level of the pump;
there is constant clogging with sand, silt, foreign objects of the intake pipe or filter mesh;
the tightness of pipes and their connections is violated from the physical influences of the soil or due to improper installation;
the circulation pump operates at low water pressure or insufficient water in heating (cooling) systems;
water is taken from a source being filled - a well (well) slowly restoring the water level, a storage tank, an unstable water supply system.

Dry run protection relay Belamos PS-7C

Connecting the idle relay to the pumping station is a prerequisite, since it operates in automatic mode without third-party control.

Dry running protection devices

The main devices that exclude the possibility of pumping equipment without water in automatic mode include:

dry running sensor for the pump;
dry running relay for the pump;
pressure switch;
float switch.

Under certain conditions, sensors and relays interrupt the power supply to the pump motor, causing it to stop. The protection operation is determined by the following parameters:

water level;
outlet pressure;
by the strength of the water flow.

The combined control on several parameters at the same time is possible. to the menu

float sensor

Float-type dry-running sensors work effectively when installed in wells, drainage systems, and storage tanks. The actuation process (power off) occurs when the water level in the source drops to a minimum value. When, together with the decreasing water, the float drops to the lower operating level, the contacts open in the power supply phase of the pump, which leads to its stop.

Connecting a pump with automatic

The float switch can be connected to submersible or surface pumps. In this case, its location should be above the bottom valve or the protective grille of the suction pipe with fixation of operation by insufficient water level.

Installation of such a sensor is not possible when taking water from wells and centralized water supply systems. to the menu

Level switch

With the help of this device, the water level in the source (tank) is monitored. When the level drops to a critical value, the control relay is activated to adjust the operation of the flow valves or turn off the pump.

The main advantage of this protection is that the power supply to the pump is switched off before it starts running in idle mode.

The level switch consists of an electronic board and three electrodes (sensors), which are installed at different heights in close proximity to each other. The electrodes, being immersed, exchange low-frequency currents, since water is a good conductor of electricity. When the water level drops to the lowest control sensor, the electrical connection between the electrodes is interrupted, which leads to the operation of the relay to stop the pumping device. When the working water level is restored, the pump is switched on again. to the menu

Pressure switch

The principle of operation of the pressure switch is based on determining sufficient pressure (from 1 bar) at the outlet pipe of the device pumping water. In the event of a pressure drop below 0.5 bar, the contacts are opened by the pressure switch.

When the pressure is restored, with pressure sufficient for the safe operation of the pump, you must manually fill the dry pump with water and turn it on yourself.

Dry running relay device LP-3

Pressure switches are used when installing household pumps connected to centralized networks water supply, water supply and fire extinguishing stations. Installation is recommended at pumping stations that work with a hydraulic accumulator (storage tank). to the menu

flow sensor

The device is a petal valve, which is installed in the flow part of the pump. The principle of its operation is to respond to the force of the flow (the passage of a certain volume of water in the pipe per unit of time).

The spring-loaded petal of the sensor, under the action of passing water, compresses the spring and interacts with the reed relay through the magnet fixed to it. In this case, the contacts included in the power supply circuit of the pump are connected. In the presence of a strong flow, the petal sensor is constantly deflected and the pump motor is running.

Without liquid in the pipeline or its weak movement, the spring deflects the petal with the magnet to its original position, which leads to the opening of the contacts and the stop of the pumping device.

Float switch MS-1

The flow sensor has compact dimensions and low weight, which allows it to be used not only in industrial, but also in home appliances. to the menu

Is it possible to do without protection against dry running?

In some cases, this is acceptable provided that:

the pump does not work often and for a short time (seasonal water supply in the country);
constant control (observation) of the operation of the pumping device is carried out;
water is taken from a guaranteed inexhaustible source;
the user has sufficient operating experience, is familiar with the design and technical characteristics of the water supply device.

How to connect a dry running relay to the pump? (video)

Home page » Pumps

The operation of the water pump, which is part of the hydraulic water supply system, must be carried out under the conditions provided by the equipment manufacturer. It is customary to refer operation without liquid to undesirable extreme conditions. This phenomenon is called "dry run".

