Compressor pressure switch connection. Adjusting the Relay

Diagram of connection of compressor pressure regulator

Use of the air pneumatic relay allows for automatic filling of the compressor’s receiver with compressed gas. The operator of equipment with a pressostat does not need to monitor the process, trying to fix the limit parameters. Engine damage is prevented as a result. Significant results, aren’t they??

If you are planning to buy a pressure switch for a compressor you are at the right place. Exactly here you will find a large amount of extremely useful information about the principles of the device, its equipment and connection methods.

We have described in detail the existing types of pneumatic relay. Connection options to the domestic and industrial network with very clear layouts were explained. Razed the typical breakdowns and ways to prevent them. Presented by us information and useful tips are supplemented by graphic, photo and video applications.

Functional principle of the pressure switch

The name of the relay is defined by its purpose. control of the piston compressor to maintain the required operating force of atmospheric pressure in the receiver. Not often found on a screw-type unit, responsible for compression and supply of air.

Considering the amount of pressure force in the pneumo-automatics, the device acts on the line for the voltage trimmer, closing or opening it. Thus, the insufficient pressure in the compressor starts the motor, the moment it reaches the required level it switches off.

This standard principle of operation, based on the connection in the chain of normal closed circuit, is used to control the motor.

All ejectors are designed with a cylinder containing air in which a certain pressure. Its reduction requires the motor to be switched on to replenish the reserve. If the situation is reversed and an excess is detected, the supply is stopped to prevent the vessel from bursting. These processes are controlled by the pressostat

There are also modifications with the opposite operating algorithm: reaching minimum values in the compression circuit, the pressostat turns off the electric motor, at maximum values. it activates. Here, the system operates in a normally open circuit.

Spring mechanisms with varying degrees of stiffness act as an operating system, reproducing the response to fluctuations in the air pressure unit.

In the process of operation, the values formed by the elastic force of the tension or compression of the springs and the pressure of the pressurized atmosphere of the device are commensurate.

Any changes automatically activate the coil action and the relay unit connects or disconnects the line for the trimmer power supply.

Note, however, that there is no regulating influence from the model in question. Exceptional effect on the engine. The user has the option of setting the peak value at which the spring is activated.

Air inflow control device

Without differential pressure switch of combustion products no boiler can work. Pressostat, included in the piping system, controls the flow of air to the gas burners of heating appliances, hot water. The pressostat casing contains a diaphragm and a switch, and the silicone drain tubes for condensate or smoke are attached to the casing. Automatics of the fan generates air pressure on the diaphragm which changes the position of the switch to ignite the burner. In case of exceeding the preset parameters of gas pressure, the excess product is evacuated from the compressor through a safety valve.

Another method, which is sometimes much more convenient and practical than the first. regulation through the reducer. A reducer is a device that takes in air already in a compressed state. This air must be transmitted to the end machine.

These devices, reducers, also have a control element in the form of a valve. The pressure control range is controllable and depends on the capacity and capability of the compressors that are connected to the reducer.

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There are special models with a function of convenient adjustment of the air pressure supplied to each specific tool. Sometimes these units even have a pressure relief option which depressurizes and prevents the surplus air from exerting a load on any connected tool in order to ensure safe and problem-free operation.

First option

The circuitry of all compressors is the same. Once the required volume of air has been reached, the control element of the automation loosens and stops the air intake. Relay controlled by air pressure, works on the principle of pressing air on a diaphragm and counteracting an elastic spring.

For the compressor’s own pressure setting, there is a switch in the form of a bolt or a nut, which allows to adjust the pressure of the unit. To access it, do the following:

  • Remove protection in the form of a shroud;
  • the compressor pressure is adjusted by turning either the bolt or the two nuts, which increase or decrease the spring pressure force;
  • There is a nut next to it to adjust the differential pressure on and off;
  • turn the pressure adjustment bolt to change the values, the desired value is determined by experiment.

