Volt-ampere and the watt is the units of measure characterizing the electric power of current. The volt-ampere is applied to measurement of full capacity of alternating current, in watts its active power is specified. Let's consider how to transfer volt-amperes to watts, on the example of a technical characteristic of the uninterruptible power supply unit.
It is required to you
- Operation manual on the uninterruptible power supply unit (UPSU).
Instruction
1. Find the technical characteristic of its power consumption specified by manufacturer in volt-amperes in the operation manual on the chosen uninterruptible power supply unit. This figure shows the maximum quantity of the electric power consumed by the device from the power supply network (that is, its full capacity). Let the full capacity of the uninterruptible power supply unit will be equal in this example 1500 volts-amperes.
2. Determine the efficiency of the uninterruptible power supply unit (power factor). It depends on quality of the device and the number of electrical equipment connected to it. The coefficient can make from 60 to 90%. For example, the system unit, the monitor, the laser printer, the cash register will be connected to the chosen uninterruptible power supply unit. Efficiency will be equal to 65% (0.65). The value of this coefficient for personal computers and office equipment in 0.6-0.7 is normal.
3. Transfer volt-amperes to watts, having calculated the power of the uninterruptible power supply unit by a formula: In = VA*KPD, where: In - the counted active power of the device in watts; VA - the power consumption of the device in volt-amperes specified by the manufacturer in a technical characteristic; Efficiency - device efficiency (power factor). Active power of the device in watts is equal in the reviewed example: 1500 (volts-amperes) of *0.65=975 (watts). This figure characterizes the power which is given by the uninterruptible power supply unit (active power consumption). Other 35% are losses of the electric power during the operation of the power supply.