Q: Step 1: Convert Horsepower to base Watts.

We know the formula is $W = HP \times 745.69987$. $W = 150 \times 745.69987$ $W = 111,854.98$ Watts.

Question 1

Step 1: Convert Horsepower to base Watts.

Accepted Answer

We know the formula is $W = HP 	imes 745.69987$.
$W = 150 	imes 745.69987$
$W = 111,854.98$ Watts.

Question 2

Step 2: Convert base Watts to Kilowatts.

Accepted Answer

We know the formula is $kW = \frac{W}{1000}$.
$kW = \frac{111,854.98}{1000}$
$kW = 111.85$ kW.
Result: You must order an electric motor rated for at least 111.85 kW.

Question 3

Step 3: Convert base Watts to BTU/hr.

Accepted Answer

We know the formula is $BTU/hr = \frac{W}{0.293071}$.
$BTU/hr = \frac{111,854.98}{0.293071}$
$BTU/hr = 381,665.12$ BTU/hr.
Result: The mechanical room's cooling system must be able to offset a maximum theoretical heat load of 381,665 BTU/hr if the pump operates at absolute maximum capacity continuously.

Question 4

What is the difference between Mechanical Horsepower and Metric Horsepower?

Accepted Answer

Mechanical horsepower (imperial) is defined as 550 foot-pounds per second, which equals exactly 745.69987 Watts. Metric horsepower (PS or cv) was created to adapt the concept to the metric system, defined as lifting a 75-kilogram mass one meter in one second, which equals exactly 735.49875 Watts. Mechanical horsepower is roughly 1.4% larger than metric horsepower. You must know the origin of the machinery (US/UK vs. Europe/Asia) to know which factor to apply.

Question 5

Why do air conditioners use "Tons" to measure power?

Accepted Answer

The term "Ton" is a historical artifact from the 19th century before mechanical refrigeration existed, when buildings were cooled by massive blocks of ice harvested from frozen lakes. Engineers needed a way to explain the cooling capacity of new mechanical air conditioners, so they equated the machine's cooling power to the amount of heat required to melt one short ton (2,000 lbs) of ice over a 24-hour period. Today, this is mathematically standardized to exactly 12,000 BTU/hr.

Question 6

Can I convert Volts or Amps directly into Horsepower?

Accepted Answer

No, you cannot convert Volts or Amps directly into Horsepower because Volts (electrical pressure) and Amps (electrical flow) are not units of power on their own. However, if you multiply Volts by Amps, you get Watts (in a standard DC circuit). Once you have calculated the Watts ($Power = Volts 	imes Amps$), you can easily convert that resulting Wattage into Horsepower by dividing by 745.7.

Question 7

Is a BTU the same as a BTU/hr?

Accepted Answer

Absolutely not. This is a critical distinction. A BTU (British Thermal Unit) is a measurement of a finite volume of heat energy, similar to a Joule or a Calorie. BTU/hr (BTUs per hour) is a measurement of power, indicating how fast that heat energy is being moved, generated, or removed. A power unit converter only deals with BTU/hr, as power is fundamentally a rate over time.

Question 8

Why is my 5 HP air compressor pulling more than 3,728 Watts of electricity?

Accepted Answer

If 1 HP equals roughly 745.7 Watts, a 5 HP motor should theoretically consume 3,728 Watts. However, the 5 HP rating refers to the mechanical output of the motor's shaft, not the electrical input required to run it. No machine is 100% efficient; some energy is always lost to heat, friction, and electromagnetic inefficiencies. An electric motor might only be 80% efficient, meaning it must pull significantly more electrical power from the wall (input) to generate that 5 HP of mechanical turning force (output).

Question 9

What does it mean when a power supply is rated in VA instead of Watts?

Accepted Answer

VA stands for Volt-Amperes, which measures "Apparent Power" in Alternating Current (AC) electrical systems, whereas Watts measure "Real Power." In simple resistive devices like toasters, VA and Watts are identical. But in devices with electronic power supplies or motors (like computers or refrigerators), the alternating current waves of voltage and current can become misaligned (phase shift). VA represents the total electrical load the wiring must handle, which is usually higher than the actual working Watts.

Question 10

How do I convert Kilowatt-hours (kWh) to Kilowatts (kW)?

Accepted Answer

You cannot directly convert kWh to kW using a standard conversion multiplier because they measure two fundamentally different things. Kilowatt-hours measure total energy volume, while Kilowatts measure the instantaneous rate of power. To find the average power (kW), you must divide the total energy (kWh) by the exact amount of time (in hours) it took to consume that energy. For example, if a machine uses 100 kWh over 5 hours, its average power draw was 20 kW.

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