Specifics of operation

Pumped water in domestic systems involves several parallel processes:

transportation of liquid to the consumer;
cooling of pumping equipment;
lubrication of the elastic elements of the pump

Particularly noticeable are the negative consequences of improper operation of vibration equipment, which is the most popular in household water supply schemes. The phenomenon for submersible, surface and drainage devices is also considered unacceptable.

If protection against dry running of the well pump is not provided, then the following occurs as a result:

moving elements heat up and increase the temperature of adjacent nodes;
most of the parts are deformed;
in a certain situation, jamming occurs, which leads to failure of the electrical part.

In the design of the pumping station, it is necessary to carry out the installation of protection in a timely manner, since the consequences of a “dry run” are not repaired under warranty, the work will have to be carried out at your own expense.

When checking the condition of a failed equipment, it will not be difficult for a specialist to determine the cause of this condition. It is evidenced by characteristic deformation signs of structural elements. In the instructions for the equipment, the manufacturer clearly indicates the inadmissibility of operating the pumps in the absence of liquid poured into the working cavities.

Alleged "culprits" of the breakdown

There are several most common reasons that lead to extreme pump operation:

Unbalanced pump power. In such a situation, fluid is quickly pumped out due to insufficient well flow rate or for pumps whose intake part is located above the dynamic level.
The connection diagram has a section of the intake pipe, in which there is a depressurization. Air will enter through the hole.
The pumping pipe is clogged, which is often the case with surface models of pumps.
Hydraulics work at reduced pressure.
When pumping liquid from any container, it is necessary to prevent air entrapment.

No installed automatic systems cope with the prevention of "dry run" is quite problematic.

VIDEO: Dismantling, revision and cleaning of the Aquarius deep pump

What is the protection against dry running for a pumping station

One of the main factors in obtaining a reliable circuit is the installation of automation. Such equipment includes the following components:

dry running sensor for the pump;
dry running relay for stations or pumps;
pressure switch;
float switch.

Float switch off

One of the universal blockers is a dry running float sensor for submersible pump. This chain element is a relatively inexpensive helper for protecting hydraulic equipment. Due to the ease of installation, this dry-running sensor for the pump is used in many schemes, for example, when pumping out from classic wells or some containers.

The dry running sensor for the submersible pump is connected to the electrical circuit for one of the power phases. A special contact inside the device will break the connection at a certain position of the float body. Thus, the pumping will stop in time. The actuation height is set when setting the float installation location. The cable that connects the dry-running sensor for the pump is installed at a certain level so that during the lowering of the float, an absolutely complete withdrawal of liquid does not occur. A certain amount of liquid must remain at the moment the contacts open.

During water sampling by surface or submersible units, the sensor is mounted in such a way that even after the contact is broken, the liquid level is still higher than the intake grate or valve.

The disadvantage of the float is its zero versatility - you cannot install it in a narrow mine.

In such a situation, one has to look for other methods by which protection against the dry running of the borehole pump will be carried out.

Water pressure switch

The dry-running protection relay used is structurally electrical, which makes it possible to break the contact in the circuit at a critical drop in pressure and, accordingly, the water level in the source. The initial minimum value is set by the manufacturer. Usually it varies in the range of 0.5-0.7 atmospheres.

Dry running pressure switch

The vast majority of dry-running relay models for household needs does not provide for self-adjustment of the threshold value.

Under normal operating conditions of the pumping station, the pressure in the system always exceeds one atmosphere. An underestimation of the indicator indicates only one thing - air has entered the intake pipe. Automation immediately breaks the contact that feeds the pump, preventing the current from flowing through the cable. The start after the break is carried out exclusively in manual mode, which is an additional protection.

The use of such a relay makes sense under certain conditions:

the presence of a closed plumbing circuit;
mounted hydraulic tank;
use of a pumping station with a surface or submersible pump.

The principle of operation of this relay is relevant for systems with deep pumps.

Water flow sensor

The circuits use special dry-running sensors that record the speed of water passed by the pump. The design of the sensor provides for a valve (petal) located in the section of the duct, and a reed microswitch. There is a magnet on one side of the spring loaded valve.

