Final answer:
Single-phase motors are typically in the 1/6 - 3/4 hp range, but can be found in a variety of sizes. High efficiency is vital for effective energy use and saving operating costs, with larger motors often reaching higher efficiencies.
Step-by-step explanation:
In general, single-phase motors are often found in lower power ranges, typically 1/6 - 3/4 hp. However, single-phase motors are available in a broader range of sizes, though for applications requiring more power, such as those exceeding 3/4 hp, you would likely look toward three-phase motors or specialized single-phase designs. Electric motors operate with high efficiency; for instance, a motor rated at 100 hp can achieve efficiencies around 90%, while smaller motors like a 1 hp motor can achieve efficiencies around 80%. It's crucial to use high-performance motors to ensure energy is being used as effectively as possible, minimizing waste and operating costs. Efficiency is especially important in higher horsepower motors, but even in lower power ranges, selecting a high-efficiency motor can result in substantial energy savings over time.