Can a 2HP DC Motor 12V Drive a 20kVA Flywheel Generator?

To determine if a 2HP DC motor running at 12V has the power to drive a 20kVA flywheel generator, we need to consider several key factors.

Power Output of the DC Motor

First, let's calculate the power output of the 2HP DC motor.

Since 1 HP is approximately 746 watts, a 2 HP motor would have a power output of: 2 HP times; 746 W/HP 1492 watts Now, we can calculate the current required at 12V using the formula P V times; I: I P / V 1492 watts / 12V 124.33 amperes

This shows that a 2HP DC motor operating at 12V provides a maximum output of around 1492 watts or 1.49 kW.

Power Requirement of the Flywheel Generator

A 20kVA generator has a real power output of 20000 watts, assuming a power factor of 1, which is often the case for generators.

This means that to run the generator, it would require significantly more power than what the 2HP motor can provide.

Conclusion

The 2HP DC motor, with a maximum output of around 1492 watts or 1.49 kW, is far below the requirement to operate a 20kVA generator, which needs around 20000 watts or 20 kW.

Therefore, a 2HP DC motor at 12V cannot drive a 20kVA flywheel generator.

Additional Considerations

Efficiency

The efficiency of both the motor and the generator can affect performance. If either device has low efficiency, the actual usable power will be even less.

Starting Current

Motors typically require a higher current to start than they do to run, which could further complicate the situation.

Mechanical and Electrical Compatibility

Ensure that the motor is mechanically compatible with the generator, including considerations for torque and speed.

In summary, you would need a significantly more powerful motor to drive a 20kVA generator.

It might be possible to use the 2HP motor to spin up the flywheel for several hours and then draw energy from the generator for a few minutes. However, a variable speed arrangement would be necessary to both start the flywheel and reach the working speed. This scenario is not practical and would be very inefficient.

Bob Ripley explains that you have 1492W available. To get 5 minutes of power out of the flywheel at 20000 watts, it would take 1492/20000 13.4 times as long to spin up the flywheel. Assuming 33% efficiency end-to-end in various conversions, that would be 402 minutes of driving for 5 minutes of generation.

If that sounds silly, it is because it is. It is not possible to take more energy out than you put in, even using a flywheel as an integrator.