The algorithm by which this sensor works is as follows:

water pushes through the valve;
due to the push, the spring is compressed;
contacts are closed and the equipment starts to work.

As soon as the flow weakens or completely ends, the pressure on the valve stops, respectively, the spring weakens, the magnet moves away from the switch and the contact breaks. The pump stops. When water appears, the entire cycle is repeated automatically.

This sensor is built into small hydraulic equipment. His job is to balance between two quantities: flow and pressure level. Positive qualities are the following characteristics:

compact dimensions;
ease of installation;
turn-off response time.

Due to the high response speed, it is possible to turn off the power in time, which reduces the risk of waterless operation.

VIDEO: What type of automation to choose for the pump?

If necessary, installation universal protection experts recommend using the device for emergency modes mini AKN. It is based on the electronic protection of self-priming equipment, which responds to the specified parameters.

The advantages of the device are:

minimum power consumption;
small parameters;
comprehensive protection from extreme conditions;
high degree of reliability;
ease of installation.

Operation without installed protection

In certain cases, you can do without the installation of additional protective nodes. This is possible in the following situations:

liquid is taken from a source in which there is always water;
direct visual control of the liquid level is carried out;
high rate of debit in the well.

If you hear that the unit starts to stop, or rather “choke”, it must be disconnected from the network yourself. It is not recommended to start the hydraulics again without checking.

VIDEO: Wiring diagram for submersible pump automation

Reading 6 min.

Most private houses have autonomous water supply, which is provided by a pump. With various layouts of systems that supply water, there is always a need for constant monitoring and control of work.

Automatic switching on and off takes place with the help of a relay, which is triggered by changes in water pressure. If the water source dries up (does not have time to recover due to intensive intake), the pump protection against idling is automatically activated and the pump turns off.

What is dry (idle) running?

Each natural water source has its own specific resource, which depends on such parameters as depth of occurrence, soil composition, intensity of movement ground water. With intensive use, the water supply is quickly exhausted, and in case of connection to centralized systems, there are accidents and planned outages.

In the absence of water, the pump runs dry. This is dry or idle.

If the pump is not turned off in time, it will overheat, which will lead to breakdown and costly. The lack of water in the house for a considerable time will be added to the trouble that has happened, if there is no spare (backup) device.

In order to eliminate this situation, manufacturers produce models with protection against the dry running of the pump. But they are more expensive than usual ones, so in some cases it makes sense to buy and install automatic protection separately.

Protection methods

In order for a running pump to automatically turn off when there is not enough water in the source, use the following devices:

automatic relay;
water flow control device;
water level sensor.

Each of these devices is able to stop the water supply (if it is not enough), to protect the pump unit from overheating and breakdown.

Protection relay

A simple electromechanical element that responds to pressure changes in the water supply system. When the pressure drops below a certain value, the power circuit is automatically broken. Power is not supplied to the pump and it stops working.

Structurally, the relay has a bending membrane, which, when the pressure drops, changes its position and closes the circuit on the contact group, which leads to a power outage.

Depending on the manufacturer's settings, the relay is activated when the pressure drops from 0.6 to 0.1 atmospheres, in the absence of water, its insufficient level or clogging of the filter on the suction pipe.

In systems in which a hydraulic accumulator is present, the operation of the relay will not be effective. This is due to the fact that usually, between the protection and the pump, a check valve is installed, which retains pressure due to the presence of water in the accumulator. And since the minimum pressure value for such a system is 1.4-1.6 atmospheres, the protection will not work even if there is no water in the source, due to the fact that it is in the drive.

How to connect a dry running relay to the pump (video)

Water flow control

The use of a pump with protection against dry running provides for the inclusion in the system of devices that control the flow of water:

relay (sensor);
controller.

The former belong to the group of electromechanical devices, the latter are electronic.

Relays (sensors)

They are produced in two versions:

The first ones are made in the form of a flexible plate, which, being in the pipe, deviates under the pressure of moving water. In the event of a cessation (absence) of water movement, the plate is leveled and closes the contacts for turning off the power supply of the electric motor.

The latter work on the principle of creating an electromagnetic field by a turbine rotating in a stream of water. With a decrease in the number of electromagnetic pulses, in the event of a weakening of the flow or its absence, the pump power is turned off, and when it increases, it resumes.