Types of pressostat devices

There are only two versions of the automatic compressor unit. This is determined according to their operating principle. In the first version, the mechanism switches off the electric motor at the moment when the air pressure in the pneumatic system exceeds the set limits. These devices are called normally open.

Schematic diagram of the diaphragm pressure switch: 1. pressure transducer; 2 and 3. contacts; 4. piston; 5. spring; 6. diaphragm; 7. screw connection

Another model with the opposite principle. it turns on the engine if the pressure is determined to be below the permissible level. Devices of this type are called normally closed.

Operating principle

Pressure switch for the compressor controls the piston installation, maintains the optimal pressure inside the receiver. Sometimes you can find such a unit on screw devices. it will be responsible for performing compression of air masses, their proper supply.

Given the force of the air pressostat, the device exerts pressure on the trimmer line under voltage. Lack of pressure starts the motor, at the moment of reaching the specified indicators. disables it. It is a standard scheme of operation, which involves connection to a closed circuit.

Role of the air pressostat

The ejector design includes an air-filled cylinder with a preset pressure. Decrease in reading requires turning the motor on, restoring the level. In the reverse described situation, the excess will be detected. The air supply is paused, otherwise the vessel would burst. A pressostat is responsible for controlling these processes.

How do the stiffening springs work?

There are modifications with a different operating algorithm. Reaching the minimum values in the compression circuit, the pressostat disables the electric motor, at maximum. activates it. That is, the system is triggered only in the open circuit of the device.

The springs with different stiffnesses act as the main working unit. They will respond in the standard way to oscillatory movements within the unit. In the course of operation of the system will be commensurate values that are obtained by compression-expansion of the springs, that is, by changing their size, shape. Changes are monitored by a spiral equipped with a relay unit. It disconnects or connects power supply lines if necessary.

There is no regulating influence in spring units; the main influence is on the motor. The user can set the optimal peak for themselves, as the maximum is triggered by a spring mechanism.

How to connect and adjust the water pressure switch

When organizing a water supply system at home you need not only a pump, but also an automation system to ensure its operation. One of the necessary devices. the water pressure switch.

This small device turns on the pump when the pressure in the system falls, and turns it off when it reaches a threshold value. The magnitude of the on and off parameters can be adjusted.

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To learn how to connect and adjust the device, see this article.

Purpose and device

In order to maintain a constant pressure in the water supply system of a private home, you need two devices. a hydroaccumulator and a pressure switch.

Both are connected to the pump through a pipe. the pressure switch is located in the middle between the pump and the hydraulic accumulator.

Most often it is located in the immediate vicinity of this tank, but some models can be installed on the pump housing (even a submersible). Let’s explain 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. One contains air under some pressure, the second one is filled with water.

The water pressure in the hydraulic accumulator and the amount of water that can be pumped there is regulated by the amount of air pumped. 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 reservoir.

compressor, pressure, switch, connection

The range of 1.4 atm to 2.8 atm is required for the normal operation of a household appliance. To maintain such a framework and requires a pressure switch. It has two trip limits, an upper and a lower limit.

When the lower limit is reached, the relay starts the pump, it pumps water into the hydraulic accumulator, and the pressure increases in it (and in the system) at the same time.

When the system pressure reaches the upper limit, the relay shuts off the pump.

In a hydraulic accumulator circuit, the water is drained from the reservoir for some time. When enough has flowed out so that the pressure has dropped to the lower threshold, the pump will turn on. This is how this system works.

The device pressure switch

This device consists of two parts. electrical and hydraulic. The electrical part is the contact group that turns the pump on and off. The hydraulic part is the diaphragm that presses the metal base and the springs (big and small) with which the pressure to turn on/off the pump can be changed.

The outlet of the hydraulic part is on the back of the relay. It can be an outlet with an external thread or with a nut on the type of American. The second option is more convenient for installation. in the first case, you must either look for an adapter with a coupling nut of the appropriate size or twist the device, screwing it on the thread, and it is not always possible.

