Connecting the pressure switch to the electrical network. Correct connection of the water pressure switch to the water intake submersible pump Pressure switch rm 5 3w water repair

More details electrical diagram Connecting the pressure switch and everything connected with it has been reviewed by us.

So, as can be seen from the diagram, A three-core single-phase power cable is connected to the pressure switch(phase, zero and ground), and a similar cable already comes out of the relay to the pump that pumps water into the system. There are, of course, three-phase devices and a water pressure switch is used accordingly, but in everyday life a single-phase one is usually sufficient.

In the water supply of a private home, single-phase surface or submersible pumps are most often used, pumping water from a well or well. The electrical power of pumps varies greatly depending on the required performance of a particular device under specific operating conditions.

Usually, the power of such a household pump does not exceed 1.5-2 kW, accordingly, to connect it, a cable with a core cross-section of 1.5 sq. mm is required. and a 10 Amp line circuit breaker.

Connecting a pressure switch to the electrical network is usually accepted in one of two ways:, each of which has its own strengths and weaknesses:

1. Mounted near the installation site of the pressure switch, on the wall electric outlet, for him. A cable with an electrical plug at the end is connected to the relay itself.

This is a universal, and often the most convenient, connection option. The main disadvantage of this method is the need extra costs on the socket device itself, as well as possible problems at the connection point, in the vicinity of the water supply system of the house.

2. The second option is the simplest and, accordingly, the most reliable. At the location where the pressure switch is installed, a power cable is pulled out of the wall, which connects the relay to the network. In this way, maximum connection reliability is achieved, because The pressure switch housing, as well as the cable entry into it, are usually sealed and they reliably protect the contact point from possible adverse influences.

The main disadvantages of this method include increased requirements for the accuracy of choosing the output location and cable length, as well as some possible complexity in subsequent maintenance. It is always easier to unplug the device from the outlet than to disassemble and disconnect the wires.

In our installation example, the second option was chosen - a cable coming out of the wall. Maintenance problem solved by installing a separate circuit breaker for pressure switch in electrical panel boiler room

Before connecting the power cable to the relay, be sure to ensure that there is no voltage at the installation location!

We proceed directly to connecting the pressure switch to the network, using the example of the Italtecnica TYPE PM/5G model.

First of all remove the protective plastic casing, to do this you need to use a straight screwdriver (slotted) to unscrew the fasteners, as shown in the image below

Then In the pressure switch, the supply cable and the cable going to the pump are laid through the cable entries.

This model uses standard sealed cable glands that are familiar to many. To fix the cable in them, you must first unscrew the plastic nut, then insert the cable first into it, and then through the input, into the relay and finally tighten the nut until it stops.

Then, having previously prepared - removing the protective insulation, connect the cable cores to the relay terminals pressure according to the following diagram.

Do not pay attention that one of the connected cables in the diagram ends with an electrical plug; in our case, instead of it, a power cable is connected that runs continuously to the electrical panel.

After connecting the wires and testing all the terminals, you should get something like this:

This completes the connection, all that remains is to carefully put it back on protective cover and secure.

Now, by turning on the electricity supply, you can check the operation of the water pressure switch and adjust its operation.

As you can see, there is nothing difficult in installing a relay, especially if you clearly understand the principle of its operation.

If you still have any questions about connecting the pressure switch to the electrical network, for example, you have a more powerful pump or it is three-phase, or just a different relay model, or you don’t know how to connect and what cable and socket to use - be sure to leave them in comments on the article, I will try to answer everyone promptly.

When organizing a water supply system at home, you need not only a pump, but also automation to ensure its operation. One of the necessary devices is a water pressure switch. This small device turns on the pump when the pressure in the system drops and turns it off when a threshold value is reached. The magnitude of the on and off parameters can be adjusted. How this device works, how to connect it and how to regulate it is in the article.

Purpose and device

In order to maintain constant pressure in the water supply system of a private home, two devices are needed - a hydraulic accumulator and a pressure switch. Both of these devices are connected to the pump through a pipeline - the pressure switch is located in the middle between the pump and the accumulator. Most often it is located in close proximity to this tank, but some models can be installed on the pump body (even submersible). Let's understand the purpose of these devices and how the system works.