Some inconvenience in the use of these devices is that they must be inside the pipeline. If solid particles (sand) get inside the system, interruptions in operation or their complete stop are possible, which requires partial dismantling of the water supply system.

Controllers

Devices that provide reliable protection of the pump motor from overheating, which, in some models, have an additional built-in check valve and pressure gauge. In fact, such devices are electronic relays that respond to changes in pressure in the plumbing system.

The main functions are protection against dry running and control of fluid pressure. The use of several parameters in the work leads to the timely shutdown of the equipment in case of a lack of water and the maintenance of a stable working pressure in the system.

The plumbing system, in which this device is included, works stably at any flow rate. water resources– when taps are opened or automatic household appliances are activated.

Level sensors

Water level sensors are installed directly in wells, wells, tanks. They are used with both submersible (submerged) and surface (above water) pumps.

According to the principle of work, they are divided into two types:

float;
electronic.

float

Designed to control the filling (to avoid overfilling of containers) or drainage (protection against dry operation) of water sources.

Models of float switches are produced that operate in two modes, i.e. turn off the pump and when the water level drops and when it is excessive in a confined space.

The principle of operation is as follows: the sensor is placed so that the float is on the surface of the water at a set height. When the level drops, the float lowers, which is pivotally connected through a lever with the contact group. During a critical lowering, the contacts of the phase wire open, and the pump motor stops.

In the case of monitoring the filling of the container, everything happens the other way around. With rising water, it rises and, whose work is set not to lower, but to raise the level.

Electronic

Such devices perform the same functions as float devices, but their principle of operation is different.

Two electrodes are lowered into the water of a source or storage tank. One to the depth to the minimum allowable level, the other to the level of working filling (basic). Since water is a good conductor of electricity, the electrodes are interconnected by small currents. The control device receives the signal and keeps the pump running. As soon as the currents disappear (when the water level falls below the critical level), the power supply is turned off, since there is no conductive material (water) between the electrodes.

The devices described above and methods of their use are suitable for protecting pumping equipment, monitoring the level and pressure of water in small systems for personal use. For a private house or cottage.

In large farms or apartment buildings, when installing autonomous water supply, for protection and control purposes, use. Their cost is much higher, but when working with powerful pumping devices, you cannot do without them.

Equipping their own source of water supply, each owner is obliged to take care of its additional protection. In addition, not only the well or well itself needs to be prevented from breaking, but also the equipment that performs the work: the so-called drainage systems and external pumps. For safety reasons and to reduce the risk of overheating, a water flow sensor is used, which must first be selected correctly.

Why is the pumping system running dry?

Incorrect operation of a pumping station installed to a reservoir may depend solely on the lack of fluid. There is absolutely no difference which body of water is used to pump water; dry running problems for the pump are relevant in any case.

Dry running float switch for pump

The reasons for idle operation often occur due to improper installation of the pump in the water supply source, as well as its incorrect selection for these purposes (non-compliance technical specifications and parameters of the well or well). To exclude overheating of the pump and its possible malfunctions, it is necessary to place the pumping device at a dynamic level, that is, in the place where the water does not decrease.

Also, the cessation of the liquid supply can occur due to a decrease in pressure in the pipeline, due to which the water flow decreases and an air plug is formed, which, penetrating into the working mechanism of the device, disables it. If the tightness of the hose or pipe is lost, similar problems may also occur.

Note! If your pump is set exclusively for manual work and operates from a constant source (from a local pond, river or lake), in this case there is no need to use an automated flow sensor. In the event that the pump is connected to small wells and does not have circuit breakers, it is worth taking care to prevent breakage.

Types of dry running sensors for pumps

In practice, there are only a few types of sensors that perform a protective function in relation to pumping equipment. Today they are divided into three main types:

pressure switch with functional protection equipment. The average cost of a domestic manufacturer of a water flow structure is about 250 rubles. A feature of the mechanism is the ability to turn off the motor when the pressure drops below the nominal level. Usually, the maximum allowable pressure is set at the factory and cannot be manually adjusted;

Disassembly of the dry running sensor for water

Some well-type pumping stations do not require special protective additions, since they have their own protection as factory parameters.

