Question 1

What are the common power units?

Accepted Answer

Watts (W), kilowatts (kW), megawatts (MW). Horsepower (mechanical, metric). BTU/hr for HVAC. Foot-pounds/second for mechanical work. All measure rate of energy transfer.

Question 2

How does power relate to energy?

Accepted Answer

Power = Energy ÷ Time. Energy = Power × Time. 1 watt for 1 hour = 1 watt-hour. 1000 watts for 1 hour = 1 kilowatt-hour (kWh), the standard billing unit.

Question 3

What's the difference between mechanical and electrical horsepower?

Accepted Answer

Mechanical HP (550 ft·lb/s) = 745.7W. Electrical HP = 746W. Metric HP (PS) = 735.5W. Boiler HP = 9810W. Different industries defined their own standards.

Question 4

How do I size a motor or generator?

Accepted Answer

Calculate peak power needs, add 20-25% safety margin. Consider duty cycle - continuous vs intermittent use affects sizing differently.

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