A hydraulic accumulator is a container divided into two halves by an elastic bulb or membrane. In one there is air under some pressure, in the second water is pumped. The water pressure in the accumulator and the amount of water that can be pumped into it are regulated by the amount of pumped air. The more air there is, the higher the pressure is maintained in the system. But at the same time, less water can be pumped into the container. Usually it is possible to pump no more than half the volume into the container. That is, no more than 40-50 liters can be pumped into a hydraulic accumulator with a volume of 100 liters.

For normal operation household appliances require a range of 1.4 atm - 2.8 atm. To maintain such a framework, a pressure switch is required. It has two response limits - upper and lower. When the lower limit is reached, the relay starts the pump, it pumps water into the accumulator, and the pressure in it (and in the system) increases. When the system pressure reaches the upper limit, the relay turns off the pump.

In a scheme with a hydraulic accumulator, water is consumed from the tank for some time. When enough has flowed out for the pressure to drop to the lower response threshold, the pump will turn on. This is how this system works.

Pressure switch device

This device consists of two parts - electrical and hydraulic. The electrical part is a group of contacts that closes and opens turning the pump on/off. The hydraulic part is a membrane that exerts pressure on the metal base and springs (large and small) with the help of which the pump on/off pressure can be changed.

The hydraulic outlet is located on the back of the relay. This could be a release from external thread or with an American type nut. The second option is more convenient during installation - in the first case, you either need to look for an adapter with a union nut of a suitable size or twist the device itself, screwing it onto the thread, but this is not always possible.

The electrical inputs are also located on the back of the case, and the terminal block itself, where the wires are connected, is hidden under the cover.

Types and varieties

There are two types of water pressure switches: mechanical and electronic. Mechanical ones are much cheaper and are usually preferred, while electronic ones are mainly delivered to order.

Name	Pressure adjustment limit	Factory settings	Manufacturer/country	Device protection class	Price
RDM-5 Gilex	1- 4.6 atm	1.4 - 2.8 atm	Gilex/Russia	IP 44	13-15$
Italtecnica PM/5G (m) 1/4"	1 - 5 atm	1.4 - 2.8 atm	Italy	IP 44	27-30$
Italtecnica RT/12 (m)	1 - 12 atm	5 - 7 atm	Italy	IP 44	27-30$
Grundfos (Condor) MDR 5-5	1.5 - 5 atm	2.8 - 4.1 atm	Germany	IP 54	55-75$
Italtecnica PM53W 1"	1.5 - 5 atm		Italy		7-11 $
Genebre 3781 1/4"	1 - 4 atm	0.4 - 2.8 atm	Spain		7-13$

The difference in prices in different stores can be more than significant. Although, as usual, when buying cheap copies, there is a risk of running into a fake.

Connecting the water pressure switch

The water pressure switch for the pump is connected to two systems at once: electricity and water supply. It is installed permanently, since there is no need to move the device.

Electrical part

To connect a pressure switch, a dedicated line is not required, but is desirable - there is a greater chance that the device will work longer. A cable with a solid copper core with a cross-section of at least 2.5 square meters must run from the shield. mm. It is advisable to install a combination of automatic + RCD or difavtomat. The parameters are selected based on current and depend more on the characteristics of the pump, since the water pressure switch consumes very little current. The circuit must have grounding - the combination of water and electricity creates a zone of increased danger.

Connection diagram of the water pressure switch to

The cables are inserted into special inputs on the back of the case. Under the cover there is a terminal block. It has three pairs of contacts:

grounding - the corresponding conductors coming from the panel and from the pump are connected;
line or “line” terminals - for connecting the phase and neutral wires from the panel;
terminals for similar wires from the pump (usually on the block located above).

The connection is standard - the conductors are stripped of insulation, inserted into the connector, and tightened with a clamping bolt. By pulling the conductor, check whether it is securely clamped. After 30-60 minutes, the bolts can be tightened, since copper is soft material and the contact may weaken.

Pipeline connection

Eat different ways connecting the water pressure switch to the water supply system. Most convenient option- installation of a special adapter with all required outputs - a five-pin fitting. The same system can be assembled from other fittings, just ready-made option always use flatter.

It is screwed onto the pipe on the back of the housing; a hydraulic accumulator, a supply hose from the pump and a line that goes into the house are connected to the other outputs. You can also install a mud pan and a pressure gauge.

A pressure gauge is a necessary thing - to monitor the pressure in the system, monitor the relay settings. Mudman - too required device, but it can be installed separately on the pipeline from the pump. In general, a whole

With this scheme, at high flow rates, water is supplied directly to the system - bypassing the hydraulic accumulator. It begins to fill after all the taps in the house are closed.