Dry running sensor diagram

The pressure control sensor or idle speed switch does its job using a separate principle. The flow device itself is a mechanism with switching contacts. Before installation, the relay has open contacts. To start the sensor, you need to press and hold the red button until the pressure level rises to the desired value. If the number of atmospheres is not enough, the sensor will be disabled.

Some installations have special nuts on springs in the design, which allow you to adjust the pressure values \u200b\u200bwhen the mechanism is triggered. Pay attention to how the diagram below depicts the entire process of action.

The layout of the dry running sensor in the water supply system

To connect water flow sensors for borehole pumps, you will need to place them in series in the power grid along with pumping equipment. When a drop in atmosphere is detected, the pump protection against dry running is activated, thereby opening the electrical network.

Attention! The installation of a flow movement relay for pumping substations in an autonomous source of water supply occurs strictly according to the concept diagram. There should not be any deviations from the specified values, since the probability of the device malfunctioning and the protection failing increases.

How to choose a device and install it at home?

Be sure to select a flow movement device taking into account the various characteristics of your pumping equipment and the capabilities of the water supply source. Before buying and directly installing a protective relay with your own hands, be sure to get the advice of an experienced specialist.

An important step after choosing a flow motion setting is to correct installation. Be sure to ensure that the pressure switch is installed before the first start-up of the water supply system. In this case, you can provide possible faults and prevent their consequences.

How to connect a dry running sensor to a pump

In order to perform a mechanical type of connection for a pressure switch, you will need skills in working with fittings. You need to cut the thread, if it is not there, and seal the structure with linen or fum tape. A special adjustable wrench will help to embed the device in the pipe. After we are engaged in connecting the electricians in the mechanism. Please note that the conductors on the sensor must be suitable in terms of power to the pump in their cross section.

Typical mistakes of masters

When arranging the pipeline with your own hands, it is important that the flow control equipment is properly connected. But unfortunately, not quite an experienced user can introduce violations into the stability of the work. To eliminate all troubles you need to know about common mistakes, which allow the wizard to connect the relay.

The device is connected incorrectly. It also happens when the sensor is connected to the water flow meter, due to which the principle of operation becomes incorrect.
Leakage of joints occurs when special seals are not used or materials of inadequate quality are selected.
The equipment for the water supply system itself is not exactly matched, and there is a discrepancy with the technical characteristics of the pump.
Schema is missing correct connection, as a result of which there may be a parallel connection of the device.
The owners are trying to change the pressure sensitivity in those mechanisms that are not provided for this.

Due to this neglect of water flow protection designs, you will not achieve a perfect working result. Most likely, the protection of the pumping station will work halfway, so there is no guarantee of the durability of the device.

Choosing a dry running sensor for a borehole pump

The choice of a dry-running sensor for a pump and its connection is best done according to a strict scheme, so as not to subsequently observe errors in the operation of the equipment.

Dry running sensor

Significantly reduces the life of the pump, emergency operation without water, the so-called "dry running". Water performs both lubricating and cooling functions. Without fluid, the pump quickly overheats, deformation of parts occurs, and the engine may burn out. A short dry run adversely affects the performance of the equipment, regardless of the type of pump (drainage, submersible or surface).

To prevent breakage, automation is used:

float switch;
dry running sensor for the pump;
dry run relay.

Protection must be provided in a timely manner, since the cost of repairs after a "dry run" is not included in the list of warranty cases. Having disassembled the pump, the specialist will quickly determine the cause of the breakdown. The operating instructions indicate that the operation of the pump without water is prohibited.

Possible causes of "dry running"

Consider the main situations of insufficient water supply:

1. Wrong choice of pump. More often occurs in cases with wells if:

pump performance exceeds well flow rate;
the dynamic level of the well is below the level of the pump installation.

2. Clogging of the pumping pipe (typical for surface models).

3. Violation of the tightness of the pipe through which water enters.

4. With low water pressure (or lack thereof) in the water supply to which the pump is connected. Without automatic devices the pump itself will not turn off and will continue to "idle" work until it is turned off, or it breaks down.

