UPS power supply capacity selection principle - Database & Sql Blog Articles

MOS power IC full range

Passive 3225G 8MHZ 10MHZ

The rated capacity of the UPS is the maximum output power of the UPS (the product of voltage V and current A).

Usually the ups power supply sold on the market, the smaller capacity is marked in units of "W" (watt); over 1 kWh, marked with "VA" (volt-amperes), the values ​​of "W" and "VA" are difference. This requires us to distinguish the specific situation to choose UPS. In general, small-capacity UPSs within 1 kW generally use "W" for capacity, and UPSs with capacities between 1KVA and 500KVA use VA instead of W to indicate capacity.

In fact, "W" is always less than or equal to "VA". The conversion relationship between them can be calculated by the following formula: W = VA × power factor. The power factor is between 0 and 1, which represents the percentage of useful work (W) made by the load current. Only the electric power factor of the electric heater or the electric bulb is 1. For other devices, some of the load is not working. This part of the current is harmonic or reactance current, which is caused by the load characteristics. Because of this part of the current, the "VA" value is larger than the "W" value, and when the power factor is 1, the "W" and "VA" values ​​are the same.

So when we choose UPS power for computers and other equipment, how to choose the right UPS capacity? If you choose improperly, there are usually two situations. One is that the capacity is too small, that is, the so-called small horse-drawn cart, which may cause damage to the equipment; the other is that the capacity is too large, resulting in waste of funds. Therefore, the correct choice of UPS capacity is an important thing for network managers.
In general, UPS should consider the following factors in capacity selection:
1, the actual load situation: P = ∑ Pi / f
That is, the actual total load capacity P can be obtained by dividing the sum of all the actual loads ∑Pi and dividing by the power factor f, f=0.6~0.8.

2. Reserved expansion:
Considering the possibility of business development, increasing the UPS output capacity without a large amount of additional investment can be achieved in two ways:
A: Select UPS products that can realize on-site expansion, such as modular UPS products currently on the market.
B: Buy a large-capacity UPS in advance, but you need to invest a lot of money in advance.

The output voltage

The UPS output voltage refers to the voltage that the mains output is used for load devices such as computers after a series of measures such as UPS shaping, filtering, and voltage regulation. This voltage is generally cleaner than the mains voltage and there are no impurity signals. Usually the output AC voltage of the UPS should be stable at 220V, and there should be no excessive deviation.

Output voltage frequency

The standard frequency of the general grid is 50Hz (Hz) or 60Hz (Hz). The UPS allows the mains frequency to have a certain range of variation. Within this range, the UPS tracks the mains frequency synchronously, and if it exceeds, it outputs at the local frequency. The frequency of this actual output is the output voltage frequency.