Adjusting the water pressure switch

Let's consider the process of adjusting the most popular model - RDM-5. It is produced by different factories. The adjustment limits change, since different sized water pipes require different pressures. This device leaves the factory with basic setup. Usually this is 1.4-1.5 atm - the lower threshold and 2.8-2.9 atm - upper threshold. If you are not satisfied with some parameter, you can reconfigure it as required. This procedure is usually necessary when installing a Jacuzzi: the standard pressure of 2.5-2.9 atm is not enough for the required effect. In most other cases, reconfiguration is not required.

The water pressure switch RDM-5 has two springs, which regulate the threshold for turning off/on the pump. These springs differ in size and purpose:

the large one regulates the limits (both upper and lower);
a small one changes the delta - the gap between the upper and lower boundaries.

The parameters change when tightening or unscrewing the nuts on the springs. If you tighten the nuts, the pressure increases, if you loosen it, it decreases. There is no need to tightly tighten the nuts; one revolution is a change of about 0.6-0.8 atm, and this is usually a lot.

How to determine relay response thresholds

The pump activation threshold (and the lower pressure threshold on the water pressure switch) are related to the pressure in the air part of the accumulator - the minimum pressure in the system should be 0.1-0.2 atm higher. For example, if the pressure in the container is 1.4 atm, the shutdown threshold is desirable to be 1.6 atm. With these parameters, the tank membrane will last longer. But for the pump to work in normal conditions, look at its characteristics. It also has a lower pressure threshold. So, it should not be higher than the selected value (lower or equal). Based on these three parameters, you select the switching threshold.

By the way, the pressure in the accumulator must be checked before setting - there are significant deviations from the declared parameters. Under the removable cover (in different models it looks and is located in different places) the nipple is hidden. Through it you can connect a pressure gauge (can be a car one or the one you have) and see the actual pressure. By the way, it can be adjusted through the same nipple - increased or decreased if necessary.

The upper threshold—pump shutdown—is set automatically during adjustment. The relay in the initial state is set to some pressure difference (delta). This difference is usually 1.4-1.6 atm. So if you set the switch-on, for example, to 1.6 atm, the switch-off threshold will automatically be set at 3.0-3.2 atm (depending on the relay settings). If you need more high pressure(raise water to the second floor, for example, or the system has many water points), you can increase the shutdown threshold. But there are limitations:

Parameters of the relay itself. The upper limit is fixed and in household models usually does not exceed 4 atm. It’s simply not possible to put up more.
Upper limit of pump pressure. This parameter is also fixed and the pump must be turned off no less than 0.2-0.4 atm before the declared characteristics. For example, the upper pressure threshold of the pump is 3.8 atm, the shutdown threshold on the water pressure switch should be no higher than 3.6 atm. But in order for the pump to work for a long time and without overloads, it is better to make a larger difference - overloads have too bad an effect on the operating life.

That's all for choosing the water pressure switch settings. In practice, when setting up the system, you have to adjust the selected parameters in one direction or another, because you need to select everything so that all water points work normally, including household appliances. Therefore, it is often said that parameters are chosen using the “scientific poker” method.

Setting up a water pressure switch for a pump or pumping station

To set up the system, you will need a reliable pressure gauge, the readings of which you can trust. It is connected to the system near the pressure switch.

The adjustment process consists of tightening two springs: large and small. If you need to raise or lower the lower threshold (pump activation), turn the nut on the large spring. If you turn it clockwise, the pressure rises, if you turn it counterclockwise, it decreases. Turn it a very small amount - half a turn or so.

The sequence of actions is as follows:

The system is started, and the pressure gauge is used to monitor at what pressure the pump turned on and off.
The large spring is pressed or released.
Turn it on and check the parameters (at what pressure it turned on, at what pressure it turned off). Both quantities are shifted by the same amount.
If necessary, adjustments are made (the large spring is adjusted again).
After the lower threshold is set the way you want it to be, proceed to adjusting the pump shutdown threshold. To do this, press or lower a small spring. Don’t twist the nut too much either—half a turn is usually enough.
Turn the system back on and look at the results. If everything suits you, they stop there.

What else do you need to know about adjusting the water pressure switch? That not all models have the ability to change the delta, so look carefully when purchasing. There is a pressure switch for the pump in a moisture- and dust-proof housing. They can be installed in a pit; some models can be installed directly on the pump body, if it has such an outlet.

