Can a 3.5 kVA Single-Phase Generator Run a 2 HP Submersible Pump?

When considering whether a 3.5 kVA single-phase generator is capable of running a 2 HP submersible pump, it's important to understand the power requirements of the pump during both start-up and operation.

Convert Horsepower to Kilowatts

To begin with, let's convert the horsepower (HP) of the submersible pump to kilowatts (kW). This conversion is crucial as it helps in determining the generator's capacity requirements.

Conversion Factors

1 HP 0.7457 kW

2 HP 2 × 0.7457 kW 1.4914 kW

Calculate the Total Power Requirement

Submersible pumps typically have a higher starting power requirement compared to their running power. Generally, starting power is 2 to 3 times the running power.

Assumptions and Calculations

Assuming a starting power of 2.5 times the running power for a submersible pump, the starting power can be calculated as follows:

Starting power 1.4914 kW × 2.5 3.7285 kW

Generator Capacity

A 3.5 kVA generator can provide a maximum of 3.5 kW, assuming a power factor (PF) of 1.

Conclusion

Given that the starting power requirement is approximately 3.73 kW, and the generator capacity is 3.5 kW, it is clear that the starting power exceeds the generator's capacity. Therefore, a 3.5 kVA generator might not be able to reliably run a 2 HP submersible pump, especially during start-up.

A generator with a higher capacity, such as at least 5 kVA, is typically recommended to ensure proper operation and to accommodate the starting surges.

Alternative Considerations

The generator's voltage must also match the pump's voltage requirements. Assuming the generator can supply the correct voltage, it may seem feasible to run the pump as follows:

Reevaluation of Power Requirements

1 HP 752 1.5 kW

With a power factor (PF) of 0.8, the power consumed is:

1.5 kW × 0.8 PF 1.2 kW (running power)

Starting power (2.5 times running power) 1.5 kW × 2.5 3.75 kW

Considering a 3.5 kVA generator, there is a margin of 100% for high current during start-up. However, several factors can impact the feasibility of running the pump:

Key Points to Consider

The generator is engine-driven, which may not have a quick response to sudden power demands.

The submersible pump may require full power from the generator upon start-up, which could cause a dip in voltage if the generator is running at idle.

A generator should be accelerated just before turning on the pump to avoid voltage drops.

A generator with a rating 3 times the motor's rating or a motor that starts at no load is recommended.

In conclusion, while a 3.5 kVA generator may seem to have a margin, practical considerations such as the generator's response time and the sudden power requirement of the pump make it impractical for a reliable start-up. A higher-capacity generator is advisable for this application.