Air pressure regulator for the compressor with his hands
Possible malfunctions of the device
There are several characteristic faults of pressostats. In most cases, they are simply replaced with new devices. However, there are minor problems, which can be eliminated by yourself without the help of a repairman.
If the pressostat was determined to be the cause of the malfunction, the foreman will insist that the device be replaced. All service actions on cleaning and replacement of contacts will cost the user more than the purchase and installation of a new device
The most common malfunction is characterized by air leakage from the relay when the receiver is on. In this case the culprit may be the trigger valve. It is enough to replace the gasket and the problem will be solved.
Frequent activation of the compressor indicates that the adjusting bolts have become loose and have come loose. Here it is necessary to recheck threshold of switching on and off relays and adjust them according to instructions of previous section.
Diagrams of connection of the pressostat to the compressor
Connection of air compression control relay can be divided into 2 parts: electrical connection of relay to unit and connection of relay to compressor through connecting flanges. Depending on what kind of motor is installed in the compressor, for 220 V or 380 V, there are different schemes of connection of the pressostat. On the basis of these schemes, on condition that you have some knowledge in electrical engineering, you can connect this relay with your own hands.
Relay connected to 380 V mains
To connect automatic control to 380 V compressor use magnetic starter. Below is a diagram of how to connect the automation to the three phases.
The circuit breaker is marked “AB” in the diagram and the magnetic contactor is marked “KM”. This diagram shows that the relay is set for 3 bar on pressure. and disconnecting. 10 atm.
Pressostat connection to 220 V mains
Connect the relay to single-phase supply using the diagrams below.
These diagrams show the various models of pressure switches of the PDK series, which can be connected to the electrical section of the compressor in this way.
Tip! There are two rows of terminals under the pressostat cover. There is usually an inscription “Motor” or “Line” next to it, which respectively indicate the contacts for connecting the motor and the electric network.
Wiring the pressostat to the unit
Connecting the pressure switch to the compressor is relatively simple.
- Screw the pressostat to the air reservoir connector using its threaded center hole. For better sealing of threads it is recommended to use vacuum tape or liquid sealant. The relay can also be connected to a pressure reducer.
- Connect a pressure relief valve to the smallest outlet, if any.
- Either a pressure gauge or a safety relief valve can be connected to the remaining outputs from the relay. It is absolutely necessary to fit the latter. If a pressure gauge is not required, the free outlet of the pressostat must be plugged with a metal plug.
- Next, the wires from the mains and from the motor are connected to the sensor contacts.
After the complete connection of the pressostat is completed, it must be set up for proper operation.
Varieties of gates
The important organ of 220V throttle bodies are single-seat, crane, diaphragm, disk, double-seat gate valves, hose gate valves with rigid or elastic seals. When the leak tightness of unpressurized valves of industrial systems decreases, the repair of 380V gate valve is carried out by the mechanical workshop after preliminary diagnostics of all parts and mechanisms.
Prophylaxis of control devices is carried out in accordance with the plan approved by the manufacturer of the product and the standards for the gas regulator. Adjustment limits are determined by the process conditions and the specifics of the operating organization.
Each device has a serial number, a passport, a certificate of conformity to state standard. All scheduled manipulations or repairs are indicated in the operation log of the gas pressure regulator.
The air pressure switch for a compressor: making and connection diagram
Air pressure switch for the compressor is an important element of the mechanism, its component. Without it, the compressor will not work for long if at all. And the resulting temporary result will be monstrous. Pressure at output will be discontinuous and electric motor will fail very quickly.
Diagrams of the connection of the pressostat to the compressor
Connection of the relay, which controls the degree of air compression, can be divided into 2 parts: electrical connection of the relay to the unit and the connection of the relay to the compressor through the connecting flanges. Depending on what kind of motor is installed in compressor, for 220 V or 380 V, there are different schemes of pressostat connection. Guided by these schemes, provided that you have some knowledge in electrical engineering, you can connect this relay with your own hands.
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Connection of the relay to the 380 V mains
To connect automatic control to a 380 V compressor, a magnetic starter is used. Below is the wiring diagram for connecting the automatics to three phases.
About Air Compressor Regulators
On the diagram, circuit breaker is marked “AB” and magnetic starter. “KM”. From this diagram it can be understood that the relay is configured for an on-pressure of 3 atm. and shutting off pressure of 10 bar.
Pressostat connection to 220 V
The relay is connected to a single-phase network according to the diagrams below.
These diagrams show different models of pressostats RDK series, which can be connected to the electrical part of the compressor in this way.
Pressostat connection for unit
Connecting the pressure switch to a compressor is quite simple.
Screw the pressostat to the receiver pipe using its threaded center hole. The use of fan tape or liquid thread sealant is recommended to improve sealing of the threads. The relay can also be connected to the receiver through a pressure reducer.
Once the complete connection of the pressostat is complete, it is necessary to set it up for proper operation.