Some water pressure relays also have an idle (dry) relay; in general, this device is in a separate housing, but there are also combined ones. Defence from idle move It is necessary so that the pump does not break if suddenly there is no water in the well or borehole. Some pumps have built-in protection of this type; for others, relays are purchased and installed separately.

To find out which is stronger - water hose, pipes or pump, you can assemble a water supply system without a pressure switch. In all other cases, when supplying water to a house, a device is built into the system that replaces manually turning on and off the supply voltage of the deep-well pump.

It is impossible to imagine individual water supply at home without a relay that allows you to automatically turn off the pump as the water supply system fills with water and turn it on after the water is consumed.

Fig.1 Design pressure switch

Structurally, a standard pressure switch for controlling a pump looks like this. The plastic case contains terminal blocks for connecting the power cable and a mechanical device control system with adjustable spring struts; a 4-inch diameter pipe is located outside for connection to the water main. The power cable enters and leaves the pressure switch through two wide inlets; the wires are clamped using a nut with a plastic ferrule.

In the normal state, the contacts are normally closed and the connected device powers the pump motor. When the pressure in the system increases, water acts on a rubber membrane with a piston installed at the inlet of the water pipe of the device. In turn, the membrane piston presses on a movable metal platform, hinged inside the device body at one point. The platform plate rises and opens the electrical contacts; when the pressure decreases, it returns to its original state, closing the contacts.

A screw with a spring and a nut is installed in the center of the device, which sets the distance of the contact plate to the membrane piston - if it is smaller, the device operates at lower pressure, an increased distance will require greater movement of the piston with the membrane to act on the contact pad, which is equivalent to increasing the pressure in the system.

At some distance from the main adjusting screw there is a second adjusting screw with a smaller spring. It sets the range of movement of the contact metal pad, establishing the difference between the pressure that turns the contacts on and off. Thus, the large adjusting screw sets the lower response threshold of the device (the pressure for turning it on), the small one regulates the range of operation of the device for shutdown (adjustment depth).

Rice. 2 Connection diagram

Relay adjustment

When purchased, the relay is configured for a specific switching mode, standard values are 1.4 and 2.8 atm, that is, at 2.8 atm. the pump will be turned off and turned on if the pressure is less than 1.4 atm. Usually, when installing a device into a system, you need to select a response threshold - for this you need to know what pressure the pump in the well provides.

If the pressure well pump 2 atm., and the standard value of 2.8 atm. remains in the relay, then the pump will never turn off (it physically cannot create a pressure that reaches the response threshold) and after intensive work will go to eternal rest. A less tragic situation is when the pump can produce a pressure of 5 atm, and the relay turns it off at 2.8 atm. In this case, the system does not work efficiently and it is advisable to install a device that matches the pressure of the well water pump.

To take measurements when adjusting the relay, you need a pressure gauge; the work consists of the following steps.

Water begins to be drained from the system, and the pump activation pressure is recorded on the pressure gauge.
Close the valves and record the pressure gauge readings at which the pump turns off.
Adjust the device with a large screw, periodically turning the water on and off until you get desired value lower pressure.
Then they move on to adjusting the range that sets upper pressure, small screw. The water is also periodically turned on and off until the required value is obtained.

Connecting the pressure switch to the water supply system

When installing a relay in a water intake system, the following rules must be observed.

Rice. 3 Connection diagram of a submersible pump to a hydraulic accumulator

The hydraulic accumulator for water supply systems and the point of connection of the device to the water supply are located nearby - this will avoid switching the pump during sudden short-term pressure surges.
When installing, please take into account temperature regime— some models operate only in warm conditions.
To simplify installation, modern surface-type pumps are equipped with a fitting to which a relay and pressure gauge can be directly connected.

Connecting a pressure switch to a submersible pump can be done in two ways:

The device is connected to water pipes through a tee using an adapter fitting.
Before connecting the hydraulic accumulator to the submersible pump, a five-pin fitting is connected to it, the connected devices (hydraulic accumulator, pressure gauge, relay) and the water main are connected at one point.

Review of popular models

There are two types of pressure switches: mechanical and electronic, the latter are much more expensive and are rarely used. The market offers a wide range of devices from domestic and foreign manufacturers, making it easier to select the required model.

RDM-5 Gilex (15 USD) is the most popular high-quality model from a domestic manufacturer.

