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 the circuit. At the top of the device is a screw for adjustment. 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. At the bottom of the modifications, nozzles of different diameters are installed.
The principle of operation of the modification
How does a dry run relay for a pump work? When the pressure inside the system decreases, a contactor is activated. Through the contacts, the voltage passes to the winding. The screw acts as a retainer. The spring is compressed by a pin. When the pressure drops, the contacts open. To turn off the voltage, a contactor is used.
Dry running relay for pump: wiring diagram
Connect the device through an adapter. In this case, the outlet pipe is connected to the tube. The cable closes at the terminal. The cap is fixed directly to 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 bushing 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 housing. To configure the model, readings from the sensor are taken. To raise the permissible pressure level, the screw rotates clockwise. Under reduced voltage, the contact closure speed slows down. Also, the problem may be in the contactor with the start system. To lower the pressure, the screw rotates counterclockwise. Much in this case depends on the parameters of the relay and the maximum power of the pumps.
Device types
There are streaming and float devices. Models can be made with one or more cameras. Low pressure modifications are suitable for low power pumps. Streaming devices are available in different sizes. For powerful pumps there is a high pressure switch.
Streaming devices
At hydroelectric stations, flow dry-running relays for the pump are often found. The principle of operation of modifications is based on a change in ultimate pressure. This process occurs due to a change in 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 wire contactors. In total there is one start button. Many models use power contacts. The circuit is closed by clamping the plates. The dry running relay for the pump is connected via an adapter.
Float models
Dry float relays for a pump are considered to be the most dimensional ones. The device is adjusted by tightening the screw. The principle of operation of the modifications is based on a change in pressure. All models have one pin in the housing. In this case, the pipe is located with a ring in the lower part of the structure. Most relays use a manual tuning system. Devices of this type work from a 220 V network . The frame, as a rule, is made of plastic. Contact plates can be in vertical position. Most relays operate at low frequency. Models are suitable for pumps with power from 4 kW. The operating frequency averages 55 Hz. At the top of the modification is a nut. The clamping screw is located on the pin.
Devices with level sensor
The 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. In this way, crashes often occur. It is also important to note that the models are not able to work 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 made with only one chamber. Contactors for versions may vary in design. Most devices operate on 220 V networks. At the same time, their operating frequency is at least 45 Hz. It is immediately worth noting that the models are suitable for pumps with a capacity of not more than 3 kW. The contacts on the plate are horizontal. The pins are mounted next to the plate. In total, the modifications have two nuts. A clamping screw is used to adjust the pressure. The pins are often used with a small diameter. Models of this type are well suited for working with submersible pumps. Frames in devices are used with varying degrees of security, and in this case a lot depends on the manufacturer.
High pressure devices
Dry run relays for high pressure pumps are very popular. First of all, models are used at hydroelectric stations. They are well suited for pumps that are used in the plumbing system. Contactors are used on two outputs. The working nuts are located in the upper part of the housing. It should also be noted that there are modifications to two cameras. The outlet pipe is located in the center of the base. Most models are based on a dipole contactor. Modifications use several pins. Devices are well suited for submersible pumps. Branch pipes are available with a diameter of 2.3 cm. The 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 rotates clockwise. Sensors are very rare in versions of this type. The start buttons are located directly on the contactors. The service models are very simple.
Single chamber models
Single chamber dry running relays for the pump are made 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 the level of 45 Hz. The first nut is located on the pin. To increase the pressure in the system, the screw rotates clockwise. If we consider the dry-running relay for the Grundfos pump (with a double contactor), then it uses two cable outlets. The minimum frequency for the modification of this type is 55 Hz.
Two-chamber devices
Two-chamber devices are manufactured with low conductivity contactors. Most models are equipped with several pins. Nuts are usually located in the upper part 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 from the 220 V network work. If we consider models with drive contacts, then they use the start 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 relay base has a gasket. Most devices are equipped with a pin grease cap.
Three Camera Models
Three-chamber devices allow for very precise control of 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 with power from 4 kW. Their operating frequency is at least 4 Hz. Some relays are made on drives. Covers are usually mounted above the pin. Some devices are manufactured with two clamping plates. The output cable moves away from the contactor. This type of relay operates standardly from a 220 V network.
Devices for 2 kW pumps
Relays for pumps are made, as a rule, with one pin. Most modifications are equipped with overlays. If we consider devices with wire contactors, then they have two outputs. It is also worth noting that there are models with support stands. Cases are most often made of stainless steel. The cable at the relay moves away from the contactor. Devices from a 220 V network work. Connection to pumps occurs through a branch pipe.