The SQ/SQE pumps are the most compact units among Grundfos submersible pumps. These 3-inch, multistage centrifugal pumps can be installed in boreholes with a diameter of 76 mm or smaller. They are ideal for supplying water to single- and multi-family houses and small farms, as well as for irrigation systems in gardens, greenhouses and orchards. The design of the SQ/SQE pumps and a number of unique functions and safety features guarantee a long period of reliable operation.
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SQ/SQE – construction and assembly
The Grundfos submersible pump bodies are made of stainless steel, and the floating impellers and bearings are made of composite materials, tungsten carbide and ceramics. This design guarantees high resistance to corrosion and abrasion by sand and allows for the extension of the pump's service life, reducing the need for service work. Another advantage of Grundfos SQ /SQE pumps is their low weight, about 40% less than conventional pumps (the largest pump weighs only 6.7 kg). This allows the pump to be installed without the use of a crane, which significantly reduces costs.
SQ/SQE pumps are available in five sizes: SQ 1, SQ 2, SQ 3, SQ 5 and SQ 7, and the numbers in the type designation indicate the optimum capacity of the pump in m3/h. SQ pumps operate at a constant speed, while SQE pumps are equipped with a variable speed drive, which allows the speed to be adjusted according to demand. This ensures a constant water pressure, regardless of the number of open taps.
A unique feature of SQ/SQE pumps and one of their greatest advantages is a high-efficiency permanent magnet motor controlled by a built-in converter that changes the supply voltage from single-phase to three-phase, which then powers the pump motor. Thanks to this, SQ/SQE pumps can be powered from a single-phase network, and the user benefits from such advantages of a three-phase motor as, for example, increased efficiency in a wide range of motor operation or increased starting torque compared to single-phase motors.
SQ/SQE pumps are single-phase powered, but do not require a starter or other safety devices - all safety devices are built into the pump as standard. SQ/SQE also require a smaller external diaphragm tank than for other pumps. These are other factors that allow for lower pump installation costs.
SQ/SQE – Features and Security
Grundfos SQE submersible pumps are equipped with a number of innovative solutions that ensure reliable operation and contribute to extended service life.
The first one is the soft start function, which significantly reduces the starting current, protecting the installation from water hammers and consequently allows to reduce the wear of the pump and installation elements. The function ensures reliable start-up without turbulence. Low starting current reduces the electrical load - its nominal value, as well as the nominal value of the pump speed, are reached after 2-3 seconds from start-up. Soft start SQ does not cause loss of starting torque, which is greater than in the case of conventional, 3-phase motors supplied directly from the network (DOL, direct on-line).
A significant advantage of the SQ/SQE pumps, particularly important wherever the mains voltage may fluctuate, is protection against voltage surges and undervoltages. SQ/SQE pump motors operate within a supply voltage range of 150 V to 280 V with very little effect on pump performance. In comparison, a conventional 4" pump motor with a nominal supply voltage of 230 V can usually only operate within the range of 207-244 V. When the supply voltage drops below 180 V, the SQ/SQE pumps continue to operate at a slightly reduced speed to protect the motor from increased current. If the voltage drops below 150 V or rises above 280 V, the pump motor switches off completely. The pumps automatically restart when an acceptable voltage level is restored. They can also withstand short-term overvoltages of up to 6000 V.
The rotor of the SQ/SQE pump motor, a rotor with permanent magnets, releases very little heat into the environment. In combination with an efficient internal heat dissipation system from the rotor, stator and bearings, this ensures optimum operating conditions for the motor. The SQ/SQE pump motors are also equipped with an additional thermal protection that switches off the motor when the temperature exceeds a critical limit. After cooling, the pump will start automatically, so there is no need to manually reset the external thermal protection, as in traditional pumps.
SQ/SQW pumps are also equipped with a dry-running protection function. The integrated protection automatically switches the pump off when it detects a water shortage. The motor will then attempt to restart every 5 minutes until water returns to the pump. This solution prevents excessive heating and, consequently, even damage to the pump motor.
SQ/SQE pumps have been a popular choice for years by well contractors and homeowners alike, who value their reliability, long life, and ease of use, as well as ease of installation. If you want to learn more about all the benefits, features, and applications of these pumps, watch the Ecademy training video series.
Check out Grundfos submersible pumps at the Onninen wholesaler