5. When water is supplied from a source (tank) to be cut off, it is necessary to constantly monitor the level of the incoming liquid.

Ways to protect pumps from running without water

Protection against "dry running" of the pump is provided by automation - sensors and relays that block the power supply at the time of the appearance of a "waterless" mode or in advance. The operation occurs in different devices, and depends on the definition of the following quantities:

water level;
pressure in the outlet pipe;
water flow;
combined scores.

Let us consider in more detail the individual types of automatic protection.

Water level switch and float

Tracking the water level, the level switch and the float sensor work. The level control switch regulates the operation of the water control valves and pump starters. It is one of the most reliable, but also expensive ways of protection. The main advantage is that it turns off the pump before a “dry run” appears.

The relay includes an electronic board, sensors (three electrodes: two working, one control) and single-core connecting wires.

Operation scheme: the control sensor is installed above the pump, the working sensors are at different levels of the well; when the water level drops to the control sensor, the pumping unit stops. When the water reaches the level of the control sensor again, the pump will automatically turn on.

The main sensor board is located in a dry place, usually in the house.

The float sensor (switch) is able to effectively solve the problem of "dry running" in wells and water supply from containers. It is mounted above the pumping unit. The level of operation is regulated by the length of the float cable and the specified location of the sensor.

The switch cable is connected to the phase supplying power to the pump. When the water level drops below the float sensor, the electrical circuit opens and the pump stops.

The fixed float level is selected taking into account the presence of water in the tank at the time the sensor is triggered. For submersible and surface pumps, the “critical” water level must be above the bottom valve or suction grate of the pump.

You can use a float sensor to protect drainage and well pumps. For guard pumping units operated in a network pipeline or wells, other automatic installations must be used.

Relay and pressure sensor

To determine the pressure level at the outlet pipe, a pressure switch and a pressure sensor function. The minimum allowable pressure is set in the relay - usually 0.5 bar. You cannot adjust the pressure limit yourself. It is possible to use a pressure switch as protection if the pump operates with a hydraulic accumulator.

When the pressure switch is operating, the contacts open if the pressure has dropped to the set limit. It should be noted that the entire range of domestic pumping units can pump water at a pressure of 1 bar. Therefore, in practice, the pressure switch is activated when the water supply is completely stopped.

The relay does not warn of an emergency, but simply states the beginning of the "dry run" mode, turning off the pump. After the resumption of the fluid supply under the appropriate pressure, it will be possible to turn on the pumping unit manually. Before each start, you must fill the pump with water yourself.

More wide range actions of pressure sensors. They signal the cessation of the pump when the pressure drops to 1 bar and below. Pressure sensors have found their application in household pumping installations of network pipelines, fire fighting and water supply pumping stations.

When the pressure of the water flow at the inlet to the pump decreases, sensors are triggered that send a signal to the control panel of the pumping unit.

Water flow sensor

On measuring the flow of water passing through the pump, the principle of operation of the flow sensor is built. The sensor consists of a valve ("petal") located in the flow part and a reed microswitch. The "petal" is spring-loaded and has a built-in magnet on one side.

Scheme of operation of the sensor: under the influence of water pressure, the petal valve moves - the spring begins to compress, and the magnet interacts with the reed switch. Closing the contacts causes the pump to work. Without the flow of liquid, the valve spring is unclenched, moving the magnet to its original position - opening the relay contacts leads to the shutdown of the pumping unit.

The flow sensor is built into booster pumps with a small capacity. Works to determine two values (pressure level and flow) of the flow switch, with an additional function of the pressure switch, the so-called “press control”. The device is distinguished by its compact dimensions (light weight and volume).

At a pressure level in the range of 1.5-2.5 bar (depending on the automation model), a command is sent to the pump to start working. The pump performs its functions until the withdrawal of water is stopped. Due to the flow sensor built into the relay, the pump stops working. The sensor very quickly registers the appearance of a "dry run", which avoids a long stay in the working "waterless" mode.

The universal device from emergency modes is Mini AKN. It is based on the electronic protection of single-phase pumping units. The mini ACV responds to the power factor and current of the pump motor. The main advantages of the device: comprehensive protection against emergencies, small dimensions and power consumption, ease of installation, reliability.

