When 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. At the bottom of the modifications, nozzles of different diameters are installed.
How the modification works
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
You must connect the device through 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. Totighten 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 at the top 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 modifications are suitable for low power pumps. Streaming devices come in a variety of sizes. For powerful pumps there is a high pressure switch.
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. This process occurs 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 wiredcontactors. 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 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. 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 relay chamber is made with a solid base.
Low pressure models
Dry running relays for low pressure pump 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 switches for high pressure pumps are very much in demand. 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 toterminal 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 pump switches 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 made 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 trigger mechanism from the module. The minimum operating frequency is 30Hz. 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 greasing the pin.
Three camera models
Device with three chambers allows 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. The connection to the pumps is through a branch pipe.