Fig.4 RDM-5

Characteristics

range: 1.0 - 4.6 atm.;
minimum difference: 1 atm.;
operating current: maximum 10 A;
protection class: IP 44;
factory settings: 1.4 atm. and 2.8 atm.

Genebre 3781 1/4″ (10 c.u.) — budget model Spanish made.

Rice. 5 Genebre 3781 1/4″

Characteristics

body material: plastic;
pressure: upper 10 atm;
connection: threaded 1.4 inches;
weight: 0.4 kg.

Italtecnica PM/5-3W (13 cu) is an inexpensive device from an Italian manufacturer with a built-in pressure gauge.

Rice. 6 Italtecnica PM/5-3W

Characteristics

maximum current: 12A;
working pressure: maximum 5 atm;
lower: adjustment range 1 - 2.5 atm.;
upper: range 1.8 - 4.5 atm.

Pressure switch - essential element in the water intake system, providing automatic individual water supply to the house. It is located next to the hydraulic accumulator, the operating mode is set using adjusting screws inside the housing.

Good afternoon, dear readers of the blog site

In the “Accessories” section we will consider a pressure switch that controls given pressures turning on and off automatic operation pumping stations, as well as superficial , or if they are used in conjunction with. By using pressure switch you can configure an autonomous water supply system, irrigation or fire extinguishing system for the required tasks.Available for sale pressure switch RM-5, RM-5G, RM-12 produced by an Italian companyItaltecnica.The main difference of the product RM-5 differs from RM-5G in that the latter uses a union nut with a connection size of 1/4″. The PM-5G relay is more convenient for installation.

The main characteristics of RM-5 and RM-12 are shown in Table 1.

Characteristics	RM-5	RM-12
1. Working pressure range (bar)	1-5	3-12
2. Factory settings for switch-on and switch-off pressure (bar)	1,4-2,8	5-7
3. Minimum pressure drop (bar)	0,6	1,5
4. Temperature working environment to (°C)	55	55
5. Maximum operating current (amps)	16 (10)	16 (10)
6. Voltage (volts)	250	250
7. Connection internal thread (inch)	1/4	1/4

Table 1

Note: When using a pressure switch to control pumping equipment, the maximum switching current is 10 A.

Recently, the product PM-5G (25 A) with maximum switching current for controlling pumping equipment components 16 A.

Relay design

Structurally, the relay is assembled in a plastic case and closed with a lid. Figure 1 shows the main elements. To remove the top cover from the product, use a slotted screwdriver to unscrew the plastic plug at its end.

Pressure switch device

1. Housing – all elements of the pressure switch are located on it;

2. Connecting flange, used to connect the automation to the water supply system. The connecting flange size is 1/4″ internal thread. The flange contains the working chamber and membrane. The flange and diaphragm are attached to the relay body using four screws;

3. Nut for adjusting the pressure difference ΔР between the on and off pressure. The more we compress the spring (tighten the nut), the greater this difference will be;

4. Pressure adjustment nut for switching off the relay. When tightening the nut, the shut-off pressure will increase, and when loosening, it will decrease. The top cover is also attached to this rod using a plastic plug;

5, 6. Terminals for connecting electrical wires;

7. Terminals for connecting ground wires from the power supply and the engine;

8. Cable clamps are used to firmly fix the mains power cable and motor connection cable.

Electrical diagram for connecting a pressure switch

In Fig. 2 shows a diagram electrical connection relay RM-5, RM-5G, RM-12.

Connection diagram for pressure switch PM-5, PM-5G, PM-12.

The diagram for connecting a relay to an electrical network is very simple. Wires are connected to terminals 5, 6 (see Fig. 1). Moreover, it does not matter which pair of terminals is input (connection ~220 V) and which pair is output (connection to the engine). After connecting the wires, you need to make sure they are reliable contact with relay terminals, if necessary, you need to tighten the contacts.

Relay operation, maintenance and adjustment

Pressure switch RM-5, RM-5G, RM-12 are very simple and reliable control devices autonomous system water supply Subject to operating conditions, they operate without interruptions and failures for a long time and reliably. However, given the quality of our water, voltage fluctuations or high humidity, malfunctions occur. Incorrect operation of the automation usually leads to pump failure.

Let's look at the most common cases.