Situations when you can not use protection

It is possible to do without installing a pump dry running sensor only in some cases:

constantly monitoring the water supply from a well or well (you will have to be nearby in order to respond in time to a change in water flow);
pumping is carried out from an inexhaustible source;
the drilled well has a high flow rate;
the person controlling the operation of the pump has experience in operation, knows the principle of operation and design of the pump.

If the operation of the pump has become intermittent, or it has turned off altogether, it must not be restarted without identifying and eliminating the causes of the breakdown.

Dry running sensor for a well pump: types and how it works

What measures can be taken to protect the pump from “dry running”. Consider the types and types of sensors.

How to protect the pump from running dry

What is a dry running pump

In order for the water supply at home to work normally, you need not only a pump, but also a dry water protection system, automatic on-off

How can the pump be protected from running dry?

There are several different devices that will turn off the pump in the absence of water:

dry run protection relay;
water flow control devices;
water level sensors (float switch and level control relay).

Dry run protection relay

A simple electromechanical device controls the presence of pressure in the system. As soon as the pressure drops below the threshold, the power circuit breaks, the pump stops working.

The relay consists of a membrane that reacts to pressure and a contact group that is normally open. When the pressure drops, the membrane presses on the contacts, they close, turning off the power.

This is what dry running protection looks like.

An idle protection relay is installed on the surface, although there are models in a sealed housing. It works normally in an irrigation scheme or any system without a hydraulic accumulator. Works more effectively with surface pumps when a check valve is installed downstream of the pump.

The electrical circuit for switching on the pump protection relay against dry running

Water flow control devices

Relay (sensors) of the flow

flow controllers

Protection against dry running of the pump: types, installation

Why do we need protection against dry running of the pump, in what ways it is possible to protect against idling, in which cases it is better to use which devices.

Dry running sensor for pump

There are 3 or 4 types of dry run protection: By pressure, by current consumption, by water sensor, by flow sensor. If only two methods are used, then 100% protection of the pump against dry running can be achieved. Let's consider this below. But you can also use only one method that will protect the pump from dry running with a 100% guarantee.

To protect the pump from running dry, you need the pump to run on water or pump water, not air. And he worked without closed taps on the pump line.

One way or another, all methods of protection individually carry the definition of water only by indirect signs.

To determine if water exists in the system where the pump is located, use indirect signs that the pump is operating in water:

1. Presence of pressure. Mainly determined by an inexpensive device (dry-running relay)

The pressure of the system is constantly maintained above atmospheric from about 1 Bar. And if this pressure drops, then the dry-running relay turns off the pump. And the dry-running relay, in turn, registers more low pressure 0.5 bar and above. How the dry run relay works is described here: How to make automatic water supply in a private house

Dry run relay setting:

This method uses: Float water sensor, electrode sensors, capacitive and others.

The float sensor works according to the principle of mechanics (the float is lighter than water and changes its position, changing the switching contact after it).

There is another way float sensor

In this method, a magnet is used in the float. With the help of magnets on the float and the contact mechanism, force is transferred to the contact. A switching contact with a magnet is hidden inside the tube. The float moves along the stem of the tube. Depending on the position of the float, the position of the magnet on the contacts changes. By these means, the closing and opening of contacts is carried out.

The electrode principle is based on the conductive effect of water (That is, if two electrodes are lowered into water, then a current can be passed between the electrodes that will pass through the water. If there is no water, then the current will not pass. And a special device will determine the passage current and execute the necessary commands for closing and opening contacts).

Capacitive level sensor

The capacitive sensor works on the principle of water touching a special surface, and again a special device detects this touch. When water comes into contact, the capacitance changes, and a special device executes commands to close and open contacts.

3. Current consumption. In this case, a special device monitors the current consumption of the pump, and if the current goes beyond the set thresholds, the pump turns off for a while. Unfortunately, such a device is either expensive or difficult to handle. Therefore, the demand for such a device is not great. Also, there is no clear explanation of such a device.

4. Flow sensor. Moving water presses on a special paddle and the paddle changes the positions of the contacts with an angular force. Or in another way. The principle is based on the determination of the flow in the pipeline. If there is no flow, then the pump will be powered off.

