SQ/SQE aizsardzības funkcijas: Aizsardzība pret darbību bez šķidruma
Grundfos SQ/SQE protection features: Dry-running protection
Learn about the built-in dry-running protection of the SQ/SQE and the many benefits it brings to both the installer and the homeowner.
The Grundfos SQ/SQE submersible pump range comes equipped with three unique protection features.
In this video, we’ll focus on Dry-Running Protection.To illustrate the feature, we’ll compare the SQ/SQE pumps with a conventional 4” submersible pump.
But first let’s have a closer look at why dry-running occurs.
The static water level around a well will rise and fall, depending on how much it rains and how much water is being pumped in the area.When you turn on a pump in a well it draws the water towards the pump inlet, creating a cone shaped drawdown zone.If the static water level is too low or if the pump capacity exceeds the maximum well yield, the drawdown will bring the water level in the well below the inlet of the pump. This means that that pump will run without water.
A conventional 4” pump has no way of detecting such a dry-run situation. It will simply keep running, only without the vital flow of water to cool the motor and lubricate the pump bearings. The result is critical wear of the bearings and an imminent risk of overheating.
If the motor has built-in thermal protection, it will shut down once a certain motor temperature is detected. But once the motor cools down, it will automatically restart and repeat the damaging dry-running pattern.Even short-term dry-running will result in reduced pump performance and loss of lifetime. If it goes on for an extended period of time, the pump may break down completely due to component wear.
For regular 4” pumps, protection against dry-run requires extra equipment.
With the SQ/SQE range, it’s a built-in feature.
Let’s see how it works.
If the water level in the well drops below the inlet, the motor power consumption will drop drastically – there’s no water to transport.
This change in operation is detected immediately by the built-in frequency converter, which stops the motor before any damage is done.
After 5 minutes, the pump will automatically resume operation, but if the water hasn’t returned yet, the pump will cease operation after only five seconds.
This pattern will repeat itself until the water has risen above the inlet level.
Pump lifetime and performance remains the same after these very brief instances of dry-running.
When the water level rises above the inlet, the pump will restart and run unaffected.
The benefits of dry-run protection for the SQ/SQE pumps are quite obvious.
The installer will avoid costly, time-consuming service calls due to pumps being damaged by long periods of dry-running.
The homeowner will have access to water, whenever it’s available in the well, with a pump that’ll protect itself and run reliably for years.