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What's volt-amps(VA) stands for? Is it equal to Watts?

What is VA stands for?

VA is an abbreviation of the electrical term volt-amps and indicates a capacity of power.

Difference between VA and Watts

Both watts (W) and volt-amperes (VA) are units of measurement for electrical power. Watts refer to “real power,” while volt-amperes refer to “apparent power.”

Power in watts(real power) is the rate at which energy is consumed (or generated). One watt is one joule (energy) per second (1 W = 1 J/s). For example, a 100-W light bulb left on for 10 hours consumes 1 kW-hour of energy (100 W x 10 hours = 1000 W-hours = 1 kW-hour).

Power in VA (apparent power) equals the product of a volt and an ampere that for direct current constitutes a measure of power equivalent to a watt. Where a reactive (capacitive or inductive) component is present in the load, the apparent power is greater than the real power as voltage and current are no longer in phase. In this situation, VA (apparent power) does not indicate the real power consumed by electrical appliances,  it shows an exchange relationship between energy, and it is also one of the indicators to measure the maximum load and endurance of electrical appliances.

Difference between VA and WATTS

imagine UPS power capacity as the amount of soda in a glass. The top of the glass represents the limit of apparent power the UPS will accept, or the VA. The actual liquid in the glass represents the real power of the UPS, or the Watts. Unless you desire a frothy glass of foam, you’ll want to maximize the actual amount of liquid in the glass. This—the Watts rating—is what you’re actually paying for.

When you’re buying a UPS and sizing your equipment, pay attention to both the VA and Wattage ratings. This ensures you will get the maximum amount of power for your investment.

How to convert VA To Watts

Here is the formula:

Watts(瓦特值)=VA*Power Factor(PF)=Volts*Amps*Power Factor

What is the real power in watts when the apparent power is 3000 VA and the power factor is 0.9?


P = 3000VA × 0.9 = 2700W