The electrical inputs are also on the back of the case and the terminal block to which the cables are connected is hidden under a cover.

Types and versions

Water pressure switches are of two types: mechanical and electronic. Mechanical ones are much cheaper and are usually preferred, while electronic ones are mostly made to order.

NamePressure adjustment range Factory settingsProducer/countryProtection classPrice
RDM-5 Gileks 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 PT/12 (m) 1. 12 atm 5. 7 bar 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 price difference in different stores can be more than substantial. Although, as usual, when buying cheap samples, there is a risk to run into a fake.

Water pressure switch connection

Water pressure switch for pump connected to two systems at the same time: electricity and water. It is installed permanently, so there is no need to move the device.

Electric part

To connect the pressure switch a dedicated line for the trimmer is not obligatory, but desirable. a better chance that the device will work longer. From the switchboard must go cable with a solid copper core cross section of at least 2.5 kv. mm.

Preferably an automatic GFCI or a residual current device (RCD). Parameters are adjusted by current and depend more on the characteristics of the pump, as the water pressure switch consumes very little current.

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The circuit must have a grounding. the combination of water and electricity create a zone of increased danger.

wiring diagram for connecting water pressure switch to electric board

The cables are fed into the special feedthroughs on the back of the housing. There is a terminal block under the cover. There are three pairs of contacts on it:

  • earthing. connect the appropriate conductors coming from the panelboard and from the pump;
  • Line terminals or “trimmer line“. to connect the phase and neutral conductors from the panelboard;
  • terminals for the same wires from the pump (usually on the block above).

Location of terminals on the body of the water pressure switch

Connection is standard. stripping wires of insulation, inserting them into the connector, tightening the clamping screw. After pulling on the conductor, check that it is firmly clamped. After 30-60 minutes, the bolts can be tightened, as copper is a soft material and the contact can loosen.

Connecting to the pipe

There are different ways to connect the water pressure switch to the water system. The most convenient option is to install a special adapter with all required outlets. a five-wire connector. The same system can be assembled from other fittings, it is just always better to use a ready-made version.

compressor, pressure, switch, connection

How to connect and adjust the pressure switch?

In a general circuit diagram of a compressor system, the pressure switch is located between the relief valve and the secondary engine control circuit. The pressure switch is normally fitted with four threaded heads. One of them is designed to connect the device to the receiver, and the second. to connect the test pressure gauge. One of the remaining connectors can be used to install a safety valve and the remaining threaded plug with a ¼ inch thread. The loose connector allows you to install the test gauge in a user-friendly location.

Connection of the pressostat is conducted in the following sequence:

  • Connect the device to the pressure relief valve of the receiver.
  • the test pressure gauge is installed (if it is not necessary, the threaded input is also plugged).
  • Connect to the contacts of the electric motor control circuit terminals (depending on the chosen connection scheme. to normally open or normally closed contacts). At fluctuations in the voltage in the network, do not connect directly, but through a surge protector. This is also necessary if the contact capacity is greater than the motor load current.
  • If necessary, set the relay for the required values of compressed air pressure using the adjusting screws.

When connecting it is necessary to check whether the voltage in the network corresponds to the factory settings of the compressor pressure switch. For example, in a three-phase network voltage of 380 V, the relay must have a three-pin group (two-phase), and for 220 V. two-pin. Always adjust with at least two-thirds full of oil compressed air. To perform this operation, the relay is de-energized and the compression of the two springs is altered by removing the upper cover. The adjusting screw, on which the larger diameter spring shaft is mounted, has the upper limit of the working pressure. A commonly used pressure symbol (P. pressure) is usually found on the side of the board with the direction of rotation of the screw to increase or decrease the pressure. The second, smaller adjusting screw is responsible for setting the necessary pressure range (differential). It is marked with the symbol ΔP, and is also provided with a direction indicator.

To reduce the set-up time, on some designs the pressure adjusting screw for changing the upper pressure limit is placed outside the pressostat housing. Check the result by reading the manometer.

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