Hard water. In hard water or in water with a high iron content, during operation the passage to the working chamber gradually becomes overgrown, or the chamber itself becomes overgrown. The diameter of the passage is small, 5–5.5 mm. There may come a time when the relay does not turn on or, on the contrary, does not turn off. To eliminate this defect, you need to clean the passage or the chamber itself by following these steps:

Disconnect the product from the power supply.
Reset overpressure by opening the water tap.
If the automation is PM-5G, then with the help open-end wrench unscrew to 17 union nut and remove the relay. If the automation is RM-5, then it is necessary to remove the cover from the pressure switch, unscrew the fixing cap using a slotted screwdriver, disconnect the cables from terminals 5, 6 and grounding (Fig. 1), loosen the cable couplings, disconnect the cables from the product using a key at 17, unscrew and remove the relay.
Use a match or other blunt object to clear the clogged passage. You need to clean it carefully for two reasons: the first is that water may splash out of the working chamber and the second reason is not to damage the rubber membrane. To clean the working chamber, you need to unscrew the four screws securing the flange to the relay body. Remove the flange and membrane (do not lose the special “nickle” during disassembly - round metal plate with two ears), rinse and clean the flange and membrane.
Reassemble in reverse order. If the automation is RM-5, then before installation, it is necessary to seal the threads using fum tape or a special sealant.

High humidity. Very often the station or automation is located in a pit. Lack of proper ventilation leads to high humidity, and humidity leads to oxidation and burning of contacts in the pressure switch. In this case, the automation begins to work unstably, turns on with a delay, or turns on when you lightly tap on the body. If there is moisture on the surface of the product when you remove the cover, and there are marks on the metal parts white plaque, then there is a high probability that the contacts are burnt. To repair such defects, you must contact your nearest service center, or call a service technician to the installation site of the station or automation.

Unstable operation of the pressure switch is also caused by fluctuations in the voltage of the electrical network and the entry of air into the water supply system.

Pressure adjustment. To adjust the pressure, two adjusting nuts and springs are used (Figure 1). Using nut 4 and a large spring, you can adjust the shutdown pressure of the system. The more we compress the spring, the higher the pressure in the system the automation will turn off. One of the most common causes of non-stop pump operation is incorrect setting of the pressure switch. Before setting up the automation, you need to look at the operating parameters of the pump, namely, what maximum pressure it produces. For example: the pump produces a maximum pressure of 40 meters of water column or 4 bar (atmosphere). Theoretically, the maximum relay setting pressure can be 4 bar, but, taking into account fluctuations in the mains voltage, gradual wear and tear of equipment, maximum pressure to which we can set the automation to no more than 3.4–3.5 bar. Using nut 3 and a small spring, we adjust the difference ΔP between the pump on and off pressure. The more we compress the spring, the greater the difference between turning the pump on and off. The minimum difference between the pump on and off pressure is 0.6 bar for the PM-5 and 1.5 bar for the PM-12 relay - this is when the small spring is completely released. On the one hand, the difference between the switch-on and switch-off pressures must be adjusted as small as possible in order to reduce pressure drops. On the other hand, with a minimum range, the number of pump starts and stops increases, this problem is solved by increasing the volume of the hydraulic accumulator. For optimal performance pumping equipment and an autonomous water supply system, it is necessary to choose the golden mean between the pump on and off pressure and the volume of the accumulator. Additionally, you can see how to configure and adjust the pressure switch. If you have any questions, please write in the comments.

Thank you for your attention.

Good day. Let's look at the diagram for connecting a mechanical pressure switch PM /5 to the network and the pump. Let's look at the diagram first.

When you unscrew the top cover, you will see the following. First, a large screw with a spring for . It is indicated by a capital "P". Second, this is a small screw with a spring to adjust the difference in this parameter in the on and off mode. It is called "delta P". Next there are two terminals for connecting the electrical wire, called the word “motor”. Two – “line”. At the bottom there are two for grounding connections. This is what PM/5 looks like inside. The pressure switch is sold inexpensively in this Chinese store.

Connecting the pump to the network

How do we connect the pump to the pressure switch and the electrical network? Three wires come out of it different color. Blue is a zero worker or simply “zero”. Brown – “phase”. Yellow-green – zero protective or simply “Earth”.

Now let's see how they will “enter” the relay and how to “exit” it. We insert all three wires through a special hole in the housing. Let's connect. Brown and blue in terminals labeled “motor”. Yellow-green to ground. Then we connect the same wires to the power plug. Brown and blue, respectively, from the “line” terminals (network). Yellow-green from grounding. All is ready. The pressure switch PM/5 is connected to the pump and to the network.