Grundfos SQ/SQE Protection features: Voltage Protection

Discover how an SQ/SQE adjusts its operation according to the actual supply voltage, providing the installer with fewer service visits and the homeowner with a long-lasting pump.

The Grundfos SQ/SQE submersible pump range comes equipped with three unique protection features.

In this video, we’ll focus on voltage protection. Before we turn to the SQ/SQE, let’s have a look at how a conventional 4” submersible pump reacts to voltage variations in a scenario in which 230 V is the standard.

In many parts of the world, the supply voltage varies quite a bit. This will have a negative effect on electrical equipment with a narrow range for supply voltage. Take a conventional 4” submersible pump, for instance. If the supply voltage drops, the motor current will increase and this will cause the temperature of the motor to rise.

Should the supply voltage decrease by more than 10% - to below 207 V – the motor contactor will simply stop the pump due to the high level of current. Once the voltage increases and re-enters the accepted voltage range, the pump may not be able to resume operation automatically if the motor contactor has a manual reset. If the supply voltage increases to a level above the nominal value, the motor speed and, as a result, the load will increase, as well. This will cause both motor current and motor temperature to go up. If the supply voltage exceeds 252 V, the motor contactor will stop the pump.

The SQ/SQE range is better suited to handle such variations. First of all, the pumps are able to operate within a very wide supply voltage range. It’s also able to automatically adjust its operation according to the actual supply voltage – keeping the motor current and temperature below the upper limits. An SQ/SQE pump for 230 V nominal voltage will deliver a flow of water as long as the supply voltage remains between 150 V and 315 V.

In fact, it will provide maximum performance with as little as 198 V. Should the supply voltage drop below 198 V, the pump will reduce the motor speed to keep the motor current below the upper limit and avoid overheating, but it will continue to deliver water to the house.Not until the supply voltage drops below 150 V will the SQ/SQE pumps cease to operate.

The same goes if the supply voltage increases. From 230 V up until 262 V the performance remains unaffected. From 262 V to 315 V, the pump will reduce the motor speed to avoid overheating.If the supply voltage exceeds 315 V, the pumps will stop. Once the supply voltage re-enters the accepted voltage range, the SQ/SQE pumps will automatically start. If the supply voltage is within 14% of the nominal value, the performance will be unaffected.

The benefits are quite clear. For the installer, the voltage protection of the SQ means less service visits. The pump is simply better equipped to handle variations in the supply voltage – even variations big enough to bring a conventional pump to a complete halt. For the homeowner, the voltage protection means a steady supply of water within a wide voltage range. Not to mention, a pump that will last for a long time as overheating is kept to an absolute minimum.

Course overview

Modules: 7
Completion time
Completion time: 40 minutes
Difficulty level
Difficulty level: Intermediate