The process flow for all compressors is identical. When the required amount of air has been drawn in, the automation control loosens and stops air intake. The relay, which is 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 nut to adjust the unit’s pressure. To access it, you need to do the following:
- remove protection in the form of a casing;
- compressor pressure adjustment is carried out by turning either the bolt or two nuts, which increase or decrease spring pressure force;
- There is a nut next to it for adjusting the differential pressure on and off;
- turn the pressure adjustment bolt to change the indicators, determine the desired value by experimenting.
Adjustment and start-up process
The factory-set parameters do not always match the customer’s requirements. In most cases this is due to insufficient compression force at the highest point.
Also the operating range of the pressostat may not be suitable. In this case, an independent adjustment of the actuator is necessary.
To begin adjusting the operating compression value, it will be necessary to examine the engraved nameplate, which indicates the parameters of the electric motor and compressor.
We only need the highest value that the device generates. This value indicates the maximum pressure which can be set on the relay, for the correct work of the entire pneumatic system.
If you set the specified value (in the figure 4,2 atm), then, taking into account all factors. fluctuations in power supply, expiry of service life of parts and other. the compressor may not reach the limit pressure, and therefore it will not shut down.
In this mode, the working parts of the equipment will start to overheat, then warp and eventually melt.
For reliable operation without shutdowns, it is necessary to set the highest cutoff pressure on the relay below the nominal value engraved on the compressor, namely by 0.4-0.5 atm. According to our example. 3.7-3.8 atm.
Having determined the level to be set, it is necessary to remove the relay body. Under it there are two regulating elements. small and large nuts (in figure 1,3).
Nearby there are arrows indicating the direction in which the tweaks will be made. thereby compressing and uncompressing the spring mechanism (2,4).
A large screw clamp and spring are used to control the compression settings. When tightening in clockwise direction, the spiral is compressed. compressor cut-out pressure increases. Reversing adjustment. loosens, respectively, decreases the pressure to turn off.
The receiver must be at least 2/3 full when playing settings.
Having understood the purpose of elements, we proceed:
- To ensure the proper level of safety, disconnect the power supply.
- Changing the spring compression level is done by turning the nut a few turns in the desired direction. On the board next to the adjusting screw, according to the standards, there is a Latin alphabetical symbol P (Pressure), the smaller one. ΔP.
- Control of the correction process is performed visually on the pressure gauge.
Some manufacturers, for convenience, put the regulating valve for changing the nominal value on the surface of the device body.
The considered receiver valve can be classified by quite a large number of features, but the main feature is the constructional features of the mechanism. There are the following designs:
- Straight type.
- Ball type.
- Flanged type.
- Installed by soldering technology.
- Made for flaring.
Classification is performed by the type of material used in the manufacture. Most often the valve is made of metal with high corrosion resistance, but there are other versions.
The locking element is also characterized by different design features. The following versions are distinguished according to this feature:
Rather popular are ball-type versions. This is due to their practicality and high reliability in use.
In addition, on sale there are versions in which the control of the locking element is represented by an electromagnetic element, rather than a spring. They are more accurate in operation, but cost much more.
Device and diagram of pressure switch for compressor
All compressor pressure switches are divided into two types:
- Turning off the compressor motor when the air pressure in the network exceeds the allowable limits (such designs are called normally open);
- Switching on the compressor motor at a decrease in pressure in the network below the allowable limits (such designs are called normally closed).
Actuating element of the pressure switch for the compressor are springs, the compression force of which is changed by a special screw. In the factory settings, the spring compression force is usually set to a pneumatic pressure of 4 to 6 atm, which is reported in the user manual. Since the stiffness and flexibility of the spring elements depends on the ambient air temperature, all industrial pressostat designs are designed for stable operation over a temperature range of.5 to 80ºC.
The design of the pressure switch includes two obligatory subassemblies. a relief valve and a mechanical switch. The pressure relief valve is connected to the air supply line between the air receiver and the compressor. It controls the operation of the electric motor. If the compressor driver is turned off, the unloading valve on the air reservoir vents excess compressed air (up to 2 atm) to the atmosphere thus relieving the moving parts of the compressor from excessive forces that they will have to develop when the compressor is restarted. This prevents a critical motor overload in terms of the permissible torque. When the unloaded motor is started, the valve is locked and does not create unnecessary load on the drive.
A mechanical switch performs a stand-by function, preventing accidental start of the motor. By pressing a button the drive is switched on and the compressor operates automatically. If the button is disabled, the compressor motor will not start even if the pressure in the pneumatic pressure system is lower than required.
In order to increase operational safety, industrial designs of compressor pressure switches are also equipped with a safety valve. It is useful, for example, in case of a sudden stop of the engine, piston breakage or other abnormal situation.
Optionally a thermal relay can also be mounted in the pressostat box, which monitors the current in the primary circuit. If for any reason this parameter increases, a thermal relay switches the motor off to prevent overheating and subsequent breakdown of the windings.