Disadvantages by indirect signs:

1. When water is determined by the presence of pressure. In the water supply system, a situation may arise when there is pressure in the system, but there is no flow, and as an evil: The water is over. At this point, the pump continues to work and will not stop until the pressure reaches the set threshold. It was discussed in more detail on the forum: http://santeh-baza.ru/viewtopic.php?f=4&t=69 it also tells how to effectively set up a dry-running relay.

2. Direct contact with water. This method only detects the presence of water where the pump is located. But the trouble arises when, for some reason, the tap on the pump line is closed and the pump is idling with water. In such a situation, you need to protect yourself from the fool and not put taps on the pump line. But here sometimes technical requirements require the installation of valves for repair and replacement of the pump. There is a way out - to install a flow switch, but without a time delay, such a "gadget" is useless. Below is a diagram.

4. Flow sensor. There is one very simple circuit where a flow sensor is used. But just the flow sensor is a dummy in protecting the pump from dry running if the pressure in the system is created by the same pump. If we consider such a scheme, then it is used only to increase the flow where pressure and flow already exist. For example, to increase pressure.

Wiring diagram operation of the flow switch with a time delay to protect the pump from idling.

Download with good resolution

Encyclopedia of plumbing 100% Pump protection against dry running

Dry running sensor for the pump There are 3 or 4 types of dry running protection: By pressure, by current consumption, by water sensor, by flow sensor. If only two methods are used, then

To begin with, let's go over the theory, answer the question: “why do you need a dry-running protection relay for a borehole pump?”, And then we will consider the principle of operation and how this relay is connected.

Dry running of the pump is a condition in which the pump runs empty, without water. In this state, the pump quickly overheats and can fail in a matter of minutes. To ensure the safe operation of the pump, a dry-running protection relay was invented.

Let's take a quick look at what can cause a pump to run dry:

When the pump power is incorrectly selected - for example, a pump with a high capacity is selected, which pumps out all the water from the well.
When the water level in the well naturally dropped.
Water pipe leakage.

The principle of operation of the dry-running relay

Now let's look at how the dry running relay works. If we disassemble the relay, then under the cover we will see: a safety button, a group of normally open contacts to turn off the pump and two springs for regulating the shutdown pressure.

When water disappears in the water pipe, the pressure in the water supply system drops sharply. At this moment, the relay, under the action of a spring, opens the contact group, which in turn turns off the supply electric current to the pump.

The relay is reactivated by pressing the safety button. The contacts are closed, thereby the circuit for turning on the pump is assembled, which creates the necessary pressure in the system, is in the range of 1 - 1.5 atmospheres. At this pressure in the system, the contacts of the dry-running relay will be permanently closed.

Relay adjustment

At the factory, the dry-running relay is set to a pressure of 0.5 - 0.8 atm. At this pressure, the contacts open and turn off the pump.

Consider the process of adjusting the shutdown pressure using the example of the LP / 3 relay. To do this, you need to do a number of operations:

Disconnect the pump from the power supply.
Open the protective cover of the relay.
On the small spring, tighten the nut clockwise, thereby increasing the initial switching pressure.
On the big spring, Tightening the nut clockwise will raise the pump shutdown pressure.
After adjusting the relay, we need to determine the shutdown pressure: for this, it is necessary to analyze the water in the system, for example, open the tap in the sink, as the water supply system is empty, the water pressure will decrease. On the pressure gauge, track at what pressure the relay contacts open. There should be a click and the safety button will pop out of the case.

Through such simple manipulations, we can set the shutdown pressure we need.

How to connect a dry running relay

The dry-running protection relay is mounted in the water supply system through the so-called five-pin, this is a fitting that has five connection pins:

Water supply to the system
Exit to hydraulic accumulator
Gauge output
Output for connecting a dry-running relay
Water outlet to the system.

This can be clearly seen in the following figure:

Since the dry-running relay is paired with pressure switch then circuit diagram The connection of these relays is as follows.

A dry-running protection relay is mandatory to install as it guarantees a long service life of the pump. In case of failure of the pump due to dry running, it is considered not guaranteed!

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